氯盐环境下再生混凝土框架边节点抗震性能试验研究

Seismic testing of exterior recycled concrete joints under chloride environment

为研究氯盐环境下再生混凝土框架边节点的抗震性能,以再生粗骨料取代率和钢筋锈蚀率为变量,设计8个钢筋混凝土框架边节点,采用覆盖海绵和不锈钢网,按1∶1比例干湿循环的方法通电加速锈蚀,达到预期锈蚀率后观测锈胀裂缝,之后进行拟静力试验,以研究模拟地震动下节点试件的破坏过程和滞回特性。结果表明:在未锈蚀的情况下,再生粗骨料取代率为50%和70%的试件在承载力、刚度、延性和耗能等方面低于普通混凝土试件,而取代率为100%的试件则与普通混凝土试件相差不大;采用干湿循环的通电锈蚀方法可较好地模拟实际氯盐环境,使钢筋产生红棕色铁锈并发生坑蚀;对再生粗骨料取代率为100%的试件,其承载力和刚度在锈蚀率小于2.18%(最大锈胀裂缝宽度为1.20 mm)时变化不大,不小于2.18%时显著下降,其延性和耗能能力在锈蚀率小于4.17%(最大锈胀裂缝宽度为3.08 mm)时略高于未锈蚀试件,不小于4.17%时(节点箍筋锈断)迅速降低。

In order to study the seismic behavior of reinforced recycled concrete joints under chloride environment,eight exterior joints with different replacement rates of recycled coarse aggregate( RCA) and reinforcement corrosion rates were designed,and seismic analyses were carried out using quasi-static tests. Corrosion was accelerated by the electrochemistry method with sponge and stainless steel wire mesh wrapping around the specimens under wet/dry( 1∶ 1) condition,and corrosion cracks were observed when reaching expected corrosion rates. The results indicate that the load-carrying capacity,stiffness,ductility and energy dissipation of uncorroded specimens with 50% and 70%RCA replacement rates are inferior to those of the normal concrete specimen,while the behavior of the specimens with100% RCA replacement rate is similar to that of the normal concrete specimen. The chloride environment can be well simulated by electrochemistry method under wet/dry( 1∶ 1) condition,leading to red rust and pitting corrosion on the reinforcing bars. For the specimens with 100% RCA replacement rate,the load-carrying capacity and stiffness decrease significantly when the corrosion rate exceeds 2. 18%( maximum crack width is 1. 20 mm),while their ductility and energy dissipation are superior to those of the uncorroded joint when the corrosion rate is less than 4. 17%( maximum crack width is 3. 08 mm),and then decrease significantly.