砌体墙体积变化应力分析与伸缩缝间距

STRESS IN MASONRY WALLS DUE TO VOLUME CHANGES AND SPACING OF MOVEMENT JOINTS

非烧结砖砌体结构房屋通常在底层窗台出现竖向裂缝,这类裂缝一般认为是由于砌体体积收缩受到地基或基础的约束引起。为了探索这类裂缝的开裂机理,采用应力函数法推导了砌体体积变化作用下墙体的平面应力问题的弹性力学解答,提出了地基或基础对墙体水平变形约束作用的基本假定,在此假定和墙体的边界条件基础上,得到了较为简便的墙体体积变化的应力分析方法。通过分析得出了在地基约束下墙体的应力分布规律,研究了影响墙体最大水平拉应力和墙体最大伸缩缝间距的主要因素,并将研究结果与我国现行规范进行了比较分析。

The vertical cracks usually appear in the unburned brick masonry wall beneath the window opening of the ground floor. The cracks are generally due to the volume shrinkage of masonry wall, which is constraint by the foundation or the ground. In order to explore the cracking mechanism, the effect of volume changes of masonry wall was investigated in the context of elasticity theory in plane stress condition by the stress function method. The hypothesis of the restraint actions in the horizontal direction between the ground and the masonry wall was proposed, and the simpler stress analysis method of volume changes was obtained according to the hypothesis and the boundary conditions of the masonry wall. Then the stress distribution of the masonry wall restricted by the foundation or the ground was obtained. The maximal horizontal tensile stress and the movement joint spacing of masonry walls were studied, and compared with the provisions in Chinese Code.