scholarly journals Modeling Uniaxial Bond Stress–Slip Behavior of Reinforcing Bars Embedded in Concrete with Different Strengths

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 783
Author(s):  
Chao-Wei Tang
Keyword(s):  
Compressive Strength ◽  
Bond Stress ◽  
Constitutive Relationship ◽  
Central Position ◽  
Test Results ◽  
Reinforcing Bars ◽  
Cross Sectional ◽  
Reinforcing Bar ◽  
Cross Sectional Dimension ◽  
Center Section

This paper aims to study the uniaxial bond stress–slip characteristics of reinforcing bars embedded in concrete with different strengths. Tests were conducted on tension–pull specimens that had a cross-sectional dimension with a reinforcing bar embedded in the center section. The experimental variable was the concrete compressive strength (20, 40, and 60 MPa). The test results show that in the specimen subjected to any fixed load, the maximum value of the concrete strain occurred around the central position, and its value increased as the compressive strength of the concrete increased. Depending on the embedded position of the steel bars, the bond stress–slip relationship was also different. In addition, the analytical results indicate that the proposed bond stress–slip constitutive relationship is very accurate in describing the true bond stress–slip relationship.

scholarly journals Experimental Study on Bond Behavior between Plain Reinforcing Bars and Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Guohua Xing ◽  
Cheng Zhou ◽  
Tao Wu ◽  
Boquan Liu
Keyword(s):  
Aluminium Alloy ◽  
Structural Characteristics ◽  
Bond Stress ◽  
Reinforcing Bars ◽  
Bond Slip ◽  
Bond Behavior ◽  
Reinforcing Bar ◽  
Test Parameters ◽  
Steel Bars ◽  
Plain Bars

To evaluate the bond behavior between the reinforcing bar and surrounding concrete, a total of six-group pullout specimens with plain steel bars and two-group specimens with deformed steel bars, serving as a reference, are experimentally investigated and presented in this study. The main test parameters of this investigation include embedment length, surface type of reinforcing bars, and bar diameter. In particular, the bond mechanism of plain steel reinforcing bars against the surrounding concrete was analyzed by comparing with six-group pullout specimens with aluminium alloy bars. The results indicated that the bond stress experienced by plain bars is quite lower than that of the deformed bars given equal structural characteristics and details. Averagely, plain bars appeared to develop only 18.3% of the bond stress of deformed bars. Differing from the bond strength of plain steel bars, which is based primarily on chemical adhesion and friction force, the bond stress of aluminium alloy bars is mainly experienced by chemical adhesion and about 0.21~0.56 MPa, which is just one-tenth of that of plain steel bars. Based on the test results, a bond-slip model at the interface between concrete and plain bars is put forward.

Confinement Effectiveness of CFRP in Axial Members under Various Loading Conditions

2013 ◽  
Vol 747 ◽  
pp. 277-281
Author(s):  
Barış Erdil ◽  
Uğurhan Akyüz ◽  
İsmail Özgür Yaman
Keyword(s):  
Experimental Data ◽  
Stress Level ◽  
Concrete Strength ◽  
Concrete Columns ◽  
Extensive Literature ◽  
Test Results ◽  
Cross Sectional ◽  
Corner Radius ◽  
Cross Sectional Dimension ◽  
Frp Confinement

In this study, parameters affecting the mechanical properties of FRP-confined cylindrical and prismatic concrete columns were studied via experimental data, which were collected after an extensive literature review. The parameters were summarized as unconfined concrete strength, FRP thickness, cylinder diameter, overlap length of FRP, sustained stress level, heating-cooling effect and corner radius in prismatic specimens. Considering these parameters the confinement effectiveness is established analytically in the light of ultimate strength values obtained from the test results available in the literature. No steel reinforcement is taken into account because the main aim is to capture the behavior of FRP-confinement only. The analytical results revealed that unconfined concrete strength, FRP thickness, cross-sectional dimension of the specimen are the main parameters controlling the confinement effectiveness in cylindrical specimens. In addition to these parameters corner radius and sustained stress level are found to be significant in prismatic specimens.

scholarly journals Modeling Local Bond Stress–Slip Relationships of Reinforcing Bars Embedded in Concrete with Different Strengths

