多室式钢管混凝土T 形短柱的非线性分析

通过定义等效方形截面和改变混凝土强约束区、弱约束区界线底角来衡量多室式T形截面内钢材对混凝土的整体约束作用,依据轴压试验结果修正了Mander 约束混凝土模型中有效侧向约束力及下降段的表达式,建立了核心混凝土的本构关系。应用ABAQUS 对8 个多室式钢管混凝土T 形短柱试件的轴压性能进行了模拟,模拟结果与试验数据的对比表明,该本构关系能较好地适用于对构件性能的非线性分析。在此基础上探讨了构件中钢材和混凝土的共同工作情况,发现其工作机理与其它截面形式的钢管混凝土柱较为一致。将多室式钢管混凝土T形柱视为由3个矩形钢管混凝土部件折减钢板后组成,应用叠加原理得出了构件的强度承载力公式,可供实际应用参考。

NONLINEAR ANALYSIS OF MULTI-CELL T-SHAPED CONCRETE-FILLED STEEL TUBULAR STUB COLUMNS

The confinement that the concrete core is subjected to in multi-cell T-shaped concrete-filled steel tubular(MT-CFST) columns is characterized by defining the equivalent square section and the angle of boundary between effectively confined area and ineffectively confined area of the concrete core.According to experimental results,the constitutive relationship of the concrete core is suggested by means of modifying the expressions of effective lateral pressure and the descending stage in Mander’s confined concrete model.Numerical simulation of 8 MT-CFST stub columns under axial load is accomplished based on ABAQUS.The comparisons between calculated results and experimental data demonstrate that the suggested concrete constitutive relationship is applicable for the finite element analysis of MT-CFST columns.Subsequent discussion on the cooperative properties of two materials shows the similarity on mechanism between the MT-CFST columns and other types of CFST columns.Considering the MT-CFST columns as a combination of three rectangular concrete-filled steel tubular units with two extra steel plates removed,the formula for their bearing capacities is proposed based on superposition principle,which may provide some references for engineering practice.