钢筋混凝土开洞深梁拉压杆模型方法与经验方法试验对比研究

针对不同的洞口尺寸和洞口位置，按拓扑优化中的遗传演化算法构造拉压杆模型和我国规范推荐的经验方法，设计了4组共8个钢筋混凝土开洞深梁试件。通过静载试验对两种方法设计的试件进行对比，结果表明：按拉压杆模型方法设计的试件不仅具有较高的受剪承载力、较充分的裂缝开展和较好的延性，而且有效解决了按经验方法设计的试件纵筋不能充分利用的问题。通过比较实测的受剪承载力和按材料标准值计算的设计受剪承载力，结果表明：拉压杆模型方法可以得到偏于安全的承载力预测值，而经验方法的预测结果偏差较大；开洞深梁的破坏形态，洞口尺寸较小时由“瓶形”斜压杆两侧的斜裂缝开展起控制作用，而洞口尺寸较大时，虽然也由斜裂缝控制破坏，但显现一定的弯曲破坏特征。

Testing comparison between strut-and-tie model method and empirical method for RC deep beams with openings

Eight reinforced concrete (RC) deep beams with openings were tested. They were classified into four groups according to the dimension and orientation of the openings. In each group, one beam was designed by empirical method of Chinese code GB 50010-2010, while the other was designed by strut-and-tie model (STM) method. The STM was obtained by topological optimization algorithm of genetic evolutionary structural optimization (GESO). Eight RC deep beams designed by these two methods were compared by static load test. The results show that deep beams designed by STM method have higher ultimate bearing capacity, fuller crack’s developing and better ductility. The problem of unyielding longitudinal reinforcements in empirical method was improved by STM method. The measured and designed ultimate bearing capacity according to the standard values of materials were compared. It shows that the ultimate bearing capacity can be predicted well by STM method. The predictive value by STM method is ideal and slightly conservative, while that by the empirical method is inaccurate completely. The failure of deep beams with smaller openings is always controlled by the development of diagonal cracks on both sides of the ‘bottle shape’ diagonal struts. The failure of deep beams with bigger openings shows some characteristic of bending failure, though its failure is because the diagonal cracks develop too.