Journal

Vol.38/No.4 (150) (2023)

作者:

Vol.38/No.4 (150) (2023)

TitleStudy on analysis of a reinforced concrete portal frame retrofitted with an elliptically hollow steel frame infilled with rubber cylinders
AuthorChia-Chuan Hsu,Chia-Wei Hsu,Hsiao-Hui Hung, Kuang-Wu Chou,Chin-Kuo Su,Yu-Chi Sung
Keywordsnear-fault ground motion, seismic retrofit, RC frame, steel oval
hollow section, rubber, equivalent brace
AbstractThis study proposes an analysis procedure for engineers to apply a new method of retrofitting a reinforced concrete frame. This retrofitting method uses an elliptically hollow member, which is created with a steel frame infilled with rubber cylinders. This method enables rapid retrofitting construction and could help the retrofitted structure bear more loadings, resist strong earthquakes, and recenter, without sacrificing too much space for usage. Moreover, applying this method could effectively reduce structural damage caused by near-fault earthquakes. The proposed analysis procedure separates the three-dimensional finite element modeling of such a complex retrofitting member from the frame analysis that engineers need to perform for design. A retrofitting member alone gets detailed finite element modeling and pushover analysis to create a brace that can equivalently represent the retrofitting member in the frame analysis of the retrofitted RC frame. The comparison of the structural analysis result and the experiment result shows the proposed analysis procedure can prudently predict the behavior of a retrofitted RC frame with acceptable bias.
TitleFlexural Behavior of Steel Beam-to-Column Connections with Concrete as Fire Protection Material
AuthorCheng-Cheng Chen, Pin-Da Wu and Chen-Wei Fan
Keywordssteel structure, steel girder, beam-to-column connection, steel
reinforced concrete structure, fire protection layer
AbstractThe mechanical properties of steel are greatly affected by high temperature; thus, steel structure buildings need to have appropriate fire protection measures to prevent premature collapse of buildings in the event of fire. In some cases, steel structure buildings use concrete as fireproofing material. Although longitudinal and transverse steel bars are also provided as auxiliary reinforcements, but the strength that can be contributed by these steel bars is not considered in the strength calculation during design process. In engineering practice, this kind of structure is known as SC structure. In this study, five beamcolumn sub-assemblage was tested under cyclic loading to investigate the influence of SC beam structural details on beam strength, ductility, and crack development. The test results show that the use of reduced beam section beamtocolumn connection detailing is necessary since it can significantly increase the flexural ductility of the SC beams. The SC beams can develop the full composite action even though without using any shear stud. The use of isolation layer between beam flange and concrete in plastic hinge region is not necessary since it only slightly increase the plastic rotation capacity of the SC beams but causes larger crack in the concrete at the beam-to-column interface. The auxiliary longitudinal rebar is provided up to the face of box column and the use of 90° hooks are not recommended since it will cause additional cracks. The local buckling of the auxiliary longitudinal rebar can be effectively avoided when the distance between the rebar is less than ten times of its diameter.
TitleStudy on New Retrofit Methods for an Reinforced Concrete Beam with the Opening
AuthorChien-Kuo Chiu ,Min-Yuan Cheng, Yu-Chen Ou, Sheng-Huei Wang, Jie-Cih Jhou, Yin-Yi He
KeywordsReinforced concrete beam, plastic hinge, opening, retrofitting method, one-piece double-square hoop, inclined U-shape stirrup, strength, deformation capacity
AbstractTo prevent a reinforced concrete (RC) beam member from undergoing shear failure instead of flexural failure or flexure-shear failure under earthquakes, it is generally not recommended to make the opening within a region extending twice the beam depth from the face of the support column toward the central position of the span of the beam. However, in recent years, for actual requirements of the pipeline configuration, the problems of arranging the openings in the plastic hinge zone of an RC beam member have been already faced in the design and construction. Therefore, it is necessary to establish a set of design guidelines for the retrofit of the openings in the plastic hinge zone of an RC beam member. A total of nine specimens are tested in this study. The main test variables include: (1) opening location, (2) retrofitting methods of the openings. All specimens are subjected to cyclic lateral load. This work investigates the crack development and mechanical behavior of reinforced concrete beams with the circular openings, and provide the novel retrofitting methods with one-piece double-square hoops and inclined U-shape stirrups for the beams with circular openings. The experimental results are used to to verify the effectiveness of the proposed retrofitting methods. Additionally, based on the experimental results, this work also investigates the application of the design formulas that are recommended from AIJ-1999 and AIJ-2010 for an RC beam with the opening.
TitleShear Strength Design for Reinforced Concrete Shear Walls of Dual System
AuthorShyh-Jiann Hwang, Shao-Kai Huang, Pu-Wen Weng, Yu-Chen Ou, Ming-Huoy Huang
KeywordsDual system, Reinforced concrete, Shear strength design, Shear wall, Softened strut-and-tie model.
Abstract

Past earthquake reconnaissance already demonstrated that the reinforced concrete dual system, which consists of ductile moment resisting frames and shear walls, is one of the most effective earthquake resisting systems. A dual system can provide the 2nd line of defense when shear walls are coupled with frames. In seismic design, the 2nd line of defense is a secure protection against impulsive earthquakes. The shear walls of the dual system provide a continuity over height, which effectively prevent the story sway mechanism and provide uniform and reduced lateral drift resulting in a better damage control. The new building design code of Civil 401-110 requires the shear capacity design of the special shear wall. After the inclusion of the over-strength effect and the dynamic amplification factor, the shear strength demand can be doubled or even tripled, which leads to the shear walls with highly improbable thickness. This strict demand will hamper the application of the dual system in seismic design. This problem should be resolved.

A feasible solution to overcome this difficulty is to adopt the dual system with the shear walls designed by the strut-and-tie method. The structural walls of the dual system are equipped with substantial boundary members appearing as both beams and columns, which create a special shear force transferring mechanism within the framed squat walls. The framed squat walls possess very high shear resisting capacities, which can effectively reduce the thickness of shear walls, if well designed by the strut-and-tie method. The objective of this paper is to demonstrate the merits of the dual system and to promote its application in seismic design. The content of this paper includes the requirements of the new building design code, the softened strut-and-tie model, the shear strength design of framed squat walls of the dual system, design verification using Japanese shaking table tests, design suggestions for shear wall and the related case study.

TitleSeismic Performance of Reinforced Concrete Buildings with Viscoelastic Damping Wall under Shanchiao Fault Earthquakes
AuthorChung-Che Chou, Jian-Lin Lai, Kuan-Hua Chen, Shu-Hsien Chao
Keywordsviscoelastic damping wall, lever viscoelastic damping wall, Shanchiao fault, near-fault effect, nonlinear response time history analysis
AbstractViscoelastic damping wall (VEW) is a common velocity-dependent energydissipating device, which is used to reduce the lateral deformation of building frames in small earthquake or wind loadings. Its allowable deformation is smaller than the displacement-dependent energy-dissipating device so that VEW is unable to reduce the earthquake response under large earthquakes. The lever viscoelastic damping wall (LVEW) is a new velocity-dependent and displacement-dependent energy dissipating device, which is composed of viscoelastic and frictional damping in one single device. Under small or service level earthquakes, the LVEW could amplify its interstory drift by using a leverage mechanism so it can amplify the shear deformation and energy dissipation of a viscoelastic mechanism to reduce the frame response. Under large earthquakes, the stopper in the LVEW limits the deformation of viscoelastic damper, and activates frictional damping for energy dissipation. In this study, 8-story and 14-story reinforced concrete (RC) buildings with moment-resisting frames and shear walls were designed, representing a fundamental period of 1.0 second and 1.8 seconds. The frames were added with the traditional viscoelastic damping wall (VEW) and the leveraged viscoelastic damping wall (LVEW) for studying their seismic response. The building site was assumed to be located in Taipei Zone 1, close to the Shanchiao fault so the analysis was conducted by using acceleration time histories obtained based on the movement of Shanchiao fault. The work was focused on investigating the seismic response of RC frames with VEWs or LVEWs under Shanchiao fault ground motions.

Vol.38/No.3 (149) (2023)

作者:

Vol.38/No.3 (149) (2023)

Special Issue: The Sixteenth National Conference on Structural Engineering and The Sixth National Conference on Earthquake Engineering
Guest Editor:  Professor Chien-Kuo Chiu, Professor Pei-Ching Chen

TitleOptimal Design of Steel Panel Damper in MRF and Optimal Design Software
AuthorYe-Ying Jan, Keh-Chyuan Tsai
Keywords

steel panel damper, moment resisting frame, seismic design, optimization, software development, web service.

Abstract

Incorporating a steel panel damper (SPD) into a moment resisting frame (MRF) can increase the stiffness, strength, and energy dissipation ability of the MRF. This research improves the previous optimization algorithm by using Sequential Least Squares Programming (SLSQP) nonlinear programming algorithm. The chosen algorithm takes less than one second to complete the optimization.Time-efficient algorithm has helped the authors to implement an optimization software into a web service to users. This paper demonstrates the optimization of single-cruciform (SC) and double-cruciform (DC) types of SPDs-to-beam subassemblies. Each SC or DC type has “Basic Design (BD)” and “1.5 times stiffened Design (1.5KD)” In the BD, the optimal depth of SPD in SC type is around 700~1200mm, while around 500~800mm in DC type. The optimal beam depth of SC type is around 700~1100mm, while around 600~800mm in DC type. The DC type can save up to 300 mm less beam depth than the SC type for a strong SPD of 1500kN nominal shear strength. Comparing the BD with the 1.5KD for both the SC and DC type subassemblies, the top three largest increases of dimensions are web thickness of elastic joint (EJ), boundary beam depth and web thickness. Applying a gravity load effect ratio 𝜉, it’s found that one can consider a ratio of 𝜉 up to 0.15 to consider the gravity load effect in the optimization without much additional cost. In the case of an 8-meter boundary beam with an SPD location eccentricity of 0.2 times the beam span, the induced SPD axial force would exceed 0.15 times of compression yield capacity of the EJ segment. It is recommended that the eccentricity be limited to less than 0.2 times the beam span. In the cases when boundary beam sizes are specified first, it is found that the DC type designs are more efficient in increasing structural stiffness than the SC type designs for the SPD-MRFs with long-span beams.

TitleShaking table test of damped-outrigger structure incorporating friction dampers
AuthorMing-Ching Chen,Meng-Lin Chung, Pao-Chun Lin
Keywordsoutrigger, large-scale test, friction damper, numerical analysis, steel structure
Abstract

The main purpose of this study is to investigate the seismic performance of damped-outrigger system incorporating friction dampers through numerical analysis and shaking table tests. A 9 m tall steel structure specimen was designed by scaling down a 20-story benchmark model. The specimen was equally divided into ten floors and the outrigger beams together with the friction dampers can be installed in different floors. The normal force in the friction damper is adjustable so that its energy performance can be modified during the test. The seismic response of the specimen was evaluated by performing response spectral analysis (RSA) using the OpenSees numerical model. The equivalent damping ratio was included in the RSA in order to evaluate the energy dissipation resulted from the friction dampers. Based on the RSA results, the specimen configurations when outrigger locates at the sixth (6F), eighth (8F), and roof floors (RF) and when the normal force in the friction damper varies between 5 kN, 10 kN, and 20 kN were tested by imposing five different ground motions with the peak ground acceleration of 0.64g. Both the RSA and test results indicated that the maximum roof drift of the specimen was around 0.7% 0.4%, and 0.3% rad., when the outrigger locates at the RF, 8F, and 6F, respectively. The greater normal force applied in the friction damper generally result in a greater amount of energy dissipation and a smaller roof drift response. Based on the experimental and numerical results, the optimal design of the damped-outrigger system incorporating friction dampers are demonstrated in this study.

