钢管混凝土圆弧拱跨中与拱脚滑移性能的研究

Application on bearing performance of concrete filled steel tube arch with slip ends

通过对6点均布加载条件下钢管混凝土圆弧拱跨中位置处位移和拱脚不同滑移量的监测,以及对钢管外壁和内部核心混凝土的应变、极限承载能力进行分析,同时通过内嵌一种无厚度黏聚力黏结单元的ABAQUS大型有限元软件建立混凝土损伤模型,对圆弧拱抗弯过程进行全过程仿真三维数值模拟分析,较为准确的展示钢管核心混凝土受压破坏过程。实验和模拟分析结果表明:与两端固定相比,钢管混凝土圆弧拱试件在拱脚滑移的过程中,由于受到拉压弯三重作用发生了破坏,核心混凝土产生裂缝,随着荷载继续增加,裂缝的存在导致混凝土体积膨胀,进而使钢管发生鼓包。在一定的拱脚滑移量范围内,跨中截面核心混凝土底部受拉顶部受压,试件跨中与拱脚的弯矩急剧增加,钢管混凝土圆弧拱的承载力随着拱脚滑移量的增加而降低。通过室内试验和数值模拟,以及现场监测的结果分析可知,圆弧拱跨中下降的位移与两侧滑移量呈两倍关系。达到极限荷载后,圆弧拱试件中钢管对混凝土的套箍作用失效。

Through the monitoring of the displacement of the middle across section and the different slip amount in the concrete filled steel tube(CFST)arch and arch foot,which 6 points fixed at both ends under the condition of uniform loading,as well as the strain and the ultimate bearing capacity of outer steel pipe and inner core of concrete which combined with ABAQUS for simulation analysis of bending process with cohesive elements as the main research method in the constitutive model of concrete.This finite analysismethod uses the three-dimensional numerical simulation which displayed accurately in the whole progress of uniaxial compression experiment in the micro aspects.The actual morniting and experiment results shows that compared with the two fixed ends of the CFST arch which damaged by the triple action of pulling、pressing and bending,some cracks appeared on the process of arch slip.When the loading increasingly,the presence of cracks leads to concrete volume expansion,and then make the steel tube drum package.In the range of a certain amount of arch foot slippage,the middle section of core concrete occurred bottom tension and top compression,the bending increased with sharp of the test block span and arch foot,the bearing capacity of steel tube reinforced concrete circular arch is decreased with the increase of the amount of slip of arch foot.Through theoretical deduction,numerical simulation and indoor test,the results of field monitoring can be seen which means the displacement of the middle section of the CFST arch was two times of the amount of slip on both arch ends.After reaching the ultimate load the yield of concrete filled steel tube(CFST)circular arch is one of the hoop action failure of the concrete.