页岩陶粒轻质混凝土双向叠合楼板受力性能试验及挠度计算分析

Mechanical Performance Test and Deflection Calculation Analysis of Shale Ceramsite Lightweight Concrete Two-way Composite Floor Slab

根据3块足尺页岩陶粒轻质混凝土双向叠合楼板试件和1块足尺现浇双向楼板对比试件的静力堆载试验结果,分析了双向叠合楼板预制底板的普通混凝土和后浇叠合层的页岩陶粒轻质混凝土采用相同强度等级时的挠度变形特点,并根据试验结果和弹性力学薄板理论推导了页岩陶粒轻质混凝土双向叠合楼板的挠度计算公式。推导了四边固支页岩陶粒混凝土和普通混凝土叠合板在竖向均布荷载作用下截面中和轴高度、抗弯刚度和挠度的计算表达式,并分别对挠度和初始刚度计算公式进行了修正,提出了考虑四边支承转动的页岩陶粒轻质混凝土双向叠合楼板挠度计算公式。结果表明:页岩陶粒轻质混凝土双向叠合楼板跨中位移呈现线弹性变化特征,页岩陶粒轻质混凝土材料的弹性模量、叠合楼板中设置的钢筋桁架以及双向叠合板的板端约束条件是影响叠合楼板刚度和跨中挠度的主要因素;采用所推导公式计算的页岩陶粒混凝土叠合楼板的挠度值与试验值吻合良好。

According to the static-load test of three full-scale shale ceramsite concrete two-way composite floor slabs and one full-scale cast-in-place concrete two-way floor slab,the deflection and deformation characteristics of the normal concrete of the two-way composite prefabricated bottom slab and the shale ceramsite lightweight concrete of the post-cast laminated layer with similar strength grade were analyzed.Based on the experimental results and the theory of elastic mechanics of thin plates,the formulas for calculating deflection of shale ceramsite concrete twoway composite floor slabs were deduced.The expressions of neutral axis height,bending stiffness and deflection of four boundary-fixed shale ceramsite concrete and ordinary concrete composite slabs under the vertical distributed load were deduced,then the calculating formulas of deflection and initial stiffness were modified.The calculation formulas of deflection for shale ceramsite lightweight concrete two-way composite floor slabs considering the rotation of four sides supports were proposed.The results show that the mid-span displacement of shale ceramsite lightweight concrete two-way composite floor slab exhibits liner elastic variation characteristic.The elastic modulus of shale ceramsite lightweight concrete,the steel truss in the composite slab and the restraint conditions at the end of the two-way composite slab are the main factors affecting the rigidity and midspan deflection of composite slab.The deflection values of the shale ceramsite concrete composite floor slab calculated by the proposed formula are in good agreement with the experimental values.