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.