DEVELOPMENT OF IMPROVED MODELS FOR ESTIMATION OF BURSTING STRESSES IN ELEMENTS UNDER HIGH-CONCENTRATED LOAD

Abstract

IN PRECAST CONCRETE SEGMENTAL TUNNELS, RADIAL AND CIRCUMFERENTIAL JOINTS ARE OFTEN THE MOST HIGHLY STRESSED PARTS AND IT IS THEREFORE IMPORTANT TO USE APPROPRIATE EQUATIONS TO ACCURATELY ANALYSED THESE JOINTS DURING DESIGN AND PROVIDE ADEQUATE STRUCTURAL CAPACITY TO AVOID FAILURE. DIFFERENT DESIGN CODES HAVE PUT FORWARD EQUATIONS FOR THE ESTIMATION OF BURSTING FORCES DUE TO CONCENTRATED LOAD ON PRECAST END BLOCKS. THE EQUATIONS WERE SPECIFICALLY DEVELOPED FOR PRE-STRESSED CONCRETE ANCHORS AND NOT SPECIFICALLY FOR PRECAST CONCRETE SEGMENTAL TUNNELS. THE DESIGN EQUATIONS OFTEN ACCOUNT FOR THE EFFECTS OF LOAD ECCENTRICITY IN ESTIMATING BURSTING FORCE BUT NOT THE PEAK STRESS. THIS PAPER ASSESSES THE ACCURACY OF PUBLISHED EQUATIONS FOR BURSTING FORCE AND PEAK STRESS BY CONDUCTING A HIGH-RESOLUTION TWO-DIMENSIONAL (2D) FINITE ELEMENT (FE) BASED PARAMETRIC STUDIES. IT WAS FOUND THAT THE EFFECTS OF LOAD ECCENTRICITY ARE SIGNIFICANT FOR HIGHLY CONCENTRATED LOADS (LOAD WIDTH RATIOS LESS THAN 0.3) AND THAT THEY INCREASE THE PEAK BURSTING STRESSES SIGNIFICANTLY. REGRESSION ANALYSIS IS USED TO DEVELOP EQUATIONS FOR ESTIMATING THE PEAK BURSTING STRESS AND BURSTING FORCE DUE TO LOAD ECCENTRICITY FOR THE DESIGN OF PRECAST CONCRETE TUNNEL SEGMENTS. THESE EQUATIONS ARE MORE ACCURATE AS COMPARED TO PRE-EXISTING EQUATIONS AND IMPORTANT FOR PRACTISING ENGINEERS AND DESIGNERS.