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.

Effect of confinement on the behaviour of high-strength lightweight concrete columns

1986 ◽  
Vol 13 (6) ◽  
pp. 741-751 ◽  
Author(s):  
R. Basset ◽  
S. M. Uzumeri
Keyword(s):  
Experimental Investigation ◽  
Lightweight Concrete ◽  
Concrete Strength ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Concrete Columns ◽  
Lightweight Aggregate Concrete ◽  
Test Results ◽  
Aggregate Concrete ◽  
Concrete Confinement

This paper summarizes an experimental investigation into the behaviour of high strength sand – lightweight concrete columns confined with rectangular ties. Fifteen reinforced and three unreinforced specimens were tested under monotonically increasing axial compression. Variables considered in this study were the longitudinal steel distribution and tie configuration, the tie steel spacing, the amount of tie steel, and the amount of longitudinal steel.The results indicated that unconfined high-strength lightweight aggregate concrete is a brittle material. The addition of lateral confining steel significantly improved the behaviour of this material, with a large amount of lateral steel resulting in very ductile behaviour. The tie configuration and resulting distribution of longitudinal steel contributed significantly to the confinement of concrete, with well-distributed steel resulting in improved behaviour. The ratio of specimen to cylinder concrete strength was observed to be 0.98, which is much higher than the commonly assumed value of 0.85.The test results were compared with results from selected theoretical confinement models. Based on the results of this investigation, existing models for concrete confinement give unconservative results for high-strength lightweight aggregate concrete and overestimate the ductility that can be achieved with this material. Key words: columns, confinement, ductility, high-strength concretes, lightweight aggregate concretes, reinforcement, stress–strain relationships, tests, ties, toughness.

Analysis of Strength Scaling Effect in Portuguese Limestone: Comparison between Three- and Four-Point Bending Tests

2010 ◽  
Vol 636-637 ◽  
pp. 1336-1341 ◽  
Author(s):  
Jorge Cruz Fernandes ◽  
Vera Pires ◽  
Pedro M. Amaral ◽  
Luís Guerra Rosa
Keyword(s):  
Experimental Data ◽  
Comparative Study ◽  
Surface Finishing ◽  
Intrinsic Volume ◽  
Cross Sectional ◽  
Weibull Statistics ◽  
Scaling Effect ◽  
Bending Tests ◽  
Four Point Bending ◽  
Cross Sectional Dimension

This paper presents a comparative study between 3- and 4-point bending tests applied to five Portuguese limestones. The study has been conducted on sawed limestone specimens, all showing the same surface finishing. The materials were compared for two distinct situations: i) using a 3-point flexure loading configuration in batches of materials with larger cross sectional specimen dimension (50 × 30 mm2); and ii) using a 4-point flexure loading configuration in the same batch of materials but with smaller cross sectional dimensions (30 × 25 mm2). In all situations, the materials have broken due to intrinsic volume defects. Formulae for the effective volumes and effective surfaces for rectangular beam specimens loaded in flexure were reviewed in order to analyse the strength scaling effect. The results show the applicability of the Weibull statistics to explain the differences in the results of the 3-point and 4-point bending tests, even when different cross sectional sizes are employed. Among other important remarks, in all the different limestone specimens used it was possible to confirm that the strength values determined experimentally via 3-point bending are of the same order as those estimated for the same loading configuration but via experimental data of 4-point bending tests using the Weibull strength scaling approach, even if employing a different cross-sectional dimension.

scholarly journals Compressive Behavior of FRP Grid-Reinforced UHPC Tubular Columns

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 125
Author(s):  
Junjie Zeng ◽  
Tianwei Long
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Ultra High Performance Concrete ◽  
Tubular Columns ◽  
Reinforced Polymer ◽  
Structural Applications ◽  
Frp Confinement

