【摘要】 火灾在短时间内产生高温并对桥梁结构造成损伤,一般虽不致使桥梁立即倒塌,但却降低了其安全性、适用性和耐久性,使其无法继续正常使用。火灾后,必须及时、科学地对受损结构构件进行损伤评估,才能为火损后桥梁的处治对策提供可靠的理论与数据支持。依托足尺预应力混凝土空心板梁火损试验,进行火损后预应力混凝土空心板梁的检测,研究火损后该类板梁构件的损伤表现。在受火过程中板梁底板混凝土可能会发生爆裂情况,可能导致钢筋及钢绞线外露,直接承受火焰的炙烤。火损后板梁的剩余承载力一方面与钢绞线处的平均过火温度有关,另一方面与混凝土的爆裂严重程度有关,若钢绞线处的平均过火温度较高且混凝土爆裂导致钢绞线外露,则在加载过程中钢绞线可能断裂,使得火损后板梁承载能力明显下降。根据实测的火损后预应力混凝土空心板梁剩余承载力大小,采用粘贴碳纤维布方式对空心板梁进行加固,研究该加固方法的实际加固效果。结果表明:钢绞线所遭受的最高温度是火损后预应力混凝土空心板梁评估中的一个重要指标。烧失量法是检测混凝土过火温度较为精确的一种方法,可供实际工程应用时参考。粘贴碳纤维布加固火损后板梁是一种行之有效的加固方法,但碳纤维布对于刚度的贡献几乎为零。更多还原

【Abstract】 Fire can reach a high temperature at short time and damage bridge structure,generally,though it does not cause the collapse of the bridge immediately,but reduces its safety,serviceability and durability,making it impossible to continue to use normally. After fire,damage assessment for structural components must be conducted timely and scientifically in order to provide reliable theory and data support for treatment measures of the damaged bridge. Based on fire damage test of full-scale pre-stressed concrete hollow slab beam,the pre-stressed concrete hollow slab beam after fire damage is detected to study the fire damage performance of these slab beam components. In the process of fire,the concrete at bottom of the slab beam is likely to burst,which may cause the steel reinforcement and steel strand to be exposed,directly bearing thefire. On one hand,the residual bearing capacity of the slab beam after fire damage is associated with the average fire temperature at steel strand,on the other hand,it is associated with the burst severity of concrete,if the average fire temperature of steel strand is higher and the steel strand is exposed caused by concrete burst,the steel strand may rupture in the loading process,making the bearing capacity of slab beam bearing decreases obviously after fire damage. According to the actual remaining bearing capacity of pre-stressed concrete hollow slab beam after fire damage,the hollow slab beam is reinforced by bonding CFRP sheets to study the reinforcement effect of the methods. The result shows that( 1) the maximum temperature of the steel strand is an important index in the evaluation of fire damaged PC hollow slab beam;( 2) the method of ignition loss is an accurate method to detect the fire temperature of concrete and can be used for reference in practical engineering;( 3) it is an effective method to strengthen the fire damaged hollow slab beam by bonding CFRP sheets,but the contribution of CFRP sheets to rigidity is almost zero.更多还原