Reverse Analysis Of Concrete Fracture Performance Based On Isight

As a kind of material with superior working performance,concrete has been widely used in construction engineering.The mechanism of concrete crack development is the foundation of safety evaluation for buildings.The current studies show that there are process and softening characteristics for concrete fracture,and the key of fracture analysis is obtaining the softening curve.Different from the traditional method of uniaxial tension tests,the menthod based on numerical model for inverse analysis of softening curve has been concerned by more and more scholars for its convenience and efficiecy.Based on the inverse method proposed by Roelfstra,used the global optimization algorithm,the inverse analysis platform of softening curve for three-point bending beam is established on commercial softwares,and then the inverse analyses of three-point bending beams have been carried out in this paper.This paper has done the following work:?1?Taking the parameters of softening curve as the optimization variables,treating the error of P-CMOD curves between inverse analyses and tests as the object function,the inverse analysis platform of softening curve is built on Isight software combined with the Python scripts of three-point bending beam and the MATLAB scripts of softening curve and error analysis.The program of obtaining the softening curve has been automatically and efficiently implemented.?2?Taking the three-point bending beam tests as the references of inverse analysis,the paper compares the difference on the results between bilinear softening curve and trilinear softening curve,and it is shown that the trilinear softening curve has the accuracy on simulating the actual fracture softening performance.And then,the results of comparison of P-CMOD curves between inverse analysis and three-point bending beam tests have reflected the advantages by inverse analysis to obtain softening curve.?3?Combined the inverse analysis and double-K fracture theory,the initial fracture toughness and unstable fracture toughness have been calculated by the peak load P_maxand the opening displacement of fracture CMOD_c for invese analysis and three-point bending beam tests.The results of calculation show that the inverse analysis and the tests are highly consistent.It indicates that the method of inverse ananlysis can be well applied in practical engineering calculation and analysis.