负弯矩荷载下钢-混凝土组合梁抗弯刚度研究

Flexural stiffness of steel-concrete composite beam under negative moment

针对负弯矩作用下钢-混凝土组合简支梁的抗弯刚度,考虑剪力连接度与纵横向配筋率等参数的影响,进行13根负弯矩作用下钢-混凝土简支组合的抗弯刚度试验研究,并运用ABAQUS有限元软件对负弯矩作用下钢?混凝土组合梁的力学性能进行模拟,其中栓钉分别采用梁单元和弹簧单元2种建模方法。在试验验证的基础上,通过足尺算例探讨剪力连接度、栓钉布置、栓钉直径、加载位置、纵筋率及跨度等参数对钢?混凝土组合梁负向抗弯刚度的影响规律。研究结果表明:剪力连接度对刚度影响最大,纵筋率的影响其次,其余参数影响不大。结合试验研究与理论分析,建议钢?混凝土组合梁负向抗弯刚度仍按规范《钢结构设计标准》(GB 50017—2017)提供的表达式,提出考虑混凝土翼板0.6hc有效厚度并计入钢梁与钢筋等抗弯刚度贡献的负弯矩折减刚度法,该方法与现有的钢-混凝土组合梁负向抗弯刚度计算公式相比精度较高。

This paper investigated the flexural stiffness of steel-concrete composite I-beam under negative bending moment through combined experimental and finite element(FE)modeling.13 composite beams were included into the experiments and parameters including shear connection degree,transverse and longitudinal reinforcement ratio were also considered and investigated.ABAQUS was employed to establish FE models to simulate the behavior of composite beams.The influences of a few key parameters,such as the shear connection degree,stud arrangement,stud diameter,loading position,longitudinal reinforcement ratio and beam length on flexural stiffness were discussed.The results show that degree of shear connection affect flexural stiffness most,reinforcement ratio has some influence,remaining arguments have little effect.In addition,Chinese code,the formula by other scholar were used to estimate the flexural stiffness and also compared with the simulation results.The results indicate that the modified formula proposed in this article may provide a better estimation in comparison to other methods.