基于钢筋分离模式优化的RC深梁静力试验研究

钢筋应力渐进结构优化以钢筋单元应力为灵敏度，针对钢筋分布演化出接近钢筋满应力目标的最优拓扑，为钢筋混凝土(RC)深梁的工程配筋设计提供新方法。按照该方法完成RC简支深梁的优化配筋设计，并开展静力试验。试验过程中发现，随着荷载的增大，深梁表面弯曲裂缝充分开展，剪切裂缝得到有效控制，在达到峰值荷载后存在明显的持荷且变形大幅增长阶段，破坏前底部纵筋大面积屈服，最终失效时呈现出正截面破坏形态，表明采用该方法设计的深梁兼具良好的承载能力、耗能能力和延性。经分析，这种基于钢筋满应力目标的深梁配筋优化设计方法中布置斜筋一方面有效补强了混凝土“瓶形”压杆，提高了构件的受剪承载力；另一方面又弱化了底部纵筋的抗力，适度降低了构件的受弯承载力，使底部纵筋控制构件的破坏。该方法既与美国规范ACI 318-14中推荐的拉压杆模型方法的设计思想统一，也与中国规范GB 50010—2010中推行的“强剪弱弯”设计理念一致，由此证实了钢筋应力渐进结构优化在深梁配筋设计上的有效性，可供工程设计参考。

Static test investigation for RC deep beam optimized based on discrete model

The structural optimization based on the evolution of reinforcement stress takes the stress as the key variable with the aim of obtaining the optimal topology for near full stress of steel reinforcement. A new design method was proposed for the reinforcement of reinforced concrete (RC) deep beams. The reinforcement design of simply supported deep beams was completed using the new method, and then a static test was carried out. During the test, the bending crack of the deep beam fully developes with the increase of load, and the shear crack is effectively controlled. After reaching the peak load, the deformation of the beam increases continuously and significantly. Finally, the normal section failure occurs along with most of the bottom longitudinal reinforcements yielding. The results show that the deep beam designed by the new method has great bearing capacity, energy dissipation capacity and ductility. On one hand, this method effectively strengthens the concrete ‘bottle’ strut by arranging oblique reinforcements, and thus improves the shear capacity of the structural member. On the other hand, it weakens the resistance of the bottom longitudinal reinforcements and moderately reduces the flexural bearing capacity, so that the bottom longitudinal reinforcements can control the failure of the structural member. It both conforms to the Strut-and-Tie model recommended by the American code of ACI 318-14 and the design concept of ‘strong shear and weak bending’ recommended by the Chinese code of GB 50010—2010. Therefore, the effectiveness of evolutionary structural optimization based on the reinforcement stress for the design of reinforcement layout in deep beams is proved, which can be used as a reference for engineering design.