Nonlinear Finite Element Analysis Of High Strength Concrete Frame Structures At Elevated Temperatures

Fire safety of the frame structures of high strength high performance concrete(hereinafter referred to as high strength concrete,HSC)is one of the main topics in the fire safety study of concrete structures and is of great significance in promoting the development and application of HSC.To investigate the fire safety of the HSC frame structure,the structural response and fire resistance rating of the frame structures of HSC under fire conditions are analyzed numerically in this thesis,mainly including the following aspects:(1)For the verification of the finite element methods used for the temperature field and non-linear structural analyses of HSC frame structure,the experiment of a one story and one span HSC frame structure reported in the literature are modeled.By comparing the numerical results with the experimental results,the validity and reliability of the finite element methods are verified.(2)By comparing the structure responses of one story-two span HSC frame structures with and without the slab and wall under fire condition,the effect of the slab and wall on the fire safety of the frame structure are analyzed.The suggestion of considering the effect of the slab and wall in the fire safety design of frame structures is given based on the analysis.(3)The deformation features and the fire resistance ratings of a one story-two span HSC frame structure with the slab and wall under one room fire and two room fire conditions are numerically analyzed and compared.The strengthening suggestions for the fire safety of the structure are given based on the numerical analysis.(4)The structural responses of a two story-three span frame structure with the slab and wall under different fire conditions are numerically studied.The effects of different fire locations and fire areas on the fire resistance rating and deformation feature of the structure are analyzed.Suggestions for the fire safety design of the structure are given based on the analysis.(5)The effects of spalling of concrete cover on the fire resistance rating of a one story-two span frame structure with slab and wall are analyzed.By comparing the effects of spalling at different locations,the most unfavorable location of spalling is investigated and strengthening suggestions are given for the fire safety of the structure.