桥梁立柱与盖梁节点的抗震设计方法研究

Discussion on Seismic Design of Bridge Column and Bent Cap Joint

摘要:

首先，介绍了地震作用下桥梁立柱与盖梁连接节点的传力机理和受力性能等研究成果；其次，分析对比了国内外设计规范标准关于节点主应力验算的具体规定，并探讨其中的受剪面积Ajv、承受立柱轴力作用的等效截面Ajh及混凝土立柱纵筋拉力Tc的取用；最后结合实际桥梁工程进行了计算分析。由分析结果可知：立柱纵向钢筋在节点核心区域内的锚固长度与节点的主应力数值大小密切相关，计算时应按实际的锚固长度计算；当配有预应力的盖梁与立柱节点中节点主压应力超限时，除了可以适当提高限值外，还可以通过调整其预应力度、立柱主筋锚固长度或盖梁高度等措施进行改善；另外在节点构造上可通过控制节点核心区域内横向箍筋的最小配筋率等措施来确保形成刚节点。

Abstract:

Firstly, the research results of the force transfer mechanism and mechanical behavior of bridge column and bent cap joint under seismic load are introduced. And than the specific provisions of domestic and foreign design codes and standards on the principal stress checking calculation of joints are analyzed and compared, and the adoption of the shear area Ajv, the equivalent cross-section Ajh that bears the axial force of the column and the longitudinal reinforcement tension Tc of the concrete column are discussed. Finally, a calculation analysis is conducted based on actual bridge engineering. The analysis result shows that the anchorage length of the longitudinal reinforcement of the column in the core area of the joint is closely related to the value of the principal stress of the joint, and should be calculated based on the actual anchorage length. When the main compressive stress of the joint between the prestressed bent cap and the column exceeds the limit, in addition to appropriately increasing the limit, the measures such as adjusting the prestressing degree, the anchorage length of the column main reinforcement, or the height of the bent cap can be also taken to improve it. In addition, the rigid joint can be formed by controlling the minimum reinforcement ratio of horizontal stirrups in the core area of the joint.