In this study, a novel form of tubular columns that is made of ultra-high-performance concrete (UHPC) internally reinforced with fiber-reinforced polymer (FRP) grid (herein referred to as FRP grid-UHPCtubular column) was developed. The axial compression test results of FRP grid-UHPC tubular columns with and without in-filled concrete are presented and discussed. Effects of the number of the FRP grid-reinforcing cages, the presence of in-filled concrete, and the presence of external FRP confinement were investigated. The test results confirmed that the FRP-UHPC tubular columns have a satisfactory compressive strength, and the strength and ductility of FRP-confined concrete-filled FRP grid-UHPC tube columns are enhanced due to the confinement from the FRP wrap. The proposed FRP grid-reinforced UHPC composite tubes are attractive in structural applications as pipelines or permanent formworks for columns, as well as external jackets (can be prefabricated in the form of two halves of tubes) for strengthening deteriorated reinforced concrete columns.

RELATIONSHIP REGULATION OF F ARDHU PRAYER WITH STRESS LEVEL OF SEMESTER 8 STUDENTS FACULTY OF MEDICINE MUHAMMADIYAH UNIVERSITY PURWOKERTO

2020 ◽  
Vol 1 (2) ◽  
pp. 77-82
Author(s):  
Rifaqul Azizi ◽  
Titik Kusumawinakhyu ◽  
Irma Finurina
Keyword(s):  
Stress Level ◽  
Pearson Correlation ◽  
Mild Stress ◽  
Test Results ◽  
Cross Sectional ◽  
Correlation Test ◽  
Peace Of Mind ◽  
Level Data ◽  
Pearson Correlation Test ◽  
The Relationship

Fardhu prayer is a compulsory activity that can create peace of mind for those who run it. For medical students in semester 8 of FK UMP who are experiencing many exams and personal problems, prayer can help calm and relieve stress. This study aims to determine the relationship between the regularity of fardhu prayer and stress levels in 8th-semester students of the Faculty of Medicine, Muhammadiyah University of Purwokerto. Methods use a correlational analysis research design with a cross-sectional approach. The study was conducted on an entire population of 48 students of the Faculty of Medicine, Muhammadiyah University of Purwokerto. Stress level data were obtained using the DASS test questionnaire, and prayer regularity data were obtained from the fardhu prayer regularity questionnaire. Data analysis with Pearson parametric correlation test. Results show the highest level of stress in students who experienced mild stress, and the results of the regularity of student prayers were found that many students regularly prayed. Based on the Pearson correlation test results, the value of p = 0.0 10 was obtained. There is a significant relationship between the regularity of fardhu prayer and the stress of the 8th-semester students of the Faculty of Medicine, Muhammadiyah University of Purwokerto, class of 2013.    

scholarly journals Influence of the Cross–Sectional Shape and Corner Radius on the Compressive Behaviour of Concrete Columns Confined by FRP and Stirrups

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 341
Author(s):  
Yang Wei ◽  
Yang Xu ◽  
Gaofei Wang ◽  
Xunyu Cheng ◽  
Guofen Li
Keyword(s):  
Mechanical Properties ◽  
Axial Compression ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Compression Tests ◽  
Cross Sectional ◽  
Compressive Behaviour ◽  
Corner Radius ◽  
The Cross ◽  
Sectional Shape

Axial compression tests were carried out on 72 FRP (fiber reinforced polymer)–stirrup composite−confined concrete columns. Stirrups ensure the residual bearing capacity and ductility after the FRP fractures. To reduce the effect of stress concentration at the corners of the confined square−section concrete columns and improve the restraint effect, an FRP–stirrup composite−confined concrete structure with rounded corners is proposed. Different corner radii of the stirrup and outer FRP were designed, and the corner radius of the stirrup was adjusted accurately to meet the designed corner radius of the outer FRP. The cross−section of the specimens gradually changed from square to circular as the corner radius increased. The influence of the cross−sectional shape and corner radius on the compressive behaviour of FRP–stirrup composite−confined concrete was analysed. An increase in the corner radius can cause the strain distribution of the FRP to be more uniform and strengthen the restraint effect. The larger the corner radius of the specimen, the better the improvement of mechanical properties. The strength of the circular section specimen was greatly improved. In addition, the test parameters also included the FRP layers, FRP types and stirrup spacing. With the same corner radius, increasing the number of FRP layers or densifying the stirrup spacing effectively improved the mechanical properties of the specimens. Finally, a database of FRP–stirrup composite−confined concrete column test results with different corner radii was established. The general calculation models were proposed, respectively, for the peak points, ultimate points and stress–strain models that are applicable to FRP−, stirrup− and FRP–stirrup−confined concrete columns with different cross−sectional shapes under axial compression.

