基于承载能力劣化的简支T梁桥寿命预测研究

Degradation on Life Prediction of Simply Supported T-beam Bridge Based on Deterioration of Carrying Capacity

为了更准确地预测混凝土简支T梁桥的剩余使用寿命,基于混凝土碳化、钢筋锈蚀模型,考虑了混凝土强度的经时变化、钢筋的时变锈蚀量、钢筋和混凝土的协同工作能力降低系数,研究了混凝土简支T梁桥的承载能力劣化规律,并根据某实际桥例建立有限元模型以承载力极限为准则分析该T梁桥剩余使用寿命与承载能力劣化的关系。研究表明:混凝土被碳化是钢筋发生锈蚀的前提,钢筋开始锈蚀的时间为混凝土保护层减掉碳化残量后的完全碳化时间;混凝土保护层开裂前钢筋锈蚀速度缓慢,混凝土强度衰减是承载力下降的主导因素,保护层开裂后钢筋锈蚀速度较快,加速了结构承载力的下降;当锈蚀量超过0.3mm后,钢筋锈蚀对承载力的影响逐渐减小;当结构承载力随着材料劣化而下降到承载力极限时,标志着结构使用寿命的终结。

bridges, taking In order to predict the remaining service life of simply-supported reinforced concrete T-beam into account of the time-dependent characteristics of concrete strength, reinforcement corrosion and co-working coefficient between concrete and reinforcement, capacity degrada based on the models of concrete carbonization and reinforcement corrosion. tion of the T-beams was investigated the background of a realistic bridge,finite element model was established and the relationship between the remaining service life and capacity degradation was analyzed according to the criterion of ultimate capacity. The results showed that reinforcement corrodes only when concrete carbonizes, and the time when reinforcement starts corroding is the time when complete carbonization of concrete cover achieves. Corrosion of reinforcement starts slowly before crack of the concrete cover, and during this stage strength degradation of concrete is the essential factor that leads to deterioration of capacity of the T-beams. When the concrete cover cracks, corrosion of reinforcement happens more quickly, which accelerates the capacity deterioration of the T-beams. The effect of the reinforcement corrosion on the capacity of the T-beams declines when the amount of corrosion exceeds 0.3mm. The service life of the T-beams comes to an end when their capacities cannot satisfy the load effects as the degradation develops.