TitleThe Study on Prediction of Lateral Load Displacement Force and Behavior of High Strength Steel Fiber Reinforced Concrete Walls with Opening
AuthorChun-Yi Huang, Yi-Ching Ho, Binh Nguyen Doan, Wen-Cheng Liao
KeywordsNew RC, Shear wall with opening, Steel fiber reinforced concrete, Vertical wall segment, Discontinuous zones
Abstract

With the gradual increase in the demand for high-rise buildings, countries all over the world have developed high-strength concrete in order to reduce the size of components to reduce the weight of the structure and increase the usable space efficiently. The New RC project in Taiwan has also begun to promote the use of high-strength materials. It mainly conducts research on construction materials with concrete compressive strength (𝑓c′) above 70MPa and steel yield strength ( 𝑓y ) above 685MPa. However, as the compressive strength of the concrete material increases, its properties will gradually become brittle. Therefore, according to the current code, it is necessary to deploy a large amount of shear reinforcements in the stress interference area or the geometric discontinuity zone (D zone) such as beam-column joints. Stirrups are used to maintain the toughness and shear strength of the parts, but dense shear stirrups cause difficulties in reinforcement assembling during construction, and poor workability of concrete during casting, which results in the poor quality of concrete components. Adding steel fibers to high-strength concrete can delay brittle failure. Since the bridging effect between steel fibers can effectively inhibit the expansion of crack width, it can greatly reduce the configuration of transverse stirrups and solve construction problems.

According to the past experiments on the structural discontinuity area (D area), such as beam-column joints and deep beams, etc., the results show that the use of steel fibers in high-strength concrete can improve the toughness and shear strength of components, so the benefits of steel fiber reinforced concrete in structural discontinuities is known. This study carried out 4 high-strength steel fiber reinforced concrete shear wall experiments as the shear walls that are also members of the structural discontinuity area. The test parameters include the presence or absence of openings, the type of openings, the ratio of steel bars in the wall, the amount of stirrups in the boundary columns, and the configuration of reinforcement bars in the openings. Through the observation of the strength and deformation behavior of the test body and the development of cracks, the role played by steel fibers and the benefits of collocation with transverse reinforcement will be clarified in order to revise the prediction model and provide reference for future design.

TitleShaking Table Test of RC Columns Using High-Strength Flexural Reinforcement with Low Axial Load
AuthorChih-Hsuan Chin, Shun-Bang Yan ,Min-Yuan Cheng
Keywordsshaking table, drift, stiffness, high-strength reinforcement.
AbstractShaking table tests of reinforced concrete columns using high-strength flexural reinforcement and under low axial force (around 0.01 Ag fc’, where Ag and fc’ was the column gross section area and concrete cylinder strength, respectively) were investigated in this research. Two reinforced concrete frame specimens were tested. Each specimen consisted of a concrete base block, two columns with a clear-height-to-depth ratio greater than 12, and a top concrete block. The two specimens were first tested on the shaking table with 16 input ground motions, followed by static test on the strong floor. Specimen C1 used conventional strength longitudinal reinforcement (yield strength of 453 MPa) and specimen H1 used high-strength longitudinal reinforcement (yield strength of 716 MPa). The two specimens were designed to have the same flexural strength. Except for flexural reinforcement ratio and strength, all other design parameters were identical in the two specimens. Shaking table test results indicated the maximum drift of specimen H1 consistently larger than that of specimen C1 in all 16 table motions. The ratio of the maximum drift between the two specimens ranged from 1.3 to 2.4. Before yielding of the longitudinal reinforcement, lateral stiffness of the two specimens decreased as the maximum drift demand increased. Specimen H1 exhibited lower lateral stiffness and damping ratio. The inelastic responses indicated that the maximum strength of the two specimens were similar. Using Shimazaki and Sozen model provided an acceptable upper bound to estimate the maximum drift of specimen C1 but was not conservative for specimen H1. Static test results showed that both specimens sustained the maximum lateral force up to 10% drift ratio. Specimen C1 had severe concrete spalling at the column base. Specimen H1, in addition to severe concrete spalling at the column base, had two longitudinal reinforcement fracture during the 2nd cycle of 10% drift cycle. In general, specimen C1 had larger normalized energy absorption ability than that of specimen H1.
TitleSeismic demand acceleration of non-structural elements attached to building floors using nonlinear pushover analysis.
AuthorTsung-Chih Chiou, Lap-Loi Chung ,Yu-Chih Lai, Yi-Han Chao, Jae-Do Kang, Koichi Kajiwara
Keywordsnonlinear pushover analysis, TEASPA, capacity Spectron, demand acceleration of building floor
AbstractTaiwan Earthquake Assessment for Structures by Pushover Analysis (TEASPA) can provide a capacity spectron of an equivalent single degree of freedom system. The predicted structural response can be applied to determine seismic demand acceleration of non-structural elements attached to building floors. The study adopts the shaking table testing results of ten-story RC building by E-defense in 2015 to verify TEASPA’s predicted response of the building. The predicted capacity Spectron Sa is compared to the maximum acceleration of an equivalent SDOF under a real excitation history. The comparison will be discussed in this paper. Eventually, the study proposed a procedure on seismic demand acceleration for non-structural components attached to building floors.

Vol.38/No.2 (148) (2023)

作者:

第三十八卷第二期 (期別148) (112年)

