不同约束方式下钢筋混凝土短柱火灾后(下)力学性能的试验研究

Experimental Study on Mechanical Performance of Reinforced Concrete Stub Columns under and after Fire with Different Restraints

为研究钢筋混凝土短柱在相邻构件约束条件下,并经荷载和火灾共同作用后的力学性能,开展了18根受不同约束方式作用的钢筋混凝土短柱火灾后(下)力学性能的试验研究。获得了火灾后(下)钢筋混凝土短柱的剩余承载力、剩余轴压刚度、荷载-轴向变形关系曲线,分析讨论了约束方式、标准升温时间及荷载比等对火灾后钢筋混凝土短柱力学性能的影响。研究结果表明,火灾下和火灾后钢筋混凝土柱试件的破坏模式类似,但后者的混凝土表面裂纹以及剥落较前者严重;不论是火灾下还是火灾后,恒刚度约束的试件破坏较恒荷载约束严重;且恒荷载约束条件下得到的试件耐火极限大于恒刚度约束条件下得到的耐火极限。

To study the behavior of reinforced concrete(RC)stub columns with the restraint of adjacent members under combined loading and fire,18 tests of RC stub columns both under and after fire were conducted.The residual load-bearing capacity,residual axial compression stiffness,and load-axial deformation curves of the tested columns were obtained.Then,the influences of restraint modes,heating time,and load ratio on the behavior of the RC stub columns were analyzed and discussed.The results show that the failure modes of the RC stub columns are similar under and after fire,but surface cracks and spalling are more severe after fire than those under fire.Moreover,the failure of the columns with constant stiffness restraint is more severe than those with constant loading restraint,and the fire resistance of the columns with constant loading restraint is greater than those under constant stiffness condition.