NUMERICAL AND EXPERIMENTAL STUDY OF CONCRETE I-BEAM SUBJECTED TO BENDING TEST WITH CYCLIC LOAD

Abstract

NUMERICAL MODELS ARE OFTEN USED IN TESTS SIMULATION TO REDUCE COSTS AND TIME, AS SUCH MODELS CAN ASSIST IN THE ELABORATION OF AN OPTIMIZED EXPERIMENTAL PROGRAM AND ALLOW THE EXTRAPOLATION OF RESULTS. HOWEVER, FEW STUDIES SIMULATE TESTS INVOLVING CYCLIC LOADING ACCOMPANIED BY DYNAMIC TESTING. IN THIS CONTEXT, THIS PAPER PROVIDES GUIDELINES FOR CYCLIC LOADING BENDING TEST SIMULATION AND MODAL ANALYSIS OF A REINFORCED I-BEAM. THE PURPOSE OF THIS WORK IS TO PRESENT A NUMERICAL MODEL CALIBRATION METHODOLOGY, AS WELL AS TO CORRELATE THE DAMAGE CAUSED BY MECHANICAL STRESS WITH THE DYNAMIC PARAMETERS OF THE STRUCTURE. FOR THIS PURPOSE, EXPERIMENTAL AND NUMERICAL STUDIES WERE PERFORMED. IN THE EXPERIMENTAL STUDY, THE CYCLIC BENDING TEST WAS PERFORMED AND THE NATURAL FREQUENCIES OF THE STRUCTURE IN THE INTACT AND DAMAGED STATES WERE MEASURED. IN THE SIMULATION OF THE CYCLIC BENDING TEST THE CONCRETE DAMAGED PLASTICITY (CDP) MODEL IMPLEMENTED IN ABAQUS FINITE ELEMENT SOFTWARE WAS USED, WHICH IS ABLE TO DESCRIBE THE CRACKING OF CONCRETE UNDER MECHANICAL LOAD. THE MODEL INPUT DATA ARE THE HARDENING AND SOFTENING LAWS OF CONCRETE, WHICH ARE DESCRIBED BY THE UNIAXIAL COMPRESSION/TENSILE BEHAVIOR OF MATERIAL AND THE LAWS OF DAMAGE EVOLUTION. BASED ON THE EXPERIMENTAL RESULTS, DIFFERENT LAWS OF TENSILE DAMAGE AS WELL AS CONSTITUTIVE MODELS FOR CONCRETE IN TENSILE AND COMPRESSION WERE EVALUATED. IN ORDER TO EVALUATE THE DYNAMIC BEHAVIOR OF THE STRUCTURE IN THE NUMERICAL MODEL, THE AUTOMATIC CALIBRATION OF THE FINITE ELEMENT MODEL BASED ON THE EXPERIMENTAL DYNAMIC RESPONSE BY GENETIC ALGORITHM WAS USED. WITH THE CALIBRATED NUMERICAL MODEL, METHODOLOGIES FOR ESTIMATING THE OVERALL DAMAGE OF THE STRUCTURE BASED ON ITS DYNAMIC PROPERTIES WERE PROPOSED. THE RESULTS SHOW THE INFLUENCE OF THE CDP INPUT PARAMETERS ON THE STRUCTURE RESPONSE AND CONFIRM THAT THE WELL-DESIGNED NUMERICAL MODEL IS ABLE TO EFFICIENTLY REPRESENT THE CYCLIC LOADING BENDING TEST, SHOWING VERY CLOSE MAXIMUM LOADING AND LOSS OF STIFFNESS DUE TO DAMAGE. IN ADDITION, THE PROPOSED GLOBAL DAMAGE ESTIMATES DEMONSTRATE THE COHERENCE BETWEEN NUMERICAL AND EXPERIMENTAL MODELS AND THE RELATIONSHIP BETWEEN DAMAGE AND DYNAMIC STRUCTURE PROPERTIES.