火灾后混凝土梁抗剪承载力试验与有限元分析

Experiment and Finite Element Analysis of Shear Strength of Concrete Beams Subjected to Elevated Temperature

对一根常温和七根火灾后混凝土梁进行抗剪试验.梁三面受火,采用ISO834标准升温曲线升温2h,待冷却后进行试验.试验主要考虑剪跨比的影响,同时对截面尺寸、受火位置的影响进行了研究.结果表明:火灾(高温)后混凝土梁抗剪承载力降低,刚度下降,极限位移增加;随着剪跨比的增加承载力降低;高温对混凝土受压区影响明显;三面受火状况下,截面高度对高温后混凝土抗剪性能的影响与常温下一致.建议了抗剪承载力有限元计算方法,其结果与试验值吻合较好.

One beam subjected to room temperature and 7 beams subjected to high temperature were tested. Three sides of the beams were subjected to IS0834 standard heating curves for 2 hours, and they were tested after being cooled. The effect of shear span ratio, sectional dimension and position subjected to fire were studied. The results show that after fire, shear bearing capacity of the concrete beams decreases, shearing stiffness of the member degrades, and the ultimate deformation increases. The results also show that the shear bearing capacity decreases as the shear span ratio increases, the high temperature influences more on compression zone, and depth of section of the beam with three sides subjected to fire has the same effect to shear performance as the one to room temperature. A finite element method is proposed to calculate the shear bearing capacity of concrete beams after fire, which has the accepted accuracy.