Fire Resistance of Non-Crack Resistant Flexural Reinforced Concrete Elements

Abstract

In developed countries only loss of property because of fire makes annually up to 2% of their national income [9, 15]. The bearing capacity of reinforced concrete structures at high temperature impact is lost within several dozens of minutes [1, 3, 5, 10, 12, 18, 25]. Disappointing statistics of increase of both the number of fires and the scope of damage due to them aggravates the actual problem of determination of reinforced concrete structures fire-endurance. The main problems and methods of evaluation of reinforced concrete structure fire resistance are stated. Within the framework of block approach to evaluation of strain of flexural reinforced concrete elements with cracks, design model of reinforced concrete thermo-force resistance is made. Extended nomenclature of influences of high temperature at fire on decrease of performance of bearing reinforced concrete structures is considered. Empirical dependencies of strength and strain characteristics of concrete and reinforcement on high temperatures are used. Proposals on specification of evaluation of fire resistance of statically indeterminate reinforced concrete structures are formulated.