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运用ANSYS有限元软件,建立三维有限元模型对一个纵向8个开间、横向2间进深的砖混结构多跨连续板收缩裂缝进行数值分析。现浇板的收缩作用是通过对板施加当量温差实现的。数值计算后,在后处理程序中可查看现浇板的应力云图,用路径操作的方法可以得到现浇板的纵向和横向第一主应力-位置曲线。现浇板混凝土收缩产生的最大拉应力主要分布在板的4个大角,以及墙体和现浇板的边界处,板跨中处较小。沿着现浇板的纵向,从端部房间到中部房间拉应力逐步增大,增大率只有5%―7%。现浇板的纵向和横向拉应力相差不大。现浇板跨中无穿线管时,最大应力出现在墙体和现浇板的边界处;而跨中设置了穿线管后,跨中出现了明显的应力集中,这成为穿线管处易出现收缩裂缝的主要原因。现浇板收缩应力的大小,取决于楼层墙体侧移刚度,墙体侧移刚度与墙体的水平截面面积成正比。增大墙体间距,能够减小墙体侧移刚度,从而减小现浇板收缩应力的水平。
ANSYS finite element software was used to establish a three-dimensional finite element model for numerical analysis of a shrinkage crack in a multi-span continuous slab with 8 longitudinal and 2 horizontal depths. The shrinkage effect of the cast-in-place board is achieved by applying the equivalent temperature difference to the board. After the numerical calculation, the stress cloud of the cast-in-place slab can be viewed in the post-processing program. The first principal stress-position curve of the cast-in-place slab can be obtained by the method of path operation. The maximum tensile stress caused by the shrinkage of cast-in-place concrete is mainly distributed at the four large angles of the slab and at the boundary between the wall and the cast-in-place slab. Along the longitudinal direction of the cast-in-place board, the tensile stress gradually increases from the end room to the middle room, with the increase rate being only 5% -7%. Casting board vertical and horizontal tensile stress or less. When the cast-in-place slab has no threading pipe, the maximum stress appears at the boundary between the wall and the cast-in-place slab. When the threading pipe is installed in the middle span, obvious stress concentration occurs in the midspan, which is prone to shrinkage at the threading pipe The main reason for cracks. The shrinkage stress of cast-in-place slab depends on the side-wall stiffness of the floor, and the lateral stiffness of the wall is proportional to the horizontal cross-sectional area of the wall. Increasing the wall spacing, wall stiffness can reduce the side shift, thereby reducing the level of shrinkage of the cast-in-place board.