scholarly journals Experimental Study on the Fracture Parameters of Concrete

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 129
Author(s):  
Zhanqiao Wang ◽  
Jin Gou ◽  
Danying Gao
Keyword(s):  
Steel Fiber ◽  
Volume Fraction ◽  
Mouth Opening ◽  
Critical Stress Intensity Factor ◽  
Crack Mouth Opening Displacement ◽  
Crack Tip Opening Displacement ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Critical Crack ◽  
Fracture Parameters

This study aimed to determine the influence of the volume fraction of steel fibers on the fracture parameters of concrete. Fifty notched steel-fiber-reinforced concrete (SFRC) beams and ordinary concrete beams with 100 mm × 100 mm × 515 mm were cast and tested via a three-point bending test. Among them, the type of steel fiber was the milling type (MF), and the volume fraction of steel fiber added was 0%, 0.5%, 1%, 1.5% and 2%, respectively. The effects of the steel fiber volume fraction (VF) on the critical stress intensity factor (KIC), fracture energy (GF), the deflection at failure(δ0), the critical crack mouth opening displacement (CMODC) and the critical crack tip opening displacement (CTODC) were studied. Through the analysis of test phenomena and test data such as the load-deflection (P-δ) curve, load-crack mouth opening displacement (P-CMOD) curve and load-crack tip opening displacement (P-CTOD) curve, the following conclusions are drawn: with the increase of the steel fiber volume fraction, some fracture parameters increase gradually and maintain a certain linear growth. The gain ratio of the fracture parameters increases significantly, and the gain effect is obvious. Through this law of growth, the experimental statistical formulas of fracture energy and the critical stress intensity factor are summarized.

scholarly journals Experimental Study on the Fracture Parameters of Concrete

2020 ◽  
Author(s):  
Zhanqiao Wang ◽  
Jin Gou ◽  
Danying Gao
Keyword(s):  
Steel Fiber ◽  
Volume Fraction ◽  
Mouth Opening ◽  
Critical Stress Intensity Factor ◽  
Crack Mouth Opening Displacement ◽  
Crack Tip Opening Displacement ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Critical Crack ◽  
Fracture Parameters

Abstract: This study was aimed to determine the influence of the volume fraction of steel fibers and on fracture parameters of concrete. Fifty notched steel fiber reinforced concrete (SFRC) beams and ordinary concrete beams with dimensions of 100mm×100mm×515mm were cast and tested via three-point bending test. Among them, the type of steel fiber is milling type (MF), and the volume fraction of steel fiber added is 0%, 0.5%, 0.5%, 1.5%, 1.5%, 2%, respectively. The effects of the steel fiber volume fraction (VF) on the critical stress intensity factor (KIC), fracture energy (GF), the deflection at failure(δ0), the critical crack mouth opening displacement (CMODC) and the critical crack tip opening displacement (CTODC)were studied. Through the analysis of test phenomena and test data such as load-deflection (P-δ) curve, load-crack mouth opening displacement (P-CMOD) curve and load-crack tip opening displacement (P-CTOD) curve following conclusions are drawn: With the increase of steel fiber volume fraction, some fracture parameters increase gradually and maintain a certain linear growth. The gain ratio of fracture parameters increases significantly, and the gain effect is obvious. Through this law of growth, the experimental statistical formulas of fracture energy and critical stress intensity factor are summarized.

scholarly journals Fracture Properties and Softening Curves of Steel Fiber-Reinforced Slag-Based Geopolymer Mortar and Concrete

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1445 ◽  
Author(s):  
Yao Ding ◽  
Yu-Lei Bai
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Inverse Analysis ◽  
Steel Fiber ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Fracture Properties

Adding short steel fibers into slag-based geopolymer mortar and concrete is an effective method to enhance their mechanical properties. The fracture properties of steel fiber-reinforced slag-based geopolymer concrete/mortar (SGC/SGM) and unreinforced control samples were compared through three-point bending (TPB) tests. The influences of steel fiber volume contents (1.0%, 1.5% and 2.0%) on the fracture properties of SGC and SGM were studied. Load-midspan deflection (P-δ) curves and load-crack mouth opening displacement (P-CMOD) curves of the tested beams were recorded. The compressive and splitting tensile strengths were also tested. The fracture energy, flexural strength parameters, and fracture toughness of steel fiber-reinforced SGC and SGM were calculated and analyzed. The softening curves of steel fiber-reinforced SGC and SGM were determined using inverse analysis. The experimental results show that the splitting tensile strength, fracture energy, and fracture toughness are significantly enhanced with fiber incorporation. A strong correlation between the equivalent and residual flexural strengths is also observed. In addition, the trilinear strain-softening curves obtained by inverse analysis predict well of the load-displacement curves recorded from TPB tests.

