• Title/Summary/Keyword: seismic performance

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Seismic performance of RC columns with full resistance spot welding stirrups

  • Yu, Yunlong;Dang, Zhaohui;Yang, Yong;Chen, Yang;Li, Hui
    • Structural Engineering and Mechanics
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    • v.73 no.5
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    • pp.543-554
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    • 2020
  • This paper aims to investigate the seismic performance of RC short columns and long columns with welding stirrups. Through the low-cyclic horizontal loading test of specimens, the seismic performance indexes such as failure modes, hysteretic curve, skeleton curve, ductility, energy dissipation capacity, stiffness degradation and strength degradation were emphatically analyzed. Furthermore, the effects of shear span ratio, stirrups ratio and axial compression ratio on the performance of specimens were studied. The results showed that the seismic performance of the RC short columns with welding stirrups were basically the same as that of the RC short columns with traditional stirrups, but the seismic performance of RC long columns with welding stirrups was better than that of RC long columns with traditional stirrups. The seismic performance of RC short columns and long columns with welding stirrups could be improved by increasing stirrup ratio and shear span ratio and reducing axial pressure ratio. Moreover, the welding stirrup have the advantages of steel saving, industrialization and standardization production, convenient construction, and reducing time, which indicated that the welding stirrups could be applied in practical engineering.

Development of Preliminary Seismic Performance Evaluation Method for Residential Piloti Buildings Using Stiffness-Based Soft Story Ratios (강성기반 연층비를 활용한 주거형 필로티 건축물의 내진성능예비평가 기법 개발)

  • Choi, Jae-Hyuk;Choi, Insub;Kim, JunHee;Sohn, JungHoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.34 no.4
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    • pp.175-182
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    • 2021
  • There have been many instances of damage to buildings with soft stories, and it is important to consider vertically irregular buildings when evaluating the seismic performance of existing buildings. However, because conventional methods do not easily reflect vertical irregularities with sufficient accuracy, it is possible to underestimate or overestimate the seismic performance of buildings with vertical irregularities. This study aims to develop a seismic performance evaluation method for vertically irregular buildings using the stiffness-based soft story ratio (SSR), which is a parameter that represents the ratio of the demand and the capacity for displacement and refers to the ratio of displacement concentration in buildings. The seismic performance evaluation method developed in this study is compared with the conventional seismic performance evaluation method for four piloti buildings, using the first-floor column as a variable. Conventional seismic performance evaluation methods often overestimate the seismic performance for models in which vertical irregularities are maximized. However, results of the proposed seismic performance evaluation method are identical to those from a detailed evaluation for all models. Therefore, it is considered that the proposed seismic performance evaluation method can provide more precise seismic performance evaluation results than conventional methods in the case of piloti buildings, where vertical irregularities are maximized.

Evaluation of Seismic Performance for Bridge Structure Using Capacity Spectrum Method (역량스펙트럼법을 이용한 교량의 내진성능평가)

  • 이창수;김승익;김현겸
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.75-80
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    • 2000
  • Evaluation method of seismic performance has mainly used elastic spectrum analysis. This method has simplicity of analysis but deficiency of accuracy. And evaluation method of seismic performance using inelastic dynamic analysis reflects accurately inelasticity of material but hardly reflects site effects. This study suggested evaluation scheme of seismic performance for bridge structure using capacity spectrum method applied inelastic static analysis and standard design response spectrum of Korea Standard Specification for Highway Bridge. Two results, capacity spectrum method and inelastic dynamic analysis method, are very similar. As a result, this study appropriately supply both simplicity of analysis and accuracy of result.

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Experimental study on seismic performance of reinforced concrete frames retrofitted with eccentric buckling-restrained braces (BRBs)

  • Yang, Yong;Liu, Ruyue;Xue, Yicong;Li, Hui
    • Earthquakes and Structures
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    • v.12 no.1
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    • pp.79-89
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    • 2017
  • As a new type of energy dissipation component with excellent mechanical performance, the Buckling-Retrained Braces (BRBs) were gradually applied in retrofitting and improving seismic performance of reinforced concrete structures in China. In order to investigate the seismic performance of reinforced concrete structures retrofitted with BRBs, quasi-static test of two single-bay and 3-story reinforced concrete frames specimens was conducted and introduced in this paper. Two 1/2 scaled specimens were designed to reflect real prototype structure. For comparison, one control specimen was designed without BRBs, and the other specimen was retrofitted with BRBs. And particularly, for the specimen retrofitted with BRBs, the BRBs were eccentric layout instead of usually concentric or x-shaped layout, aiming to be more suitable for large-span frames. In the test, the failure mode, carrying capacity, deformability, ductility and energy dissipation ability of both two specimens were investigated. Based on the test results of the measured hysterical curves, skeleton curves, the seismic performances such as bearing capacity, plastic deformability, energy dissipation ability and ductility of two specimens were fully studied. And from the test results, it was indicated that the specimen retrofitted with BRBs showed much better seismic performance than the control specimen without BRBs, and the BRBs could effectively improve the seismic performance of the reinforced concrete frame. For the specimen retrofitted with BRBs, the BRBs firstly yielded before the beam-ends and the column-ends, and an expected yielding process or yielding mechanism as well as good seismic performance was obtained. For the specimens without BRBs, though the beam-ends yielded prior to the column-ends, the seismic performance was much poor than that of the specimen with BRBs.

