高温后钢筋再生混凝土梁受力性能试验及承载力计算

为了研究高温后钢筋再生混凝土梁的受力性能，以再生粗骨料取代率、历经最高温度、混凝土强度、剪跨比为变化参数，设计了34个试件（其中高温后试件26个，常温对比试件8个）进行静力加载试验。观察了试件的破坏过程及其破坏形态，得到了烧失率、荷载-挠度曲线、截面应变分布、峰值荷载、峰值挠度等受力性能指标，分析各参数对其承载能力、挠度、延性、损伤等的影响。同时，对高温后钢筋再生混凝土梁受弯及受剪承载力的计算公式进行了推导。研究结果表明：高温后钢筋再生混凝土梁的破坏形态与其在常温下的相似，根据剪跨比的不同，发生了剪切斜压破坏和弯曲破坏；高温后试件的烧失率在0.44%~8.95%之间，随着温度和取代率的提高，烧失率逐渐增大；高温后钢筋再生混凝土梁的剩余承载力、峰值挠度及延性均不低于高温后普通钢筋混凝土梁；随着取代率的增大，承载力和延性呈先提高后降低的趋势，峰值挠度和损伤则逐渐增大；温度越高，承载力、峰值挠度和延性越低，损伤越重；剪跨比的增大使其承载力降低，峰值挠度增大；提高混凝土强度，能有效提高高温后再生混凝土梁的承载力，减小其峰值挠度。

Mechanical behavior and calculation on bearing capacity ofreinforced recycled aggregate concrete beam afterelevated temperature

To investigate the mechanical behavior of reinforced recycled aggregate concrete beam (RRACB) after exposure to elevated temperature, 34 specimens, including 26 specimens after high temperature and 8 specimens at room temperature, were designed for static loading test. The replacement percentage (RP) of recycled coarse aggregate, highest temperature, concrete strength and shear span ratio were considered as parameters. The failure mode of specimens was observed and the ignition mass loss, load-deflection curves, strain distributions of cross-section, peak load, peak deflection were obtained from the test. The bearing capacity, bending, ductility and damage value of specimens with different parameters were investigated. Meanwhile, a calculation method of flexural bearing capacity and shear capacity on RRACB after high temperature was put forward. The results show that the failure modes of RRACB after high temperature are similar to those under normal temperature. All the failure modes of specimens are bending failure and shear failure. With the increase of temperature and RP, the mass loss increases gradually, ranging from 0.44% to 8.95%. The residual bearing capacity, peak deflection and ductility value of RRACB are superior or comparable to those of conventional reinforced concrete beam. With the increase of RP, the bearing capacity and ductility increase initially and decrease afterwards, the peak deflection and damage increase gradually. The higher the temperature, the lower the bearing capacity, peak deflection, ductility value, and the greater the damage. The increase of shear span ratio reduces the bearing capacity and increases the peak deflection. Improving the strength of concrete can enhance bearing capacity and decrease peak deflection.