Numerical Analysis of Different Influencing Factors on the In-Plane Failure Mode of Unreinforced Masonry (URM) Structures

The research work herein presented is aimed at investigating the effects of different influencing factors on the in-plane failure mode of unreinforced masonry (URM) structures. Firstly, the in-plane stress failure criterion cited in this paper was introduced, and the corresponding judgment procedure was demonstrated. Then, various finite element models considering different influencing factors were established, which included the aspect ratio of pier (eta), stiffness ratio of pier to spandrel (rho) and vertical load (sigma). Furthermore, the in-plane stress failure criterion that we introduced was used to evaluate the failure modes of each model. The main findings of the simulations were as follows: under the condition of (eta <= 1.0), three failure modes emerged in all models, which included pier, mixed and spandrel failure modes, with the gradual increase in rho. Once the value of eta exceeded 1.0, all models exhibited the pier failure mode regardless of whether the value of rho increased or decreased. Moreover, under the identical aspect ratio (eta = 1.0), the failure modes of the models altered regularly with the increase in the value of sigma (from 0.3 MPa to 0.6 MPa), which transferred from pier failure to mixed failure, and from mixed failure to spandrel failure. The research results not only provide theoretical reference for the design of new masonry buildings, but also provide technical guidance for the judgement and prediction of failure modes of existing masonry buildings.