油池火下横隔梁对多肋钢筋混凝土T梁桥温度场的影响

基于油池火焰蔓延特性，探究了火灾下横隔梁对多肋钢筋混凝土T梁桥温度场的影响。理论分析了T梁底火焰蔓延总长度与热释放速率间的无量纲关系，用FDS建立4种火灾场景的流体计算模型，分析T梁边界温度时空分布规律，将FDS计算结果加载到T梁桥有限元模型上，计算截面内部温度场。结果表明：在开放空间，T梁底火蔓延与无量纲热功率之间的线性比值大于封闭空间的2.58；横隔梁有效降低了火焰邻近区域的温度，在顺桥向将T梁边界温度场分成4个区域，各分区间温度比无横隔梁时分别降低9.7%、41%、56.8%。说明横隔梁限制了热传递，使火源直接作用的梁构件温度梯度梁肋中部提高33%，梁底提高13.3%，翼板底提高5%。

Impact analysis of transverse diaphragms on the temperature field of reinforced concrete T-girder bridge under pool fires

The effect of transverse diaphragms on the temperature field of concrete bridge with T-girders under fire was investigated based on the character of pool fire flame spread in this study. Firstly, the dimensionless relation ship between the total flame extension length and the heat release rate was studied theoretically. Then the fire models of the T-girders bridge with 4 fire scenarios were built in the FDS to analyze thespatio-temporal distribution of the boundary temperature. Boundary temperature and heat flux were subsequently translated to the finite element model of T-girder after surface fitting in order to analyze numerically the temperature field inside the T-girders. The simulation result shows that:the proportional coefficient of 2/5 power of dimensionless heat release rate to the dimensionless total flame extension length is greater than 2.58. The diaphragm effectively reduces the boundary temperature of the indirect influence area of the fire source, and divides the boundary temperature along T-girders into four step sections with 9.7%, 41%, and 56.8% respectively in boundary temperature reduction compared to the case of no diaphragm. Besides, diaphragm reatrains the heat transmitting along the girders. In the section above fire source, the temperature girders of the T-girder are 33% and 13.3% higher in the center and bottom of the rib and 5% higher in the bottom of flange than the similar case without diaphragms.