锈蚀钢筋再生混凝土梁试验研究及刚度分析

Experimental study and rigidity analysis on corroded reinforced recycled concrete beams

通过12根不同钢筋锈蚀率下粗骨料取代率为100%再生混凝土梁的静荷载试验,分析钢筋锈蚀率对再生混凝土梁的破坏形态、裂缝发展规律、荷载-挠度曲线、平截面假定的影响。结果表明:当钢筋锈蚀率小于10%时,梁由于材料强度遭到破坏而发生弯曲延性破坏;当钢筋锈蚀率大于10%时,梁由于钢筋与再生混凝土的粘结失效而发生粘结-剪切脆性破坏;随着钢筋锈蚀率的增加,钢筋与再生混凝土之间的粘结性能先增加后降低,但再生混凝土梁承载力将逐渐降低;在逐级加载过程中无论钢筋锈蚀率大小,再生混凝土梁正截面混凝土应变变化仍满足平截面假定要求。基于普通混凝土梁抗弯刚度规范公式,引入钢筋应变不均匀系数的修正系数,建立了锈蚀钢筋再生混凝土梁抗弯刚度的计算方法。

Static loading tests were carried out on 12 recycled aggregate concrete beams with 100% coarse aggregate replacement rate and different corrosion rate.The effects of steel bar corrosion ratio on failure modes,crack development law and load-deflection curves and plane-section assumption of recycled aggregate concrete beams were analyzed.Results show that when the steel corrosion rate is less than 10%,bending ductile failure occurs because the strength of the material is damaged.When the steel corrosion rate is greater than 10%,beam bond-shear brittle failure occurs because bond failure between steel bars and recycled concrete.With the increase of steel corrosion rate,the bond performance between steel bars and recycled concrete increases first and then decreases,but the carrying capacity of recycled aggregate concrete beam gradually decreases.The strain change of the normal section of recycled concrete beam still meets the requirements of plane-section assumption regardless of the rebar corrosion rate in step-by-step loading process.Based on the code formula of concrete beam flexural stiffness,correction factor of steel strain uniform coefficient was introduced,and calculation method of bending stiffness of corroded reinforced recycled concrete beam was established.