| Reinforced concrete structure is the main form of building structure today.Its fire will not only cause structural damage,but also cause people’s loss of life and property,and even cause severe social impact.Therefore,it is an important research direction to study the fire resistance of reinforced concrete building structures and its components.However,most of the current researches on concrete members under the action of fire and high temperature have not considered the impact of concrete high temperature spall,and the spall has become an important factor that cannot be ignored due to its frequent occurrence and uncertainty.Therefore,this paper selects reinforced concrete beams as the object of high temperature fire research,conducts fire tests and static test research,and uses finite element software to compare and analyze the cross-section temperature distribution and mechanical properties of reinforced concrete beams under different spall conditions.In this way,the influence of high temperature concrete spall on the temperature and mechanical properties of concrete beams is studied.The specific research work is as follows:(1)Carding out the change of mechanical parameters of concrete beams under / after high temperature.This paper summarizes the thermal parameters and mechanical properties of concrete and steel bars at high temperature and after high temperature proposed by scholars at home and abroad,and establish parameter change forms under temperature changes.(2)Carry out fire tests and post-disaster static tests on reinforced concrete beams.Carry out high-temperature fire tests on reinforced concrete beams,observe changes in beam spall and other conditions under heating conditions,and determine the temperature distribution of the beam section under high temperature and the bearing capacity of the beam after high temperature.(3)Carry out the numerical simulation of the effects of high temperature burst of reinforced concrete beams.Reinforced concrete beam at a high temperature and after high numerical simulation of the temperature field and the mechanical properties of the reinforced concrete beams are calculated with finite element analysis software ANSYS.Discussion on spall uncertain influence of different conditions of temperature and mechanical properties of the beam,and to analyze come to different parameters affecting the general rules change based on numerical models.(4)Establish a calculation method for the bearing capacity of reinforced concrete beams considering spall.Based on the high-temperature spall-corrected finite element model,the bearing capacity of the reinforced concrete beam under the influence of high-temperature spall is obtained through equivalent section and strength calculation. |
