预应力混凝土叠合空心楼板静力性能试验研究

Experimental study on static behavior of prestressed concrete composite hollow floors

结合现浇空心楼板与叠合楼板的优点,提出在一种预应力叠合楼板中布置筒芯内模形成的叠合空心楼板。进行了预制带肋底板叠合空心楼板、矩形底板叠合空心楼板及现浇空心楼板3种截面形式,2种截面尺寸分别为230 mm×500 mm、300 mm×600 mm的10块板带在单调荷载作用下的足尺模型试验。通过改变预制底板类别、筒芯内模的直径及其布置方式,对叠合空心板带的破坏形态、截面整体工作性能、正截面受弯承载力、短期刚度、叠合面水平受剪性能等进行了研究。结果表明:从开始加载到破坏,叠合空心楼板与现浇空心楼板表现出相似的受力特点和变形特征,按筒芯最薄弱翼缘处的工形截面计算叠合板的开裂荷载、正截面受弯承载力、平均裂缝间距等与实测值吻合较好;在所研究的板厚范围内,筒芯直径大小及布置方式的变化并未造成叠合面出现滑移开裂的现象,但不同程度地削弱了试件的受拉刚化作用,建议叠合空心楼板开裂后的短期刚度取控制截面的开裂刚度。通过叠合面受力分析,将横孔板顺筒肋宽度和上、下翼缘厚度的计算限值与楼板实际构造尺寸进行对比,实际工程中叠合面的抗剪强度可满足安全使用要求。两种预制底板预应力混凝土叠合空心楼板与预应力现浇空心楼板的总体受力性能较为接近,均可满足工程设计要求。

A new kind of composite hollow floor was proposed based on the combination of the advantage of cast-in-situ hollow floor and composite floor. Ten slab strips of hollow floor were tested under monotonic loading. The cross sections of specimens are 230 mm × 500 mm and 300 mm × 600 mm,which were classified into two types by the precast panel with or without longitudinal rib and a cast-in-situ hollow specimen to investigate the failure mode,monolithic action of the entire cross section,positive flexural strengths of normal section and short-term stiffness,and the horizontal shear performance,etc. The results indicate that composite hollow slab and the cast-in-situ hollow slab show the same mechanical characteristics and deformation characteristics from being loaded to failure. The calculated values of cracking moment,ultimate bending moment,and average crack interval for composite hollow slab,which is calculated using I-shaped cross-section of the weakest flange in the tube filler,agree well with testing values. For the present investigation conditions,the change of the arrangement methods and diameter of the tube filler has not caused cracks and slip problems in lamination but weakened the tension stiffening in the specimens to varying degrees,so that the short-term stiffness after cracking is suggested as a cracking stiffness of controlling section. By comparing the calculated values of the tube filler spacing and the flange thickness to real size of the flange with the actual identical size of the floor,the shear strength of the lamination may ensure the safety and use of the real projects according to the force analysis of the lamination. The overall mechanical properties of the two types of composite hollow slabs are similar to those of the cast-in-situ hollow slabs,and can meet the engineering design requirement.