Numerical modelling of in-plane behaviour of URM walls and an investigation into the aspect ratio, vertical and horizontal post-tensioning and head joint as a parametric study

Masonry is a complex composite material with non-linear material properties, which make the numerical investigation of its structural behaviour a difficult task. In this paper, a micro non-linear model created using a general purpose finite element code, is discussed with respect to its ability to simulate the in-plane behaviour of unreinforced masonry walls. That is, the capability of model in predicting the cracking, crushing, and sliding phenomena, as well as the global-orthotropic behaviour of previously tested masonry walls are examined. The model is then used within a parametric study to investigate the effect of different aspect ratios, vertical and horizontal post-tensioning as well as the effect of head joints on the capacity of the masonry walls. It will be shown that, while enhancing the lateral in-plane strength of the masonry walls, vertical post-tensioning can also reduce their ductility. On the contrary, horizontal post-tensioning can cause a small reduction in the initial stiffness and yielding shear force of the masonry walls, but increases their integrity, thereby preventing them from sliding and shear failure. Furthermore, it will be shown that, in spite of having a significant influence on local behaviour, head joints do not influence the global behaviour of the masonry walls.