Abstract

Asymmetric structures experience higher seismic damage compared with their symmetric counterparts. This damage is mainly attributed to the coupled torsional vibrations, which tend to induce twisting in the structural floors and increase the shear demands in the corner column of the flexible side (CCFE) of asymmetric structures with in-plan stiffness eccentricity. Such floor twisting consequently leads towards the damage concentration in the critical region of CCFE and produce relatively higher local deformations and stiffness degradation of the structural component. Therefore, the investigation of such damage concentration is important as it can potentially lead towards local and global seismic failure. In this regard, this research aims at evaluating the damage behaviour of CCFE of a plan-asymmetric reinforced concrete (RC) structure. For this purpose, a quarter scaled asymmetric structure with in-plan stiffness eccentricity was experimentally tested under progressive seismic excitations. Internal seismic damage in the critical region of CCFE was monitored using Fibre Bragg grating (FBG) sensors during the structure’s transformation from elastic state to a highly plastic state. To validate the experimental findings, a calibrated finite element model was established in ABAQUS and a comparison of the damage behaviour of CCFE is presented to highlight the influence of stiffness eccentricity on damage concentration in the critical structural element. Finally, based on the experimental and numerical investigations, the mechanism of the local response behaviour both at the flexible and stiff edge of the plan-asymmetric structure is discussed and compared. This research concludes that CCFE in plan-asymmetric structures requires substantial design redundancy and special seismic detailing to resist extreme seismic events.

摘要

与非对称结构相比，非对称结构遭受的地震破坏更高。这种损坏主要归因于扭转振动耦合，它倾向于在结构地板上引起扭曲，并增加具有平面内刚度偏心的非对称结构的柔性边角（CCFE）的角柱的剪力要求。因此，这种地板扭曲导致损伤集中在CCFE的关键区域，并导致结构部件的局部变形和刚度降低。因此，对这种破坏集中度的研究很重要，因为它有可能导致局部和全局地震破坏。在这方面，本研究旨在评估平面不对称钢筋混凝土（RC）结构CCFE的破坏行为。为此，在渐进式地震激励下，对具有平面内刚度偏心度的四分之一比例非对称结构进行了实验测试。在结构从弹性状态转变为高塑性状态期间，使用光纤布拉格光栅（FBG）传感器监控了CCFE关键区域的内部地震破坏。为了验证实验结果，在ABAQUS中建立了校准的有限元模型，并对CCFE的破坏行为进行了比较，以突出刚度偏心率对关键结构元件中破坏集中的影响。最后，在实验和数值研究的基础上，讨论并比较了平面非对称结构在柔性和刚性边缘处的局部响应行为机理。