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针对火灾下预应力混凝土T梁桥的整体刚度衰变问题,给出了结构挠变率与刚度衰变率关系方程,建立了刚度衰变与结构挠变率(挠度变化速率)耦合计算模型,利用热力耦合计算方法分析了火灾全程多梁式预应力混凝土T梁桥的结构挠变率,揭示了火灾全程多梁式预应力混凝土T梁桥刚度衰变规律。研究结果表明:T梁桥下部整体受火时,温度峰值点出现在梁肋马蹄角点处,直角点温度高于钝角点温度;火灾全程中单肋受火T梁挠变率线性递增,两肋及两肋以上受火T梁挠变率呈二次抛物线趋势递增;单侧非间隔梁肋受火的挠变率稍大于同数间隔梁肋受火的挠变率;随着延火时间的增加,多肋受火的预应力混凝土T梁整体刚度损伤呈非线性增加。火灾全程预应力混凝土T梁桥的刚度衰变研究可为预应力混凝土梁桥的灾后评价提供依据。
In order to solve the problem of overall stiffness decay of prestressed concrete T-beam bridge under fire, the equation of the relationship between the structural deflection rate and the stiffness decay rate is given. Coupled calculation model of the stiffness decay and structural deflection rate (deflection rate) The method of calculation is used to analyze the structural deflection rate of the full multi-beam prestressed concrete T-beam bridge and the law of stiffness decay of the full multi-beam prestressed concrete T-beam bridge is revealed. The results show that when the whole lower part of T girder is exposed to fire, the peak temperature appears at the point of horseshoe angle and the right-angle temperature is higher than the obtuse angle. The deflection rate of T-beam increases linearly during the whole fire, The deflection rate of the T-beam above the rib and two ribs is in the trend of quadratic parabola; the deflection rate of the unilateral non-separated beam is slightly larger than that of the beam with the same number of spaced apart ribs; with the delay time Increasing, multi-ribbed fire prestressed concrete T beams showed a non-linear increase in overall stiffness. The research on the stiffness decay of the prestressed concrete T-beam bridge in fire can provide the basis for the post-disaster evaluation of the prestressed concrete beam bridge.