Modal strain-based post-earthquake damage characterization of r/c frame buildings
Modal strain-based post-earthquake damage characterization of r/c frame buildings
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发表时间：
2018-06
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通讯作者：
Bianca Decarli;A. Giaralis
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作者：
Bianca Decarli;A. Giaralis
本文提出了一种新的数值研究方法，以评估两种最广泛使用的基于模态应变的损伤指标在钢筋混凝土多层平面框架建筑受弯结构构件损伤检测中的潜力。为此，建筑物被视为横向振动的梁状结构，模态应变（即模态振型的二阶导数）是根据在破坏性地震事件之前（健康状态）和之后（破坏状态）沿建筑物高度已知的每层/板水平的横向平移模态振型坐标计算的。采用模态曲率（MC）随建筑高度的变化和模态应变能（MSE）的变化作为损伤敏感指标，并对其在不同楼层柱或梁单元损伤局部化和损伤严重程度表征方面的有效性进行了面对面的测试。这是通过考虑计算机生成的模态振型数据来完成的，这些数据来自应用于两个不同的10层r/c平面框架的有限元模型的线性模态分析，一个是单舱的，一个是双舱的，在健康状态和几种不同严重程度的相对轻损伤状态下。所提供的数值结果表明，对于大多数考虑的损伤情况，基于第一模态振型数据评估的MC指数和由前三个模态振型数据确定的MSE指数都能够同样地定位损伤和表征损伤的严重程度。进一步的研究需要考虑噪声现场记录的模态振型数据的影响，以及稀疏仪器，其中加速度传感器没有部署在每个建筑楼层。
This paper contributes a novel numerical study to assess the potential of the two most widely used modalstrain based damage indices for damage detection in structural components under flexure for post-earthquake damage characterization of reinforced concrete multi-storey planar frame buildings. To this aim, buildings are treated as transversely vibrating beam-like structures and modal strains (i.e., second derivatives of mode shapes) are computed from lateral translational mode shape ordinates known at each floor/slab level along the height of buildings before (healthy state) and after (damaged state) a damaging seismic event. In this setting, the change of modal curvature (MC) along the height of the building as well as the change of modal strain energy (MSE) are adopted as damage sensitive indices and their effectiveness to localize damage to column or to beam elements at different floors and to characterize damage severity is gauged vis-a-vis. This is accomplished by considering computer-generated mode shape data obtained from linear modal analyses applied to finite element models of two different 10-storey r/c planar frames, a single-bay one and a two-bay one, under healthy and several different relatively light damaged states of varying severity. The furnished numerical results demonstrate that both the MC index evaluated based on first mode shape data and the MSE index determined from the first three mode shape data are equally able for both damage localization and severity characterization for most of the damaged case scenarios considered. Further research is warranted to account for the influence of noisy field-recorded mode shape data as well as for sparse instrumentation in which acceleration sensors are not deployed on every building floor.