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利用三维非线性有限单元模型分析高温下型钢混凝土组合柱性能。对两端铰接型钢混凝土柱施加轴向荷载,分析不同截面尺寸、结构钢比例、粗骨料以及轴向荷载大小的柱的抗火性能。本模型在考虑了型钢、混凝土和纵横向钢筋等材料的非线性特性及高温下箍筋对混凝土约束效应的基础上,分析了型钢与混凝土、纵向钢筋与横向钢筋、钢筋与混凝土之间接触面的咬合力在试验模型中对柱的横向变形的影响。此外,本模型考虑了初始偏心距的影响,评价了组合柱的时间-温度曲线、柱失效后的变形和时间-荷载曲线、破坏准则与抗火性能;还分别比较了荷载比、粗骨料及长细比的不同对组合柱的抗火性能的影响。结果显示:随着柱长细比的减小或用钢量的增加,组合柱的抗火性能更好,并且粗骨料的改变对时间-变形曲线有显著影响。由本模型得到的组合柱的抗火性能与根据Eurocode 4规范的计算结果对比可知,除了荷载比为0.5或荷载比为0.4且长细比为0.96的组合柱外,EC4规范适用于其他所有的型钢混凝土组合柱。
Analysis of the Performance of Steel Reinforced Concrete Composite Column under High Temperature by Using Three Dimensional Nonlinear Finite Element Model. Axial loads were applied to the hinged steel reinforced concrete columns at both ends to analyze the fire resistance of columns with different section sizes, structural steel ratios, coarse aggregates and axial load. Based on the nonlinear characteristics of the material such as steel, concrete and longitudinal and transverse reinforcement, and the confinement effect of the stirrups on the concrete under high temperature, this model analyzes the contact surface between steel and concrete, longitudinal steel bar and transverse steel bar, steel bar and concrete The influence of the occlusal force on the transverse deformation of the column in the experimental model. In addition, the model considers the influence of initial eccentricity, and evaluates the time-temperature curve, the deformation and time-load curve, failure criterion and fire resistance of the composite column. The load ratio, coarse aggregate And slenderness ratio of the combination of column fire resistance. The results show that the fire resistance of the composite columns is better with the decrease of the slenderness ratio or the increase of the amount of steel, and the change of the coarse aggregate has a significant effect on the time-deformation curve. The fire resistance of the composite column obtained by this model is compared with the calculation results according to the Eurocode 4 standard. The EC4 standard is applicable to all other sections except the composite column with a load ratio of 0.5 or a load ratio of 0.4 and a slenderness ratio of 0.96 Concrete composite column.