HPFL加固受火RC梁二次受力正截面承载力研究

Study on bearing capacity of right section on second load for RC beam strengthened by HPFL and suffered from fire

高性能复合砂浆钢筋网(high performance ferrocement laminate,HPFL)作为一种新型的加固方式,具有防火、耐高温、施工简易等优点.为研究其加固受火钢筋混凝土(reinforced concrete,RC)梁的性能,结合已有的对高性能复合砂浆钢筋网的试验研究和对受火后混凝土梁强度、弹性模量等性能的研究成果,采用ANSYS中的PLANE55单元对高温后RC梁截面的温度场进行模拟,并利用计算二台阶模型简化成等效T形截面,考虑未卸载完全下高性能复合砂浆钢筋网同原材料间的应力—应变滞后现象,计算初始荷载下待加固构件的滞后应变,在此基础上结合构件受力情况推导出高性能复合砂浆钢筋网加固受火RC梁二次受力下的正截面承载力计算公式,将计算结果同试验数据进行比较,并给出了工程实际算例.结果表明,理论值与试验值吻合较好,采用高性能复合砂浆钢筋网加固后能提高受火RC梁的承载力,可供有关混凝土结构加固设计参考.

High performance ferrocement laminate（HPFL） is a new method of structural reinforce- ment with advantages of its fire-proofing, heat-resisting and can be easily constructed. To study the performance of reinforced concrete beam strengthened by HPFL and suffered from fire, existing test results of high performance ferrocement laminate and reinforced concrete beam suffered from fire were combined, PLANE 55 in ANSYS was used to simulate temperature distribution in cross section of RC beam after fire which section was simplified to an equivalent T cross section based on calculation of two steps model. Considering with stress-strain hysteresis phenomenon between high performance ferrocement laminate and concrete, initial strain of strengthened element was obtained in initial load. Through analyzing the stress state, the method for calculation of bearing capacity of the right section of RC beam under second load was put forward and com- pared with the test datum by an example of practical engineering. The result shows that theoretical formula coincides well with tests, and high performance ferrocement laminate can improve bearing capacity of RC beam after fire, which offers references for reinforcing concrete structure.