TitleEffects of chamber geometry on electro-slagwelding failure
AuthorChun-Yao Yang, Keh-Chyuan Tsai
Keywordssteel box column, welded moment connection, electro-slag welding,SM570M-CHW steel, flared chamber, finite element model analysis, steel fracture prediction model.
Abstract“In order to transfer the steel beam moment, diaphragm plates are welded inside the box column at the beam flange elevations. Electro-slag welding (ESW) is commonly used to attach the diaphragms to the column. Due to the fabrication imperfection or the frame beam depth difference, eccentricity between beam flange and diaphragm elevations may exist. This situation could lead to brittle fracture initiated at the tip of initial slit near heat affected zone (HAZ). By changing the ESW chamber from a rectangular to a flared cross section, the fusion zone can be increased, but with a price of increasing the thermal input. Considering its advantage of high heat tolerance, SM570M-CHW high strength steel column is considered. This study firstly applied the MM-CVGM fracture prediction model to the tests of two ESW component specimens and seven full-scaled steel beam-to-box column (BC) subassembly specimens conducted in previous studies. Analytical results indicate that the difference between MM-CVGM prediction and test results is no more than one loading cycle, which is more accurate and conservative than the previous model. Additionally, four full-scale BC specimens were fabricated and tested to investigate the effects of chamber geometry and column flange thickness on ESW performance. Results show that the joint with a rectangular ESW failed at the 1.5% inter-story drift ratio (IDR) cycle, while the fractures were delayed until the 4% IDR when the ESW sections were changed to a large or small flared shape. The fracture criterion of the MM-CVGM model was modified in this study. The overall failure initiation is determined by the difference of the first crack initiation between the element and the group. Applying this conditional fracture criterion to the test results, the difference between the prediction and test results is no more than one loading cycle. Circumferential-notched tensile coupon tests were conducted to investigate the ductility difference between the base and weld metals. This study utilized representative volume element models in finite element model analyses. Results show that even the steels are from different sources, very similar failure response can be observed for the same grade of steel with a difference less than 10%. Analytical results indicate that the slope of damage evolution curve of HAZ in the SM570M-CHW base metal is 114% of ESW zone and 88% of CJP zone. Three regions have the same critical damage threshold and the difference is within 5%. When the base metal is changed to SN490C, the critical damage threshold of HAZ is reduced to 29%. Based on the research results, it is recommended that the ESW chamber be considered with a flared section when grade SM570M-CHW or SN490C steel is selected for the column in order to effectively delay the ESW crack initiation.”
TitleExperimental Study on the Effect of Crosstie Configuration on the Seismic Performance of Reinforced Concrete Beams
AuthorTai-Kuang Lee, Cheng-Cheng Chen
Keywordsreinforced concrete beams, crossties, seismic performance
Abstract“The current Building Code Requirements for Structural Concrete stipulates that in the plastic hinge zone of reinforced concrete beams, the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties used as lateral support. However, in Taiwan reinforced concrete construction practice, the longitudinal reinforcement of RC beams is densely arranged, making construction difficult. In this study, four large-scale reinforced concrete beam specimens were planned and fabricated to conduct experiments to verify the effect of crosstie configuration on the seismic performance of reinforced concrete beams. The transverse reinforcement spacing of S6D and S4D specimens is 6 and 4 times the minimum beam longitudinal reinforcement diameter (D25) respectively, and the longitudinal reinforcements in the middle of the beam are not enclosed with crossties. The transverse reinforcement spacing of S6D-SHB S6D-SHT specimens is 6 times the minimum beam longitudinal reinforcement diameter (D25), the longitudinal reinforcement in the middle is enclosed with crossties, and the seismic hook engages the longitudinal reinforcement at the bottom and the top of the beam, respectively. The total confining force of the transverse reinforcement of S6D-SHB and S6D-SHT specimens (3-D10 reinforcements of SD 280W) is the same as that of S6D specimen (2-D10 reinforcements of SD 420W). It is found that: (1) With respect to the seismic performance in the negative direction (the longitudinal reinforcement at the top of the beam is under tension and the longitudinal reinforcement at the bottom is under compression), the S6D-SHB specimen is the best, the S6D-SHT specimen is second, and the S4D specimen is the third. S6D specimen is the worst. It is because that the middle vertical crosstie is configured in the S6D-SHB specimen and its seismic hook engages the longitudinal reinforcement at the bottom of the beam, delaying the effect of buckling of the longitudinal reinforcement at the bottom. (2) In the same transverse reinforcement total confining force, the ultimate drift angle and plastic rotation angle of the specimen with outer closed hoop and middle vertical crosstie and its seismic hook engaging the longitudinal reinforcement at the bottom of the beam are 5% and 12% higher than those of the specimen with outer closed hoop. It is recommended that during construction, within a range close to 2 times the depth of the beam at the RC beam-column connection, the bottom and side forms are not assembled in advance, and then after the crossties are assembled, the bottom and side forms are installed to solve the construction difficulties. (3) The ultimate drift angle and plastic rotation angle of the specimen with the transverse reinforcement spacing of 4 times the minimum beam longitudinal reinforcement diameter are equal to and 8% higher than those of the transverse reinforcement spacing of 6 times the minimum beam longitudinal reinforcement diameter. The transverse reinforcement spacing of RC beams has no significant effect on the seismic performance of RC beams. (4) Under the same total confining force of transverse reinforcements, when the outer closed hoops and the middle vertical crossties are configured and the
seismic hooks engage the longitudinal reinforcement at the bottom of the beam, the ultimate drift angle and plastic rotation angle of the specimen are 5% and 12% higher than those of the specimen with outer closed hoop. When the outer closed hoops and middle vertical crossties are configured and the seismic hooks engage the longitudinal reinforcements at the top of the beam, the ultimate drift angle and plastic rotation angle of the specimen are 2% and 4% higher than those of the specimen with outer closed hoops. This study found that in Section 15.4.3.3 of Building Code Requirements for Structural Concrete, for the plastic hinge zone of RC beams, the rule that the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties used has no significant effect on the seismic performance of RC beams. (5) All four specimens have no significant attenuation in the positive lateral strength, and the negative lateral strength has significant attenuation. In addition, the pinching effect is obvious, and the ultimate drift angle can reach more than 4.0% rad. The required plastic rotation angle is 0.03 rad, so the seismic performance (plastic rotation angle) of all specimens basically does not meet the requirement of 3.0% rad for earthquake-resistant structures. It is speculated that the reason should be caused by flexural-shear failure. (6) For RC beam-column connections, the amount of longitudinal reinforcement at the top is generally slightly greater than the amount of longitudinal reinforcement at the bottom. Therefore, the main failure mode of the T-shaped beam should be the compression failure of the longitudinal reinforcement at the bottom, and the expansion of the closed hoops and crossties. The seismic hook of vertical crosstie engaging the longitudinal reinforcement at the bottom of the beam should also have the effect of delaying the compression and buckling of the longitudinal reinforcement at the bottom.”
TitleThe Shear Strength of Brick Wall of Window Spandrel
AuthorShuenn-Yih Chang , Hao-En Hung
KeywordsReinforced concrete frame, window spandrel, pushover analysis, failure theory of brick wall, shear strength of brick wall of window spandrel
AbstractThe previous experimental study of reinforced concrete frames infilled with brick wall of window spandrel revealed that the shear strength of the brick wall cannot be reliably predicted by the current computing formula. This might result in an unreliable result that is obtained from a pushover analysis. To overcome this difficulty, a series of cyclically loading tests of the eight reinforced concrete frames infilled with this type of brick walls were conducted and thus a new computing formula can be proposed for reliably predicting the shear strength of the brick wall of window spandrel. There are two drawbacks of the current computing formula for predicting the shear strength of brick wall of window spandrel: (1) the height of the infilled brick wall of window spandrel is not considered; and (2) the strength for the rupture of brick is not accounted by the current computing formula for high brick walls of window spandrel. Based on the failure modes of brick walls, the main contributions to shear strength include the horizontal friction force between the mortar and brick, the rupture of motor in vertical direction and the rupture of brick. These two drawbacks will disappear after considering the effect of the ratio of the height over width of brick walls and the rupture of brick for the high brick walls of window spandrel. After modelling the computing formula for predicting the shear strength, a regression analysis is conducted to determine the coefficients of the computing formula based on the test results of eight specimens. To affirm the feasibility of this formula, two test results that were reported in the literature are also compared. Although they adopt the Flemish bond for bricklaying and is different from the use of the English cross bond for the eight specimens for developing the new computing formula, the calculated results are still in good agreement with the test results.
TitleSeismic Testing and Design of Steel Panel Dampers
AuthorJin-Ting Lai, An-Chien Wu, Wei-Yang Li, Keh-Chyuan Tsai
Keywordsseismic stud column, steel panel damper, shear yielding, web stiffener, seismic design, cyclic loading test
AbstractThe 3-segment steel (shear) panel damper (SPD) can be viewed as a type of seismic stud column capable of dissipating energy through inelastic core (IC) shear deformations. In this study, the concept of capacity design is adopted to design a novel SPD with a continuous web plate and doubler plates in the elastic joint (EJ) segments. Considering the IC web buckling resisting stiffeners design guides for SPDs from Japan, and for shear links from the US, this research proposed a simplified design procedure for the IC stiffeners. Cyclic loading tests were conducted on two full-scale 3-segment SPDs with the same EJ doubler plates but different IC web stiffeners. Specimens are 2.6m high and 1.0m deep with a nominal shear strength of 1128kN. Test results show that both specimens had remarkably similar strength and hysteresis response until the 4% inter-story drift ratio was reached. The cumulative plastic deformation index was more than 400. After calibrating the finite element material model, parametric analysis results confirm that the properly deigned plug welds are required for the doubler plates in the EJs thereby delaying shear buckling. Using six additional analysis models for three different target shear deformations of 2%, 4% and 6% radians in the IC segments, it is demonstrated that AISC design specifications on shear link web stiffeners are more conservative and costly. Seismic design recommendations for the IC web stiffeners are concluded.
TitleSeismic performance and design of high-rise building incorporating buckling-restrained brace outrigger system
AuthorShou-June Tsai, Pao-Chun Lin
KeywordsHigh-rise structures, outrigger truss systems, buckling beam bracing, nonlinear response spectrum analysis, Nonlinear response yime history analysis
AbstractThe keen purpose of this study is to investigate the seismic performance of buildings equipped with damped-outrigger system using the buckling-restrained brace (BRB) system (BRB-outrigger) and to propose the optimal design recommendation for buildings with a different height. The numerical models with building heights of 72, 144, 216 and 288m, each contains two layers of BRB-outrigger and a 40m by 40m structural plan are analyzed using response spectral analysis (RSA) and nonlinear response history analysis (NLRHA) procedures. To get more closer to the actual reality, the member-by-member benchmark models are designed based on the seismic code requirement. In the response spectral analysis procedure, the equivalent damping ratio is computed in order to include the BRB’s inelastic response. For the main purpose of parametric study, a simplified model which will be using a Timoshenko beamcolumn element in order to capture shear-type to flexural-type lateral deformation for a lower to higher raising buildings are proposed. The dimensionless parameters that actually describe the relationships between the core structure stiffness, outrigger flexural stiffness, the axial stiffness of BRB and perimeter column in the parameter study are considered based on practical design and allowable structural sections. The optimization targets include the maximum roof drift, inter-story drift ratio, core structure base shear, core structure overturning moment and the BRB energy dissipation performance. Based on the analyzed result, the ranges of optimal design parameters vary in the different optimization targets and building heights. This study concludes with a design recommendation for building equipped with BRB-outrigger system with different building heights.

Vol.38/No.1 (147) (2023)

作者:

Vol.38/No.1 (147) (2023)

TitleDiscussion on Influence of Reinforced Concrete Beam Reinforcement Detail with Flush Outside Faces of Beams and Columns on Seismic Performance
AuthorTai-Kuang Lee, Cheng-Cheng Chen
Keywordsreinforced concrete beams, columns, flush outside faces of beams and columns, seismic performance
Abstract        In domestic buildings, the eccentric beam-column connections with the flush outside faces of beams and columns are common, and the ductility of RC beams with eccentric connections has not been experimentally verified. In view of such domestic engineering practice problems, this study plans four large-scale reinforced concrete beam specimens, and conducts experimental verification at the Materials Experiment Center of the Architecture and Building Research Institute, Ministry of the Interior, Taiwan. In this study, the R specimen (the main reinforcement of the beam is not offset, and the stirrups are of normal size), the RH/SU specimen (the main reinforcement of the beam is offset inward and the stirrups are reduced in size, the side is equipped with U-shaped transverse auxiliary reinforcement and two longitudinal auxiliary reinforcements are fixed), the RH specimen (beam main reinforcement is shifted inward and stirrups are reduced in size), and the SH/SLB specimen (beam main reinforcement is shifted inward and the stirrups are normal size, and two longitudinal auxiliary reinforcements are arranged at the corners of the stirrup) are fabricated. The research results show that: (1) All specimens (including 3 beam reinforcement details with flush outside faces) can develop beam end rotation angle of 4% radian, which can meet the seismic requirement of the specification. For the seismic performance in the negative direction, the RH/SU specimen is the best, the RH specimen is the second, the R specimen is the third, and the SH/SLB specimen is the worst. There is only one top and bottom main reinforcement of the SH/SLB specimen, which is surrounded by the corner of the stirrup. The longitudinal auxiliary reinforcement is arranged at the corner of the stirrup of the beam, which may have an adverse effect on the seismic performance of the RC beam. Therefore, it is recommended that the corners of the stirrups should be equipped with the main beam reinforcement. (2) The concrete cover on one side of the RH specimen is 85 mm, but the results of this study show that the lateral strength and seismic performance of the RH specimen are not inferior to the R specimen. It is acceptable to use the type of the RH specimen in practice. (3) The seismic performance of the RH/SU and RH specimens is better than that of the R specimen, but the RH specimen has wider crack width and the degree of spalling of the concrete cover is obviously more serious than that of the RH/SU specimen. Therefore, it is recommended to use the type of the RH/SU specimen in practice.
TitleAnalyses and designs of the connections jointing the new steel structure and the existing RC structure in NCREE’s office building extension
AuthorYu-Cheng Lin, Ming‐Chieh Chuang, Guan-Hong Lin, Pin-Pin Deng, Keh-Chyuan Tsai, Ching-Yi Tsai, An-Chien Wu, Jui-Liang Lin
Keywordsseismic design, strengthened connection, chemical anchor, finite element analysis, nonlinear response history analysis
Abstract        The existing six-story office building of the National Center for Research on Earthquake Engineering (NCREE) was extended to thirteen-story from October 2019 to November 2020. This study presents the analysis and design of the connections jointing the existing RC structure and the new steel service core from the second to seventh floors. A steel bracket, which is welded to the steel beam bottom flange and connected to the RC column using chemical anchors, was considered as the basic design of the connection to transfer the gravity shear from the steel beam. This shear connection detail could avoid the congested reinforcing bars inside the RC beam-to-column joint, however, three alternative designs using strengthened schemes are investigated in this study.
        Nonlinear response history analyses (NRHAs) using PISA3D program for the NCREE’s 13-story composite building were conducted in order to gain insight into the possible maximum seismic force and deformational demands on the connections. The features of dual mass centroids and dual rigid diaphragms for the second to seventh floors are incorporated into the PISA3D model. The 6DOF joint elements are utilized to represent the aforementioned bracketed connections on the interface. The axial push-pull stiffness of 100 tf/mm, computed from an Abaqus finite element model (FEM) analysis for the connections, is utilized for all the 6DOF joint elements. A total of sixteen sets of ground accelerations are utilized. NRHA results indicate that the maximum axial force and maximum in-plane rotation of the connection at the steel beam end are about 165 tf and 0.01 radian, respectively.
        The Abaqus FEM analyses were conducted for investigation of four connection types including the basic design and three improved designs. The FEM analysis results indicate that the beam bracket of the basic design exhibits obvious shear yielding. The uneven anchor bolt forces developed are very evident. The improved load-carry capacity and a more uniform bolt forces developed are found in the strengthened designs, such as the stiffened steel angles at the beam web and bracket with cover plate. In addition, an approximately 200×200 mm triangular region on the cover plate corner with a low stress demand is observed. Based on these connections’ FEM analysis results, this study confirms that the strengthened scheme adopts double-sided stiffened steel angles at the beam web, the straight bracket with the angular cuts on the cover plates is suitable. The strengthened scheme adopted in the project not only meets the seismic demands but also allows the inspections of the anchor bolts in the future, if necessary.
TitleMechanical Characteristics and Testing Device Development
of Headed Reinforcements for Uniaxial Tension Test
AuthorKer-Chun Lin, Chen-Yu Ou, Kai-Ning Chi, Sheng-Jhih Jhuang, Wen-I Liao
Keywordsheaded reinforcement, testing device to test single headed reinforcement in tension, slip of head part, elongation, tensile strength
Abstract        This paper mainly investigates mechanical characteristics of headed reinforcements in tension popular used in Taiwan and develops a fixture for testing to effectively shorten test time. A total of 41 headed reinforcement specimens that include four types of steel grade, SD 420W、SD 490W、SD 550W and SD 690, and three main types of head part, welded head, threaded head, grouted sleeve head. Test results related to head part slip showed that upper loading bounds of 0.7Py and 0.95Py to assess head part slip can acquire the same identified results those are qualified or not. The slip results for the various head parts indicated that the slip of welded head by friction was very limit. The slips of head part with the other heads from small to large in sequence were threaded head and grouted sleeve head. For the threaded heads of the headed reinforcements, all the slips were smaller than 0.2 mm. For the grouted sleeve heads of them, the slips of head part without a restraining-slip nut were more significant than 0.3 mm, but the slips of head part with a restraining-slip nut enable to be reduced under 0.3 mm as long as using proper fabricated process. Test results also presented that the maximum tensile strengths of each specimen exceeded its minimum specified ultimate strength and 1.25 times its minimum specified yield strength. The testing device developed in this study can install measure instruments quick and visually and get reliable measure results of head part slip. It also significantly reduces 78% of testing time per piece compared with the existed testing fixture. The load capacity of the fixture is for #12 reinforcement of SD 690.
TitleA Study on Nonlinear Dynamic Behavior of Reinforced Concrete Structures using Concentrated Plasticity Model
AuthorFu-Pei Hsiao, Lyan-Ywan Lu, Hsuan-Wen Huang, Hung Cheng
Keywordsconcentrated plasticity model, nonlinear RC, shaking table test, TEASDA, ASCE 41, ETABS, OpenSees, ModIMK
AbstractIn recent years, some strong earthquakes, including the 921 Chi-Chi Earthquake, the 0206 Meinong Earthquake, and the 0206 Hualien Earthquake, have caused the collapse of med-to-high rise reinforced concrete (RC) buildings, and resulted in heavy casualties and severe property losses. Because of this, it is crucial to perform accurate numerical simulation for the nonlinear structural response of med-to-high rise RC buildings. This paper establishes a 7-story RC frame model with different plastic hinges using the commercial software ETABS and the open-source finite element software OpenSees developed by the University of California at Berkeley, USA. The effect of different plastic hinge settings on nonlinear time history analysis of the RC building is explored in this study. Then, based on the shaking table test results of the 7-story RC building, it is judged which plastic hinge analysis results are closer to the experimental structural response. Furthermore, since ETABS is a commercial software, its extensibility is relatively limited. In other words, users cannot add newly developed materials and elements to ETABS, nor connect ETABS with the experimental control system to conduct experiments. Therefore, this paper proposes a method to convert an ETABS model to a OpenSees model. This method will enable researchers to establish the plastic hinges for an equivalent OpenSees model with the help of ETABS, and to take the openness advantage of OpenSees software for analysis.
TitleRegional evaluation of resilience based on FEMA P58: a case study for nonductile reinforced concrete frames in Los Angeles
AuthorPeng-Yu Chen, Ertugrul Taciroglu
KeywordsProbabilistic seismic assessment, regional evaluation, FEMA P58, nonductile reinforced concrete frames, incremental dynamic analysis, resilient index
Abstract        Seismic damage and loss assessment are highly related to buildings’ performance. However, the current nonlinear static analysis for performance evaluation is a deterministic methodology, where the uncertainties and variation of ground motion and numerical modeling cannot be considered. Furthermore, the outcome of engineering parameters is difficult to be utilized by decision-makers who may not have engineering backgrounds. While the world is toward developing resilient city, it is still not clear to structural engineers how to quantify the seismic resilience and evaluate it for large-scale regions. Hence, this research proposes a framework for regional resilience evaluation, which is based on probabilistic seismic assessment (i.e., FEMA P58) to incorporate incremental dynamic analysis and Monte Carlo simulation for damage and loss assessment. Moreover, the outcome of the regional evaluation is used to quantify the resilience index to illustrate the ability of a city for recovering from an earthquake. To demonstrate the application of the proposed framework, 1,452 nonductile reinforced concrete frames in Los Angeles are simulated by developing an automatic modeling program. Around 950,000 nonlinear time history analyses are conducted through a supercomputer, and the outcomes are used for loss estimation and resilience quantification. The results show that the mean loss ratio for nonductile frames under maximum-considered earthquake is 37.3%, and the resilience index indicates that the city needs at least 3 years to recover. While the presented work is a US-based case study, the authors hope the framework can be extended and localized for Taiwan’s development of resilient city.

