钢筋混凝土箱梁非线性及剪滞效应的试验研究

制作了钢筋混凝土简支箱梁模型，试验包括模型梁开裂范围内的加载及开裂后的加载。在开裂范围内，对该试验梁分别进行了顶板满布均布荷载、均布荷载作用于肋板上方、集中力作用于跨中以及对称集中力作用下的加载;对开裂后的试验梁，进行了对称集中力作用下的加载。用应变采集仪与电脑连接，并用半桥测量，温度自补偿方法测取应变值，采用百分表测试梁体挠度，采用读数显微镜观测裂缝。测量得到应力、应变的分布规律,验证了钢筋混凝土箱梁中存在剪滞效应。试验结果与考虑混凝土非线性的有限段法的计算结果吻合较好，验证了有限段法在混凝土箱梁剪滞效应分析中的适用性。

Experimental Study of the Nonlinear and Shear-lag Effect of R.C. Box Girder

A simply supported reinforced concrete (R.C.) box girder model was manufactured in order to study its nonlinear and shear lag effect. Experiments include both loading within cracking range of box girder model and loading after its cracking. The experiment before model cracking includes four different loading patterns: uniformly distributed load on the roof, uniformly distributed load acting on the rib board, concentrated force acting on the span middle section and symmetrical concentrated forces acting on 1/4 section and 3/4 section. The experiment after model cracking only includes symmetrical concentrated forces acting on 1/4 section and 3/4 section. During experiment, adopting half bridge measurement and temperature self compensation, the strain values were obtained by strain collection instrument connected with computer; using dial indicator, the beam deflection was measured; using reading microscope, the cracks were observed. The stress and strain distribution regularities measured in experiments verify the existence of shear lag in reinforced concrete box girder. Experimental results present better agreement with the calculation of finite segment taking into account nonlinear of concrete and confirm the applicability of finite segment method in R.C. box girder shear lag.