不同温度和位移边界下混凝土楼板配筋建议

Suggestions for reinforcement increment in concrete floor slabs under different temperature and displacement boundary conditions

为了定量地确定温度对楼板承载能力和裂缝宽度的影响,在温度场和应力场有限元分析理论的基础上,采用ANSYS软件,对角板和边板2种温度边界条件和多种位移约束条件下的楼板,进行数值模拟分析.结果表明,相对于楼板的承载能力,温度应力对裂缝的影响更大.考虑温度应力后,楼板将从纯弯构件变成拉弯构件,满足承载能力的楼板配筋将增加,同时,温度应力将导致楼板裂缝宽度增大.在实际应用中,为简化计算,对于有明显温差影响的楼板,仍可按纯弯构件计算,但满足此纯弯构件承载能力和裂缝宽度所得配筋量,建议分别增加15%和25%,以抵消温度应力所致钢筋应力的增量.

In order to quantitatively determine the temperature effects on the bearing capacity and width of crack in slabs, on the basis of finite element method analyses of temperature field and stress field, two kinds of floor slabs with different temperature and various displacement constraint boundary conditions were analyzed employing ANSYS software. The results show that temperature stresses have greater im- pact on crack width than on bearing capacity in floor slab. After considering the temperature stress, the mechanical behaviors of slabs are transformed from pure bending to bending combined with axial tension, hence, reinforcements of floor slabs required for bearing capacity should be increased. Meanwhile, the temperature will also lead to the crack width broadening. In practice application, the floor slabs subjected to obvious temperature impacts can still be calculated as pure bending elements in order to simplify compu- tation, however, whose reinforcements required for bearing capacity and crack width resisting are sugges- ted to increase 15~ and 25~, respectively, so as to safely counteract the temperature influences on the in- crement of reinforcement stress in floor slabs.