GHPFRCC框架梁抗火性能试验研究

Experimental Study on Fire-resistance Properties of Green High-performance Fiber-reinforced Cementitious Composites Frame Beams

绿色高性能纤维增强水泥基复合材料(green high-performance fiber-reinforced cementitious composites,GHPFRCC)是在传统ECC基础上加入大掺量粉煤灰制成的一种新型绿色建筑材料。GHPFRCC具有高延性特点,很适合用于框架梁、柱及节点,但GHPFRCC框架梁作为一种新型结构其抗火性能研究较少,为了探明GHPFRCC框架梁的抗火性能,进行10根GHPFRCC框架梁的耐火试验,研究荷载比、纵筋率、剪跨比等因素对火灾下GHPFRCC框架梁的跨中挠度、温度场分布的影响。试验结果表明,火灾下GHPFRCC框架梁升温速度最快的是梁底面,速度最慢的是梁顶面;剪跨比为火灾下GHPFRCC框架梁破坏形态的主要影响因素;跨中挠度曲线近似线性下降,且剪跨比越大,跨中挠度下降斜率越大;纵筋率可有限提高GHPFRCC框架梁的抗剪承载力,箍筋对保证火灾下GHPFRCC框架梁的抗剪性能至关重要。

Green high-performance fiber-reinforced cementitious composites(GHPFRCC)is a new type of green building material that is based on the traditional engineered cementitious composites(ECC)and mixed with a large amount of fly ash.GHPFRCC has high ductility and is suitable for frame beams,columns and joints.However,as a new type of structure,the fire resistance of GHPFRCC frame beams has not well understood.In order to find out the fire resistance of GHPFRCC frame beams,fire resistance tests on 10 GHPFRCC frame beams were carried out to study the effects of load ratio,longitudinal reinforcement ratio,and shear span ratio on the mid-span deflection and temperature field distribution of GHPFRCC frame beams under fire.The experimental results show that the fastest heating rate of GHPFRCC frame beams under fire is found in the bottom of the beam section,and the slowest is for the top of the beam.Shear span ratio is the main factor affecting the failure mode of GHPFRCC frame beams under fire.The mid-span deflection curve of the GHPFRCC frame beams decreases approximately linearly,and the larger the shear-span ratio,the larger the mid-span deflection decline slope.The longitudinal reinforcement ratio can slightly improve the shear capacity of GHPFRCC frame beams.The stirrups are very important to ensure the shear performance of GHPFRCC frame beams under fire.