A simplified design procedure for seismic retrofitting of RC frames with setbacks using eccentric steel braces having vertical shear link elements

IF 3.8 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Bulletin of Earthquake Engineering Pub Date : 2025-04-04 DOI:10.1007/s10518-025-02163-4

Amar Louzai, Ahmed Abed

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引用次数: 0

Abstract

The main aim of this study is to derive a simple design procedure to determine the required sizes of vertical shear links and eccentric steel braces for the seismic retrofitting of an existing reinforced concrete frame structure with in-elevation irregularities due to setbacks designed for gravity load only. The proposed procedure distributes the vertical shear links and eccentric steel braces over the height of the structure to dissipate seismic energy away from the main structural members without any numerical iterative strategy. In fact, the capacity curve through the extension of the improved upper-bound pushover analysis method, adapted to the frame structures with setbacks, and the capacity spectrum method are the only required input parameters. A six-story RC frame structure with a towered type of setback at the second story is used in a numerical investigation to assess the effectiveness of the proposed design procedure. The structure has to be retrofitted to withstand the seismic demand imposed by the current Algerian seismic design code in a high-risk area. Nonlinear time-history analyses of original non-retrofitted and retrofitted frames are carried out considering a set of seven artificially generated records for obtaining the mean value of structural responses, which corresponds to the specified seismic demand. The results show that the proposed simplified design procedure is effective in significantly reducing both global and local seismic demand parameters and in avoiding structural instability due to the formation of a column-hinging mechanism, which has occurred at the second story where the setback is located.

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利用具有垂直剪力连接件的偏心钢支撑对后退的 RC 框架进行抗震改造的简化设计程序

本研究的主要目的是推导出一个简单的设计程序，以确定现有钢筋混凝土框架结构的抗震改造所需的垂直剪切连接和偏心钢支撑的尺寸，该框架结构由于仅为重力荷载设计的挫折而产生高度不规则。所提出的程序在没有任何数值迭代策略的情况下，将垂直剪切连接和偏心钢支撑分布在结构的高度上，以分散主要结构构件的地震能量。实际上，通过扩展改进的上界推覆分析方法得到的容量曲线，适用于具有挫折的框架结构，而容量谱法是唯一需要的输入参数。一个六层的钢筋混凝土框架结构，在第二层有一个塔式的挫折，用于数值调查，以评估所提出的设计程序的有效性。该结构必须进行改造，以承受当前阿尔及利亚在高风险地区的地震设计规范所施加的地震要求。考虑一组人工生成的7条记录，对原始未改装和改装框架进行非线性时程分析，得到符合规定抗震要求的结构响应均值。结果表明，所提出的简化设计程序有效地降低了整体和局部地震需求参数，并避免了由于柱铰机制的形成而导致的结构失稳，这种失稳发生在挫折所在的第二层。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Bulletin of Earthquake Engineering 工程技术-地球科学综合

CiteScore

8.90

自引率

19.60%

发文量

263

审稿时长

7.5 months

期刊介绍： Bulletin of Earthquake Engineering presents original, peer-reviewed papers on research related to the broad spectrum of earthquake engineering. The journal offers a forum for presentation and discussion of such matters as European damaging earthquakes, new developments in earthquake regulations, and national policies applied after major seismic events, including strengthening of existing buildings. Coverage includes seismic hazard studies and methods for mitigation of risk; earthquake source mechanism and strong motion characterization and their use for engineering applications; geological and geotechnical site conditions under earthquake excitations; cyclic behavior of soils; analysis and design of earth structures and foundations under seismic conditions; zonation and microzonation methodologies; earthquake scenarios and vulnerability assessments; earthquake codes and improvements, and much more. This is the Official Publication of the European Association for Earthquake Engineering.