Resistance Capability Investigation Of Building Structure In Fire

The high temperature will severely degrade the property of structural material in fire, which leads to the redistribution of inner force in the structure members, then leads to drastic structure deformation. Consequently, the bearing capability of structure reduces greatly, which will cause the structural local or integral collapse or breakage. Therefore, how to process fire resistance design of structure rationally, especially, a scientific, reliable and practical method of fire resistance design of structure by systematic theoretical analysis and investigation, has drawn interests in academe and engineering.Based on previous results by other scholars, in this paper, further research has been done in terms of the mechanics state in the reinforced concrete structure and steel structure under fire temperature and the dynamic response of the simply supported steel beam under impulsive load in fire. The main contents are:1. Based on nonlinear elasticity and elasto-plasticity theory, the constitutive relationship and structural mechanics analysis process of reinforced concrete in fire has been discussed. Further, the deformation and the mechanics state of reinforce concrete frame under the co-existence of structure load and fire temperature has been simulated.2. Thorough an amount of experimental data and material mechanical property change under high temperature, the computation formulas of the ultimate loads of structure have been established under fire temperature.3. Based on the analysis the ultimate loads of the structure members in different structural types under fire temperature, the equivalent floor live-load has been used in depicting the effects of fire temperature on structure and members. The formulas of the equivalent floor live-load have been established and their changing laws have been analyzed, so it could make the bearing loads analysis of structure in fire more simple and perspicuity, the demand of engineering computation can be satisfied. 4. The non-linear structural analysis for steel frame under fire temperature has been developed. The relationship among the increment of inner force in structure element, the increment of displacement and the change of temperature in structure element has been deduced. The relationship between the stiffness matrix of integral structure and imbalance inner force has been given. The simulation has been exerted in the deformation and the state of inner force under the co-existence of structure loads and high temperature with the integral structure as a goal, which make it possible to analyze and describe the state of structure inner force of steel frame more rationally.5. According to the inner temperature change of steel beam in different time point, the influence of fire temperature on Young's modulus and yielding strength has been considered. Moreover, the dynamic response of the steel beam simply supported at both ends under impulsive load in fire has been analyzed.