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3701
Author(s):  
Chao-Wei Tang ◽  
Chiu-Kuei Cheng
Keyword(s):  
Prediction Models ◽  
Concrete Strength ◽  
Bond Stress ◽  
Analytical Models ◽  
Test Results ◽  
Reinforcing Bars ◽  
Model Code ◽  
Steel Bar ◽  
Proposed Model ◽  
Comparison Results

Although many different analytical models of local bond stress–slip have been proposed, considering the possible differences between materials in different countries, their applicability needs to be further explored. In this paper, the local bond stress–slip characteristics of reinforcing bars embedded in concrete with different strengths were experimentally studied. The experimental variables included the concrete strength (20, 40, and 60 MPa) and deformed rebar size (#4, #6, and #8). The experimental results of the bond stress–slip relationship were compared with the Euro-International Concrete Committee (CEB-Comité Euro-International du Béton)-International Federation for Prestressing (FIP-Fédération Internationale de la Précontrainte) Model Code and prediction models found in the literature. In addition, based on the test results, an empirical model of the bond stress–slip relationship was proposed. The evaluation and comparison results show that, regardless of the concrete strength grades, the predicted value calculated using the CEB-FIP Model Code will underestimate the bond strength of the specimens with different steel bar diameters. From this perspective, it is more conservative. In contrast, the proposed model can predict the test results with a reasonable accuracy.

scholarly journals Development of a Novel Concrete Curing Method Using Induction Heating System

2020 ◽  
Vol 11 (1) ◽  
pp. 236
Author(s):  
Chi-Hyung Ahn ◽  
Jinbok Lee ◽  
Dong-Jin Kim ◽  
Hyun-Oh Shin
Keyword(s):  
Induction Heating ◽  
Cold Weather ◽  
Maximum Temperature ◽  
Strength Development ◽  
Test Results ◽  
Compression Tests ◽  
Cross Sectional ◽  
Heating Efficiency ◽  
Cross Sectional Dimension ◽  
Curing Method

This study aimed to develop an accelerated concrete curing method based on induction heating (IH) technology. The proposed curing method provides improved heating efficiency and safety since it directly heats only the metallic forms in a non-contacting manner. It also has the advantage of being capable of heating the concrete according to a desirable heating scenario. The effects of several parameters on its performance were evaluated using a finite element method (FEM)-based thermal analysis and heating performance tests. The FEM analysis revealed the steel form to be appropriate for the IH system. The analysis also revealed that equally spaced three-turn coils yielded increased temperature uniformity in the steel form, which was verified by results of the steel form heating experiments. Furthermore, the minimum temperature generated in the form was sufficient for concrete curing. The efficiency of the use of IH for concrete curing and the effects of curing parameters were further investigated through compression tests after applications of various curing methods and by examining the temperature distributions during curing. The test results revealed early strength development even under water freezing conditions. This demonstrated the effectiveness of IH for concrete curing in cold weather. However, the efficiency decreased when the cross-sectional dimension of the specimen increased. The test results also verified that the maximum temperature and duration of induction heat curing affect the early age strength of concrete.

Variasi Penambahan Sika Cim Dan Fiber Kawat Pada Beton Mutu Fc’ 30 Mpa

2018 ◽  
Vol 9 (2) ◽  
pp. 67-73
Author(s):  
M Zainul Arifin
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Normal Concrete ◽  
Astm Method ◽  
Additive Type ◽  
Composition Variation ◽  
Compressive Strength Of Concrete

This research was conducted to determine the value of the highest compressive strength from the ratio of normal concrete to normal concrete plus additive types of Sika Cim with a composition variation of 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1 , 50% and 1.75% of the weight of cement besides that in this study also aims to find the highest tensile strength from the ratio of normal concrete to normal concrete in the mixture of sika cim composition at the highest compressive strength above and after that added fiber wire with a size diameter of 1 mm in length 100 mm with a ratio of 1% of material weight. The concrete mix plan was calculated using the ASTM method, the matrial composition of the normal concrete mixture as follows, 314 kg / m3 cement, 789 kg / m3 sand, 1125 kg / m3 gravel and 189 liters / m3 of water at 10 cm slump, then normal concrete added variations of the composition of sika cim 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1.5%, 1.75% by weight of cement and fiber, the tests carried out were compressive strength of concrete and tensile strength of concrete, normal maintenance is soaked in fresh water for 28 days at 30oC. From the test results it was found that the normal concrete compressive strength at the age of 28 days was fc1 30 Mpa, the variation in the addition of the sika cim additive type mineral was achieved in composition 0.75% of the cement weight of fc1 40.2 Mpa 30C. Besides that the tensile strength test results were 28 days old with the addition of 1% fiber wire mineral to the weight of the material at a curing temperature of 30oC of 7.5%.