Test for Crack Opening Displacement of Steel Fiber Reinforced Concrete under Three-Point Bending

2010 ◽  
Vol 36 ◽  
pp. 157-161 ◽  
Author(s):  
Tin Gyi Zhang ◽  
Yuan Bao Leng ◽  
Dan Ying Gao
Keyword(s):  
Crack Opening Displacement ◽  
Crack Opening ◽  
Mouth Opening ◽  
Crack Tip ◽  
Crack Mouth Opening Displacement ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Critical Crack ◽  
Critical Crack Opening ◽  
Crack Tip Opening

Based on the principle of electrical measurement method, the clip gauge was made to measure the crack opening displacement (COD).Through the three-point bending test on the specimens of steel fiber reinforced high strength concrete (SFHSC), the effect of the fiber volume fraction (ρf) upon the critical crack opening displacement (the critical crack tip opening displacement and the critical crack mouth opening displacement) was studied. The result shows that the effect of ρf on mouth-tip ratio (the ratio of critical crack mouth opening displacement to critical crack tip opening displacement) can reflect its effect upon the critical crack opening displacement. According to the geometrical relationship between the initial crack length and the critical crack opening displacement，calculation method for the initial crack length was proposed. Based on the test result, the formula was established for calculating the critical crack tip opening displacement.

scholarly journals Steel fiber bond strength to estimate fRi parameters

2021 ◽  
Author(s):  
Aaron Kadima ◽  
Jeandry Bule Ntuku ◽  
Dênio Ramam Carvalho de Oliveira
Keyword(s):  
Bond Strength ◽  
Steel Fiber ◽  
Mouth Opening ◽  
Fiber Reinforced Concrete ◽  
Crack Mouth Opening Displacement ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Fiber Aspect Ratio ◽  
Model Code

This paper presents the results of the safety assessment of the β_1 coefficient that correlates the residual flexural tensile strength parameters fRi (i = 1, 2, 3, and 4) in steel fiber reinforced concrete (SFRC), collected through experimental notched beam flexural tests in three points, according to the fib Model Code 2010 (fib, 2013), with the bond strength (fu,f) of the hook-end type steel fiber in the concrete mix. The SFRC beams were chosen, which presents the load-opening ratio curve of the crack, F-CMOD (Crack Mouth Opening Displacement) in softening behavior, the compressive strength of the concrete, 25 MPa < fc < 80 MPa, the fiber volume content, 0.25 % < Vf < 0.80 % and the fiber aspect ratio, 60 < lf/df < 95. The results in 46 prisms notched of the database formed by 13 studies, showed a considerable influence of the fRi x fu,f ratio with lower variability of around 10%. Thus, through statistical resources, empirical proposals were established to estimate the residual flexural tensile strengths, as a viable and economical alternative to the design project.

Critical Crack Tip Opening Displacement for X70 and X80 Steels - A Parametric Study

2017 ◽  
Vol 898 ◽  
pp. 719-724 ◽  
Author(s):  
Xiao Ben Liu ◽  
Qing Quan Duan ◽  
Bao Dong Wang ◽  
Hong Zhang
Keyword(s):  
Mouth Opening ◽  
High Strength ◽  
Crack Mouth Opening Displacement ◽  
Specimen Thickness ◽  
Pipe Steels ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Critical Crack ◽  
Line Pipe ◽  
Crack Tip Opening

High strength line-pipe steels are widely used in long distance gas pipelines. Fracture toughness is one major parameter in the performance evaluation of these line-pipe steels. For high strength line-pipe steels, critical crack tip opening displacement (CTOD) is one typical quantity for fracture toughness. In this paper, a series of experimental studies were conducted to investigate the influences of steel property and specimen thickness on critical CTOD by three points bending tests for X70 and X80 line-pipe steel. Results showed that the critical CTOD is mainly depended on the plastic crack mouth opening displacement of the specimen. For the same size specimens, the critical CTOD of X80 steel was much less than X70 steel. The specimen thickness had a significant influence on the plastic crack mouth opening displacement. With the decrease of the specimen thickness, the critical CTOD increased.

scholarly journals Steel fiber bond strength to estimate fRi parameters

2021 ◽  
Author(s):  
Aaron Kadima ◽  
Jeandry Bule Ntuku ◽  
Dênio Ramam Carvalho de Oliveira
Keyword(s):  
Bond Strength ◽  
Steel Fiber ◽  
Mouth Opening ◽  
Fiber Reinforced Concrete ◽  
Crack Mouth Opening Displacement ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Fiber Aspect Ratio ◽  
Model Code

This paper presents the results of the safety assessment of the β coefficient that correlates the residual flexural tensile strength parameters f (i = 1, 2, 3, and 4) in steel fiber reinforced concrete (SFRC), collected through experimental notched beam flexural tests in three points, according to the fib Model Code 2010 (fib, 2013), with the bond strength (f) of the hook-end type steel fiber in the concrete mix. The SFRC beams were chosen, which presents the load-opening ratio curve of the crack, F-CMOD (Crack Mouth Opening Displacement) in softening behavior, the compressive strength of the concrete, 25 MPa < f < 80 MPa, the fiber volume content, 0.25 % < V < 0.80 % and the fiber aspect ratio, 60 < l/d < 95. The results in 46 prisms notched of the database formed by 13 studies, showed a considerable influence of the f x f ratio with lower variability of around 10%. Thus, through statistical resources, empirical proposals were established to estimate the residual flexural tensile strengths, as a viable and economical alternative to the design project.

