角钢桁架型钢混凝土梁纯扭试验及损伤分析

Pure torsional experiment and damage analysis of angle steel truss reinforced concrete beams

为研究角钢桁架型钢混凝土梁的纯扭性能,设计加载装置并完成了7个角钢桁架型钢混凝土梁在纯扭荷载作用下的静力试验,考虑了型钢配钢形式、型钢保护层厚度和混凝土强度等级3个变化参数。通过试验观察了试件的破坏形态,揭示其破坏机理,获取了扭矩-应变曲线、扭矩-扭转角曲线及相关特征点等,并分析各变化参数对其抗扭性能的影响,基于能量守恒定律,分析了在纯扭作用下试件的耗能和损伤规律。试验结果表明:角钢桁架型钢混凝土梁纯扭破坏时角钢受拉屈服、棱角处混凝土被压碎,具有良好的抗扭和耗能性能。适当增加型钢体积配钢率和混凝土强度等级均能有效提高角钢桁架型钢混凝土梁的抗扭和耗能性能,增加斜向腹杆效果更显著。增加型钢保护层厚度会降低其抗扭和耗能性能。同时损伤规律基本呈现前期较小、后期较大的特征。

To research pure torsional properties of angle steel truss reinforced concrete beams, loading device was designed and 7 specimens of angle steel truss reinforced concrete beams were tested in static load test under pure torsional loads. Three vary parameters were considered in the experiment such as steel disposition form, steel protective layer thickness and concrete strength grade. The failure patterns were observed and the failure mechanism was revealed. The torque-strain curves, torque-torsion angle curves and relevant feature points were obtained. The influence of each vary parameter on the torsional properties was analyzed. The energy dissipation and damage role of pure torsional specimens were analyzed based on the law of conservation of energy. The results of experiment show that ： failure pattern of angle steel truss reinforced concrete beams under pure torsional loads was that angle steel tress yields and concrete in the comer was crashed, which has better torsion resistance and energy dissipation properties. The increase of the volumetric percentage of steel and the concrete strength grade can improve torsion resistance and energy dissipation properties, effectively increase of oblique web member. The increase of steel protective layer thickness can reduce torsion resistance and energy dissipation properties. The characteristics of damage role presents that damage index is smaller in the early stage and bigger in the late stage.