绿色高性能纤维增强水泥基复合材料（GHPFRCC）加固火损框架柱抗震性能试验研究
发布时间：2018-08-07 10:34
【摘要】：绿色高性能纤维增强水泥基复合材料(GHPFRCC)是一种使用大掺量粉煤灰取代水泥的新型建筑材料,较普通混凝土有出色的延性和较高的能量吸收能力。火灾现在已经成为影响结构安全的重要因素,高温作用会导致混凝土的力学性能降低,影响混凝土结构的安全性。本文研究了高温后GHPFRCC三轴抗压性能以及GHPFRCC加固火损框架柱的抗震性能。主要内容包括以下几方面:(1)进行了高温后GHPFRCC三轴抗压试验。通过三轴抗压试验测得GHPFRCC试块经历不同高温后的抗压强度和应变,分析加载速率、围压和温度等因素对三轴抗压强度、弹性模量和应变的影响。试验表明:16组不同配合比和最佳配合比试块的抗压强度随经历温度的增加而降低,随围压的增加而提高;极限荷载对应应变均达到2%以上;25℃、200℃时抗压强度受围压影响较小,此时强度主要是由材料强度和纤维提供,400℃、600℃、800℃试块的抗压强度由围压提供。加载速率对GHPFRCC抗压强度影响不是很大。(2)进行了框架柱的火损试验。进行2根GHPFRCC框架柱和2根C30混凝土框架柱耐火试验,分析框架柱截面温度场分布及火损情况。试验结果表明,GHPFRCC框架柱表面温度最高为242℃,柱角温度可达358℃,C30框架柱表面温度最高为388℃,柱角温度可达456℃,GHPFRCC框架柱截面温度总体低于C30框架,表明GHPFRCC抗火性能良好。主要是因为GHPFRCC中的纤维在高温时熔化形成细密的贯通孔隙,构件内部水蒸气可以通过孔隙逸出,保持了框架柱截面有效面积,迟缓了热量的传递和对流,抑制了柱内温度的上升,使柱体处于较低温度。(3)进行了GHPFRCC加固火损框架柱的拟静力试验。对4根火损柱中的1根GHPFRCC框架柱和1根C30框架柱进行通长加固。将2根加固后的框架柱、2根未加固的火损柱、2根未受火的框架柱(共6根)进行拟静力试验,对比分析GHPFRCC加固火损框架柱、火损框架柱和未受火的框架柱的抗震性能和耗能能力。试验中未加固的火损C30框架柱和未受火的C30框架柱破坏较严重,柱身出现多条较宽的主裂缝,柱侧面出现较多的斜向裂缝,柱底柱角混凝土被压碎破坏;未受火的GHPFRCC框架柱和GHPFRCC加固的火损框架柱破坏较轻,柱身裂缝均为细密裂缝,均匀分布在柱底部,侧面裂缝也大多为水平方向,柱底没有被压坏脱落,构件破坏是由于柱身和底座形成铰而引起。结果表明,GHPFRCC加固的火损框架柱较未加固的火损框架柱的抗震性能及耗能能力均有较大提高;GHPFRCC加固火损框架柱的刚度损失速度要低于未加固的火损框架柱;GHPFRCC框架柱的极限荷载承载力要整体好于相应的C30框架柱。
[Abstract]:Green high performance fiber reinforced cement matrix composite (GHPFRCC) is a new type of building material which uses large amount of fly ash instead of cement. It has better ductility and higher energy absorption ability than ordinary concrete. Fire has become an important factor affecting the safety of concrete structures. High temperature will lead to the reduction of mechanical properties of concrete and affect the safety of concrete structures. In this paper, the triaxial compressive behavior of GHPFRCC after high temperature and the seismic behavior of frame columns strengthened with GHPFRCC are studied. The main contents are as follows: (1) the triaxial compression test of GHPFRCC after high temperature is carried out. The compressive strength and strain of GHPFRCC specimen were measured by triaxial compression test. The effects of loading rate, confining pressure and temperature on triaxial compressive strength, elastic modulus and strain were analyzed. The test results show that the compressive strength of different mix ratio and optimum mix ratio of w / 16 groups decreases with the increase of temperature and increases with the increase of confining pressure, and the compressive strength is less affected by confining pressure when the corresponding strain of ultimate load is more than 2% at 25 鈩，
本文编号：2169753
[Abstract]:Green high performance fiber reinforced cement matrix composite (GHPFRCC) is a new type of building material which uses large amount of fly ash instead of cement. It has better ductility and higher energy absorption ability than ordinary concrete. Fire has become an important factor affecting the safety of concrete structures. High temperature will lead to the reduction of mechanical properties of concrete and affect the safety of concrete structures. In this paper, the triaxial compressive behavior of GHPFRCC after high temperature and the seismic behavior of frame columns strengthened with GHPFRCC are studied. The main contents are as follows: (1) the triaxial compression test of GHPFRCC after high temperature is carried out. The compressive strength and strain of GHPFRCC specimen were measured by triaxial compression test. The effects of loading rate, confining pressure and temperature on triaxial compressive strength, elastic modulus and strain were analyzed. The test results show that the compressive strength of different mix ratio and optimum mix ratio of w / 16 groups decreases with the increase of temperature and increases with the increase of confining pressure, and the compressive strength is less affected by confining pressure when the corresponding strain of ultimate load is more than 2% at 25 鈩，
本文编号：2169753
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