Nonlinear analysis of large scale masonry structures

本文提出的主要研究目的是研究魁北克水电公司的一些发电站和变电站的无筋砌体结构的抗震性能。重点是评估相应的安全相关边际和评估不同的改造策略。Hydro-Quebec的砖石建筑位于魁北克南部和东部的地震带，是具有复杂几何形状的具有战略意义的大型结构。它们的分析需要超越当前工程实践的先进方法。所提出的研究具有很强的基础成分，涉及用于描述结构砌体非弹性响应的基于连续体的本构关系的发展。该公式将调用中观和宏观分析。中尺度方法的目标是双重的；它可以用于小型砌体结构（例如砖墙/拱门）的分析，这里主要感兴趣的是，它可以提供一组开发宏观方法所需的“虚拟数据”。后者，即连续体表示，将考虑结构各向异性的影响，以及与离散宏观裂纹扩展相关的不连续破坏模式的描述。在细观和宏观尺度上发展的本构关系将被纳入有限元分析的框架。还将开发一个专门的包，用于识别嵌入在连续体描述中的材料功能。这里的输入是来自中尺度分析的“虚拟数据”。将对Hydro-Quebec选定的一些大型砌体结构进行广泛的非线性地震分析，使用加拿大NBC指定的适当加速度计。数值分析的主要结果将是提出一套关于适当和经济地翻新和提高这些结构的战略的建议。

The main objective of the research proposed here is to examine the seismic performance of unreinforced masonry structures for a number of powerhouses and sub-stations of Hydro-Quebec. The focus is on assessment of the corresponding safety-related margins and evaluation of different retrofit strategies. The masonry buildings of Hydro-Quebec, which are located in seismic zones of southern and eastern Quebec, are large-scale structures of strategic importance that have a complex geometry. Their analysis requires advanced methodologies that go beyond the current engineering practice. The proposed research has a strong fundamental component that deals with the development of continuum-based constitutive relations for describing the inelastic response of structural masonry. The formulation will invoke both meso and macroscale analysis. The objective of the mesoscale approach is two-fold; it can be employed for analysis of small scale masonry structures (e.g. brick walls/arches) and, what is of primary interest here, it can provide a set of 'virtual data' that is required to develop a macroscale approach. The latter, i.e. the continuum representation, will account the effects of structural anisotropy as well as description of a discontinuous failure mode associated with propagation of discrete macrocracks. The constitutive relations developed at both meso and macroscale will be incorporated in the framework of finite element analysis. A specialized package will also be developed for identification of material functions embedded in the continuum description. The input here will the 'virtual data' from mesoscale analysis. Extensive nonlinear seismic analysis will be performed for a number of selected large-scale masonry structures of Hydro-Quebec using appropriate accelerograms specified by NBC of Canada. The main outcome of the numerical analysis will be a set of recommendations regarding the strategy for an adequate and economic refurbishment and upgrading of these structures.