A HYBRID PROCEDURE FOR CRACKING, CREEP, SHRINKAGE AND THERMAL GRADIENT IN CONTINUOUS COMPOSITE BRIDGES

Abstract

A HYBRID ANALYTICAL-NUMERICAL PROCEDURE HAS BEEN PRESENTED IN THIS PAPER FOR THE SERVICE LOAD ANALYSIS OF CONTINUOUS COMPOSITE BRIDGES. THE PROCEDURE ACCOUNTS FOR THE EFFECTS OF CONCRETE CRACKING, CREEP AND SHRINKAGE IN THE CONCRETE PORTION AND THERMAL GRADIENT ACROSS THE CROSS-SECTION. THE PROCEDURE IS ANALYTICAL AT THE ELEMENTAL LEVEL AND NUMERICAL AT THE STRUCTURAL LEVEL. A CRACKED SPAN LENGTH BEAM ELEMENT CONSISTING OF AN UNCRACKED ZONE IN MIDDLE AND CRACKED ZONES NEAR THE ENDS HAS BEEN PROPOSED TO DRASTICALLY REDUCE THE COMPUTATIONAL EFFORT. THE PROGRESSIVE NATURE OF CRACKING OF CONCRETE HAS BEEN TAKEN INTO ACCOUNT BY DIVISION OF THE TIME INTO A NUMBER OF TIME INTERVALS. CLOSED FORM EXPRESSIONS FOR THE STIFFNESS MATRIX, END DISPLACEMENTS, CRACK LENGTHS, INTERPOLATION COEFFICIENTS, AND THE MID-SPAN DEFLECTION OF THE BEAM ELEMENT HAVE BEEN PRESENTED IN ORDER TO REDUCE THE COMPUTATIONAL EFFORT AND THE BOOK-KEEPING. THE PROCEDURE HAS BEEN VALIDATED BY COMPARISON WITH THE EXPERIMENTAL AND ANALYTICAL RESULTS REPORTED ELSEWHERE AND WITH FEM. THE PROCEDURE CAN BE READILY EXTENDED FOR THE ANALYSIS OF INTEGRAL COMPOSITE BRIDGES AND THREE DIMENSIONAL FRAMED BUILDINGS.