FRACTURE BEHAVIOUR OF CONCRETE PAVEMENT MATERIAL IN BENDING UNDER MONOTONIC AND CYCLIC LOADING

摘要

Current concrete pavement design methods rely heavily on statistical calibration rather than mechanistic understanding when it comes to prediction of fatigue damage. A need is identified to replace current design methodology with a fracture mechanics based approach. The aim of this paper is to explore in detail the fracture behaviour of concrete beams in bending under both monotonic and cyclic loading. The experimental part of the study includes three point bending (TPB) tests on beams during which the material response in fracture is monitored, as well as additional tests to determine material properties required for numerical simulation of fracture. The fracture mechanics parameters determined in the experiments are used to simulate the crack propagation under monotonic loading using the embedded discontinuity approach. The post crack tensile behaviour of the material is defined using a simple exponential softening curve. The results of the numerical simulation provide a good fit to the material behaviour observed in the tests. A comparison of the load-displacement response in monotonic and cyclic experimental TPB tests seems to indicate that the load- displacement curve of the monotonic tests may act as an envelope for the cyclic load- displacement evolution.