钢筋混凝土浅梁受剪承载力的修正计算

Modified calculation of shear capacity of slender reinforced concrete beams

在更新钢筋混凝土矩形截面简支梁受剪试验数据的基础上,分析了GB 50010—2010《混凝土结构设计规范》中钢筋混凝土浅梁受剪承载力计算公式存在的问题。通过对集中荷载作用下987根无腹筋梁受剪试验数据进行非线性拟合得到混凝土项,并利用103组配对试件受剪试验结果验证了45°桁架模型的合理性,进而提出了修正计算式。结果表明GB 50010—2010《混凝土结构设计规范》中钢筋混凝土浅梁受剪承载力计算公式的安全度偏低,而对混凝土强度取值范围的限制偏于保守。修正计算式采用统一的表达式,且考虑了纵向受拉钢筋配筋率和尺寸效应的影响。集中荷载和均布荷载作用时,修正计算式的可靠指标较接近,且都能满足GB 50068—2001《建筑结构可靠度设计统一标准》的基本要求。

Based on updating the shear test data of simply-supported rectangular cross-sectional reinforced concrete beams subjected to one or two concentrated loads,some problems existing in the present shear design formula for slender reinforced concrete beams in the GB 50010—2010‘Code for design of concrete structure’were identified and analyzed.A calculation model for concrete contribution was proposed by nonlinear fitting of the test data of 987 beams without web reinforcement under concentrated loads,and the rationality of a 45 degree truss model was proposed for calculating the stirrup contribution,which was examined by comparing the test results of 103 paired beams,and then a modified calculation model was proposed.The results show that the shear capacity formulas for slender reinforced concrete beams in GB 50010—2010 could be unsafe based on the updated test data,but the stipulated limitation of the range of the concrete strength is conservative.The modified calculation formula adopts unified expression,and it sufficiently takes longitudinal tensile reinforcement ratio and size effect into account.For the beams subjected to concentrated and uniform loads,the reliability indexes are relatively closer and can meet the basic requirements of GB 50068—2001‘Unified standard for reliability design of building structures’.