钢筋混凝土立柱爆破后钢筋骨架承载特征研究

Bearing Characteristics of Reinforcement Steel Cage after Reinforced Concrete Pillar Blasting

钢筋混凝土立柱爆破后通常会残留钢筋骨架,钢筋骨架的承载特性是判断结构局部失稳的重要前提,同时也是确定立柱爆破高度的理论依据。基于立柱爆后实际形态,开展了具有初弯曲形态的立柱钢筋骨架缩尺模型试验,模拟了顶部有水平向约束和无水平向约束两种工况。试验结果表明:立柱钢筋骨架的承载力随着其高度和初始挠度的增加而显著降低;顶部无水平约束钢筋骨架的失稳形态主要表现为侧向倾斜,顶部有水平约束钢筋骨架的失稳形态主要表现为竖向压缩和钢筋外凸。模型试验实测承载力远低于欧拉等直压杆模型计算值,而高于初弯曲压杆模型计算结果,且实测值与初弯曲压杆模型计算值存在线性关系。根据试验结果,给出了初弯曲压杆失稳模型的修正建议。

The reinforced concrete pillar will remain steel cages after blasting. Bearing characteristics of steel cage is an important precondition for judging building instability, which is also the theoretical basis for determining pillar blasting height. According to the practical form of steel cage, the experiment of initial bending compression bar mechanical model is carried out. With these models ,two conditions on the considering of horizontal restraint are sim- ulated. The experiment results show that the bearing capacity of the bending steel cage decreases significantly with the height and the initial deflection increasing. The steel cage without horizontal restraint deforms to one side after collapse. However, the steel bar cage with horizontal restraint is compressed and steel cage bends outside. The meas- ured bearing capacity is less than the value by Euler straight compression bar formula, but bigger than calculated by initial bending compression bar mechanical model. The measured value has high linear relation with initial bending compression bar model. Based on experiment results, improved suggestions for initial bending compression bar model is obtained.