中文摘要：

从现役亚健康桥梁的实际情况出发，提出了损伤极限状态的概念，揭示了亚健康桥梁使用承载能力的内涵，指出了其使用承载能力的评估途径，分析了亚健康桥梁可靠度与新建桥梁可靠度的异同，初步从理论上回答了亚健康桥梁运营车辆荷载科学合理限制的问题。

英文摘要：

Depending on the actual service condition of sub-health bridge, the following investigation is developed： （1）The concept of damage limit state is proposed, from which the subject of the serviceability carrying capacity is revealed, then the evaluation path of serviceability carrying capacity of sub-health beam is given. （2） The difference between the reliability of sub-health bridge and new bridge is analyzied, consequently, the problem about reasonable limit vehicle load is solved preliminarily in theory.