Fire Performance Of Green High Performance Fiber Reinforced Cementitious Composites Frame Joint

Green High Performance Fiber Reinforced Cementitious Composites(GHPFRCC)is made of cement,water,high content fly ash,quartz sand,polyvinyl alcohol fiber(PVA),and high efficiency Water-reducing agent and other raw materials prepared.GHPFRCC has the ability of multi-slit cracking and strain hardening at room temperature.It has been shown that the new frame beam-column joints produced by GHPFRCC exhibit excellent seismic performance and energy dissipation at room temperature.However,the mechanical properties of GHPFRCC are degraded due to the melting of PVA fibers at high temperatures,so the fire resistance of GHPFRCC framework nodes needs to be studied.In this paper,the GHPFRCC framework node is taken as the object of study,and the effect of node pouring form and stirrup rate on the fire resistance of GHPFRCC frame nodes is studied by fire resistance test.The main contents include the following two parts:The first part mainly introduces the GHPFRCC framework node fire test.According to the basic principle of "strong column weak beam,strong shear weak bend",we use five kinds of frame nodes of the same size using GHPFRCC and C30 concrete materials with the best mix ratio to make fire test preparation under high temperature and constant load coupling.The effects of different casting materials,pouring form and core area on the fire resistance of the joints were studied.The second part mainly analyzes and discusses the influencing factors and laws of fire resistance of GHPFRCC framework node.The fire resistance,bursting phenomenon,beam-column displacement and beam-end failure of the frame nodes after high temperature and high temperature are analyzed and discussed.The experimental results show that(1)Although the thermal stability of GHPFRCC is not good at high temperature,and the bursting of GHPFRCC frame joints is more serious than that of concrete frame joints,the fire resistance limit of GHPFRCC frame joints is larger than that of concrete frame joints;(2)C30 concrete mixed pouring frame beam column joints under high temperature under the maximum fire resistance limit,the smallest specimen damage,showing excellent fire resistance.(3)It has been shown that GHPFRCC can only reduce or even replace the configuration of the stirrups in the core area at room temperature.However,this test found that the need for the configuration of stirrups in the core area at high temperatures,The GHPFRCC framework node has obvious shear failure under the action of high temperature,and the joint core area of the GHPFRCC is uplifted.The fire resistance of the frame joint is the shortest and the destruction is the most abrupt.