施工期变约束刚度对混凝土楼板温度应力的影响研究

Study on the influence of variable constraint stiffness on the temperature stress of concrete floor during construction

混凝土楼板由于温度作用产生变形,且受到周围梁柱的约束不能产生自由变形,从而产生温度应力导致结构开裂.针对梁对混凝土楼板温度应力分布及发展状况的影响,通过改变约束混凝土楼板梁的宽度角度,建立了梁宽分别为200、250、300、350 mm的有限元模型,并对其进行数值模拟,以研究施工期变约束刚度对混凝土楼板温度应力的影响情况.数据及研究表明随着梁宽度增加,约束刚度增强,楼板温度应力会呈现整体增长,并由板角高应力区逐渐向板中底应力区域扩散,达到混凝土抗拉强度的区域面积因此逐渐增大.梁宽度为200 mm时,角柱及边柱的各自梁约束处楼板板角底面和顶面均达到混凝土抗拉强度,中柱及梁约束处板角应力则没有达到混凝土抗拉强度.随着梁宽度不断增大至350 mm,中柱及梁约束处板角顶面会逐渐达到混凝土抗拉强度,但是板角底面仍为弹性.

The concrete floor deforms due to the action of temperature,and cannot freely deform due to the constraint of the surrounding beam and column,so the temperature stress results in the structure cracking.In view of the beam and the temperature stress distribution of concrete floor and the influence of the development status,it through changing the width of the floor beam Angle of confined concrete,established the beam breadth is respectively 200,250,300 and 350 mm of the finite element model,and carries on the numerical simulation of the variable constraint stiffness during the construction is to study the influence of the temperature stress of concrete floor.Data and research show that with the increase of beam width and constraint stiffness,the temperature stress of floor slab will increase as a whole,and gradually diffuse from the high-stress zone at the board angle to the stress zone at the middle and bottom of the slab,so that the area of concrete tensile strength increases gradually.When the beam width is 200 mm,the bottom surface and top surface of the floor slab at the constraint of the beams of the angular column and the side column reach the tensile strength of concrete,while the angular stress of the slab at the constraint of the column and the beam does not reach the tensile strength of concrete.As the beam width continues to increase to 350 mm,the top surface of the column and the plate angle at the beam constraint will gradually reach the tensile strength of concrete,but the bottom surface of the plate angle is still elastic.