再生混凝土抗剪键接缝受剪性能及承载力计算

Shear Performance and Capacity Calculation Method for Recycled Aggregate Concrete Shear Connector

为研究再生混凝土抗剪键接缝的受剪性能,以抗剪键数量、再生粗骨料取代率和轴向应力为变化参数,设计了6个再生混凝土抗剪键接缝试件和2个无键直缝试件进行单调推剪试验,获取了试件的破坏形态、剪力-剪切位移曲线和抗剪承载力,分析了不同变化参数对再生混凝土抗剪键接缝承载力的影响规律,提出了再生混凝土抗剪键接缝的抗剪承载力计算公式。研究结果表明:再生混凝土无筋抗剪键接缝和直缝均沿水平结合面发生剪切破坏,键槽内灌浆料存在斜裂缝,抗剪键接缝的峰值剪切位移随轴向应力的增大而减小,再生粗骨料取代率对试件剪力-剪切位移曲线影响较小,再生混凝土抗剪键接缝的抗剪承载力明显大于无键直缝,抗剪键接缝的抗剪承载力随再生粗骨料取代率的增加而减小,随轴向应力的增加而增大,所提出的承载力计算公式可用于计算无筋再生混凝土抗剪键接缝的抗剪承载力,计算结果偏安全。

In order to study the shear performance of recycled aggregate concrete joint with keys,six recycled aggregate concrete keyed joints and two recycled aggregate concrete plain joints were designed to conduct direct shear tests.The main design parameters were the number of shear keys,recycled coarse aggregate(RCA)replacement percentage and axial stress.The failure modes,shear load versus displacement curves and shear capacity were presented and discussed.The influence of different variation parameters on the shear bearing capacity was analyzed.The test results indicated that all specimens were finally loaded with the characteristic of shear damage in the joint plane,with some diagonal cracks located in the keyed joint.The shear displacement corresponding to the peak load of the keyed joint reduced with the increase of axial stress.The RCA replacement percentage had little influence on the shear load versus displacement curve.The shear keys were contributed to enhance the shear capacity in comparison to the plain joint.Shear capacity of the keyed joint increased with the increase of axial stress,however,reduced with the increase of RCA replacement percentage.The proposed formulas which had relatively safe calculation results were applicable for predicting the shear bearing capacity of the RAC joint without shear reinforcement.