混凝土桥梁以其施工方便、造价经济、养护方便、跨越能力强等优点而得到广泛应用，而近年来公路桥梁火灾事件频频发生，火灾时的高温作用能使组成桥梁的混凝土、普通钢筋以及预应力钢筋等受到损伤，同时又能使组成桥梁的各部件产生损伤。火灾不仅对混凝土桥梁自身造成极大损伤，而且严重影响交通运输的正常运营。火灾后必须对受损桥梁进行及时且合理科学的损伤评估，并制定合理的处置加固方法，以达到恢复结构承载能力、保证路网通畅的目的。本文以一座遭遇火灾的混凝土桥梁为背景，对火灾后混凝土桥梁结构受损评价分析方法及处置加固方法进行系统研究，主要研究如下： （1）在现有研究成果的基础上，从混凝土桥梁的组成材料角度出发，归类分析了混凝土、普通钢筋以及预应力钢筋在火灾时和火灾后的损伤特点，为过火混凝土桥梁的检测评估提供了依据。 （2）在了解混凝土桥梁各组成材料损伤特点的基础上，提出了适用于过火桥梁结构的检测评估程序，并对过火背景桥各构件按照该程序进行一系列受损检测，验证了该检测评估方法和流程的可操作性，本文提出的过火桥梁损伤检测方案具有一定参考价值。 （3）研究分析了过火桥梁的几种评价方法，针对现有研究不足，提出了过火混凝土桥梁结构性能的综合评价法，详细给出了其损伤评价过程，并成功应用于背景桥的损伤评估中。 （4）研究了过火桥梁处置加固的基本原则以及火灾后桥梁各构件的主要加固方法，并讨论了各加固方法的适用性。最后提出了背景桥梁加固维修方案，并通过对加固后的背景桥进行理论分析计算验证了该方案安全可靠，为同类型桥梁的加固维修提供依据。

Concrete bridge has been widely used for its convenient construction, economical construction, convenient maintenance and strong crossing capability. In recent years, the fire incidents of bridge structure occur frequently. The high-temperature action of fire can damage the concrete, ordinary steel bar and prestressed steel bar, at the same time causing damage to the components of the bridge. The fire not only cause great damage to the concrete bridge itself, but also seriously affect the normal operation of transportation. After the fire, timely and reasonable damage assessment of damaged bridges must be carried out, and reasonable reinforcement method should also be designated in order to achieve the restoration of structural carrying capacity and to ensure the smooth road network purposes. This paper is based on a concrete bridge encountered a fire, and the research of fire damage assessment and reinforcement methods on bridge structure are systematically studied. The main results are as follows: (1)Based on the existing research results, the damage characteristics of concrete, ordinary steel bar and prestressed steel bar in fire and after fire are categorized and analyzed from the point of view of the composition of concrete bridge, which provide the basis for the detection and evaluation of concrete bridge encountered a fire. (2)On the basis of understanding the damage characteristics of the concrete bridges, the testing and evaluation procedures for the bridge structures are put forward, and a series of damage detection are carried out for each component of the fire background bridge, which verifies the operability of the evaluation methods and processes. The damage detection scheme proposed in this paper has certain reference value. (3)Several evaluation methods of bridge encountered a fire are studied and analyzed. Aiming at the insufficiency of existing research, a comprehensive evaluation method of the structural performance of the damage concrete bridge is proposed. Meanwhile, the damage assessment process is given and successfully applied to damage assessment of the background bridge. (4)The basic principles of reinforcement and the main reinforcement methods of various components of fire damaged bridges are studied, and the applicability of each reinforcement method is discussed. Finally, the reinforcement scheme of the bridge is proposed and proven safe and reliable according to the theoretical analysis of the background bridge after reinforcement, which provides the basis for the reinforcement and maintenance of the same type of bridge.