EFFECT OF TYPE AND POSITION OF CONSTRUCTION JOINT ON BEHAVIOR AND CAPACITY OF REINFORCED CONCRETE ONE WAY SLABS

Abstract

This work involves experimental study for the effect of construction joint on behavior of R.C. one way slabs. Eight slabs of 1000×450×70 mm were tested. One of them is cast monolithically while the other seven were cast by two stages with presence of construction joints. Different types of joints were considered (vertical, inclined and key) with different forms and locations for these types. The results indicated that these joints have different effects on cracking and ultimate capacities and on load deflection response. Transversal
inclined joint has the largest effect on ultimate capacity (reduction is 24.6 %), while long key joint has smallest effect (reduction is 1.8 %). The slab involved inclined in plane joint has the closest load deflection response to the reference slab response and has few and narrow final cracks. Slabs of vertical middle and transversal inclined joints have stiff behavior in earlier loading stages but becomes more soft in advanced stages. Side joint caused sudden shear failure on contrast for the other slabs failed by flexure. Inclined in
plane joint, key in plane joint and long key in plane joint are the best types of construction joints due to their smallest effects on slabs behavior.