Determination of Residual Fracture Toughness of Post-Fire Concrete

2013 ◽  
Vol 712-715 ◽  
pp. 1062-1066
Author(s):  
Rui Zhang ◽  
Zhou Dao Lu ◽  
Jiang Tao Yu
Keyword(s):  
Fracture Toughness ◽  
Weight Function ◽  
Analytical Method ◽  
Function Method ◽  
Crack Opening ◽  
Fracture Parameter ◽  
Opening Displacement ◽  
Weight Function Method ◽  
Critical Fracture

Determination of double-K fracture parameter using both analytical and weight function method is carried out in present research. In calculating the cohesive fracture toughness, two situations are divided at critical load. Wedge-splitting tests with ten temperatures varying from 20oC to 600oC are implemented. The complete load-crack opening displacement curves are obtained from which the initial and critical fracture toughness could be calculated experimentally. The validation of double-K fracture model to the post-fire concrete specimens is proved. Meanwhile the weight function method agrees well with the analytical method.

scholarly journals Toughness Calculation of Postfire Normal Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Qingyang Chen ◽  
Anjing Tang ◽  
Zhoudao Lu
Keyword(s):  
Fracture Toughness ◽  
Critical Load ◽  
Crack Opening Displacement ◽  
Analytical Method ◽  
Crack Opening ◽  
Fracture Model ◽  
Opening Displacement ◽  
Normal Concrete ◽  
Critical Fracture ◽  
Fracture Tests

Fracture tests of postfire normal concrete with ten temperatures up to 600°C are implemented. Residual fracture toughness using analytical method is determined. Two situations are divided at critical load when calculating the cohesive fracture toughness. The initial and critical fracture toughness could be calculated from the complete load-crack opening displacement curves. Finally, the validation of double-Kfracture model to the postfire concrete specimens is proved.

Determination of Stress Intensity Factor for Cracked Brazilian Disc Using Weight Function

2013 ◽  
Vol 577-578 ◽  
pp. 285-288
Author(s):  
Yan Hua Zhao ◽  
Jin Liu ◽  
Hong Bo Gao ◽  
Huan An He ◽  
Tao Zhang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Weight Function ◽  
Numerical Method ◽  
Function Method ◽  
Weight Function Method ◽  
Brazilian Disc ◽  
Distributed Pressure

To reduce stress concentration near the loading point, Brazilian test, normally used for the indirect determination of tensile strength for rock or concrete quasi-brittle materials, is usually subjected to uniformly distributed pressure over finite width (or arc) of the Brazilian disc. As an extension, the same geometry, in which a central notch is introduced in the symmetrical plane of applied forces, can be used to determine fracture toughness of the materials. For this purpose, accurate expression for stress intensity factor (SIF) for central cracked Brazilian disc should be provided first. To this end, weight function method is used in this paper where weight function for central cracked disc is available in general SIF handbooks. Meanwhile, the exact stress solution in the intact Brazilian disc subjected to uniformly distributed pressure is derived by use of numerical method. In the end, some finite element analysis is carried out using the program package ABAQUS on the Brazilian disc, and the comparison results regarding the SIF between the weight function method and numerical method prove the validity of the proposed method.

The Combined Weight Function Method Application for the Estimation of the Crack Opening Area for Through Crack in the Shells

2012 ◽  
Author(s):  
Igor V. Orynyak ◽  
Elena S. Yakovleva ◽  
Volodymyr R. Kozlov
Keyword(s):  
Weight Function ◽  
Displacement Field ◽  
Function Method ◽  
Simple Procedure ◽  
Crack Opening ◽  
Approximate Expression ◽  
Piping System ◽  
Linear Component ◽  
Weight Function Method ◽  
Leak Before Break

The through–wall crack opening area is one of the main calculation parameters for the “leak before break” analysis of the piping system with postulated through crack. The existing methods for calculation of COA, in fact, consider the shell (pipe) to be a flat body and neglect the linear components across the pipe wall thickness (as in the theory of plate) both of load distribution as well as displacement field. Based on the combining weight function method the simple procedure for determination of approximate expression for the fundamental displacement field under polynomial loading of the crack surfaces in the shell as a sum of the uniform and linear components is proposed. Based on this method the formulas for calculating COA at the polynomial membrane and linear loading are derived. The comparison of the obtained COA values with results existing in the literature is performed for the cylindrical shell with axial and circumferential cracks. The contribution of the linear component of the COA to its total value has been estimated.

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