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Title:Mixed mode fracture of concrete
Author(s):Kono, Susumu
Doctoral Committee Chair(s):Hawkins, Neil M.
Department / Program:Civil and Environmental Engineering
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Civil
Abstract:The static mixed mode I and II fracture aspects of diagonal tension failure in reinforced concrete and prestressed concrete members were studied using a hybrid experimental-numerical analysis.
For an experimental phase, a fracture process zone associated with stable crack growth in single edge-notched three point bend concrete specimens was created under the mixed mode loading conditions by applying reinforcing constraints. The observed crack curving was similar to that in reinforced concrete and prestressed concrete beams and the reinforcing constraints increased the degree of crack curvature and the load carrying capacity of the beam specimens. The experimental phase also revealed the three dimensional features of the fracture process under the mixed mode I and II loading conditions.
For a numerical phase, the resulting crack paths and the recorded global parameters such as load, CMOD, and the constraining reinforcing bar force were used to drive a finite element model of fracture specimens. The fracture process zone characterizing the concrete fracture was represented by a discrete crack model with stress transfer along a cracked interface. The stress transfer in the fracture process zone can be expressed by the crack closing stress and the crack opening displacement relation only and the shear stress along the crack interface did not need to be included. The crack closing stress was inversely proportional to the crack opening displacement but the exact shape of the curve was not confirmed due to the sensitivity of parameters employed. A proposed crack propagation direction criterion considered a far field stress effect of a crack tip and produced a better prediction than the conventional crack propagation direction criteria based on a near tip stress field. The critical field variable controlling stable crack growth was still unknown.
The sensitivity study showed that local parameters were critical to characterize the fracture process of concrete and the use of multiple number of local parameters were recommended. The use of global parameters only to characterize the fracture process may produce a large error since global parameters are insensitive to the characteristics of fracture models.
Issue Date:1995
Rights Information:Copyright 1995 Kono, Susumu
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9624396
OCLC Identifier:(UMI)AAI9624396

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