中文摘要：

为研究多肋火灾下混凝土T形梁桥的剪力滞变化规律,以横桥向5片T形梁组成的混凝土简支梁桥为背景进行分析。采用ANSYS建立混凝土T形梁桥多肋火灾模型,分析多梁肋在对称火荷载作用下,混凝土T形梁桥实体剪力滞比的变化特征。结果表明：所有梁肋受火时,随火温持续时间的延增,剪力滞比呈指数曲线趋势逐渐增加,且处于负剪力滞分布状态;单侧半跨5片梁肋受火,火温持续时间在20min内时,剪力滞比变化明显,火温持续时间在20～60min时,剪力滞比基本回至初值,且随火温持续时间的延增,剪力滞比时程曲线逐渐向初始状态靠拢,走势平坦;桥跨方向非连续梁肋受火,近火梁肋剪力滞比显著。

英文摘要：

To study the varying laws of the shear lag of the concrete T-girder bridge with its multiple girder ribs exposed to fire, a concrete simply-supported girder bridge comprised of 5 Tgirders in the transverse direction of the bridge was cited as an example and was analyzed. The software ANSYS was used to build up the models of the T-girder bridge with its multiple girder ribs exposed to fire and the varying features of the solid shear lag ratios of the bridge under the action that the girder ribs were subjected to the symmetric fire load were analyzed. The results of the analysis show that when all the girder ribs of the bridge are exposed to fire, with the exten- sion of the fire temperature duration, the shear lag ratios present the tendency of gradually in- creasing in the exponential curves and are in the state of negative shear lag distribution. When the 5 girder ribs of half a span on one side are exposed to fire and the fire temperature duration is within 20 min, the varying of the shear lag ratios is significant. When the fire temperature dura- tion is within 20～60 min, the shear lag ratios basically come back to their initial values and with the extension of the fire temperature duration, the time-history curves of the shear lag ratios gradually approach their initial state and the varying of the curves is fiat. For the discontinuous girder ribs along the bridge spans exposed to fire, the varying of the shear lag ratios of the girder ribs closed to fire is significant.