INVERSE ANALYSIS OF NOTCHED-BEAM TEST DATA FOR OBTAINING TENSILE STRESS-CRACK OPENING RELATION OF FIBER REINFORCED CONCRETE

摘要

The simulation of fracture processes in fiber concretes and the analysis of fiber reinforced concrete structures require the knowledge of the fundamental cohesive stress versus crack opening displacement curve (σ-w). Difficulties with the tension test for directly obtaining the σ-W curves necessitate alternative procedures based on the inverse analysis of data from simpler test configurations. In this paper, an inverse analysis procedure is described for obtaining σ-W curves from three-point bending tests performed on notched prismatic specimens. A σ-W curve, with a user-defined shape, is fitted so that the experimentally-obtained load versus crack mouth opening displacement (P-CMOD) curve is matched. An object-oriented software program has been developed for obtaining the parameters of the σ-W curve by minimizing the error between the experimental and numerical data using a least-squares approach. The procedure has been validated through a parametric study based on results obtained from tests of steel fiber reinforced concrete beams. The σ-W curves obtained from the inverse analysis are compared with data from uniaxial tension tests of cores of the same concrete.