Seismic Performance Index of Reinforced Concrete Shear Wall Buildings (철근콘크리트 전단벽식 건물의 내진성능지수)

  • 권영웅`;김민수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.148-151
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    • 2003
  • This paper concerns the seismic performance index of highrise reinforced concrete shear wall buildings assessed by FEMA 273 and ATC-40 provisions. The applied buildings are 10 to 35 stories and the evaluation level is life safety level. The seismic performance index results of $1^{st}$ and $2^{nd}$ evaluations are as follows; (equation omitted)

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Seismic Performance Level Criteria and Evaluation Methods (기존시설물 내진성능평가를 위한 평가항목 분류체계와 평가방법)

  • 김남희
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.251-260
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    • 2000
  • Seismic performance evaluation systems require rational classification of structure systems, proper evaluation criteria, and their scoring index for synthesis. Current seismic performance systems need expert judgments based on collection of available data, approximate analysis of important items, and various scoring system. This study presents a three-step seismic performance evaluation system for building structures in Korea. Each evaluation step determines the seismic performance and the method depends on the degree of refinement of analysis. The preliminary step evaluation involves the global attributes of structures such as vertical irregularity, asymmetric plan, redundancy, and age of structures. The second step requires an elastic analysis for estimation of forces acting on critical sections and checks the strength and ductility. The final step requires inelastic capacity of structures. Each stephas own evaluation scheme with proper weighing factor dependent on the importance and consequence. This study applies the fuzzy theory to a scoring method that synthesizes the individual quantity to a representative value.

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Evaluation of Seismic performance of RC setback frames

  • Habibi, Alireza;Vahed, Meisam;Asadi, Keyvan
    • Structural Engineering and Mechanics
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    • v.66 no.5
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    • pp.609-619
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    • 2018
  • When the irregularities occurred in buildings, affect their seismic performance. This paper has focused on one of the types of irregularities at the height that named setback in elevation. For this purpose, several multistorey Reinforced Concrete Moment Resisting Frames (RCMRFs) with different types of setbacks were designed according to new edition of Iranian seismic code. The nonlinear time history analysis was performed to predict the seismic performance of frames subjected to seven input ground motions. The assessment of the seismic performance was done considering both global and local criteria. Results showed that the current edition of Iranian seismic code needs to be modified in order to improve the seismic behaviour of reinforced concrete moment resisting setback buildings. It was also shown that the maximum damages happen at the elements located in the vicinity of the setbacks. Therefore, it is necessary to strengthen these elements by appropriate modification of Iranian seismic code.

Seismic Performance Improvement of Concrete Gravity Dam by Post-tensioned Anchors (앵커공법을 적용한 기존 콘크리트 중력식 댐의 내진성능 보강방안)

  • Kim, Yongon;Kim, Se-Il;Ok, Seung-Yong
    • Journal of the Korean Society of Safety
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    • v.28 no.5
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    • pp.49-53
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    • 2013
  • This paper describes the assessment of seismic performance of the concrete gravity dam seismically reinforced by post-tensioned anchors. In order to evaluate the seismic performance, the response spectrum analyses have been carried out for 7 different configurations of the post-tensioned anchors, and then their performance improvement in the maximum tensile and compressive stresses is compared to each other. The comparative results demonstrate that the layout of the post-tensioned anchors strongly influences the seismic performance of the concrete gravity dam. In this study, the slightly-inclined vertical anchorage system shows the largest improvement on the overall performance of the seismically-excited concrete gravity dam.

Use of SMA bars to enhance the seismic performance of SMA braced RC frames

  • Meshaly, Mohamed E.;Youssef, Maged A.;Abou Elfath, Hamdy M.
    • Earthquakes and Structures
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    • v.6 no.3
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    • pp.267-280
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    • 2014
  • Shape Memory Alloy (SMA) braces can be used to reduce seismic residual deformations observed in steel braced Reinforced Concrete (RC) frames. To further enhance the seismic performance of these frames, the use of SMA bars to reinforce their beams is investigated in this paper. Three-story and nine-story SMA-braced RC frames are designed utilizing regular steel reinforcing bars. Their seismic performance is examined using twenty seismic ground motions. The frames are then re-designed using SMA reinforcing bars. Different design alternatives representing different locations for the SMA reinforcing bars are considered. The optimum locations for the SMA bars are identified after analysing the design alternatives. The seismic performance of these frames has indicated better deformability when SMA bars are used in the beams.

A study on the Seismic Performance Evaluation Process for Urban Railway Bridges (도시철도 교량의 내진성능 평가체계에 관한 연구)

  • Park, Beom-Ho;Lee, Tae-Hyung;Kim, Kee-Dong;Lim, Nam-Hyoung
    • Proceedings of the KSR Conference
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    • pp.1143-1147
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    • 2010
  • The verification of the seismic performance of many urban railway bridges will be done or is done by the regulations of "Seismic Performance Evaluation Methods(Tips) of Existing Bridges" developed by KISTEC in 2004. This present process may involve some of the issues such as the unreflecting of the characteristics of the urban railway bridge and the appearance of ductility-based seismic design method. In this paper, the new and improved seismic performance evaluation system is proposed.

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