受火后钢-混凝土组合梁材料性能试验研究

Experimental analysis of the mechanical performance of steel-concrete girder under fire loading

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.