BEHAVIOR AND DESIGN OF TENSILE LAPPED JOINTS IN REINFORCED CONCRETE BEAMS

TESTS OF TENSILE LAPPED JOINTS, WITH A COVER OF 1 X THE BAR SIZE, HAVE BEEN MADE USING STRAIN GAUGES TO STUDY THE MAIN BAR AND LINK PERFORMANCE. THE BOND AND FAILURE MECHANISM IN THE JOINTS HAS BEEN DESCRIBED, AND THE MANNER IN WHICH THE FACTOR OF SAFETY APPLIES TO LONG LAP LENGTHS IS DEMONSTRATED. IT IS SHOWN THAT CONCRETE COVER, POSITION OF THE BARS DURING CASTING, AND AMOUNT OF LINK REINFORCEMENT ARE SIGNIFICANT FACTORS IN LAPPED JOINTS. BY CORRELATING THIS RESEARCH WITH WORK DONE BY OTHERS ON END ANCHORAGES, IT HAS BEEN POSSIBLE TO DERIVE DESIGN VALUES OF AVERAGE BOND STRESS FOR LAPPED JOINTS. IT IS SHOWN THAT THESE ARE CONSISTENT WITH THE SIMPLIFIED PROPOSALS IN THE NEW UNIFIED CODE OF PRACTICE FOR CONCRETE. /TRRL/