ABSTRACT

This paper investigates the structural response of unreinforced masonry arches subjected to asymmetrical vertical concentrated loads, by studying global force-displacement response curves and collapse mechanisms. The micromechanical modeling approach is adopted, which describes the detailed arrangement, geometry and mechanical properties of the masonry constituents. This is introduced in a 2D finite element procedure modified and enriched to describe masonry curved geometry and the occurring damage and friction mechanisms. Linear elastic behavior is assumed for bricks, whereas a damage-friction law is considered for the mortar to describe flexural and shear failure mechanisms. First, to prove the efficiency of the adopted model, the response of experimentally tested arches is numerically reproduced. Then, a parametric analysis is performed to analyze the effect of the geometric parameters on the global structural response. It is proved that, as the thickness/internal radius ratio increases, the failure mechanism moves from the formation of flexural hinges to shear sliding, leading to a more brittle response. Moreover, influence of relevant material parameters is investigated and the numerical outcomes are compared with those obtained by the classical limit analysis approach. It appears that the maximum predicted load generally exceeds the limit analysis collapse value, depending on the material properties mostly influencing the failure mechanisms.

摘要

本文通过研究全局力-位移响应曲线和倒塌机制，研究了非加筋砌体拱在不对称竖向集中荷载作用下的结构响应。采用微机械建模方法，描述了砌体成分的详细排列、几何形状和力学性能。这是在修改和丰富的二维有限元程序中引入的，以描述砌体弯曲的几何形状以及发生的损坏和摩擦机制。假定砖具有线性弹性行为，而砂浆则考虑损伤摩擦定律来描述弯曲和剪切破坏机制。首先，为了证明所采用模型的效率，对实验测试拱的响应进行了数值再现。然后，执行参数分析以分析几何参数对整体结构响应的影响。事实证明，随着厚度/内径比的增加，破坏机制从弯曲铰链的形成转变为剪切滑动，导致更脆的响应。此外，研究了相关材料参数的影响，并将数值结果与经典极限分析方法获得的结果进行了比较。似乎最大预测载荷通常超过极限分析坍塌值，这取决于主要影响失效机制的材料特性。破坏机制从弯曲铰链的形成转变为剪切滑动，导致更脆的响应。此外，研究了相关材料参数的影响，并将数值结果与经典极限分析方法获得的结果进行了比较。似乎最大预测载荷通常超过极限分析坍塌值，这取决于主要影响失效机制的材料特性。破坏机制从弯曲铰链的形成转变为剪切滑动，导致更脆的响应。此外，研究了相关材料参数的影响，并将数值结果与经典极限分析方法获得的结果进行了比较。似乎最大预测载荷通常超过极限分析坍塌值，这取决于主要影响失效机制的材料特性。