中文摘要：

目前缺乏对配置腹部水平钢筋网的柱下承台冲切承载力的理论研究。进行了3个对照组,6个该种配筋形式柱下4桩承台的冲切试验研究。结果表明：其传力机理为空间桁架;其破坏机理可以是斜压杆起自于中部的劈裂终止于两端面剪压的破坏,也可以是中腹部水平钢筋网以及底部纵筋的配筋量不足而引起的屈服破坏,但即使是该钢筋网的屈服破坏,也必伴随着斜压杆破坏的产生;腹部水平钢筋网能够提高承台冲切承载力及其延性,主要原因就在于该钢筋网承担了斜压杆中腹部的劈裂拉力,并据此推导出了与现存试验结果吻合良好的承载力计算公式。研究成果有望有效降低承台与桩筏筏板的厚度,减少配筋量,最终赢得行业宏观经济效益。

英文摘要：

To study the punching bearing capacity of pile caps under columns with belly horizontal mat reinforcement,punching tests are carried out with 3 comparison groups and 6 four-pile caps under columns with the reinforcement.The results indicate a spatial strut-and-tie load mechanism,and a failure mechanism of either a strut failure,which begins with the splitting in the mid-part of the strut and ends with shear-compression failure at the two ends of the strut,or a yield failure resulted from inadequate belly horizontal mat reinforcement as well as the bottom longitudinal bar reinforcement,with the mat reinforcement yield failure also accompanied by strut failure.The belly horizontal mat reinforcement is capable of improving the punching bearing capacity and the ductility of the pile caps,with the main reason being the mat reinforcement bearing the splitting tensile force from the mid-part of the strut.Formulas for calculating the bearing capacity are derived,which are found in good agreement with the test results.It is thus hopeful that the thickness of pile caps and pile-raft slabs and the reinforcement could be reduced.