Vol.37/No.4 (146) (2022)

作者:

Vol.37/No.4 (146) (2022)

Special Issue: Application of Artificial Intelligence in Structural Engineering
Guest Editor: Tzu-Kang Lin

TitleFramework of Advanced Building Inspection withRoute Planning, Defect Detection, and Damage Rating
AuthorShun-Hsiang Hsu, Ho-Tin Hung, Yun-Man Hsu, Chia-Ming Chang, Tzung-Wu Chen, Chun-Chung Chen
Keywordsvisual inspection; damage detection; damage quantification; deep learning
AbstractVisual inspection is commonly adopted for building operation, maintenance, and safety. The durability and defects of components or materials in buildings can be quickly assessed through visual inspection. However, implementations of visual inspection are substantially time-consuming, labor-intensive, and error-prone because useful auxiliary tools that can instantly highlight defects or damage locations from images are not available. Therefore, an advanced building inspection framework is developed and implemented with route planning, realtime and detailed damage recognition, and damage rating in this study. The inspection route sketching is first exploited to provide an efficient plan with significantly reduced disruption. Then, Scaled-YOLOv4 and SOLOv2 models are considered in this study to detect defects even in a large-scale field quickly and acquire pixel-level damage recognition for more precise quantification, respectively. Finally, damage levels of components are rated following the importance and numbers per unit area of the detected defects. This entire framework is also implemented and verified by the hallway of an elementary school to detect and quantify surface damage of concrete components. As seen in the results, the conventional building inspection is significantly improved by the aid of the proposed framework in terms of damage localization, damage quantification, and inspection efficiency.
TitleLinear Static Analysis with Graph Neural Networks
AuthorYuan-Tung Chou, Kuang-Yao Li, Po-Chih Kuo, Wei-Tze Chang, Yin-Nan Huang , Chuin-Shan Chen
Keywords 
AbstractStructural design is an iterative process for optimum selection, which relies on structural analysis results and experience from structural engineers. Since iterative structural analysis is a necessary for getting a good design, accelerating structural analysis is an important task. In this work, we adopt deep learning approaches as a surrogate model for linear static analysis, which provides fast and accurate structural response prediction. Based on the similarity between the structure’s topology and graph data structure, we represent structures as graphs and leverage graph neural networks (GNNs) to learn the relationship between given external forces and corresponding structural responses. The GNN model is trained with random-generated structures, including random story number, span number, beam-column length, and value of external forces. The results show that the GNN model has good performance on displacement and force predictions and excellent generalizability on unseen, taller structures. In addition, it is shown that based on the analysis of feature importance, the GNN model can extract important physical attributes from the input features.
TitleDATA ANOMALIES DETECTION AND CLASSIFICATION USING MACHINE LEARNING AND STATISTIC INFORMATION
AuthorTian-Xun Lin, Shieh-Kung Huang, Jau-Yu Chou
Keywordsdata anomaly, machine learning, pattern recognition network, GoogLeNet
AbstractStructural health monitoring (SHM) and structural integrity management (SIM) are emerging recently. To continuously track the condition and constantly detect early deterioration of the infrastructure, huge amounts of data are produced and abnormal measurement is inevitable. The corrupted data can produce a lot of problems and, generally, they are examined and classified by humans. In this study, the detection and classification are replaced by the techniques of machine learning (ML) and improved by using statistic information. The neural networks based on 1-dimensional and 2-dimensional data are studied via a field dataset collected from a long-span cable-stayed bridge. Therefore, a shallow network, called pattern recognition network, is selected to use 1-dimensional data as an input and a deep network, GoogLeNet, is selected to use 2-dimensional data. The results show that both models can detect and classify the data anomalies and the usage depends on the assigned application and the trade-off between computation and performance.
TitleApplication of Convolution Neural Network and Neural Network Entropy Algorithm for Structural Health Monitoring
AuthorTzu-Kang Lin, Yi-Ting Lin, Kai-Wei Kuo
KeywordsStructural Health Monitoring, NNetEn, Convolution Neural Network
AbstractThis study combines Neural Network Entropy (NNetEn) and Convolutional Neural Network (CNN) to develop a practical structural health monitoring system. In order to verify the feasibility of the system, the failure experiment of a seven-story steel frame has been carried out with a numerical model of the same structural characteristics as the steel frame. The state space method is used to simulate the sixteen failure modes on the steel frame, where the acceleration signals of each floor at the time of failure are analyzed by neural network entropy. An entropy database is established based on the model to train the neural network model. To avoid the misjudgment and automatic interpretation of human factors, this study uses the visualized heatmap to quantify the change of entropy value, and the convolutional neural network analysis is selected for image processing. By converting the entropy value into image data, not only the number of parameters in the model can be reduced, but its operation speed can be improved. During the training process, the neural network model extracts and learns the damage features in the entropy value. After the training is completed, the model can allocate the damage area of the structure by identifying the damage features of the input data. Finally, through the verification of 16 failure cases simulated on the seven-story steel frame of the National Center for Research on Earthquake Engineering (NCREE), the performance of the proposed SHM system is evaluated by both numerical simulation and experimental verification with confusion matrix. The SHM system proposed in this study combines the emerging entropy analysis method with a neural network. The test results of the final verification have an accuracy rate of 93.13%.
TitleImproved Acceleration Tracking Performance of Seismic Simulators using Supervised Deep Learning
AuthorKui-Xing Lai and Pei-Ching Chen
KeywordsSeismic shake table; acceleration control, three-variable control; deep learning, long short-term memory neural network
AbstractSeismic shake table testing has been widely used for various structural systems such as steel structures, reinforced-concrete structures, energy-dissipated and base-isolated buildings, and nonstructural components etc. Therefore, accurate replication of shake table acceleration is particularly important to these tests. In this study, supervised deep learning approach is applied as an alternative for seismic shake table control. The Long Short-Term Memory (LSTM) neural network is built for training the controller to improve acceleration performance of the shake table. A large-scale servo-hydraulic uniaxial shake table is adopted. A steel specimen is designed and fabricated for performing a large number of shake table tests. Then, the shake table testing data are used to train a feedforward controller using LSTM which is implemented close to an existing Three-Variable Control (TVC) loop. The validating experimental results prove that the acceleration tracking performance is improved compared with conventional TVC. The control-structure interaction is also suppressed. The experimental results demonstrate the proposed control scheme reduces the acceleration tracking error effectively compared with conventional TVC control. The research results also show great potential for deep learning application to seismic shake table control in the future. Keywords: Constitutive model, anisotropy, shear-slip and re-contact, mesh-sensitivity, non-proportional loading, concrete, finite element
TitleSynthetic Power Distribution Network Construction Based on Deep Learning Algorithm
AuthorYue-Hung Lin and Chi-Ying Lin
Keywordssynthetic power distribution network, deep learning, object detection, geo-positioning
AbstractGlobal warming has caused high energy consumption and an increasing scale of disasters, which make people draw more attention to public asset management to reduce energy consumption and predict losses caused by disasters. Based on a deep learning based object detection approach, this study develops a synthetic power distribution network that can serve as an alternative to the real power distribution net-work and be used to analyze its reliability. This research uses the street view images to detect utility poles and conduct geo-positioning to locate utility poles on the map. For object detection, the Mask R-CNN and YOLOv4 are trained with controlled du-ration, and then the accuracy of the two models is compared to determine which method is suitable for this research. Second, the model’s hyperparameters are adjusted and compared to determine the best model setting for the object detection task in this study. Then the selected model is used to perform the object detection task for each street in the research region. Two sorting methods, namely, the latitude and longitude sorting method and the shortest path sorting method, are proposed to sort the poles for pole geopositioning and supplementation. With two sorting methods, pole geopositioning is conducted based on two approaches: The first is the Markov random field (MRF) approach, and the second is the line of bearing (LOB) with density-based spatial clustering of application with noise (DBSCAN). After determining the detected pole location, pole supplementation is conducted to ensure the maximum allowable distance between poles. Third, four sets of results are obtained by merging all streets and removing duplicate poles by means of distance iteration. Finally, four results are compared with the coordinates of real utility poles. The most suitable method for study region is selected to establish the synthetic power distribution network using the minimum spanning tree (MST). In the future, this model can be improved to make it more in line with the real power distribution network, and the synthetic power distribution network can be used for power grid reliability analysis, public asset management, disaster analysis, power demand-supply analysis, etc.