scholarly journals Compressive Behavior of Bamboo Sheet Twining Tube-Confined Concrete Columns

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4124
Author(s):  
Xunyu Cheng ◽  
Yang Wei ◽  
Yuhan Nie ◽  
Gaofei Wang ◽  
Guofen Li
Keyword(s):  
Concrete Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Test Results ◽  
Compressive Behavior ◽  
Concrete Core ◽  
Strain Relationship ◽  
Mode Stress ◽  
New Type ◽  
Good Agreement

This study experimentally investigated various axial compressive parameters of a new type of confined concrete, which is termed bamboo sheet twining tube-confined concrete (BSTCC). This new composite structure was composed of an outer bamboo composite tube (BCT) jacket and a concrete core. Under axial compression, the parameters of thirty-six specimens include concrete strength (i.e., C30 and C50) and BCT thickness (i.e., 6, 12, 18, 24, and 30 layers). The mechanical properties of the BSTCC specimens from the perspective of the failure mode, stress-strain relationship, effect of BCT thickness and dilation behavior were analyzed. The results showed that, in compression, with an increase in BCT thickness in the range of 18-layers of bamboo sheets, the strength increased remarkably. When the strength of the concrete core was high, the confinement effect of the BCT was reduced. In addition, the BCT thickness relieved the dilation of the BSTCC specimens. Finally, the experimental results were compared with predictions obtained from 7 existing FRP-confined concrete models. All the predictions had good agreement with the test results, which further confirmed that the models developed for FRP-confined concrete can provide an acceptable approximation of the ultimate strength of the BSTCC specimens.

scholarly journals Axial Strength of Eccentrically Loaded FRP-Confined Short Concrete Columns

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1261 ◽  
Author(s):  
Cheng Jiang ◽  
Yu-Fei Wu
Keyword(s):  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Experimental Program ◽  
Test Results ◽  
Axial Strength ◽  
Strength Enhancement ◽  
Reinforced Polymer ◽  
Frp Confinement ◽  
The Relationship ◽  
Increasing Load

This paper presents an experimental program that includes 78 fiber reinforced polymer (FRP)-confined square concrete columns subjected to eccentric loading. The degradation of the axial strength of FRP-confined short concrete columns due to the load eccentricity is investigated in this work. A larger load eccentricity leads to a greater decrease in the axial strength. From the test results, it is found that FRP confinement can cause less strength degradation compared with that of unconfined concrete specimens. For FRP-confined square concrete specimens, the strength enhancement due to FRP confinement increases with increasing load eccentricity. However, the increasing load eccentricity decreases the confinement efficiency for FRP-confined circular concrete specimens. The relationship between the strength of eccentrically loaded FRP-confined square columns and their corner radii is evaluated.

Ultra-High-Strength Concrete-Filled FRP Tubes: Compression Tests on Square and Rectangular Columns

2013 ◽  
Vol 575-576 ◽  
pp. 239-244 ◽  
Author(s):  
Togay Ozbakkloglu
Keyword(s):  
Aspect Ratio ◽  
High Strength Concrete ◽  
High Strength ◽  
Experimental Program ◽  
Test Results ◽  
Compression Tests ◽  
Cross Sectional ◽  
Strength Concrete ◽  
Corner Radius ◽  
Frp Tubes

