混凝土梁抗扭性能分析及承载力修正公式

摘要

The torsional behaviour of reinforced concrete beam at different ages was analysed by ABAQUS finite element software under different strength grades. The concrete damaged plasticity model was employed in constitutive relationship among different ages, while tensile fracture energy was used as tensile indexes ( indicators) . The ( finite element analysis) results indicate that the anti-torsional capacity of reinforced concrete at different ages increases with the growth of ages. Further-more, the torsional capacity of the reinforced concrete at the early age is mainly taken by concrete and little by steel bar before it cracks. Meanwhile, the first three days is the fastest time for concrete to increase torque capacity. The concrete’ s cracking torque and ultimate torque can reach 60%at 28 days. Finally, the improved cracking torque and ultimate torque formula of concrete beam at early a-ges are also proposed based on available standards.%采用ABAQUS有限元软件对各种强度等级下各龄期钢筋混凝土梁的受扭性能进行分析。各龄期混凝土的本构关系采用塑性损伤模型，受拉指标采用断裂能。有限元分析结果表明：各龄期混凝土的抗扭承载力随龄期的增长而增长，开裂前早龄期混凝土梁的抗扭承载力主要由混凝土承担，钢筋的贡献很小；前3 d是混凝土扭矩增长最快的主要时间段，开裂扭矩和极限扭矩达到28 d的60％左右。最后，根据有限元参数分析结果，在现行规范的基础上提出了早龄期混凝土梁开裂扭矩和极限扭矩的修正公式。