Vol.37/No.3 (145) (2022)

作者:

Vol.37/No.3 (145) (2022)

TitleDesign Revision of Column and Beam-to-Column Moment Connection in Taiwanese Specification of Steel Reinforced Concrete Structures
AuthorYu-Fang Liu, Te-Kuang Chow, Chung-Che Chou, Szu-Jui Huang, Lien-An Chen
KeywordsSteel-Reinforced-Concrete (SRC) Structure, Column, Width-to-Thickness Ratio, Beam-to-Column Moment Connection, Shear Strength of Connection,
AbstractThe design specifications and literatures related to SRC columns and beamcolumn connections in the United States, Japan, and Taiwan were collected for the revision of Taiwan Design Specifications and Commentary of Steel- Reinforced-Concrete Structures. The revision recommendation will be expected to be an essential reference for design and construction of SRC structures in Taiwan. Design of Reinforced-Concrete-Column and steel beam connection (called RCS connection) has been included in the design specifications of United States and Japan. However, this connection type has not been included in Taiwan specifications. This work was focused on revision of SRC code in Taiwan. In terms of SRC column design, concrete strength, steel strength, column reinforcement spacing, and column width-to-thickness ratio are revised based on AISC 341 (2016). Integrating the design theories of U.S. and Japan, as well as the research results in Taiwan, a new section of RCS design was recommended to the updated SRC code.
TitleA Study of BRBs using Varying Section Steel Truss Restrainers
AuthorLu-An Chen, An-Chien Wu, Chun Chen, Keh-Chyuan Tsai
Keywordsbuckling-restrained brace, truss-confined restrainer, flexural rigidity, shear rigidity, buckling load, finite element analysis
AbstractBuckling-restrained braces (BRBs) can effectively improve the stiffness, strength, ductility, and energy dissipation capacity of building structures. Recently, a novel type of BRB called truss-confined BRB (TC-BRB) has been investigated. The feature of the TC-BRB is attaching an additional truss system outside the central steel casing. The truss system is composed of several steel open-web truss frames thereby providing the overall restraining rigidity, reducing the steel casing section size and infilled mortar. The overall self-weight is reduced as compared to the conventional BRB, especially in the cases of longspan and large load-carrying BRB applications. This study extends and improves the stability assessment methods of the TC-BRB investigated previously. The equivalent flexural rigidity and shear rigidity of varying-section truss confining system are re-examined first. The method of computing the effective shear area of central casing is developed. The results are integrated into the calculations of elastic buckling strength of the restraining system. A simplified computing method is also proposed. Two additional 1/3-scaled specimens each of about 6.3m long and 90tf (853kN) yield strength were designed and tested in the MATS facility in NCREE. Considering tests results of four specimens of similar size and capacity in the previous and this studies, the relationship between the elastic buckling strength of restrainer and the ultimate compressive strength of entire TC-BRB is constructed. The required design parameters are provided for practical applications. In addition, a numerical modeling procedure which can effectively simulate the effects of the BRB compressive over-strength and the residual stresses in the chord members is introduced. Analytical results indicated that the proposed calculations in the restrainer’s elastic buckling strength are reliable and the specimens’ hysteresis behavior can be captured satisfactorily.
TitleDiscussion on the Residual Capacity and Plastic Hinge Properties of Earthquake Damaged RC Shear Walls
AuthorWen-I Liao, Yu-Ming Zheng, Xuan Ling Chen
KeywordsReinforced concrete, shear wall, residual seismic capacity, plastic hinge
AbstractDue to the high lateral strength and stiffness of the RC shear wall, it can effectively improve the structural system and increase the seismic capacity of the building structure. However, the high stiffness property of RC walls will also easily induce cracking or damage as compared to the beam-column members in the earthquake. The technical problems for judgment of damage status and simulation of damaged components are often difficult to be determined, especially for those RC walls that are only at slightly or moderately damaged status, they may not need retrofitting but their residual seismic capacity should be evaluated. When using the nonlinear pushover analysis procedure to evaluate the residual seismic performance of damaged RC walls. Because researches on the residual seismic performance of damaged RC walls earthquakes are very limited. There is still no quantitative method for the selection of reduction factors on strength, stiffness, and deformation capacity of RC walls with various damaged statuses. Therefore, the main purpose of this paper is to collect and analyze the relative research works of literature on the post-earthquake behavior of RC shear walls. The suggested criteria, parameters, and procedures of the existing post-earthquake assessment guidelines in the U.S. and Japan are compared with those latest publications in the area of the residual capacity of RC walls for discussing their suitability. Finally, a reduction method based on Taiwan seismic evaluation procedure was proposed for modifying the nonlinear hinge properties of damaged RC walls with different damaged states.
TitleA Review of Seismic Metamaterials for Seismic Protection
AuthorHsu-Ci Su, Hsiang-Jung Wang, Wen-Chung Chang, Tzu-Kang Lin, Cheng-Hung Lin, Tung-Yu Wu, Kuo-Chen Chang, Tung-Yang Chen
Keywordsseismic metamaterial, seismic waves, local resonance, periodic structure, wave propagation
AbstractCurrent seismic-resistant technologies include enhancement of structural strength and ductility, application of isolation systems, and adoption of energy dissipation devises. These approaches target a single building and integrate isolation and damping devices. In the area with significant numbers of aging buildings like Taiwan, retrofitting existing infrastructure with traditional methods may not be a pragmatic solution. Seismic metamaterials have emerged as a state-of-the-art research topic in the last decade. They block or deflect waves by forming a seismic shield outside the area around existing structures without direct contact with the actual buildings. The seismic metamaterials are able to complement the techniques used in current earthquake engineering; however, domestic study on this subject is limited. Therefore, Professor Tungyang Chen assembled an interdisciplinary team to conduct the 3-year integrated project titled “Seismic Metamaterials towards Cloaking Earthquakes: Theoretical Framework, Numerical Modelling and Experimental Verifications”, under the support of the Ministry of Science and Technology, Taiwan since 2021. This review article includes literature review on seismic metamaterials, current progress in Taiwan, and future work. The study introduces the insights of seismic metamaterials for engineers and researchers, and aims to provide alternatives from seismic isolation and energy dissipation.
TitleKinematics and Identification Study Applied to the Shaking Table by Using the Actuator Measurement: Take MAST for example
Author

Chin-Ta Lai, Shih-Wei Yeh, Pu-Wen Weng, Fu-Pei Hsiao, Bai-Yi Huang

Keywordsshaking table, Stewart platform, actuator kinematics, force transformation, parametric identification
Abstract“A shaking table test is one of the experimental methods widely adopted to inspect the seismic performance of structures. A multi-axial seismic test system (MAST) equipped in Tainan Laboratory, National Center for Research on Earthquake Engineering (NCREE) is a hydraulic powered six-degree-of-freedom shaking table, which consists of a rigid mass and six actuators. The placement of the actuators follows the design of the Stewart platform. Hence the MAST system can achieve 6-DOF dynamic motion with the least amount of actuators; in other words, reducing the cost and the redundancy of the system.
This article introduces the MAST system in the very first paragraph. Then the kinematics study based on the geometric relation between the actuators and the rigid platen will apply to the forward and inverse conversion of the actuator displacement/force and the platen 6-DOF displacement/force. In addition, this study proposed system identification methods to evaluate the equivalent mass and the equivalent damping and friction force of the MAST system, which are critical characteristic parameters for simulating the system’s dynamic responses. As a result, the identified equivalent mass approximates the design value, which shows the high fidelity of the proposed system identification method. Moreover, a Bouc-Wen model, which is wildly adopted on describing the friction force and numerical-friendly, is validated in this study. The parameters for Bouc-Wen model are obtained through the regression analysis by utilizing the experimental data. While the simulated results based on the Bouc-Wen model are consistent with the experimental data, it can be concluded that the equivalent mass and damping force of the MAST system or similar systems can be quickly evaluated through the proposed identification methods in this study. With the help of the proposed method, it’s possible to simulate the table motion of the MAST system or similar shaking table system, and then conduct further study, such as dynamic interaction between the system and the specimens.”
TitleDiscussion on“Design of partial rigid joint of precast girder and Beam” by Tzu-Liang Wu and Shyh-Jiann Hwang
Author

Cheng-Ping Chen

Keywordsanchorage, load transfer path, shear friction
AbstractThis article discusses some concerns about the design of partial rigid connection presented in the manuscript entitled “Design of partial rigid joint of precast girder and beam”. In the case where precast beam anchored at the spandrel beam, the negative flexure reinforcement of the precast beam should satisfy not only the development length requirements but also the integrity of load transfer path.

