应力状态对RC梁混凝土碳化损伤及承载力的影响

为研究应力状态对钢筋混凝土(reinforced concrete,RC)梁碳化损伤及承载力的影响规律,制作了7根RC梁进行加速碳化环境与荷载耦合作用试验研究。将RC梁放入环境箱中,进行三点弯曲静力持荷条件下的7 d、14 d、28 d加速碳化试验,得到不同持荷时间下的RC梁受拉、受压不同区域的混凝土碳化深度,进一步开展加速碳化作用、加速碳化与荷载耦合作用后的RC梁三点弯曲试验,探讨应力状态时碳化深度对RC梁极限承载力的影响机制。结果表明:通过对RC梁受压、受拉区的混凝土碳化深度分析,发现压应力状态会抑制碳化反应的进行,而拉应力状态会促进碳化反应的进行,28 d后受拉区混凝土碳化深度比受压区增加了34.7%。混凝土碳化损伤导致抗压强度降低、钢筋锈蚀影响了试验梁的极限承载力,加速碳化作用28 d后RC梁的极限承载力下降了10.7%,加速碳化与荷载耦合作用28 d后RC梁的极限承载力下降了14.9%。

Influence of Stress State on carbonation Damage and Bearing Capacity of RC Beam Concrete

To investigate the impact of stress state on carbonation-induced damage and the bearing capacity of reinforced concrete (RC) beams, a study was conducted using seven fabricated RC beams. These beams were employed in an investigation involving an accelerated carbonation environment and load coupling tests. Placed within an environmental chamber, the RC beams underwent accelerated carbonation testing, employing a three-point bending configuration under static load conditions for durations of 7 days, 14 days, and 28 days. The carbonation depths of the RC beams in both tension and compression zones were measured across different load-holding durations. Subsequently, three-point bending tests were conducted after subjecting the beams to accelerated carbonation alone, as well as accelerated carbonation combined with load coupling. The objective was to elucidate the mechanism by which carbonation depths impact the ultimate bearing capacity of RC beams in varying stress states.The outcomes underscore the dependence of the ultimate load capacity of RC beams on the depth of carbonation within specific stress conditions. The analysis of concrete carbonation depth in the compression and tension zones of RC beams revealed that the carbonation reaction is hindered by a compressive stress state, while conversely, a tensile stress state promotes the carbonation reaction. Notably, after 28 days, the depth of concrete carbonation in the tension zone was found to be 34.7% greater compared to that in the compression zone.The decrease in compressive strength due to concrete carbonation-induced damage and reinforcement corrosion had a discernible impact on the ultimate bearing capacity of the test beams. After 28 days of accelerated carbonation, the ultimate bearing capacity of the RC beams experienced a reduction of 10.7%. This reduction in ultimate bearing capacity further amplified to 14.9% after 28 days of combined accelerated carbonation and load coupling.