圆端形椭圆钢管混凝土短柱局部轴向受压性能研究

Study on the Behavior of Round-Ended Elliptical Concrete-Filled Steel Tube Stub Columns Under Axial Local Compression

圆端形椭圆钢管混凝土构件作为新型异形钢管混凝土构件,具有合理的主、次轴分布和较小的阻流系数,可应用在桥梁墩柱、高架柱和拱塔上,然而目前对其局部轴向受压性能的理论研究尚有不足。提出了一种圆端形椭圆核心约束混凝土等效本构关系模型,考虑了圆端形椭圆截面特征、材料非线性、钢管与核心混凝土的复杂接触问题,建立了局压作用下圆端形椭圆钢管混凝土短柱的数值分析模型;通过试验验证了有限元分析模型的准确性;系统研究了局压面积比、钢材强度、混凝土强度、含钢率、长宽比、截面面积和垫块形状等诸多参数对其局压承载力的影响,揭示其工作机理和破坏模式,基于统一理论提出了圆端形椭圆钢管混凝土短柱的局压承载力计算方法。研究结果将为圆端形椭圆钢管混凝土柱设计和应用提供参考依据。

Round-ended elliptical concrete-filled steel tube(RECFST)member is a novel special-shaped composite member which can be used as bridge pier column,viaduct and arch tower,because of its reasonable distribution of major-minor axis and low flow resistance.However,the investigations on RECFST stub columns under axial local compression are still limited.This paper presents a finite element(FE)analysis model for RECFST members under axial local compression based on a simplified equivalent method for providing the constitutive model of confined core concrete.The crosssection feature,material nonlinearity and contact interaction between steel tube and core concrete are considered as well.The accuracy of FE modeling is verified by the test and FE results.The influence of local compressive area ratio,steel strength,concrete strength,steel ratio,cross-section slenderness and scale effect on the axial local compressive performance of RECFST stub columns are evaluated.Failure modes and working mechanism of locally-loaded RECFST stub columns are revealed.Finally,a simplified empirical formula for predicting the ultimate axial local compressive capacities of RECFST stub columns is proposed in this paper.The results can provide a reference for the design and application of RECFST columns in engineering practice.