Vol.37/No.2 (144) (2022)

作者:

Vol.37/No.2(144) (2022)

Special Issue: Advanced Concrete 
Guest Editor: Chung-Chan Hung

TitleStudy on Seismic Retrofit of Concrete Frames using High-strength Fiber Resin Mortar
AuthorFu-Pei Hsiao, Pu-Wen Weng, Chia-Chen Lin, Takanori Kawamoto, Yi-Ching Lin, Asahi Oogami, Chia-Yi Ho
KeywordsHigh-strength Fiber Resin Mortar, Earthquake-proof Furniture, Seismic Assessment and Retrofitting
AbstractThe traditional seismic retrofitting methods often affect the regular operation of the building, and it takes a lot of time during the construction period. So it isn’t easy to carry out reinforcement work in private houses. This research aims to develop seismic retrofitting methods, so we use high-strength fiber resin mortar for existing reinforced concrete structures. It can effectively improve the performance of seismic retrofitting methods. By using the high-strength fiber resin mortar, its expected strength can be achieved within two weeks. Therefore, it takes just a small impact during construction, which does not affect the existing functions of the building. It has high application value for hospitals, commercial buildings, and private residences. In this research, the different kinds of seismic retrofitting methods will be tested at the NCREE Laboratory. There are three kinds of seismic retrofitting methods, such as steel frame bracing, shear wall, stub column. The experimental specimens were tested in horizontally cyclic loading to compare the seismic behavior and the difference of seismic retrofitting methods. It uses popular seismic assessment methods for each test and compares them with the experimental results in this research.
TitleFeasibility study on the Early-High-Strength
Repairing Geopolymer Materials at Bridge Expansion Joints
AuthorMohammad Rizwan Bhina, Kuang-Yen Liu, Chih-Ta Tsai
KeywordsGeopolymer material, early-high-strength, rapid repairing, expansion joint.
AbstractGlobal warming has become a serious issue worldwide and it was evident that the greenhouse gases are mainly responsible for global warming. CO2 is considered as the major greenhouse gas. Among all the industries, cement industries contributed 5-7 ℅ CO2 emissions to the environment. Demand for concrete is increasing by 3% per year as concrete is the material used worldwide next to the water. If the engineering materials can be exempted from the use of cement, the purpose of carbon reduction can be achieved. Additionally, expansion joints play an important role in the stability of the bridge deck and also in accommodating thermal, lateral, and rotational moments. Hence, bridge industries demanded a high-strength, rapid setting material to replace the joints quickly and reopen the traffic. Considering all these issues, the early-high-strength repairing geopolymer material by using fly-ash and ground granulated blast-furnace slag (GGBS) are developed in this study. The high calcium inorganic polymer material was prepared by mixing fly-ash (Class-F) and GGBS (S4000) as a bonding agent with a varied ratio, NaOH alkali solution with 10 molarity (SiO2/Na2O=1.28) as an activator and pre-heated river sand as a fine aggregate to enhance the polymerization reaction. The main objectives of the present investigation were to develop a high strength geopolymer material (GPM) to provide 35MPa in 5 hours and examined the properties with regard to the effect of pre-heated fine aggregate, compressive strength (hot air-cured for 1,3 and 5 hours) and bond strength of GPM with ultra-high-performance material (UHPM) as well as high-strength non-shrinkage material (HS-NSM) from the slant shear test. The experiment was also carried out by varying the fly-ash to GGBS ratio and water to NaOH ratio. A total of 36 GPM specimens with an aspect ratio of 1 were tested. Results revealed that the hot mix procedure of GPM with the fly-ash to GGBS and water to NaOH ratio 1:3 and 10%, respectively produced greater compressive strength (52.67 MPa/5 hours) and fly-ash to GGBS and water to NaOH ratio 1:2 and 10%, respectively indicated excellent bond strength of 34.93 MPa. Results of the present investigation revealed that by increasing the amount of GGBS, the initial and final setting time and the flow rate of GPM have decreased. It was suggested that by applying GPM on the actual construction site, strength and workability should be considered simultaneously.
TitleA Study on the Static and Dynamic Mechanical Behaviors of Recycled Carbon Fiber Reinforced Concrete
AuthorYeou-Fong Li, Jin-Yuan Syu, Shu-Mei Chang, Ming-Yuan Shen, Fa-Jun Huang, Li-Chen Lin, Pei-Jun Huang, Jia-Lu Yu
KeywordsRecycled carbon fiber, microwave-assisted pyrolysis, carbon fiber concrete
AbstractFiber reinforced concrete can improve the flexural strength and toughness of concrete, and also can reduce the shrinkage and cracking of concrete. In this study,  microwave-assisted pyrolysis was used to recycle carbon fibers from the waste carbon fiber polymer composites to make recycled carbon fiber- reinforced concrete. The lengths of the recycled carbon fibers were 5-10 mm, 15-20 mm, and 30-50 mm, respectively, and the fiber to cement weight rations were 0.5%, 1.0%, and 1.5%, respectively. The water-cement ratio was 0.6, and the aggregate fineness modulus (F.M.) was 6.78. The mechanical performances of recycled carbon fiber-reinforced concrete (RCFRC) were investigated by using compression, bending, splitting and impact tests. The test results show that when the fiber to cement weight ratio is 1.5%, the mechanical performance of the recycled carbon fiber- reinforced concrete is the best compared to other fiber to cement weight ratios. Compare to the benchmark specimen, for 1.5% fiber to cement ratio and fiber length from short to long, the compressive strengths of the RCFRC increase 48.71%, 56.15% and 48.88% respectively; the flexural strengths of RCFRC increase 55.76%, 43.63% and 27.31%; the splitting strengths of RCFRC increase 28.96%, 45.70% and 47.58% respectively. The impact test results show that with 1.0% fiber to cement ratio and an impact energy of 50 joules, the impact times of RCFRC with a fiber length of 30-50 mm increased by 3,615% compared to benchmark specimen. The above results show RCFRC can effectively improve the mechanical properties of concrete.
TitleFeasibility of additive manufacturing technology for structural components: the case study of 3D printing using cementless binders
AuthorChia-Yun Huang, Wei-Ting Lin, An Cheng, LUKÁŠ FIALA
Keywordscementless blended material; 3D printing technology; printing flow; viscosity
AbstractIn recent years, 3D printing of structural components or elements for construction has been a popular construction automation technology. 3D printing technology has the advantages of fast construction, saving construction materials and stable quality, and the diversity of printing spraying materials is the key to its development. In this study, three industrial by-products (fly ash, ultra-fine fly ash and ground-granulated blast-furnace slag) were mixed to form a ternary cementless blended material without the addition of alkaline activators. The test results were compiled through viscosity tests, setting time tests, syringe injection tests and flowability tests. The results revealed that a viscoelastic solid paste with a viscosity of over 6000 cP could be used as a spraying material for liquid deposition modeling 3D printers. The results confirmed that a ternary cementless blended material made from 10% slag, 40% ultra-fine fly ash and 50% fly ash, at a water to binder ratio of 0.25, could be used as a spraying material for 3D printing and that the spraying flow rate of the printer should be set at 40% to achieve the best aesthetic integrity of the sprayed specimens. The compressive strength tests were conducted to verify that the 3D printed specimens have higher compressive strength and casting quality than the conventional molded specimens. The cementless blended material developed in this study is suitable for use as a 3D printing spraying material and is in line with the promotion of high-value industrial by-product technology.
Title High-Fidelity Nonlinear Cyclic Response Simulations of Squat RC Shear Walls
Author Tzu-Han Wen, Chung-Chan Hung, Hexin Zhang, Phu Anh Huy Pham, Terry Y.P. Yuen*
Keywords Constitutive model, anisotropy, shear-slip and re-contact, mesh-sensitivity, non-proportional loading, concrete, finite element
Abstract As stipulated by most of the prevailing structural design standards, nonlinear response analysis with high-fidelity numerical models would be inevitable for
designing unconventional reinforced concrete structures under extreme seismic loading. The core of nonlinear numerical models is the constitutive modelling of materials, particularly for concrete materials. Nevertheless, many of the existing concrete constitutive models could not resolve some critical issues that involve crack-induced anisotropy, change of stress transfer mechanisms under non-proportional loading, shear-slip and re-contact behaviour, mesh-size sensitivity, and balance between computational efficiency and modelling the detailed responses. To this end, this paper presents a robust and experimentally validated constitutive model that was developed recently (Yuen et al., 2022) for high-fidelity nonlinear response analysis of reinforced concrete elements. The key features include (1) the total-strain based formulation with loading-history dependent internal variables, (2) cyclic normal and tangential stress-strain responses prescribed on crack planes, (3) fixed 3D crack plane coordinate that is uniquely determined by a novel crack plane searching algorithm, (4) multi-axial strain interaction modelled by the equivalent uniaxial-strains transformation method, (5) shear-slip and re-contact of the crack planes modelled by the modified shear retention model, and (6) mesh-size sensitivity mitigation through the model parameter regularisation. The proposed model was already implemented into ABAQUS through the user-subroutine and successfully applied to simulate reserved-cyclic loading tests on shear panels and a full-scale shear-controlled column (Yuen et al., 2022). This paper presents a further validation study of the proposed model on a high-strength squat RC wall. The high-fidelity model can again well capture the damage evolutions and complete load-deflection hysteresis response of the tested wall. Hence, with the demonstrated performances, the proposed model could be a competent candidate for the high-fidelity nonlinear analysis of next generations of concrete structures that feature unconventional design.
TitleAS3600:2018 THE AUSTRALIAN CONCRETE STANDARD AND IMPLICATIONS FOR REINFORCED CONCRETE DESIGN IN TAIWAN
AuthorSturm, A.B.
Keywords 
AbstractDespite being a small country Australia has long maintained independent reinforced concrete design standards with significant differences to the US and European standards which most people outside of Australia would be familiar. This is in part due to the long history of high-level research into reinforced concrete within Australia. Therefore, in this paper I will review the latest edition of the Australian design standards and contrast this with ACI 318-19. From this I will draw implications for reinforced concrete design in Taiwan. Unique aspects of this standard include the approach to time effects, shear as well as fibre reinforced concrete.

Vol.37/No.1 (143) (2022)

作者:

Vol.37/No.1(143)(2022)