Effects of Weld Strength Mismatch on Estimation Procedures for J and CTOD Fracture Parameters Using SE(B) Specimens

2007 ◽  
Author(s):  
Gustavo H. B. Donato ◽  
Claudio Ruggieri
Keyword(s):  
Mouth Opening ◽  
Estimation Procedure ◽  
Primary Objective ◽  
Weld Strength ◽  
Crack Mouth Opening Displacement ◽  
Opening Displacement ◽  
Fracture Parameters ◽  
Wide Range ◽  
Estimation Procedures ◽  
Fracture Specimens

This work presents an exploratory development of J and CTOD estimation procedures for welded fracture specimens under bending based upon plastic eta factors and plastic rotation factors. The techniques considered include: i) estimating J and CTOD from plastic work and ii) estimating CTOD from the plastic rotational factor. The primary objective is to gain additional understanding on the effect of weld strength mismatch on estimation techniques to determine J and CTOD fracture parameters for a wide range of a/W-ratios and mismatch levels. Very detailed non-linear finite element analyses for plane-strain models of SE(B) fracture specimens with center cracked, square groove welds provide the evolution of load with increased load-line displacement and crack mouth opening displacement which are required for the estimation procedure. The results show that levels of weld strength mismatch within the range ±20% mismatch do not affect significantly J and CTOD estimation expressions applicable to homogeneous materials, particularly for deeply cracked fracture specimens. The present analyses, when taken together with previous studies, provide a fairly extensive body of results which serve to determine parameters J and CTOD for different materials using bend specimens with varying geometries and mismatch levels.

Modeling and CMOD Mapping of Surface-Cracked Wide Plates

2008 ◽  
Author(s):  
Da-Ming Duan ◽  
Yong-Yi Wang ◽  
Yaoshan Chen ◽  
Joe Zhou
Keyword(s):  
Test Data ◽  
Driving Force ◽  
Mouth Opening ◽  
Quality Data ◽  
Crack Mouth Opening Displacement ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Crack Driving Force ◽  
Strain Capacity ◽  
Test Conditions

Curved wide plate (CWP) tests are frequently used to measure the tensile stress and strain capacity of pipeline girth welds. The parameters affecting the CWP measurement include specimen geometry and cooling setups. High-quality data is obtained when valid test conditions are confirmed. Crack mouth opening displacement (CMOD) is often measured in CWP tests. CMOD is a direct indicator of the amount of deformation at the cracked plane. It is an indirect indicator of the crack driving force (CDF) imparted on the crack. For a given test geometry and material, certain relationships can be derived between the measured CMOD and the more conventional representation of crack driving force, such as CTOD (crack tip opening displacement) and J-integral. Such relationships are a key element in fracture toughness testing standards. This kind of relationship is also particularly useful in strain-based design where CWP specimens are used for strain capacity and flaw growth prediction. In this paper finite element (FE) analysis is first used in modeling CWP testing conditions for X100 specimens with girth weld flaws to validate the test conditions. A novel approach called CMOD mapping is then developed to characterize the flaw behavior which, by making a direct use of CMOD test data from the CWP tests, is used to estimate the crack growth in the CWP. Finally analysis of strain limits using crack driving force (CDF) for the CWP specimens is also given by comparing experimental test data and FE estimation.

Stress Intensity at the Initiation of Instability by R Curve

2014 ◽  
Vol 592-594 ◽  
pp. 1160-1164 ◽  
Author(s):  
S. Sundaresan ◽  
B. Nageswara Rao
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Critical Stress ◽  
Mouth Opening ◽  
Compact Tension ◽  
Critical Stress Intensity Factor ◽  
Pressure Vessels ◽  
Crack Mouth Opening Displacement ◽  
Opening Displacement

The life expectancy or failure of aerospace pressure vessels is evaluated by the critical stress intensity determined by the crack growth resistance curve of a material. Load versus crack mouth opening displacement data is generated from the Compact Tension specimens made from the weld joints of maraging steel rocket motor segments. The steps involved to generate critical stress intensity factor is explained. A power law is adopted to model the crack extension in terms of stress intensity factor and determine the maximum failure load of weld specimens. Maximum failure loads of CT specimens obtained by test and analysis are presented.

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.

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