FAKTOR PERSONAL YANG BERHUBUNGAN DENGAN KOMITMEN ORGANISASI PERAWAT RSUD EMBUNG FATIMAH BATAM

2020 ◽  
Vol 5 (3) ◽  
pp. 875
Author(s):  
Asfri Sri Rahmadeni
Keyword(s):  
Organizational Commitment ◽  
Turnover Rate ◽  
Sampling Technique ◽  
Hospital Nurses ◽  
Test Results ◽  
Personal Factors ◽  
High Turnover ◽  
Chi Square ◽  
Cross Sectional ◽  
Chi Square Test

<p class="Normal1"><em>Commitment is the attitude or behavior of likes or dislikes shown by someone against the organization at work. Indonesia is recorded as a nurse who has a low organizational commitment (76%) so it harms services. This phenomenon in the hospital can be seen from the indicator of the high turnover rate of nurses which reaches 30.9% which exceeds the standard &lt;5%. Many factors affect organizational commitment. The purpose of this study was to analyze the Personal Factors Associated with Organizational Commitment of Hospital Nurses. This study is a cross-sectional analytic study and purposive sampling technique with a sample of 59 nurses. Chi-Square test results obtained personal factors that have a relationship with organizational commitment Nurse Hospital is age with p = 0,000 and education with p = 0,000, personal factors not related to organizational commitment are gender p = 1,053 and years of service with p = 1,147. Hospitals should conduct research/surveys on Organizational Commitment periodically as an evaluation material in the context of the organization's development and development in the future</em>.</p>

Faktor yang Berhubungan dengan Penggunaan Partograf dalam Persalinan oleh Bidan Praktik Mandiri

2020 ◽  
Vol 2 (2) ◽  
pp. 72-80
Author(s):  
Niluh Nita Silfia
Keyword(s):  
Total Population ◽  
Sampling Technique ◽  
Population Data ◽  
Statistical Test ◽  
Influential Factor ◽  
Test Results ◽  
Cross Sectional ◽  
Factors Associated ◽  
Survey Results ◽  
Research Criteria

Partographs are guidelines for childbirth observations that will facilitate labor assistants in first identifying emergency cases and complications for mothers and fetuses. Preliminary survey at the Sigi Community Health Sub-Center (Pustu) of the 8 Pustu midwives found two midwives (25%) to complete a complete partograph, six midwives (75%) incomplete. The purpose of this study was to determine the determinant factors associated with the use of partographs in labor. The design of this study used observational analytic methods with a cross-sectional approach. 24 BPM survey results were obtained with 30 samples of midwives who met the research criteria and data completeness. The sampling technique was by the total population. Data analysis used logistic regression. The multivariate analysis results showed that APN training was the most influential factor in the use of partographs in labor by midwives. Statistical test results obtained a POR value of 37.7 (95% CI 12.1 - 60.2). This study suggests that midwives must have APN certificates to be valid in providing services.

PENGKAJIAN KEKUATAN BETON STRUKTUR JEMBATAN PASCA KEBAKARAN

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Sudarmadi Sudarmadi
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Strength Assessment ◽  
Concrete Testing

In this paper a case study about concrete strength assessment of bridge structure experiencing fire is discussed. Assessment methods include activities of visual inspection, concrete testing by Hammer Test, Ultrasonic Pulse Velocity Test, and Core Test. Then, test results are compared with the requirement of RSNI T-12-2004. Test results show that surface concrete at the location of fire deteriorates so that its quality is decreased into the category of Very Poor with ultrasonic pulse velocity ranges between 1,14 – 1,74 km/s. From test results also it can be known that concrete compressive strength of inner part of bridge pier ranges about 267 – 274 kg/cm2 and concrete compressive strength of beam and plate experiencing fire directly is about 173 kg/cm2 and 159 kg/cm2. It can be concluded that surface concrete strength at the location of fire does not meet the requirement of RSNI T-12-2004. So, repair on surface concrete of pier, beam, and plate at the location of fire is required.

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