TitleBond Splitting Performance of Concrete and Development Length in Tension for High-Strength Deformed Bars
AuthorKer-Chun Lin, Yuan-Yan Lin, Kai-Ning Chi, Sheng-Jhih Jhuang, Yung-Chih Wang
KeywordsHigh-strength reinforced concrete, development length, modification factor of steel grade, split index, bond stress
AbstractFor ACI 318-19 Code, a modification factor of steel grade of Ψ􀯚 that is equal to 1.15 or 1.3 for 550 or 690 MPa grade of steel bar exceeding 420 MPa was added to increase straight development length in tension for deformed bar. It is known that the design equation of development length stipulated in the existing ACI 318 Code was obtained based on a mechanism of concrete splitting primarily dominated by contact characteristics between concrete and steel bar. This paper was intended to investigate the rationality of the Ψ􀯚 included in the design equation of development length. A total of 20 beam-end specimens was carried out to study bond behaviors of concrete splitting with a deformed bar in this research. A #10 bars for three various grades of 420, 550 and 690 MPa was used as developed steel bar per specimen. Concrete strength and split index were study parameters as well. Test results indicated that the anticipated concrete splitting occurred in 15 specimens of all 20 ones even took place in the specimens with the split index of 4.93. Based on analysis overcomes of the test bond stress in this research, it was confirmed that under upper limitations of 70 MPa for the concrete strength and 2.5 for the split index, the average bond stresses of the three various grade bars for ACI 318-14 Code ranged from 1.72 to 2.4. The modification factor of steel grade of Ψ􀯚 seemed to not be needed in the provisions of straight development length of ACI 318-19 Code. It was certificated as well that raising the limit limitations of 100 MPa for the concrete strength and 5.0 for the split index, good results with around 10% conservative margin could be obtained according to the provisions of straight development length of ACI 318-14 Code. However, a safety factor should be considered for applications of engineering practice.
TitleEstablishment of Time Dependent Functions for Ordinary and Pozzolanic Concrete Compressive Strength and Modulus of Elasticity in Taiwan
AuthorYing-Chieh Wang, Wen-Cheng Liao
Keywordsfly ash, slag, strength, elastic modulus, time function
AbstractConcrete is a widely used construction material composed of aggregate, cement, water, mineral admixture in a specific proportion. Not only safety, longterm serviceability is also the main consideration for buildings and infrastructures made of concrete. The volume of concrete changes over time, such as shrinkage and creep, and all the above influence the long-term serviceability. The elastic modulus of concrete, mainly determined by composition of concrete, directly affects shrinkage and creep behaviors of concrete. However, because materials vary from different resources, a localized prediction model is essential to account for characteristics of concrete in Taiwan and this specific prediction model shall involve localized time function of strength and elastic modulus as well. In view of the importance of elastic modulus and strength in practical applications, and in recent years, the addition of fly ash and water-quenched blast furnace slag in concrete has been widely used, so this research also investigates the shrinkage and creep test data from the database. A comprehensive experimental program, including compression and elastic modulus tests for seven different water-to-cement ratios of ordinary concrete and six different fly ash and slag replacement ratios of water-to-binder ratio of 0.42 for 3, 7, 14, 28, 56, 91 and 180 days, were conducted. The prediction models of time function for strength and elastic modulus for ordinary and fly ash/slag concrete in Taiwan are proposed for further modification of shrinkage and creep model and practical applications.
TitleBrief Introduction to Applications of Second-order Analysis in Design of Steel Structures
AuthorJui-Lin Peng, Liang-Jenq Leu, Siu-Lai Chan, Yao-peng Liu, Wai-Fah Chen
KeywordsCritical load, Direct analysis method, Notional lateral force, Initial imperfection, Second-order analysis
AbstractIn recent years, the steel structural design codes of advanced countries such as Europe and the United States have stipulated the related regulations of“second-order analysis” or “direct analysis method.” In fact, the second-order analysis, widely adopted in the steel structural design codes of the European Union and the Commonwealth of Nations, is the geometric nonlinear analysis. The American engineering community believes that the terms of “the secon-dorder analysis” and “the second-order bending moment” are easily confused, so the “direct analysis method” is used to replace the “second-order analysis” in the steel structural design code. Traditional steel structural design is mostly carried out on the basis of component strength, which is an indirect design concept. The second-order analysis is designed based on the strength and the stability of the overall structural system. It is a direct and more reasonable design method, which is the reason for the adoption of steel structural design codes in advanced countries such as Europe and the United States. The second-order analysis is especially suitable for the design of steel structures that combine nonhorizontal beams and non-vertical columns, have irregular shapes and aesthetic appearances, and is difficult to determine the effective length. This paper makes a preliminary introduction to the second-order analysis of steel structural design codes in advanced countries such as Europe and the United States. In order to make it easier for engineers to grasp the content, the paper especially makes key excerptions from chapters related to the second-order analysis and the direct analysis method in the steel structural design codes of various countries. It is hoped that through the introduction of this paper, domestic engineers can understand the development of steel structural design in advanced countries, and their designs can be synchronized with international designs in the future.
TitleDesign of partial rigid joint of precast girder and beam
AuthorTzu-Liang Wu, Shyh-Jiann Hwang
Keywordsprecast, partial rigid joint, shear transfer
AbstractIn 2016, the Chinese Institute of Civil and Hydraulic Engineering and the Taiwan Concrete Institute began to revise the design provisions of Chapter 9 of the ” Design Code of Concrete Structures [2] “, “Precast concrete Structures”, which were approved and published by the Construction and Planning Agency Ministry of the Interior in August 2017 [3]. The revised provision is only a principle description, which is not easy for designers to understand; this article mainly provides supplementary explanations on partial rigid joint design of the code, including the description of the main content of the revised provisions, the establishment of the structural model of the precast beams, and the definition of partial rigid joint and design, and reinforcement details, etc. In particular, the path and calculation formula for possible failure of the shear force transmitted by the partial rigid join between girder and beam are proposed for the designer’s reference. Finally, a design case is provided as an illustration, so that those interested in precast design can fully understand.
Title Lateral displacement and axial force protocols of the first-story steel column in buckling-restrained braced
frames under near-fault earthquake motions
Author Yu-Fang Liu, Chung-Che Chou, Guan-Ru Peng, Kuan-Ju Chen
Keywords static cyclic loading, loading protocol, near-fault earthquakes, nonlinear dynamic analysis, buckling-restrained brace
Abstract Most of the domestic researchers considered the loading protocol for beam to column moment connections in moment resisting frame (MRF), specified by AISC, as the reference for static cyclic test. The loading protocols for buckling restrained braced frame (BRBF) had not been developed yet. The nonlinear behavior of a structure cannot be truly reflected using the loading protocols of different type of structure. Since the first story columns are generally used to represent the seismic behavior of a building, loading protocols for the first story columns in BRBF with varied axial force and lateral drift should be developed. Moreover, the loading protocols suggested by American specifications might omit the effect of near-fault earthquakes which is common in Taiwan. Therefore, the near-fault effect on buildings is necessary to be considered for better developing the loading protocols for BRBF in Taiwan. This research has completed the nonlinear static and nonlinear dynamic analysis of BRBF which is designed with various periods for a better understanding of seismic performances of BRBF and developing loading protocols for the first story columns in BRBF with varied axial force and lateral drift. The developed loading protocols for BRBF is expected to be a beneficial reference to steel structure study in the future.

Vol.36/No.4 (142) (2021)

作者:

Vol.36/No.4 (142) (2021)

TitleDetailed evaluation and its checking for seismic performance of steel building structures
AuthorLap-Loi Chung, Dan Chiao, Min-Lang Lin, Jing-Fang Liang, Tsung-Chih Chiou, Kai-Wen Deng
Keywordssteel structure, nonlinear hinge, pushover analysis, detailed evaluation method of seismic capacity
AbstractWith the evolution of the times and the development of the code, the existing steel structures may also be insufficient in earthquake resistance, which need to be evaluated and reinforced. The detailed evaluation method of steel structure is a continuation of the principle of the detailed evaluation method of seismic capacity of reinforced concrete buildings. It is based on the capacity spectrum method and nonlinear static pushover analysis by using ETABS program. In this paper, the rationality and applicability of the nonlinear hinge are checked by referring to ASCE 41-13. After the capacity curve (the relationship between the structural base shear and the roof displacement) is obtained from the pushover analysis, this paper further proposes the checking method, including the structural stiffness (the slope of the capacity curve) and the maximum base shear, so as to confirm the rationality of the pushover analysis results, and avoid the poor communication between the engineer and the analysis program, which leads to systematic errors. If the engineer fails to detect the error of the analysis result immediately, he may misjudge the evaluation result seriously. Finally, a case is used to evaluate the seismic capability in detail, and then the evaluation results are verified to be reasonable.
TitleSimplified Seismic Detailed Evaluation Method on Mid-to High-Rise Buildings
AuthorKai-Wen Teng, Chu-Yuan Chang, Yu-Chih Lai, Lap-Loi Chung, Tao Lai, Gin-Show Liu
Keywordsmaximum base shear, seismic evaluation, simplified seismic evaluation method
AbstractTo find out the buildings with less seismic capacity is an important issue. However, conducting detailed evaluation for all buildings will cost a lot and uneconomical. This article focuses on Simplified Seismic Detailed Evaluation for mid-rise to high-rise buildings. The method needs not to use structural analysis software to obtain the results, but only consider strength of member, failure mode, etc. The article uses Ultimate Moment Balanced Method to evaluate the maximum base shear of building and assesses the seismic ability of the building. The result of Simplified Seismic Detailed Evaluation can be reference for engineers to check with Seismic Detailed Evaluation. The article adopts both Simplified Seismic Detailed Evaluation and Seismic Detailed Evaluation for a mid-rise to high-rise building to compare the differences of two methods. The Seismic Detailed Evaluation in the article is the method provided by NCREE. The results show that the base shear and seismic ability evaluated by both two methods only with minor difference. The method can be proposed to conduct seismic evaluation on mid-rise to high-rise buildings.
TitleSeismic Analysis of NCREE Office Building Extension
AuthorGuan-Hong Lin, Ming‐Chieh Chuang, Keh-Chyuan Tsai, Jui-Liang Lin
KeywordsComposite structure, RC structure, Steel structure, RC shear wall, FRP strengthening, BRB, SPD, FVD, PISA3D, Nonlinear response history analysis
AbstractThis study conducts the seismic analysis of NCREE office building extension. The extended NCREE building becomes a composite structure including the original six-story RC structure with RC shear walls and FRP strengthened beams, vertically added seven-story steel structure with BRBs, SPDs and FVDs. In addition, a service core was extended from the first floor to the roof at the north side of the building. PISA3D program was used for conducting the modal and nonlinear response history analyses (NRHAs). Bilinear, degrading, hardening material models were adopted for RC beam and column, RC shear wall, steel members, BRB and SPD. Maxwell model was applied on FVDs. In order to gain insight into the force transfers between the RC structure and steel service core interfaces, dual rigid diaphragms with two individual mass centers and several 6DOF joint elements were incorporated into the lower six floors of the structural model. Single rigid diaphragm and mass center were considered in all other floors. Modal analysis results show that the first three natural periods are 1.24s (longitudinal translation), 1.19s (transverse translation and rotation) and 1.05s (rotation), respectively. A total of 21 sets of ground accelerations and scaling factors were chosen in fitting the Taipei Zone 2 DBE design spectrum. The scale factors range from 2.22 to 6.35. 0921TAP042 earthquake scaled spectrum is closest to the design spectrum among all selected earthquake records. SLE and MCE earthquake hazard levels are 0.29 and 1.3 times of DBE, respectively. Under three different earthquake hazard (SLE, DBE, MCE) levels, maximum story drifts (SD) are distributed evenly in the LG direction but unevenly in the TR direction and coupled with rotation. Obvious story rotations occurred from the 2nd to the 7th floor. The averaged SDs occur at the LG 7th floor and TR 5th floor, which are 0.35, 1.22, 1.61% radians and 0.34, 1.12, and 1.52% radians respectively. In the DBEs, the SDs are less than 1.5% radians, and within the ASCE/SEI 7-10 limitation of the risk3 category having an importance between hospital and general buildings. In the MCEs, SDs are less than 2% radians within the FEMA356 performance limitation for life safety. Through the results of NRHAs, the satisfactory seismic performance of the extended NCREE building can be demonstrated.
TitleStudy on the Earthquake Response of Shulin Art & Administrative Building in New Taipei City
AuthorCheng, Li-Hui
Keywordssystem identification, earthquake response, building health monitoring, vibration period, building period
AbstractFor promoting the building safety AI system, Taiwan Architecture & Building Center installed an earthquake monitoring system including four triaxial seismometers and a host computer in Shulin Art & Administrative Building in New Taipei City for health monitoring in October, 2020. Earthquake response data of the building will be collected by the system in the following consecutive three years. The research is based on the data recorded from the earthquakes on Dec.10, 2020 and Jan. 09, 2021 in North Taiwan. By system identification methods, the periods of the building are 0.3 second in X direction and 0.35 second in Y direction while the results of damping ratio are about 3%~5%. Since the building was just finished in July 2019, the identification results from the above earthquake records can be regarded as the initial properties of the structural stiffness which could be the reference for the building health monitoring in the future. In addition, the identified periods of the studied building are only 1/3 of both the empirical equation of Taiwan’s earthquake designing code and dynamic analysis of ETABS base on a mere RC frame model assumption. Thus, the research infers that, without taking the inner and outer walls into analysis consideration, the estimation of building periods will be much different from the actual values. Furthermore, in the studied building, the designing earthquake forces based on the empirical period equation might be less 10% than the forces based on the periods given from the identification results. In the result, the research proposes that the relationship between the periods and building categories shall be studied more thoroughly.
TitleOptimal Sensors Placement for Micro-Vibration Monitoring of Mid-High Rise Building
AuthorYen-Yu Yang, Leng-Jenq Leu
KeywordsOptimal Sensors Placement, Structural Health Monitoring, Stochastic Subspace Identification, Cubic Spline Interpolation
AbstractTaiwan is located in the seismic zone with high frequency earthquake occurrences. In order to increase structure safety, it needs to monitor the structural health before and after disaster occurs. This study proposes a method to obtain the optimal sensors placement(OSP), which could reduce the number of sensors for building monitoring. In additions, the method could find out the higher modal frequencies for structures. First, collect the real time-histories and use Cubic spline interpolation method to obtain simulated time-histories for each floor. Second, use Stochastic Subspace Identification to generate stabilization diagrams. Third, K-means clustering method is used to obtain modal frequencies. Finally, use Genetic Algorithm method to find OSP. There are four in-situ experiments for the method verifying, one is in National Taiwan University Cancer Center, one in Tamsui(a new building) and others are 5 years buildings in Banqiao.