This paper presents the partial results of an experimental program undertaken to investigate the behavior of square and rectangular ultra-high-strength concrete (UHSC)-filled fiber reinforced polymer (FRP) tubes (UHSCFFTs) under axial compression. The effects of the amount of confinement, cross-sectional aspect ratio and corner radius were investigated experimentally through the tests of 24 concrete-filled FRP tubes (CFFTs) that were manufactured using unidirectional carbon fiber sheets and UHSC with 108 MPa average compressive strength. Test results indicate that sufficiently confined square and rectangular UHSCFFTs can exhibit highly ductile behavior. The results also indicate that HSCFFTs having tubes of low confinement effectiveness may experience a significant strength loss at the point of transition on their stress-strain curves. Examination of the test results have led to a number of important observations on the influence of corner radius and sectional aspect ratio, which are presented and discussed in the paper.

scholarly journals The Relationship Between Workload and Stress Level in Emergency Department of RSU Kabupaten Tangerang

2019 ◽  
Vol 2 (2) ◽  
pp. 51
Author(s):  
Shieva Nur Azizah Ahmad ◽  
Bunga Hidinopti
Keyword(s):  
Emergency Department ◽  
Job Stress ◽  
Stress Level ◽  
Cross Sectional Study ◽  
Hard Work ◽  
P Value ◽  
Test Results ◽  
Chi Square ◽  
Cross Sectional ◽  
The Relationship

 The burden of nurses is a dimension of all this activity or activities performed by a nurse for serving in a unit of health services. Service fast and exactly is needed in the service of the emergency room that can lead to the workload in the nurse, like encountering patients with various complaints of different diseases and patients come with the conditions are not stable, with the families of patients who can't wait, in addition to monitor and entering the patient's condition repeatedly is a unique and very unexpected because it can affect the stress. The research aims to identify how the workload with the stress level of work a nurse in Emergency Department RSU kabupaten Tangerang. The design of the deskriptif koleration with the cross sectional. Study sample as much as 40 of the respondents a nurse using the method of non probabiliti sampling techniques purposive sampling in accordance with the criteria for inclusion and eksklusi. Instruments in this study uses a questionnaire on the workload and level of job stress. The results showed the burden of hard work with the stress level of hard work as much as 15 respondents (88.2 %). The test results Chi Square to show p-value 0.002 (α < 0.05) that Ho is rejected and Ha is in, there is the relationship between workload with the stress level of work a nurse in Emergency Department RSU kabupaten Tangerang. Keywords: Level of Stress, Workload

scholarly journals STRENGTH OF CONCRETE UNDER LOCAL COMPRESSION TAKING INTO ACCOUNT THE RELATIONSHIP OF THE ELEMENT HEIGHT TO THE SIZE OF THE LOADING AREA

2021 ◽  
pp. 61-67
Author(s):  
I.H. KUZNIETSOVA ◽  
O.О. DOVZHENKO ◽  
V.V. POHRIBNYI
Keyword(s):  
Concrete Strength ◽  
Basalt Fiber ◽  
Test Results ◽  
Cross Sectional ◽  
Important Place ◽  
Determining Factors ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship ◽  
Concrete Elements

Formulation of the problem. Reliability of buildings and structures from reinforced concrete largely depends on efficiency of construction solutions of supporting areas and joins of elements of bearing systems. At the same time, an important place is given to the issues of ensuring their bearing capacity. One of the ways to solve this problem is to increase the strength characteristics of concrete, in particular by using basalt fiber. The purpose of the article is to improve the method of calculating the strength of concrete elements under the local compression on a general theoretical basis and to clarify the impact on the strength of determining factors. Conclusion. To calculate the strength of concrete elements under the local compression, the theory of concrete plasticity is promising. The application of the variational method and the principle of virtual velocities is proposed. According to research, the strength of concrete, in addition to the ratio of the area of application of the load and the cross-sectional area, is affected by the ratio of the height of the element to the width of the stamp and both characteristics of concrete strength. The proposed kinematic failure schemes have found experimental confirmation. Analysis of test results of concrete elements and assessment of their strength on the basis of the theory of plasticity allowed making the program of experimental research of fibroconcrete on basalt fibers under local compression.

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