脱空对钢管混凝土短柱偏压性能的影响研究

Research on Debonding Effect of Steel Skin and Concrete Core on Responses of Short Concrete-Filled Steel Tubular Column Under Eccentric Loads

为研究脱空对钢管混凝土拱肋偏压性能的影响,以某上承式钢管混凝土拱桥钢管混凝土拱肋脱空检测结果为依托,采用Abaqus有限元软件建立模型,分析不同脱空率下圆钢管混凝土偏心受压短柱的破坏模式、累积塑性应变、钢管环向应力、极限承载力等,并提出在钢管内侧焊接PBL加劲肋的构造优化方案以降低脱空影响。结果表明:核心混凝土脱空导致钢管中部出现大面积凹曲,凹曲程度和累积塑性应变随脱空率的增大而增大;在轴向平均应变小于800με时,钢管对混凝土基本无约束力,后期随着脱空高度增加套箍效应逐渐减弱;极限承载力随脱空率的增大而降低,降低幅度逐渐减缓;PBL加劲肋可改善脱空构件的破坏模式,在增加一定含钢率的情况下,显著提高极限承载力,降低脱空带来的影响。

In this paper,the debonding effect of steel skin and concrete core on the responses of the concrete-filled steel tubular(CFST)arch is studied.Based on the inspection of the debonding in a deck-type concrete-filled steel tubular arch bridge,a finite element model was established by Abaqus,to analyze the responses of CFST column under the action of eccentric loads,specifically the failure mode,accumulated plastic strain,circumferential stress of steel tube and ultimate load bearing capacity.And the effect of welding PBL stiffeners inside the steel tube to alleviate debonding of steel skin and concrete core was examined.It is shown that the debonding of core concrete resulted in a large area of concave curvature in the central section of the steel tube,where the extent of concave curvature and accumulated plastic strain were increased as the debonding rate was enlarged.When the average axial strain was less than 800με,the steel tube lost restricting force to the core concrete.At the late stage,the increase of debonding depth led to the decrease of confinement effect.The ultimate load bearing capacity was reduced as the debonding was intensified,but the reduction was increasingly weakened.PBL stiffeners could modify the failure mode of the debonded components,when the content of steel was enhanced,the ultimate load bearing capacity was remarkably improved,which would alleviate the consequences of debonding.