板及基础冲切承载力随混凝土强度的变化

Variation of punching shear capacity of slabs and footings with concrete strength

文中提出了一种参数影响评估方法 ,并从国内外大量冲切试验资料中 ,提出以混凝土强度为唯一变量的 1 8组试验数据 ,用于考察板及基础抗冲切能力随混凝土强度的变化规律 ,评价中外规范公式的适用性。共计 71个试件中 ,包括普通钢筋混凝土平板及柱下单独基础、钢纤维轻骨料混凝土板和带边界约束板等多种类型 ,混凝土立方强度fcu 约在 1 2～ 1 2 3MPa间变化。参数评估及可靠度分析结果表明 ,我国规范公式对混凝土强度的影响估计过高 ,英国标准及CEB模式规范所采用的形式f1/ 3cu 能合理反映冲切承载力与混凝土强度之间的关系 ,值得我国规范修订时借鉴。

A rational method is presented to investigate the effect of concrete strength on punching shear capacity of slabs and footings. For this purpose,18 groups of data from punching shear tests with concrete strength as the sole variable are chosen from a large number of test results at home and abroad.With concrete strength between 12 MPa and 123 Mpa,the specimens concerned include RC slabs and footings,lightweight concrete slabs with steel fibers and partially restrained ones.Analyses show that the GBJ10-89 expression predicts too rapid a variation of punching resistance with concrete strength.The treatments of BS 8110 and CEB MC 90 are worth learning from when our codes are revised.