Limit states of modern unreinforced clay brick masonry walls subjected to in-plane loading

Abstract

Recent research showed that the in-plane horizontal displacement capacity of unreinforced masonry (URM) walls depends on numerous factors that are not yet captured by current empirical drift capacity models; e.g., axial stress, shear span, geometry of the walls and the material used. In order to improve the performance-based assessment of URM wall buildings, future research should aim at developing numerical and mechanical models that link the global force-displacement response of URM walls to local deformation measures such as strains. This paper addresses the behaviour of modern clay brick masonry and makes first contributions to such an endeavour by the evaluation of experimental results: first, two sets of limit states are proposed that link local damage limit states to characteristic points of the global force-displacement response of the URM wall. The two sets define limit states for walls developing a shear or a flexural mechanism respectively. Second, local deformation measures deemed suitable for the characterisation of these limit states are evaluated from optical measurement data of quasi-static cyclic wall tests. These include strains, compression zone depth and the ratio of shear to flexural deformations.

Force–displacement response of in‐plane‐loaded URM walls with a dominating flexural mode

“…assumption only holds as long as no significant diagonal crack separates the walls [20]; this limits the application of the model to walls with a dominating flexural mode. For determining the displacement capacity of flexure-dominated URM walls, local LSs need to be predicted as well as their influence on the kinematics of the wall implemented in the model from Section 3.…”

“…Experiments showed that walls do not reach lateral load failure with the occurrence of first splitting cracks (LS-F3) but that at this instant, the walls are still able to sustain the applied lateral load and that the load can even increase slightly until first parts of the compression zone break completely apart (LS-F4, [20]). Figure 6 shows the crack pattern in the compression zone just after reaching LS-F3 (Figure 6(a)) and just before LS-F4 occurred (Figure 6(b)).…”

“…It is assumed that the continued formation of cracks when loading beyond LS-F3 allows a certain stress redistribution in the compressed toe [20]. The resulting reduction of the compression length at LS-F4 is restricted to account for the limited deformation capacity of masonry in compression.…”

“…Optical measurements taken during the testing of the walls yielded information on the walls' displacement fields. From these measurements, the shear and flexural horizontal displacement components are computed [20] and compared with the predicted displacement components in Figure 9. In Figure 10, the vertical displacement and the top rotation are compared.…”

Editorial for the VEESD 2013 special issue

“…Penna (2015) discusses in his contribution several aspects of the seismic response and capacity of stone masonry buildings. By the evaluation of experimental results Petry and Beyer (2015) address the horizontal in-plane …”