scholarly journals Fracture Energy Analysis of Concrete considering the Boundary Effect of Single-Edge Notched Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ping Xu ◽  
Jinyi Ma ◽  
Minxia Zhang ◽  
Yahong Ding ◽  
Lingqi Meng
Keyword(s):  
Fracture Energy ◽  
Boundary Effect ◽  
High Strength ◽  
Specimen Size ◽  
Distribution Model ◽  
Single Edge ◽  
Local Fracture ◽  
Loading Test ◽  
Effect Model ◽  
Published Research

The method of determining concrete fracture energy recommended by RILEM has an obvious size effect, so determining fracture energy that is unaffected by size of the test specimen is difficult. In this study, 60 high-strength concrete single-edge notched beams (SENBs) of different sizes, crack length-to-depth ratios, and span-to-depth ratios were subjected to the three-point loading test as recommended by RILEM. Then, the influences of the boundary effect on the fracture energy were identified. Based on the SENB boundary effect model, a piecewise function of the interrelationships between the experimental test fracture energy Gf, the local fracture energy gf, and the fracture energy unaffected by specimen size GF was established. The applicability of the boundary effect model was verified using the test results from this study and from the previously published research. The results show that the local fracture energy distribution in the boundary influence region was nonuniform. The smaller the local fracture energy was, the closer it was to the rear boundary of the specimen. The influence length al∗ of the boundary increased with the increasing specimen size. Based on the bilinear distribution model of the local fracture energy gf, the fracture energy unaffected by beam size GF can be obtained according to the fracture energy Gf measured for laboratory-scale small-sized SENB specimens. Furthermore, the model predictions are in good agreement with experimental observations.

Boundary Effect on the True Specific Fracture Energy of Concrete

2007 ◽  
Vol 348-349 ◽  
pp. 933-936
Author(s):  
Yan Hua Zhao ◽  
Shi Lang Xu ◽  
Zhi Min Wu ◽  
Hong Bo Gao
Keyword(s):  
Size Effect ◽  
Fracture Energy ◽  
Boundary Effect ◽  
Apparent Size ◽  
Specimen Size ◽  
Test Results ◽  
Bilinear Model ◽  
Local Fracture ◽  
Specific Fracture Energy ◽  
Specific Fracture

The apparent size effect of the specific fracture energy of concrete according to the RILEM procedure has been confirmed by numerous published works. The paper offers an explanation for this size effect by considering the specimen boundary influence on local fracture energy over the ligament length, which is closely associated with the measured fracture energy of concrete. To address this boundary influence, boundary affected length is introduced, over which local fracture energy is different from that in the bulk far away from the surface of the specimen. Based on previous work, a continuous smooth function is hypothesized to simulate the distribution of local fracture energy. At the same time, the model established was compared to the existing models, i.e. Perturbed Ligament Model (PLM) and Bilinear Model (BLM). Some test results from wedge splitting specimen in the literature were used to verify these three models. The results show that the true fracture energy of concrete, irrespective of the specimen size, could be obtained from the measured values directly from RILEM, and is less sensitive to determination approach. The predicted boundary affected length when the crack reaches the specimen surface is more close to the value of the perturbation length in PLM.

Asymptotic Analysis of Boundary-Induced Size Dependence of Fracture Properties

2006 ◽  
Vol 324-325 ◽  
pp. 1209-1212
Author(s):  
Kai Duan ◽  
Xiao Zhi Hu
Keyword(s):  
High Strength Concrete ◽  
Size Dependence ◽  
Boundary Effect ◽  
Brittle Materials ◽  
High Strength ◽  
Asymptotic Model ◽  
Fracture Properties ◽  
Asymptotic Boundary ◽  
Effect Model ◽  
Fracture Tests

The recently-developed boundary effect concept and associated asymptotic model are used to explain the size effect phenomena in fracture of quasi-brittle materials. It is demonstrated that the size dependence of the fracture toughness and strength of quasi-brittle materials is indeed due to the influences of specimen boundaries on the failure mode and therefore, on the strength of the specimen. To verify the boundary effect concept, fracture tests on a high strength concrete reported by Karihaloo et al are analysed and predicted using the asymptotic model. The results show that the predictions of the asymptotic boundary effect model agree very well with those experimental results.

scholarly journals Numerical Simulation on Size Effect of Fracture Toughness of Concrete Based on Mesomechanics

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1370 ◽  
Author(s):  
Juan Wang ◽  
Qianqian Wu ◽  
Junfeng Guan ◽  
Peng Zhang ◽  
Hongyuan Fang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Numerical Model ◽  
Fracture Process ◽  
Boundary Effect ◽  
Peak Load ◽  
Specimen Size ◽  
Three Point Bending ◽  
Linear Elastic ◽  
Coarse Aggregates ◽  
Effect Model

The fracture performance of concrete is size-dependent within a certain size range. A four-phase composite material numerical model of mesofracture considering a mortar matrix, coarse aggregates, an interfacial transition zone (ITZ) at the meso level and the initial defects of concrete was established. The initial defects were assumed to be distributed randomly in the ITZ of concrete. The numerical model of concrete mesofracture was established to simulate the fracture process of wedge splitting (WS) concrete specimens with widths of 200–2000 mm and three-point bending (3-p-b) concrete specimens with heights of 200–800 mm. The fracture process of concrete was simulated, and the peak load (Pmax) of concrete was predicted using the numerical model. Based on the simulating results, the influence of specimen size of WS and 3-p-b tests on the fracture parameters was analyzed. It was demonstrated that when the specimen size was large enough, the fracture toughness (KIC) value obtained by the linear elastic fracture mechanics formula was independent of the specimen size. Meanwhile, the improved boundary effect model (BEM) was employed to study the tensile strength (ft) and fracture toughness of concrete using the mesofracture numerical model. A discrete value of β = 1.0–1.4 was a sufficient approximation to determine the ft and KIC values of concrete.

Effect of fracture path on the fracture energy of high-strength concrete

2001 ◽  
Vol 31 (11) ◽  
pp. 1601-1606 ◽  
Author(s):  
An Yan ◽  
Ke-Ru Wu ◽  
Dong Zhang ◽  
Wu Yao
Keyword(s):  
Fracture Energy ◽  
High Strength Concrete ◽  
High Strength ◽  
Fracture Path ◽  
Strength Concrete

Fracture energy for three-point-bend tests on single-edge-notched beams

1988 ◽  
Vol 28 (3) ◽  
pp. 266-272 ◽  
Author(s):  
L. J. Malvar ◽  
G. E. Warren
Keyword(s):  
Fracture Energy ◽  
Single Edge ◽  
Bend Tests ◽  
Point Bend
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