Study on failure mechanism of reinforced concrete beam based on cohesive zone model

基于内聚力模型的钢筋混凝土梁破坏机理研究

¹ Jinan Rail Transit Group Co., Ltd., Jinan 250014, China
² School of Qilu Transportation, Shandong University, Jinan 250002, China
³ School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, China

Received: 13 April 2021

Abstract

The problem of crack propagation in reinforced concrete beams is common in practical engineering. It is very important to correctly describe the law of crack propagation, the mechanism of fracture failure and the internal stress and deformation characteristics of the beams. Based on cohesive zone mode, the mechanical mechanism of fracture failure of 3D reinforced concrete beams under external load is studied in this paper. By comparing the numerical simulation with the experimental results of the reinforced concrete beam, the crack distribution, expansion law and failure mode of the reinforced concrete beam under the conditions of different reinforcement ratio and spiral stirrup inclination angle are investigated. The results show that: ①a small amount of reinforcement and a superfluous amount of reinforcement will make the reinforced concrete beam show the characteristics of brittle failure, while the moderate reinforcement ratio can give full play to the ductility of the reinforced concrete beam, which is easier to bear the load of the beam; ②when the inclination angle of spiral stirrup is about 80°, the bearing capacity of normal section and oblique section of the beam reach the maximum value.

摘要

基于内聚力模型理论探讨钢筋混凝土梁在外荷载作用下断裂破坏的力学机制, 对比分析钢筋混凝土梁原型实验与数值计算结果, 研究钢筋混凝土梁在不同配筋率和螺旋箍筋倾角条件下, 梁体裂纹的分布、扩展规律和破坏形式。研究结果表明: ①内聚力模型模拟钢筋混凝土结构断裂破坏优势显著, 能够再现梁体裂纹萌生、扩展和断裂破坏过程; ②少量和超量配筋均会使钢筋混凝土梁表现出脆性破坏的特征, 而配筋率适中则能充分发挥钢筋混凝土梁的延性特征, 更加易于梁体承载; ③螺旋箍筋倾角为80°时, 梁体的正截面承载能力与斜截面承载能力均达到最大值。