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依据现有试验资料并结合我国工程实践的经验,对几个较成熟的问题提出了以下修订建议: (一) 适当降低不配抗冲切钢筋的冲切强度安全系数现行规范对不配抗冲切钢筋的冲切强度要求满足KQ_c≤0.75R_lSh_0的条件。其中安全系数K取2.2。对搜集到的国外239个试件试验结果进行分析比较,试件冲切破坏试验值与用上式算得的冲切破坏荷载值之比,平均值为1.52,标准差为0.38,保证率为94.7%。可见现行规范公式偏于安全。但是这些试件的纵向配筋率均较高(0.37%～3.7%),而配筋率对冲切破坏试验值有一定影响。纵向配筋率愈高,其梢栓作用愈大,因而对冲切强度的提高也愈大。考虑到
Based on the existing test data and combined with the experience of China’s engineering practice, the following revised recommendations are proposed for several more mature issues: (1) Properly reducing the safety factor of punching strength of unpunched reinforcing steel bars The current specification does not apply punching shear reinforcement The punching strength is required to satisfy the condition of KQ_c≤0.75R_lSh_0. The safety factor K takes 2.2. Analyze and compare the results of the 239 test pieces collected abroad. The ratio of the test piece punching failure test value to the value of the punching failure load calculated with the above formula. The average value is 1.52, the standard deviation is 0.38, and the guarantee rate is 94.7. %. It can be seen that the current specification formula is somewhat safe. However, the longitudinal reinforcement ratio of these specimens is high (0.37% to 3.7%), and the reinforcement ratio has a certain influence on the value of the punching failure test. The higher the longitudinal reinforcement ratio is, the larger the tipping effect is, and therefore the greater the improvement of punching strength. considering