ABSTRACT

Coupled shear walls (CSW) are an efficient lateral load-resisting system. Their seismic performance depends primarily on their coupling beams (CBs) ability to provide adequate stiffness and strength. However, many existing buildings with CSW resisting system were designed and constructed according to old codes and standards with insufficient requirements for seismic design. These systems feature unsatisfactory behaviour and prematurely collapse in case of major earthquake events. Therefore, their seismic retrofit is urgently needed. The main objectives of this study are, i) evaluate and compare the seismic performance of CSWs designed to old and new codes; ii) highlight the deficiencies of CSWs designed to old codes; iii) investigate a retrofit method using externally bonded (EB) carbon fibre reinforced polymer (CFRP) composites to enhance the seismic response of deficient CSWs. To that end, a 20-story CSW is considered with different design details including one according to old National Building Code of Canada (NBCC) before the 1970s and the other one designed consistent with the new NBCC 2015 National Building Code of Canada (NBCC). 2015. Institute for research in construction, National research council of Canada, Ottawa, Ont. [Google Scholar] and the Canadian Standard Association, CSA A23.3–14, for Eastern seismic Canadian zone. The nonlinear analyses of CSWs under earthquake records are conducted in two steps. At first, the nonlinear time-history analyses of two types of CSWs are carried out using RUAUMOKO program and the deficiencies of old-designed CSW are identified through the comparison of obtained results. In the second step, the old design CSW is retrofitted using CFRP sheets and reanalysed to investigate the benefits of the retrofit technique in mitigating the shortcomings. The results indicate that CFRP retrofitting is an efficient method to enhance the seismic performance of deficient old CSWs in terms of story displacement, inter-story drift, CBs rotation, and ductility demand.

摘要

耦合剪力墙 (CSW) 是一种有效的横向抗荷载系统。它们的抗震性能主要取决于它们的连梁 (CB) 提供足够刚度和强度的能力。然而，现有的许多抗CSW系统的建筑物都是按照旧的规范和标准设计和建造的，对抗震设计的要求不足。这些系统的特点是性能不理想，并且在发生重大地震事件时会过早崩溃。因此，迫切需要对其进行抗震改造。本研究的主要目标是，i) 评估和比较根据新旧规范设计的 CSW 的抗震性能；ii) 突出针对旧规范设计的 CSW 的缺陷；iii) 研究一种使用外部粘合 (EB) 碳纤维增强聚合物 (CFRP) 复合材料的改造方法，以增强缺陷 CSW 的地震响应。为此，考虑了具有不同设计细节的 20 层 CSW，其中一个根据 1970 年代之前的加拿大国家建筑规范 (NBCC)，另一个根据新的 NBCC 设计2015加拿大国家建筑规范 (NBCC)。2015 年。建筑研究所，加拿大国家研究委员会，安大略省渥太华。 [Google Scholar]和加拿大标准协会，CSA A23.3-14，针对加拿大东部地震带。地震记录下 CSW 的非线性分析分两步进行。首先，利用 RUAUMOKO 程序对两种类型的 CSW 进行了非线性时程分析，并通过对所得结果的比较找出了旧设计的 CSW 的不足之处。第二步，使用 CFRP 板对旧设计的 CSW 进行改造，并重新分析以研究改造技术在减轻缺点方面的好处。结果表明，CFRP 改造是一种有效的方法来提高有缺陷的旧 CSW 在层位移、层间漂移、CB 旋转和延性需求方面的抗震性能。