Method of determining load-displacement complete curve of concrete I-II composite cracks

A technique of I-II and crack loading, which is applied in directions such as applying a stable bending force to test the strength of materials, can solve the problem that it is difficult to obtain the descending section of the load-displacement curve of the four-point shear beam specimen, and the three-point bending of the straight-biased crack Beam specimen technology can not be obtained and other issues

Inactive Publication Date: 2019-06-21
DALIAN UNIV OF TECH
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Problems solved by technology

[0008] The purpose of the present invention is to provide a concrete I-II compound type fracture test method with simple operation, which can not only solve the problem that the three-point bending beam test piece technology of straight deviation crack cannot obtain a larger K Ⅱ / K I The problem of K can also be solved Ⅱ / K I It is difficult to obtain the descending section of the load-displacement curve with the four-point shear beam specimen technique when it is relatively large

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  • Method of determining load-displacement complete curve of concrete I-II composite cracks

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[0019] The specific embodiments of the present invention will be described in detail below in conjunction with the technical solutions and accompanying drawings.

[0020] see Figure 1-3 , a right-angled broken-line crack 1 with a bending angle of 90° was cut in the mid-span of a traditional three-point bending beam concrete specimen, and an improved three-point bending beam concrete specimen 2 was obtained. The improved three-point curved beam concrete specimen 2 is used to test the full curve of load-crack opening displacement (P-CMOD) and load crack opening shear displacement (P-CMSD), and three dimensions are taken as l×b×h = 700mm × 40mm × 150mm three-point bending beam, cut a right angle broken line crack 1 at the mid-span, the length of the initial crack in the horizontal direction and vertical direction is a = 45mm, and do arc treatment at the break point, the crack circle The curvature ρ of the arc is 1 / 45. The test adopts three-point loading, and the load is applie...

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Abstract

The invention provides a method of determining a load-displacement complete curve of concrete I-II composite cracks, which belongs to the technical field of concrete fracture test. In the new test method, a right-angled broken line crack is cut in the midspan of the traditional three-point bending beam concrete specimen, an improved three-point bending beam concrete specimen is obtained, the crackhas the same lengths in a horizontal direction and a vertical direction, and the break point is subjected to arc treatment; the initial crack height ratio a / h is 0.2 to 0.5, and the value of the curvature pho of the arc has a range of 1 / a to 15 / a; and the test adopts three-point loading, load is applied to the midspan of the improved three-point bending beam concrete specimen by a test machine, apredetermined loading scheme is realized, and a load-displacement complete curve is obtained. The initial crack tip of the test piece has large KII / KI, the load-displacement complete curve can be tested under simple test operation, a numerical value simulation result can be verified accurately and effectively, and a certain reference value is provided for testing accuracy of the concrete I-II composite fracture analysis model and the numerical value analysis theory.

Description

technical field [0001] The invention belongs to the technical field of concrete fracture tests, and relates to a method for performing concrete I-II composite fracture tests by using a three-point bending beam with right-angled broken line cracks in the midspan to measure its full load-displacement curve. Background technique [0002] Scholars at home and abroad often use the combination of numerical simulation and experiment to study the theory of concrete I-II composite fracture, and make the load-crack opening displacement (P-CMOD) and load crack opening shear displacement (P-CMSD) curves as a comparison object. So far, concrete I-II composite fracture tests have been systematically carried out at home and abroad. The test methods used are divided into: plate specimens, prism specimens and beam specimens (directly deflected crack three point bending beams, skew cracked three-point bending beams, and four-point shear beams). [0003] (1) For the test of bilateral notched...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/20
Inventor 吴智敏孙阊禹刘鸿辰
Owner DALIAN UNIV OF TECH
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