Reinforced Concrete Arch Component High-temperature Mechanical Properties Under Study

Reinforced concrete arched structure, having wide applications, is a common structure form in civil engineering. The study of the arched structure at high temperature is particularly relevant. So far, however, little research on the fire resistance of reinforced concrete arched structure has been done. According to the experiment and finite element analysis, this paper takes the arched member as an example and lays emphasis on the study of the temperature distribution and mechanical performance of the members in different high-temperature fire. The main content and conclusion of the research are as follows:(1)Regarding the ultimate capacity analysis of the members at normal temperature, an improved support which is between a fixed and a hinge support is used, the structure's detail treatment was optimized, which reflected better the actual force condition of the members, and the result is compared with the experiment and the reasonableness of the settings about simulation method and boundary conditions is verified, which contribute to the analysis on load ratio influence the fire resistance of the members.(2)The experiment on the reinforced concrete arched member shows that the members' upwarp velocity and degree increases with the high-temperature fire. The curved shape of the arched structure decides the members tend to upwarp due to material thermal expansion at high temperature, which is opposite to the load effect, thus be favorable for fire resistance. The experiment on members and finite element calculation on temperature field indicate that different heating curve and fire situation have a great influence on the heating rate and temperature distribution inside the members.(3)Comparing the relationship of the failure time and load ratio while fired by one side and both sides, it is found that the fire-resistant time of the members while fired by both sides is longer as the load level is low. It reverses as the load level goes high.(4)Through the analysis of the stress state of the members, the failure mechanism of the arched members at high temperature was discussed. It is suggested that the mid-span section is mainly compressed at high temperature. The upper and lower surfaces of the members fails in compression successively while the load and materials performance deteriorates.The experiment data and analysis provides a reference for the fire protection design and fireproof methods of the reinforced concrete arched structure. It also provides a basis to evaluate the damage performance of same structures after fire and draw up a restauration and reinforcement scheme.