Optimal Design for the Maximum Load of Three-Point Bending Concrete Beam Based on the Analyzing of Critical Crack-Mouth Opening Displacement

2012 ◽  
Vol 193-194 ◽  
pp. 954-957
Author(s):  
Xue Qin Wang ◽  
Lin Wang
Keyword(s):  
Optimal Design ◽  
Concrete Beam ◽  
Mouth Opening ◽  
Maximum Load ◽  
Least Square ◽  
Crack Mouth Opening Displacement ◽  
Engineering Practice ◽  
Unstable Fracture ◽  
Resistance Curve ◽  
Three Point Bending

An optimal design method for the maximum load of three-point bending concrete beam is proposed in this study. The statistics model is built according to the theory of GR resistance curve. With the help of least square method and Matlab® computing platform, the optimal design results are very similar of the experimental results, and thus a new criterion for unstable fracture in crack extension resistance curve theories is constructed. It can able to monitor safety and stability of specimens in engineering practice at any time.

scholarly journals Vibrated Concrete vs. Self-Compacting Concrete: Comparison of Fracture Mechanics Properties

2014 ◽  
Vol 601 ◽  
pp. 199-202
Author(s):  
Sara Korte ◽  
Veerle Boel ◽  
Wouter de Corte ◽  
Geert de Schutter
Keyword(s):  
Fracture Mechanics ◽  
Mouth Opening ◽  
Bending Test ◽  
Crack Mouth Opening Displacement ◽  
Self Compacting Concrete ◽  
Opening Displacement ◽  
Three Point Bending ◽  
Fracture Parameters ◽  
Wedge Splitting Test ◽  
Splitting Test

This study focuses on the fracture mechanics aspect of self-compacting concrete, compared to vibrated concrete. The most commonly used experiments to investigate the toughness and cracking behaviour of concrete are the three-point bending test (3PBT) on small, notched beams, and the wedge-splitting test (WST) on cubic samples with guiding groove and starter notch. From the resulting P-CMOD curves (applied load versus crack mouth opening displacement), different fracture parameters, such as fracture energy and fracture toughness, can be extracted. Moreover, using inverse analysis, the σ-w relationship (tensile stress versus crack width) can be derived. This paper lists the results of a series of tests on samples, made of VC, SCC of equal strength, and SCC with identical w/c factor. Subsequently, a comparison of the mechanical characteristics is made, revealing important differences regarding several fracture parameters.

scholarly journals Influence of Graphite Powder on the Mechanical and Acoustic Emission Characteristics of Concrete

Buildings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 18
Author(s):  
Wei He ◽  
Wenru Hao ◽  
Xia Meng ◽  
Pengchong Zhang ◽  
Xu Sun ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Acoustic Emission ◽  
Mouth Opening ◽  
Graphite Powder ◽  
Crack Mouth Opening Displacement ◽  
Cement Stone ◽  
Unstable Fracture ◽  
Sharp Rise ◽  
Ae Signals

In this paper, uniaxial compressive strength (UCS) test and three-point bending (TPB) test, together with an acoustic emission (AE) system, were performed to investigate the mechanical properties and AE characteristic changes of concrete with different graphite powder (GP) content. The results show that: (1) Poor adhesion and low interlocking of graphite with cement stone increase the initial defects of concrete, reducing its elastic modulus and the cyclo-hoop effect, and thus weakening the compressive strength. (2) For concrete with a low graphite content, the second sharp rise in ringing counts or energy released during the compressive process can be regarded as a failure alarm. However, as GP content increases, the second sharp rise fades away, while the first sharp rise becomes more visible. At high GP content, the first sharp rise is better for predicting failure. (3) The initial defects caused by GP significantly lower the initial fracture toughness, but its bridging effect greatly increases the critical crack mouth opening displacement and thus significantly enhances the unstable fracture toughness of concrete, by up to 9.9% at 9% GP content. (4) In contrast to compressive process, the sharp increase in AE signals preceding failure during the fracture process cannot be used to predict failure because it occurs too close to the ultimate load. However, as GP can significantly increase the AE signals and damage value in the stable period, such failure precursor information can provide a safety warning for damage development.

