圆端形钢管混凝土构件纯弯力学性能

Mechanical Behaviors of Concrete-filled Round End Steel Tubular Members Under Pure Bending

为研究圆端形钢管混凝土构件的纯弯力学性能,对4个构件进行了纯弯试验,分析了高宽比和含钢率对纯弯曲作用下圆端形钢管混凝土构件破坏形态、挠度曲线、截面应变、抗弯承载力的影响。基于ABAQUS建立有限元模型对圆端形钢管混凝土构件纯弯性能进行模拟,试验结果与模拟结果吻合良好,利用验证后的模型对圆端形钢管混凝土构件进行了受力全过程分析以及参数分析。最后基于ABAQUS参数分析结果提出了圆端形钢管混凝土构件抗弯承载力计算公式,公式计算结果与试验结果吻合良好。结果表明:圆端形钢管混凝土构件在纯弯曲作用下发生了明显的挠度变形,当跨中挠度达到L/25(L为试件长度)时,试件仍能承受较大的荷载,表现出良好的延性;圆端形钢管混凝土构件的挠度曲线可假设为正弦半波曲线,其跨中截面基本保持为平截面;当构件达到抗弯承载力时,钢管承受了大部分弯矩,圆弧段钢管相较于平直段钢管对混凝土的约束作用更强;圆端形钢管混凝土构件的抗弯承载力随钢材强度的增大而增大,而混凝土强度的改变对其抗弯性能影响较小。

In ordor to explore the flexural behavior of concrete-filled round end steel tubular(RCFST)members,4 members were tested under pure bending.The effects of sectional aspect ratios and steel ratios on failure mode,deflection curve,section strain and bending capacity of RCFST members under pure bending were analyzed.The flexural behavior of RCFST members was simulated by the finite element model based on the software ABAQUS.The experimental results were in good agreement with the simulation results.The verified model was used to analyze the whole process and the effects of parameters.Finally,based on ABAQUS simulation analysis,a formula for calculating the bending capacity of RCFST members was proposed.The calculation results agreed well with the experimental results.The results show that RCFST members have obvious deflection deformation under pure bending.When the mid-span deflection reaches L/25(L is the length of specimen),the specimens can bear large load and perform good ductility.The deflection curve of RCFST members can be assumed to be a sinusoidal half-wave curve,and the mid-span section is substantially maintained as a flat section.When the members reach the bending capacity,the steel tube bears most of the moment,and the round end steel tube has stronger confinement effect on the concrete than the rectangular part of the steel tube.The bending capacity of RCFST members increases with the increase of the steel strength,while the change of the concrete strength has little effect on the flexural behavior.