EFFECT OF CHANGE CONCRETE GRADE ON THE BEHAVIOR OF BEAM-COLUMN JOINTS

Abstract

Beam-column joint is representing the connection between columns and beam where several straining actions exist. A joint is critical localized point in a structure where high moments and shears occur. There are various types of joints in a structure such as corner, exterior, and interior joints. In the last few decades earthquakes of many magnitudes have struck in different countries of the world which caused severe damage to reinforced concrete structures and many RC structures poorly behaved due to beam-column joint failure. Shear failure of beam column joint is not accepted due to its brittle nature. In this study, testing of external type of joint having concrete grades different than that of the attached column or beam will be conducted to study its effect on the response of joint under simulated lateral loading. Experimental work was conducted to study the general deformational behavior of ultra-high and medium strength concrete beam-column connections. Eight medium scale connections, all specimens with over all length of column 1500 mm. and length of beam 900 mm. cross section of column (150 x 250 mm.) and cross section of beam (150 x 300 mm.) were tested under cyclic load. The main variables of this study were the characteristics strength of concrete, column axial load and change the shape of stirrups in joint region. The results of this experimental work formulate some recommendations for designers and researchers concerning the analysis, design and construction of ultra-high strength concrete connections