Detection of Crack Evolution in Plain Concrete by Electronic Speckle Pattern Interferometry

2017 ◽  
Vol 744 ◽  
pp. 92-96
Author(s):  
Hong Niao Chen ◽  
Jia Jian Chen ◽  
Ray Kai Leung Su
Keyword(s):  
Speckle Pattern ◽  
Mouth Opening ◽  
Plain Concrete ◽  
Crack Mouth Opening Displacement ◽  
Electronic Speckle Pattern Interferometry ◽  
Crack Evolution ◽  
Opening Displacement ◽  
Full Field ◽  
Three Point Bending ◽  
Initiation And Propagation

In order to study crack evolution in concrete, Electronic Speckle Pattern Interferometry (ESPI) technique was applied to measure full-field displacement of concrete beam subjected to three-point bending. Basic principles of ESPI technique were introduced. Mid-span deflection and crack mouth opening displacement were measured by linear variable differential transformers (LVDTs) and clip gauge, respectively. Typical load-displacement curves measured by different methods were compared and analyzed. Analysis results indicated that ESPI results were in good agreement with that measured by LVDT (clip gauge), verifying the validity and accuracy of ESPI measurement. From displacement contours, crack evolution including its initiation and propagation was observed. Furthermore, strain profiles near the crack at different loading levels were determined. Strain profile was nearly linear before crack initiation and became nonlinear with crack growth.

Derivation of J-resistance curve for through wall cracked pipes from crack mouth opening displacement

2006 ◽  
Vol 83 (9) ◽  
pp. 686-699 ◽  
Author(s):  
Suneel K. Gupta ◽  
Vivek Bhasin ◽  
K.K. Vaze ◽  
A.K. Ghosh ◽  
H.S. Kushwaha ◽  
...  
Keyword(s):  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Resistance Curve ◽  
Crack Mouth ◽  
Opening Displacement

Effect of Calcium Dissolution on the Fracture Properties of Concrete Exposed to Nitric Acid Environment

2011 ◽  
Vol 374-377 ◽  
pp. 1974-1978
Author(s):  
Hai Long Wang ◽  
Chun Ling Guo ◽  
Xiao Yan Sun
Keyword(s):  
Fracture Toughness ◽  
Nitric Acid ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Unstable Fracture ◽  
Crack Mouth ◽  
Acid Attack ◽  
Opening Displacement ◽  
Fracture Properties ◽  
Initial Fracture

The effect of calcium leaching by nitric acid on fracture properties of concrete was experimentally studied. The double-K fracture parameters were investigated using three-point bending beams, and the deterioration regularity of fracture properties of concrete chronically attacked by nitric acid was gotten on basis of these results. The load-crack mouth opening displacement curves under different nitric attack periods were obtained by pasting some strain gauges onto the pre-crack tip. On basis of the double-K criterion, the unstable fracture toughness as well as the initial fracture toughness was calculated according to the critical crack mouth opening displacement, the unstable fracture load and initial cracking load which can be obtained from the test. The experimental results indicated that the ratio of the initial fracture toughness to the unstable fracture toughness varied between 0.47 and 0.61 approximately. Both of the unstable fracture toughness and the initial fracture toughness decrease with attack period especially during the early 60 days, then drop to a stable trend gradually. In addition, the initial fracture toughness is less sensitive to acid attack compared with the unstable fracture toughness.

scholarly journals An Investigation of Softening Laws and Fracture Toughness of Slag-Based Geopolymer Concrete and Mortar

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5200
Author(s):  
Yao Ding ◽  
Yu-Lei Bai ◽  
Jian-Guo Dai ◽  
Cai-Jun Shi
Keyword(s):  
Fracture Toughness ◽  
Inverse Analysis ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Unstable Fracture ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Tension Softening ◽  
Initial Fracture ◽  
Crack Tip Opening

This paper aimed to determine the softening laws and fracture toughness of slag-based geopolymer (SG) concrete and mortar (SGC and SGM) as compared to those of Portland cement (PC) concrete and mortar (PCC and PCM). Using three-point bending (TPB) tests, the load vs. mid-span displacement, crack mouth opening displacement, and crack tip opening displacement curves (P-d, P-CMOD, and P-CTOD curves) were all recorded. Bilinear softening laws of the PC and SG series were determined by inverse analysis. Furthermore, the cohesive toughness was predicted using an analytical fracture model. The cohesive toughness obtained by experimental study was consistent with that predicted by analytical method, proving the correctness of the tension softening law obtained from inverse analysis. In addition, both initial and unstable fracture toughness values of SG mortar were lower than those of PC mortar given the same compressive strength. Moreover, the initial fracture toughness of SG concrete was generally lower than that of PC concrete, whereas the unstable fracture toughness exhibited an opposite trend.