Vol.36/No.3 (141) (2021)

作者:

Vol.36/No.3 (141) (2021)

Special issue: Bridge engineering

Guest editor: Dzong-Chwang Dzeng

TitlePlanning and Design of AnShin Bridge, the Ankeng LRT System Xindian River Crossing Bridge
AuthorTeo Eng-Huat, Chang Jhih-Bin, Chang Jung-Tzu
KeywordsCable-Stayed Bridge, Steel Truss Bridge, Wind Tunnel Test
Abstract    Ankeng LRT, located in New Taipei City, is a part of the “3 ring & 6 line railway project”. The route goes through Xindian and Ankeng area, and the section crossing Xindian River is the AnShin Bridge. Since the route crossing Xindian River has a skew with the river channel in 41 degrees, and there is a big turn in the Xindian side in order to enter the K9 station, it makes distance crossing river over 500 m. Moreover, there is a restriction which allows only 2 piers in the Xindian river reservation. In order to fulfill the requirement of the hydrographic as well as the railway system, a cable-stayed and truss composite bridge is used, which is the first in Taiwan and are seldom used in the foreign as well. AnShin Bridge crosses the deep trench area with a big span, a three-span continuous truss girder is used (225m+150m+127m=502m) for the bridge, not only can fulfill the deflection restriction of the railway structure, but also can keep the deformation continuity of the rail and structure at the curve route section. Since the location of the pier is restricted, the A-shaped inclined tower with single pier and the arrangement of the cable was well designed to surmount the imbalanced force due to unbalanced span. Last but not least, the analysis and modeling of the cable-stayed bridge with truss girder, the design detail of the curve and gradient steel truss, and the extra consideration for the railway bridge are some of the design features of AnShin Bridge which is different from the usual. The Anshin Bridge are special not only in the scale, span and design features, but also in the steel details and construction challenge. The design of AnShin Bridge is carried out in this article, some railway bridge design feature including seismic design, wind resistance design as well as the structural detail are also introduced, provide as a reference for the future engineering related project.
TitlePlanning, Design and Construction of the Sanying Second Bridge in New Taipei City
AuthorKang-Yu Peng, Ming-Sing Wu, Tien-Jen Hsiao
KeywordsAdjacent precast PC inverted T-beam, Accelerating Bridge Construction, Construction crossing over the railroad
Abstract

    In recent years, New Taipei City Government has made great efforts to develop various constructions and promote tourism. The rapid growth of traffic volume in Tucheng District, Shulin District, Sanxia District and Yingge District must be actively responded and improved, facing the factors such as urgency of transportation construction, road safety requirements, bottleneck section improvement and the demands for access roads to tourism-developing districts. Among other things, the Sanying Bridge is an important one connecting Yingge and Shulin to Sanxia City Road No.110 and Sanying Interchange of National Highway No. 3. As the current service level of traffic has reached F-level during peak hours, in order to actively improve the traffic bottleneck, New Taipei City Government promotes the construction of the Sanying Second Bridge (hereinafter referred to as this project) to connect the 40m road (Dayi Road) in the Designated Area of Taipei University to share the traffic flow of City Road No. 110 and the Sanying Bridge.

    The planned route of the Sanying Second Bridge connects City Road No. 114 in a turning manner after crossing National Highway No. 3, the Dahan River and the track of Taiwan Railway. It adopts the first domestic inverted T-shaped, precast and prestressed beam to strive for the clearance under the bridge and to boost construction to ensure maintaining smooth traffic of national highway. By using large-span steel box girder for the bridge to cross the Dahan River and the track of Taiwan Railway, the design overcomes the risks of construction during the flood season and railway adjacency. This article aims to provide the design considerations and construction experience of this project which is expected to give a constructive reference to the domestic construction community.

TitleDevelopment of Computer-aid Design System for Prestressed Concrete Bridges Considering Weight-minimum
AuthorGuan-Chun Chen, Po-Hsin Lee, Guan-yu Sung, Jia-Hsuan Li, Chih-Hsing Peng, Zheng-Hong Chen, Yu-Chi Sung
KeywordsPrestressed concrete bridges; Weight-minimum design; Program development
Abstract    Based on the specifications of railway bridges and highway bridges, this study developed the computer-aid design system for weight-minimum of prestressed concrete railway bridges. Creep, shrinkage, and relaxation would cause variation of the prestress tendons and deflection of the structure, leading to a lot of analyses in design. Through the computer-aid design system, complicated analysis can be performed quickly to obtain results, reduce human errors, and improve design efficiency.The results show that the optimized section is valid for reducing the superstructure section area by around 20 % and reducing the area of the pier section by around 2.5%.”
TitleSeismic Performance Design of New RC Bridges subjected to Near-Fault Earthquakes
AuthorKuang-Yen Liu, Chen-Yang Wu
Keywordshigh-strength concrete, bridge column, near-fault earthquake, strain rate, seismic performance assessment
Abstract    This study adopts the stress-strain relationship of localized high-strength reinforced concrete to explore the effect of replacing general-strength concrete with high-strength concrete on the reduction of the cross-sectional dimensions of the bridge column and the amount of steel under the same superstructure load. Case analysis shows that the increase in material strength reduces the crosssection of the bridge column, resulting in an extension of the structural period and a decrease in seismic force, which further achieves the dual goal of reducing the main reinforcement of the bridge column. In addition, when the bridge site is located near the fault, if conventional and high-strength reinforced concrete materials are used, and the contribution of the speed pulse to the high strain rate and the enhancement of the material strength is incorporated, it can also effectively reduce the cross-section of the bridge column and save the amount of main reinforcements. The design results adopt the ATC-40 capacity seismic spectrum method and the Fu-R-T strength and ductility reduction method, and the seismic performance assessment are consistent, verifying that the crosssectional size and the amount of steel reinforcement of the high-strength concrete bridge column are more economical.
TitleEffects of Longitudinal Reinforcement and Aspect Ratios on Deteriorated Hysteresis Behaviors of Reinforced Concrete Bridge Columns
AuthorPing-Hsiung Wang, Wei-Chung Cheng, Kuo-Chun Chang
Keywordsreinforced concrete, bridge column, longitudinal reinforcement, aspect ratio, hysteresis behavior, deteriorations
Abstract    To study the effects of longitudinal reinforcement and aspect ratios on the deteriorated hysteresis behaviors of reinforced concrete (RC) bridge columns, five rectangular RC column specimens with hoop and tie reinforcements are tested under cyclic loading considering longitudinal reinforcement ratios of 0.75%, 1.5%, and 3.0% and aspect ratios of 3, 6, and 10. Furthermore, another five circular RC columns with spiral reinforcement and similar test scheme obtained in the literature are included to further compare the differences of deterioration characteristics resulting from various confining mechanisms. Test results show that the stiffness degradation and pinching severity of column would increase as its longitudinal reinforcement decreases. The pinching severity of column would also increase with decreasing aspect ratio, but the stiffness degradation is barely affected by the aspect ratio. Moreover, due to the well confinement effects, the severity of deteriorations of circular columns are less than those of rectangular columns with the same longitudinal reinforcement ratio and the minimum transverse reinforcements required by seismic design codes. Besides, the failure of rectangular columns is mainly caused by the loosening of transverse reinforcements at seismic hooks, leading to gradually deteriorated confinement and strength. In contrast, the failure of circular columns is primarily induced by the fracture of spirals, resulting in destruction of confinement mechanism and sudden strength loss.
TitleRecommendations of Pushover Analysis and 𝑭𝒖- 𝑹- 𝑻 method for Bridge Seismic Capacity Evaluation and its Algorithm
AuthorDzong-Chwang Dzeng, Dzong-Chwang Dzeng, Ching-Yu Liu, Tsan-Hsiang Chou
Keywordsdynamic time history analysis, pushover analysis, capacity curve, capacity spectrum curve, bilinearization, EPA (Effective Peak Acceleration)
Abstract    While the approach combined pushover analysis with 𝐹௨- 𝑅- 𝑇 process is universally adopted in examination and evaluation of seismic capacity for domestic bridge, there are still many aspects to be reviewed, clarified, expanded and improved to further recognize its applicability and variation and to ensure the reliability of the analyzed results. This work presents an algorithm expanding the period 𝑇଴ at the end of constant spetral design acceleration plateau to obtain the 𝐸𝑃𝐴 (effective peak acceleration) corresponding to any spectrum displacement 𝑆ௗ ), establishing the continuous 𝐸𝑃𝐴 and load condition curve (e.g. displacement and plastic hinge ductility ratio) and verifying its applicability and reliability by comparing the results of simplified regular bridge model analysis with nonlinear dynamic time-history analysis. Combining this continuous EPA and load condition curve with seismic hazard at bridge site, it could be the basis for quantified calculation of bride seismic risk costs and the benefits of retrofit. In addition, this work also studies and reviews the bilinearization method of capacity spectrum curve. It proves that a much greater seismic capacity would be obtained by the “non-elastoplastic bi-linearization method” than the “elastoplastic bi-linearization method” . It should be cautious in practical applications.
TitleHysteretic Model Parameters with Using Support Vector Regression
AuthorTzu-Kang Lin, Tzu-Hui Yang, Hao-Tun Chang, Ping-Hsiung Wang, Kuo-Chun Chang
Keywordssupport vector regression, smooth hysteretic model, pinching, stiffness degradation
Abstract    This study developed artificial intelligence–based models for predicting smooth hysteretic model (SHM) parameters. Recently, an SHM based on the Bouc–Wen model was developed to determine damage accumulation and path dependence of reloading. The model comprises five main parameters that describe the seismic behavior of ductile, flexure-dominated reinforced concrete (RC) bridge columns. However, each time-variant parameter can be derived only through practical experiments and cannot be tested on actual structures; therefore, the SHM is not very practical. In this study, support-vector regression (SVR) was adopted to capitalize on the advantages of the developed SHM, which exhibits superior performance to other existing hysteresis models. Nine different RC bridge columns were tested under displacement time histories, and a total of 119 samples were acquired. Of the samples, 80% were used for training and the remaining 20% were used for testing. The longitudinal reinforcement ratio, aspect ratio, and displacement or residual displacement of individual columns were set as the inputs to the SVR models, and the pinching and stiffness degradation parameters were set as the model output. Time-variant parameters could be predicted accurately with low deviation and error percentages. Moreover, hysteresis loops were generated using the identification parameters, and the SVR prediction results were compared with experimental data. The results indicated that the seismic behavior of the RC bridge columns could be estimated with high reliability using the proposed method without the support of experimental progress and support the SHM to predict the degree of damage. “