Fracture resistance on aggregate bridging crack in concrete
- ZHANG Xiufang, XU Shilang
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School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116024, China;
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Published |
05 Mar 2007 |
Issue Date |
05 Mar 2007 |
Abstract
Fracture toughening exhibited in quasi-brittle materials such as concrete is often mainly related to the action of aggregate bridging, which leads to the presence of a fracture process zone ahead of stress-free cracks in such materials. In this investigation, the fracture resistance induced by aggregate bridging, denoted by GI-bridging, is the primary focus. In order to quantitatively determine it, a general analytical formula is firstly developed, based on the definition of fracture energy by Hillerborg. After this, we further present the calculated procedures of determining this fracture resistance from the recorded load vs. crack opening displacement curve. Then, both numerical simulations and fracture experiments are performed on concrete three-point bending beams. Utilizing the obtained load against crack opening displacement curve, the value of GI-bridging at any crack extension as well as the change of GI-bridging with the crack extension is examined. It is found that GI-bridging will firstly increase with the development of crack and then stay constant once the initial crack tip opening displacement reaches the characteristic crack opening displacement w0. The effects of material strength and specimen depth on this fracture resistance are also investigated. The results reveal that the values of GI-bridging of different specimens at any crack propagation are strongly associated with the values of fracture energy of specimens. If the values of fracture energy between different specimens are comparable, the differences between GI-bridging are ignored. Instead, if values of fracture energy are different, the GI-bridging will be different. This shows that for specimens with different strengths, GI-bridging will change greatly whereas for specimens that are different in depth, whether GI-bridging exhibits size effect depends on whether the fracture energy of specimens considered in the calculation of GI-bridging is assumed to be a size-dependent material parameter.
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ZHANG Xiufang, XU Shilang.
Fracture resistance on aggregate bridging crack in concrete. Front. Struct. Civ. Eng., 2007, 1(1): 63‒70 https://doi.org/10.1007/s11709-007-0006-2
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