圆端形钢管混凝土偏压柱截面优化研究

为研究圆端形钢管混凝土(RRCFST)柱的截面优化方法,基于混凝土分区思想将RRCFST截面分割为中部矩形与2个半圆形,分别采用不同的混凝土约束本构关系,利用有限元软件ABAQUS建立有限元模型,并用13个RRCFST柱构件的试验结果与有限元结果进行对比,验证了模型的合理性。通过有限元建模方法设置3组共462个RRCFST柱模型,在保证每组内各模型混凝土与钢材的强度及用量恒定的情况下,细致研究了截面高宽比对RRCFST柱偏压承载能力的影响。通过有限元分析RRCFST柱轴向压力-弯矩(N-M)破坏曲线中的直线段部分与截面高宽比的关系,进一步验证了GB 50396—2014中钢管混凝土短柱偏压构件设计方法对RRCFST短柱构件的适用性。根据RRCFST短柱偏压构件设计方法,控制混凝土与钢材的强度及用量不变的情况下,通过偏压验算式推导得到RRCFST短柱构件的N-M破坏荷载包络曲线表达式。提出基于材料强度及用量层面的RRCFS短柱偏压承载力验算方法及满足承载要求的截面高宽比计算方法,为截面优化研究及工程应用提供参考。结果表明:在固定材料强度及用量不变的条件下,RRCFST短柱的N-M破坏荷载包络曲线由一段直线段及2段曲线段组成; 推导得到上述包络曲线表达式后,可在构件设计过程中直接计算判断所用材料是否足量,并计算确定构件最优截面尺寸。

Sectional Optimization of Round-ended Rectangular Concrete-filled Steel Tubular Columns Under Eccentric Compression

In order to study the sectional optimization method of round-ended rectangular concrete-filled steel tubular(RRCFST)columns, the finite element model was established by using ABAQUS based on the idea of concrete partition that the round-ended rectangular section of concrete was divided into middle rectangle and two semi-circular cross-sections for using different concrete constitutive relationships, the simulation results were compared with the test results of 13 RRCFST stub columns, and the rationality of the model was verified. Then three groups of 462 RRCFST column models were set up by using the finite element modeling method, under the condition that the strength and amount of concrete and steel of each model in each group were constant, the influence of aspect ratio on load bearing capacity of RRCFST column under compression was studied in detail. The relationship between the straight line part of the axial compression-bending moment(N-M)failure curve of RRCFST column and the aspect ratio was analyzed by finite element method, and the applicability of the design method of concrete-filled steel tubular(CFST)members under eccentric compression proposed by GB 50396-2014 for RRCFST stub column members was further verified. According to the design method of eccentric compression RRCFST members and assuming that the strength and amount of concrete and steel were constant, the N-M failure load envelope curve expression of RRCFST members based on level of material strength and amount was derived by using the eccentric pressure checking formula. The bearing capacity checking method of RRCFST stub column under eccentric compression based on level of material strength and amount, and the calculation method of aspect ratio that meeting the bearing requirements were both proposed, which provided the reference for sectional optimization research and engineering application. The results show that the N-M failure load envelope curve of RRCFST short column consists of a straight line segment and two curved segments under the condition that the material strength and dosage remain unchange. After deriving the expression of the envelope curve, it can directly calculate and judge whether the material is sufficient or not in the process of component design, and calculate the optimal section size of the component.