Best Practice Techniques for Numerical Modelling of Complex Unreinforced Masonry Buildings

Abstract

Masonry is a composite material with highly variable and relatively uncertain anisotropic mechanical properties. In contrast to other popular construction materials such as reinforced concrete and steel, common numerical modelling approaches are not fully applicable to unreinforced masonry (URM) buildings, and serious mistakes can be made if engineering practitioners lack fundamental knowledge on how to model the specific characteristic of URM buildings. In New Zealand, concerns have been raised on the performance and safety of URM buildings following the 2010/2011 Canterbury earthquakes. A New Zealand methodology for the detailed seismic evaluation of simple one- and two-storey URM buildings where extensive numerical modelling is not required, has been published to provide a hand-based analysis for seismic assessment. However, currently no New Zealand guidance available to practicing engineers on appropriate strategies for the numerical modelling of complex URM buildings. In response to this situation, a literature review was undertaken to summarise appropriate URM modelling techniques and subsequently determine best practices using available resources in the structural engineering industry. In this thesis, major components of a numerical modelling strategy are first addressed, including modelling methods and analysis procedures, with a focus on modelling complex URM buildings to determine their potential seismic deficiencies. A new classification of URM buildings based on damage mechanism was proposed for the purpose of numerical modelling. Furthermore, a systematic numerical modelling framework is promulgated as an easy-to-follow guidance for modelling the seismic response of URM structures. There is six proposed types of building within the framework, from simple and small scale buildings to large scale multi-storey buildings including special structures with complex geometry. The appropriate modelling strategies are summarized in the modelling framework and the best practice for each type of buildings is recommended. A case study of the Basilica of the Sacred Heart in Timaru, New Zealand is used to illustrate application of the proposed numerical modelling framework to an actual project. Finitediscrete element method and macro-block method are adopted in the case study for the modelling of complex geometry and seismic response of URM church. A detailed modelling procedure is demonstrated through the case study which provided a good technical reference for practicing engineers.