曲线筋PC梁受剪性能试验研究--基于纵筋配筋率(As组)

EXPERIMENTS ON SHEAR BEHAVIOR OF PRESTRESSED CONCRETE BEAMS WITH DRAPED TENDONS:LONGITUDINAL REINFORCEMENT RATIO(A_s GROUP)

对3根曲线筋PC梁和1根RC对比梁的受剪性能进行试验研究,剪跨比均为1.8,主要以纵筋配筋率为研究变量。研究表明:正常配筋率的小剪跨比梁更倾向于发生弯剪破坏;纵筋配筋率越低,梁刚度丧失越快;对于曲线筋PC梁,存在某一临界配筋率ρcrit,小于此值时,梁拱效应减弱,不宜考虑曲线筋的竖向预剪作用,而大于此值时,可充分考虑竖向抗剪作用。此外,采用基于截面的抗剪设计方法和拉压杆模型(MSTM)对试验梁受剪承载力进行了预测,与试验结果对比表明:基于截面的抗剪设计公式不适用,而MSTM预测结果最为精确,且其较好地反映了纵筋的影响。

Three PC beams with draped tendons and one RC beam were tested and the primary variable is the longitudinal reinforcement ratio ρ. All the beams had a shear span to depth ratio, a/ho, of 1.8. Several results were obtained： beams with both small a/ho and normal amount of ρ were inclined to suffer a flexural - shear failure; the lower the ρ, the faster the damage of beams; there seems to be a critical longitudinal reinforcement ratio, ρcrit that is, if p is lower than ,it, the arch action would weaken, or else the arch action would be significant. Besides, sectional design methods and modified strut-and-tie model （MSTM） were used to predict the beam shear strengths, and comparisons with test results indicate that sectional methods are not suitable for such predictions but MSTM not only gives accurate results, but also well account for the effect of the longitudinal reinforcement.