Vol.37/No.3 (145) (2022)
| Title | Design Revision of Column and Beam-to-Column Moment Connection in Taiwanese Specification of Steel Reinforced Concrete Structures |
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| Author | Yu-Fang Liu, Te-Kuang Chow, Chung-Che Chou, Szu-Jui Huang, Lien-An Chen |
| Keywords | Steel-Reinforced-Concrete (SRC) Structure, Column, Width-to-Thickness Ratio, Beam-to-Column Moment Connection, Shear Strength of Connection, |
| Abstract | The 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. |
| Title | A Study of BRBs using Varying Section Steel Truss Restrainers |
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| Author | Lu-An Chen, An-Chien Wu, Chun Chen, Keh-Chyuan Tsai |
| Keywords | buckling-restrained brace, truss-confined restrainer, flexural rigidity, shear rigidity, buckling load, finite element analysis |
| Abstract | Buckling-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. |
| Title | Discussion on the Residual Capacity and Plastic Hinge Properties of Earthquake Damaged RC Shear Walls |
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| Author | Wen-I Liao, Yu-Ming Zheng, Xuan Ling Chen |
| Keywords | Reinforced concrete, shear wall, residual seismic capacity, plastic hinge |
| Abstract | Due 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. |
| Title | A Review of Seismic Metamaterials for Seismic Protection |
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| Author | Hsu-Ci Su, Hsiang-Jung Wang, Wen-Chung Chang, Tzu-Kang Lin, Cheng-Hung Lin, Tung-Yu Wu, Kuo-Chen Chang, Tung-Yang Chen |
| Keywords | seismic metamaterial, seismic waves, local resonance, periodic structure, wave propagation |
| Abstract | Current 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. |
| Title | Kinematics and Identification Study Applied to the Shaking Table by Using the Actuator Measurement: Take MAST for example |
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| Author | Chin-Ta Lai, Shih-Wei Yeh, Pu-Wen Weng, Fu-Pei Hsiao, Bai-Yi Huang |
| Keywords | shaking 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.” |
| Title | Discussion on“Design of partial rigid joint of precast girder and Beam” by Tzu-Liang Wu and Shyh-Jiann Hwang |
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| Author | Cheng-Ping Chen |
| Keywords | anchorage, load transfer path, shear friction |
| Abstract | This 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. |