为研究火灾高温后组合梁桥的基本材料力学性能与特征，共制作3片具有代表性的缩尺梁模型：简支T形梁、简支箱形梁及连续箱形梁，利用火灾试验炉进行局部三面受火试验，并给出详细的试验方案。通过受火后取样试件与未受火试件的材性试验结果对比，可以发现受火(最高温度在700～900 ℃)对钢板材料的屈服强度及极限强度均有一定程度的降低，降低幅度为10%～20%；而钢板材料弹性模量随温度升高略有变化，但变化值不大。火灾对混凝土强度材性的影响可以忽略不计，但对其冷却后的材料强度有一定影响，相对于常温混凝土其强度会降低5%左右。

In order to investigate the basic mechanical performances of the composite girder under the fire loads, three typical experimental models including simple-support T-section girder, simple-support box-section girder, and continuous box-section girder, were built. After establishing a detailed experimental plan, a fire experiment loaded on three sides was conducted in a laboratory fire furnace. The comparative study on the material characteristics of steel between the models before and after the fire loads showed that the yield and limit strengths decreased by 10%~20 % after fire loads with the 700~900 ℃.The elastic modulus of the steel girder only slightly changed with the increase of temperature. The influence on the concrete material during the fire could be almost ignored; however, 5% decrease of the concrete material strength could be found after cooling off. The results provided good experimental and theoretical foundation for determining the basic material characteristics in the anti-fire design of the composite girders.

交通运输部西部建设科技项目(2011318812970)