Parametric numerical study on two-way bending capacity of unreinforced masonry walls

Abstract

Investigations on unreinforced masonry (URM) walls subjected to natural hazards, such as earthquakes and wind loads, identify the out-of-plane (OOP) failure as one of the most common failure mechanisms. Concerning the OOP failure, two types of failure mechanisms can be distinguished in URM walls: one-way bending in which lateral edges of walls are not supported; two-way bending in which at least one lateral edge of walls is supported in addition to the supports at the top and bottom. Compared with walls in one-way bending, walls in two-way bending are more widely encountered in practice considering that the lateral edges of walls are usually connected with pillars or return walls. Therefore, the failure of URM walls in OOP two-way bending can be more common. Even so, research on the geometric parameters that can have a major influence on the two-way bending capacity of URM walls, such as the aspect ratio, pre-compression and opening, is quite scarce. Due to a lack of experimental evidence and systematic numerical study, the current analytical formulations, namely the Yield Line Method (YLM) incorporated in the European Standard Eurocode 6, and the Virtual Work Method (VWM) incorporated in the Australian Standard AS3700 and Dutch Practical Guideline NEN-NPR 9998, assessing these geometric parameters can be limited in accuracy and application range.
This thesis aims at improving the analytical formulations assessing the influence of geometric parameters on the two-way bending capacity of URM walls. As a starting point, the accuracy and application range of the current analytical formulations are assessed and geometric parameters having a crucial influence on the two-way bending capacity are revealed (Chapter 2). A dataset of 46 testing specimens from 8 international testing campaigns is created and used for the assessment. The analytical formulations based on the VWM are found to return the most accurate predictions for the testing specimens. Even so, drawbacks and limitations are identified for the VWM. Besides, the precompression, wall aspect ratio and openings are identified to have a crucial influence on the two-way bending capacity of URM walls....