Stability of unreinforced masonry members under simultaneous vertical and out-of-plane lateral loads.

摘要

A description of the state-of-the-art studies of the stability of unreinforced masonry members under simultaneous vertical and out-of-plane lateral loads is presented in Chapter 1. The uniaxial stress-strain relationships that have been used for the out-of-plane masonry stability are reviewed and commented. The slenderness parameter is defined and the scope of this research is described.; In Chapter 2, a two-dimensional finite element model is developed for the combined material and geometric nonlinear analysis of slender URM members. The masonry is treated as a homogeneous material with some tensile strength. Stress resultants are computed by explicit rather than numerical integration. Displacement control and arc-length control method are implemented and used to trace the entire equilibrium path.; In Chapter 3, the finite element model is validated by comparing the computed numerical results against the analytical and numerical results available in published literature and the experimental results obtained from two groups of tests respectively for solid and hollow URM walls.; In Chapter 4, the out-of-plane lateral behavior of slender solid URM members under monotonic proportional loading is investigated systematically, using a very slender wall with a height-thickness ratio of 30 under different restraint conditions. The influence of tensile strength, restraint and load conditions on the stability about the weak axis is emphasized.; In Chapter 5, the results obtained by the FEM model are presented for a slender hollow URM member with different cavity depths and subjected to simultaneous vertical and out-of-plane lateral loads. The influence of cavity depth on stability is emphasized.; In Chapter 6, tentative design formulas for checking the stability of slender URM members based on the numerical results obtained from the FEM model are put forward.; In Chapter 7, the effect of initial imperfections on the global stability behavior of URM members is investigated. Two overall reduction factors accounting for the effect on the buckling capacity, respectively for new and existing URM members, are proposed.; In Chapter 8, the stability behavior of URM members subjected to two-phase loading is investigated. Comparisons are made between the results of an URM member under two-phase loading and under proportional loading.