Experimental Research On The Fire-Resistance Of Full Scale Reinforced Concrete Portal Frame Structure

Reinforced concrete structure is one of the most widely used structures in modern architecture; but, there were numerous examples of losing its function of carrying capacity due to fire. People have consistently focused their attention on the mechanical property under high temperature and safety design of the reinforced concrete structure. Hence the fire-resistance of the structure under high temperature has increasingly become an important research. Based on the national natural science foundation of China,"The fire-resistance research of reinforced concrete structure based on’residual strength’thermal damage model (NNSF:51178474)", this paper mainly studies the experiment and theoretical analysis of full scale reinforced concrete portal frame structure under high temperature. The main contents and innovative achievements are as follows:(1) The study of experiment, theory and numerical simulation of the reinforced concrete structure was systematically investigated at home and abroad. The thermal parameter and mechanical property of concrete and steel at elevated temperature were compared in different documentation of domestic and foreign countries. It provided the beneficial reference to experiment and study of the paper.(2) Eleven full scale specimens of reinforced concrete portal frame structure were designed by us. The fire tests included three temperature levels(600℃,800℃,1000℃) and three temperature levels (21kN,28kN,35kN) had been conducted to nine among of them with ISO-834 standard heating up curve. The surface characteristic and damage form of specimens were investigated through the tests. The specimens had been measured the midspan deflection change curve and distribution temperature field of cross section. The change of the deflection and the temperature measuring of points of heating rate were discussed under different temperatures and loads.(3) The static load tests had also been done under room temperature to the above (T1-T9) specimens after high temperature test and (T10) specimen without undergone the high temperature test. Through the damage morphology of the specimens were observed, we can analyze that fire temperature and fire load had an influence on the mechanical property of the full scale specimens. Then we discussed the change law of specimen under high temperature. Emphasis was laid on the relationship between temperature and compressive strength.(4) Through the research method of structural mechanics, material mechanics and elastic-plastic mechanics, midspan deflection of reinforced concrete portal frame structure was theoretical calculated to compare with the test results, and analyzed the reason of the difference.