Seismic Analysis of Multi-story Unreinforced Masonry Buildings with Flexible Diaphragms

Keywords: Unreinforced masonry, flexible diaphragms, out-of-plane loading, earthquake simulator tests, seismic assessment, performance based assessment.

Abstract: The main goal of this study was to develop simulation capabilities supported by experimental testing to evaluate the seismic performance of typical unreinforced masonry buildings with flexible diaphragms located in NYC. Simplified nonlinear macro-models of wood diaphragms, masonry walls and floor-to wall connections were developed and validated individually using data from past experiments. The models are implemented in both commercial and research software to demonstrate their practical use. In particular, a new approach for modeling flexible diaphragms is proposed that is shown to provide similar accuracy to detailed finite element models at a fraction of the computation cost. The models developed were also validated at the system level, through shake table testing of two full-scale specimens conducted as part of this study. The specimens were designed and constructed to represent the expected loading conditions of a central portion of a one-story URM building and constructed of materials representative of older masonry construction. The tests provide a unique data set that captures the interaction between flexible floors, out-of-plane walls and their connections at full scale.