PERFORMANCE OF REINFORCED CONCRETE BEAM COLUMN CONNECTIONS EXPOSED TO FIRE UNDER CYCLIC LOADING

Abstract

ABSTRACTFire could dramatically reduces the characteristic strength of the reinforced concrete elements [1,2]. A lot of efforts has been devoted to study the effect of fire on the reinforced concrete elements during past decades. These previous studies focused on evaluating fire resistance for concrete elements, [3] and provide some recommendations of structural fire-resistance [4] such as cover thickness, reinforcement ratio and coating materials. A lot of research focused on RC columns [5,6,7], beams [8] and slabs [9] which has been exposed to fire, where less efforts aimed to study the effect of fire on RC beam column connections [10,11,12].The main objective of the present work is to study the structural behavior of reinforced concrete beam-column connections exposed to fire under cyclic loading [13,14] and to evaluate the reduction in concrete strength during fire process. To achieve these goals, this research consists of two parts, the first part is experimental program, and the second is the theoretical analysis. The experimental program include 12 one- third scale specimens half of them casted from normal concrete and other half from SCC. The effect of some parameters on the connection's behavior like reinforcement ratio, type of concrete (normal or self-compacted concrete) [15] and exposure fire time were studied. Experimental program extended also to study heat distribution inside RC beam–column connections by measuring temperature at 65 point Distributors at 5 sections all over the RC connection. Theoretical analysis was done by using finite element program (ANSYS12.1) and a comparison between experimental program and theoretical analysis was done SCC showed good properties in hardening state when exposed to high temperature compared with normal concrete [16]. Increasing reinforcement ratio of RC connections increases its fire resistance Good agreement between analytical and experimental work was observed.