考虑孔道及核心面积影响的混凝土局部受压承载力试验研究

为了深入考察预留孔道、间接钢筋内表面范围内混凝土核心面积和局部受压面积比等关键参数对局部受压承载力的影响,完成了12个素混凝土试件、9个配置网片式间接钢筋的混凝土试件和9个配置螺旋式间接钢筋的混凝土试件的轴心局部受压承载力试验。获得了间接钢筋的应变分布、楔形体特征及破坏形态等试验资料。试验结果表明:预留孔道的存在将使混凝土局部受压承载力提高系数降低,其降低幅度随孔道直径的增大而增大;当网片式间接钢筋的种类、直径、根数、网片间距不变或螺旋式间接钢筋的种类、直径及螺旋间距不变时,局部受压承载力随混凝土核心面积的增加而线性提高。建立了基于试验结果的考虑预留孔道直径和核心面积大小影响的混凝土局部受压承载力计算公式,可供相关设计标准修订时参考。

Experimental research on local compression bearing capacity of concrete considering the influence of ducts and core area

In order to make sound understanding of the influence of some key factors to local compressive bearing capacity of concrete, such as ducts, concrete core area within the range of inner surface of indirect reinforcements, and the ratio of calculated bottom area for local compression to local compression area of concrete, axial local compression experiments on 12 plain concrete specimens, 9 concrete specimens with the mesh indirect reinforcement, and 9 concrete specimens with the spiral indirect reinforcement were completed. Experimental data included as strain distribution of the indirect reinforcement, features of the wedges and their failure modes. Experimental results show that the enhancement coefficient of concrete strength for local compression decreases due to ducts, particularly when the diameter of the ducts increases. If the type, diameter, number, and spacing of mesh indirect reinforcement are identical, or if the type, diameter, and spacing of spiral indirect reinforcement are same, the local compressive bearing capacity of concrete increases linearly with the increase of concrete core area. Based on experimental results, calculation formulas for local compressive bearing capacity of concrete considering the influence of diameter of ducts and concrete core area are established.