The Effect of Concrete Quality on the Acoustic Emission Parameters during Three-Point Bending Fracture Test

2014 ◽  
Vol 897 ◽  
pp. 149-152 ◽  
Author(s):  
Michal Matysík ◽  
Libor Topolář ◽  
Petr Daněk ◽  
Tomáš Vymazal ◽  
Iveta Plšková
Keyword(s):  
Acoustic Emission ◽  
Large Scale ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Fracture Test ◽  
Opening Displacement ◽  
Three Point Bending ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture

Acoustic emission is an experimental tool well suited for monitoring fracture processes. The paper presents experiment focused on analysing acoustic emission signals captured during three-point bending fracture test of specimens of concrete. Quantitative acoustic emission techniques were used to measure micro fracture properties. For three different concrete mixtures typical acoustic emission patterns were identified in the acoustic emission records to further describe the under-the-stress behaviour and failure development. If we have a better understanding of the relationships between micro structural events and macroscopic behaviour we can better formulate predictive models for large-scale structural performance and reliability. An understanding of microstructureperformance relationships is the key to true understanding of material behaviours. Three-point bending fracture tests were conducted on these specimens and load versus crack mouth opening displacement (Load-CMOD) diagrams were recorded during the testing.

scholarly journals Estimation of Post-Cracking Dissipation Capabilities of Fiber Reinforced Concretes in Three Point Bending Test Monitored with Application of Digital Image Correlation System

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5088
Author(s):  
Duyen Trinh-Duc ◽  
Andrzej Piotrowski ◽  
Cezary Ajdukiewicz ◽  
Piotr Woyciechowski ◽  
Marcin Gajewski
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Structural Engineering ◽  
Crack Opening ◽  
Mouth Opening ◽  
Image Correlation ◽  
Bending Test ◽  
Crack Mouth Opening Displacement ◽  
Three Point Bending ◽  
Correlation System

Concretes with dispersed reinforcement are increasingly used in structural engineering. The basic source of knowledge on their application and design are the Model-Code 2010 guidelines. These guidelines, however, apply mainly to steel rebar reinforcement and are not fully sufficient in the analysis of the load-bearing capacity of elements made of concrete with dispersed reinforcement. Therefore, scientific research in this field is carried out continuously. The main goal of our work is to provide experimental data for the calibration of constitutive models of the cracking mechanics of concrete with reinforcement in the form of steel and polypropylene fibers. This article shows the possibility of using the digital image correlation system (DIC) to achieve this goal. The method of sample preparation and the method of conducting the tests were modeled on the recommendations contained in the PN-EN 14651: 2007 standard. The tests were carried out on prismatic elements with a notch loaded in a three-point bending setup. The results of standard strength tests are presented in the form of column graphs and tables. As an extension, the results of calculations of energy dissipated in fracture process are given. Moreover, the experimentally obtained graphs of the relationship between the force, displacement and crack opening were presented, which were supplemented with the images of crack development obtained with the use of DIC. The development of the crack net is characterized not only qualitatively but also quantitatively as a function of deflection or crack mouth opening displacement. Conclusions concerning the adopted research methodology and the tested materials are presented at the end of the article.

Evaluation of Three-Point Bending Fracture Tests of Selected Concrete: Crack Initiation and Acoustic Emission Parameters

2017 ◽  
Vol 259 ◽  
pp. 58-63
Author(s):  
Hana Šimonová ◽  
Libor Topolář ◽  
Ivana Havlíková ◽  
Michal Matysík ◽  
Petr Daněk ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Crack Initiation ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Opening Displacement ◽  
Unstable Crack ◽  
Three Point Bending ◽  
Damage Process ◽  
Fracture Tests ◽  
Bending Fracture

In this paper, authors concentrate attention on crack initiation and acoustic emission (AE) parameters obtained from records of three-point bending fracture tests on eight sets of concrete specimens with initial stress concentrator at the age of 28 days. Resistance to stable and unstable crack propagation was quantified via evaluation of load vs crack mouth opening displacement diagrams using Double-K fracture model. The AE technique was used to monitor damage process taking place during testing in specimens.

Comparison of Fracture Tests Numerical Models Created with Real Material Properties

2018 ◽  
Vol 774 ◽  
pp. 601-606
Author(s):  
Jiří Klon ◽  
Jakub Sobek
Keyword(s):  
Material Properties ◽  
Numerical Models ◽  
Mouth Opening ◽  
Compact Tension ◽  
Crack Mouth Opening Displacement ◽  
Opening Displacement ◽  
Three Point Bending ◽  
Real Material ◽  
Splitting Test ◽  
Fracture Tests

This contribution discusses numerical models of three different fracture tests – three-point bending (3PB), modified compact tension (modCT) and wedge-splitting test (WST). The aim is to compare loading diagrams (loading force vs. crack mouth opening displacement) obtained from these numerical models, created with real material properties. These properties were acquired from experimental data measurement. To assemble the numerical models, ATENA Science FEM software was used. In this software, damaging of the structure/specimen occurred by cracks can be modelled, their initiation and progressive propagation can be seen throughout the loading process.

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