偏心荷载作用下细长型高强钢管混凝土柱的防火性能

对受偏心轴向荷载作用、分别填充普通混凝土和高强混凝土的细长型圆钢管柱进行24组防火试验。此试验是对Romero等人在2011年所做的中心荷载柱的试验结果的进一步探讨。此防火试验中的试验参数涵盖了混凝土标准强度(30MPa和90MPa)、填充类型(普通混凝土、钢筋混凝土和钢纤钢筋混凝土)、轴向荷载水平(20%和40%)和荷载偏心(20mm和50mm)。在固定的边界条件下对室内温度下相对长细比高于其他样本0.5的柱进行试验。研究这种内填混凝土组合件偏心荷载的影响。试验结果显示,与填充普通混凝土的柱相比,添加钢纤维并不能提高细长型柱在偏心荷载下的防火性能。然而,在混凝土柱中添加钢筋则可以提高防火性能。在中空圆钢管中填充混凝土可以提高其防火性能,钢管高强混凝土柱在承载力方面有更明显的提升。与欧洲规范4-1-2中的简易计算模型相比较,尽管此方法可用于偏心荷载作用下的柱,但在预测内填普通混凝土柱和钢纤维钢筋混凝土柱时仍会产生较大的误差。

Fire Behavior of Eccentrically Loaded Slender High Strength Concrete-Filled Tubular Columns

This paper describes a series of 24fire tests conducted on slender circular hollow section columns filled with normal and high strength concrete , subjected to eccentric axial load.It is a continuation of a previous research paper (Romero et al. , 2011 1]), where test results on centrally loaded columns were presented.The test parameters covered in this fire testing program were the nominal strength of concrete (30 and 90MPa), the infilling type (plain , barreinforced and steel fiber reinforced concrete), the axial load level (20% and 40%) and the load eccentricity (20 and 50 mm) .The columns were tested under fixed-pinned boundary conditions , with a relative slenderness at room temperature higher than 0.5for all the specimens.The aim of this paper is to study the influence of eccentricity in combination with the type of concrete infill.The results show that the addition of steel fibers does not improve the fire resistance of slender columns under eccentric loads , as compared to columns filled with plain concrete.However , the addition of reinforcing bars increases the fire resistance of the columns in this situation.Filling the steel hollow section columns with concrete increases their fire resistance , the increase in load bearing capacity being more noticeable for columns filled with high strength concrete.A comparison with the current simple calculation model in Eurocode 4 Part 1.2shows that , although the method is safe for eccentrically loaded columns , it produces a high error in the predictions for columns filled with plain or steel fiber reinforced concrete.