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Date of Publication:2022-10-04

Journal:工程力学

Affiliation of Author(s):建设工程学部

Volume:27

Issue:9

Page Number:41-48

ISSN No.:1000-4750

Abstract:For studying crack propagation process, four-point shearing specimens,
   with the maximum size of 2500mm*600mm*200mm, are utilized to
   systematically investigate the crack initiation, stable propagation and
   unstable failure of concrete by means of photoelastic coatings. Using
   camera, the complete crack propagation process of concrete that appeared
   as interference fringes on the photoelastic coatings was recorded and
   the whole process of stable propagation and unstable development of the
   main crack was recorded. Based on the colored strain sequence, the
   strain distribution around the crack tip was measured and the curve of
   P-a was also obtained. In the presence of the crack extended length of
   photoelastic coatings, the finite element method was applied to simulate
   the process of crack propagation and count the variation of stress
   intensity factor at the tip of crack during crack extension. The results
   show that there is an obviously crack stable propagation before an
   unstable propagation, and that it can be recorded using photoelastic
   coatings. Therefore, the failure criterion, taking no account of P-a, is
   conservative. It can be also concluded that fracture mode has been
   turned into I mode from Ⅰ-Ⅱ mixed mode after crack initiation, although
   the loading condition is Ⅰ-Ⅱ mixed mode

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