现浇混凝土空心楼板横向受剪试验研究

对混凝土空心楼板横向受剪时隔离体平衡和受剪破坏机理分析可知,肋宽和翼缘厚度是影响其受剪承载力的主要因素。进行了A、B两类18个现浇混凝土空心楼板试件的受剪试验,A类试件保持板厚和空心管直径不变,肋宽分别为50、75、100 mm,研究肋宽对受剪承载力影响;B类试件保持板厚不变和较大肋宽,上、下翼缘厚度分别为40、60、80mm,研究翼缘厚度对受剪承载力影响。试验研究表明,在肋宽较小时,剪切破坏发生在肋上,裂缝先在孔内壁主拉应力较大处出现,随之近似水平开展并与相邻圆孔贯通,受剪承载力随肋宽的增大而增大;当肋宽较大时,空心板剪切破坏发生在上、下翼缘处,裂缝先在孔内壁靠近上、下翼缘位置出现,逐渐延伸到板的表面,受剪承载力与上、下翼缘厚度存在明显正比关系,承载力随翼缘加厚而线性增大。综合试验和理论分析结果给出了混凝土空心楼板横孔方向受剪承载力计算的双控计算式。

Experimental study on shear capacity of cast-in-situ concrete hollow floor in transverse direction

The width of the rib and thickness of the flange were found to be the main factors influencing the shear capacity of cast-in-situ concrete hollow floor slab in transverse direction based on the analysis of equilibrium and the shear failure mechanism. 18 specimens of class A and class B were designed to be tested. In class A, the influence of the rib widths on the shear capacity was studied keeping the hollow diameters and thicknesses unchanged with the rib widths of 50 mm, 75 mm and 100 mm respectively. In class B, the influence of the thickness of the flange on the shear capacity was studied keeping the thickness unchanged and bigger rib width and with the thicknesses of upper and lower flanges of 40 mm, 60 mm and 80 mm respectively. Experimental study shows that the shear failure occurs on the rib when the rib width is small. The crack is found first on the inner wall of the hollow at the point of larger principal tensile stress, and the crack is developed to the adjacent hollow nearly horizontal. The shear capacity is increased with the increase of the rib width. The shear failure occurs on the upper and lower flanges when the rib width is bigger. The crack is found first on the inner wall of the hollow near the upper or lower flange, and gradually extended to the upper or lower surfaces of the plate. The shear capacity is positively correlated with the thickness of the flange. The shear capacity calculation formula of double control in transverse direction of cast-in-situ concrete hollow floor was given based on the experimental results and theoretical analysis.