Nonlinear analysis of large scale masonry structures

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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.