scholarly journals Parameters estimation of Drucker-Prager plasticity criteria for steel confined circular concrete columns in compression

2018 ◽  
Vol 149 ◽  
pp. 01048
Author(s):  
Walid A. Al-Kutti
Keyword(s):  
Concrete Strength ◽  
Empirical Relationship ◽  
Compressive Loading ◽  
Strain Curve ◽  
Concrete Columns ◽  
Friction Angle ◽  
Parameters Estimation ◽  
Confined Concrete ◽  
Composite Section ◽  
Finite Element Package

This paper explores the possibility to use Drucker-Prager model in Steel-Concrete composite section. Numerical simulation was conducted using finite element package to simulate the steel-concrete composite section subjected to uniaxial compressive loading. After calibration with experimental study, parametric study was conducted to evaluate the effect of the friction angle and the cohesion constant c on the stress-strain curve of composite section. Empirical relationship between the friction angle and the confined concrete compressive strength was developed and a range of cohesion constant c between 5-10 MPa was suggested for confined concrete strength range of 25 to 100 MPa, respectively.

Strength model of FRP confined concrete columns based on analytical analysis and experimental test

2019 ◽  
Vol 11 (1) ◽  
pp. 82-106 ◽  
Author(s):  
Mahfoud Touhari ◽  
Ratiba Kettab Mitiche
Keyword(s):  
Concrete Strength ◽  
Compressive Force ◽  
Concrete Columns ◽  
Fiber Reinforced Concrete ◽  
Confined Concrete ◽  
Fiber Reinforced ◽  
Reinforced Concrete Column ◽  
Theoretical Assumption ◽  
Hoop Strain ◽  
Content Type

Purpose Covering a fiber-reinforced concrete column (fiber reinforced plastic (FRP)) improves the performance of the column primarily. The purpose of this paper is to investigate the behavior of small FRP concrete columns that are subject to axial pressure loading, in order to study the effect of many parameters on the effectiveness of FRP couplings on circular and square concrete columns. Design/methodology/approach These parameters include the shape of the browser (circular and square), whole core and cavity, square radius of square columns, concrete strength (low strength, normal and high), type of FRP (carbon and glass) and number of FRP (1–3) layers. The effective fibrillation failure strain was investigated and the effect of effective lateral occlusion pressure. Findings The results of the test showed that the FRP-coated columns improved significantly the final conditions of both the circular and square samples compared to the unrestricted columns; however, improvement of square samples was not as prominent as improvement in circular samples. The results indicated that many parameters significantly affected the behavior of FRP-confined columns. A new model for predicting compressive force and the corresponding strain of FRP is presented. A good relationship is obtained between the proposed equations and the current experimental results. Originality/value The average hoop strain in FRP wraps at rupture in FRP-confined concrete specimens can be much lower than that given by tensile coupon tests, meaning the theoretical assumption that the FRP-confined concrete cylinder ruptures when the FRP material tensile strength attained at its maximum is not suitable. Based on this observation, the effective peak strength and corresponding strain formula for FRP concrete confined columns must be based on the effective hoop rupture strain composite materials.

scholarly journals BEHAVIOUR OF HIGH-STRENGTH CONCRETE CIRCULAR COLUMNS CONFINED BY HIGH-STRENGTH SPIRALS UNDER CONCENTRIC COMPRESSION

2020 ◽  
Vol 26 (6) ◽  
pp. 564-578
Author(s):  
Chongchi Hou ◽  
Wenzhong Zheng ◽  
Wei Chang
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Concrete Compressive Strength ◽  
Strength Concrete ◽  
Proposed Model ◽  
High Strength Concrete Columns

This paper tested the behaviour of 32 high-strength concrete columns confined by high-strength spirals under concentric compression. The test parameters included unconfined concrete compressive strength, spiral yield strength, volumetric ratio, and spiral spacing. The results showed that bulging and shear sliding were the two characteristic types of failure patterns of the thirty-two confined columns, depending on spiral spacing and concrete strength. Moreover, the spiral in most specimens did not yield at the confined concrete compressive strength. An analytical confinement model for high-strength concrete columns confined by high-strength spirals was proposed. In this proposed model, the calculated value of the spiral stress at the confined concrete compressive strength was used to calculate the feature points of the stressstrain curve. The proposed model showed good correlations with available experimental results of 64 columns.

Impact Factors Study on Strength of Steel Tube Confined Concrete Columns under Axial Compression

2013 ◽  
Vol 639-640 ◽  
pp. 1069-1072
Author(s):  
Hao Xiong Feng ◽  
Wei Jian Yi
Keyword(s):  
Axial Compression ◽  
Theoretical Basis ◽  
Concrete Strength ◽  
Concrete Columns ◽  
Steel Tube ◽  
Confined Concrete ◽  
Impact Factors ◽  
Working Mechanism

This paper describes principle and working mechanism of the steel tube confined concrete, to analyze impact factors of steel tube confined concrete strength. By the studies, presents several solutions to improve the strength of steel tube confined concrete, fully execute the behavior of steel tube and filled-in-concrete, strengthen the interactions between steel tube and filled-in-concrete to provide theoretical basis for the design and use of steel tube confined concrete.

A constitutive model of concrete confined by steel reinforcements and steel jackets

2005 ◽  
Vol 32 (1) ◽  
pp. 279-288 ◽  
Author(s):  
Y-F Li ◽  
S-H Chen ◽  
K-C Chang ◽  
K-Y Liu
Keyword(s):  
Constitutive Model ◽  
Concrete Strength ◽  
Strain Curve ◽  
Steel Reinforcement ◽  
Confined Concrete ◽  
Stress Strain ◽  
Steel Jacket ◽  
Proposed Model ◽  
Concrete Cylinders ◽  
Different Types

In this paper, a total of 60 concrete cylinders 30 cm in diameter and 60 cm in length confined by steel jackets of different thicknesses and different types of lateral steel reinforcements are tested to obtain the stress–strain curves of the cylinders. A constitutive model is proposed to describe the behavior of concrete confined by steel reinforcement, steel jackets, and both steel reinforcement and steel jackets used to retrofit and strengthen reinforced concrete structures. The confined concrete stress–strain curve of the proposed model is divided into two regions: the curve in the first region is approximated using a second-order polynomial equation, and that in the second region using an nth-order power-law equation, where n is a function of the unconfined concrete strength and the lateral confining stress. The results of the experiments show that different types of lateral steel reinforcement contribute greatly to the compressive strength of concrete cylinders confined by the reinforcement. Comparing the stress–strain curves of the uniaxial test with that from the proposed model, we conclude that the proposed model for concrete confined by a steel jacket and lateral steel reinforcement can predict the experimental results very well.Key words: constitutive model, steel jacket, confined concrete.

Experimental Study on Compressive Behavior of CFRP Confined Concrete Columns

2012 ◽  
Vol 446-449 ◽  
pp. 3725-3729
Author(s):  
Wei Hua Ma ◽  
Hong Zhen Kang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Concrete Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Concrete Column ◽  
Compressive Behavior ◽  
Reinforcing Effect ◽  
Research Results ◽  
Compressive Tests

Compressive tests of 30 concrete column specimens with three concrete strength grades are carried out in this paper to study ultimate compressive strength of specimens. The specimens are divided into three groups, that is, unconfined, confined by CFRP with no initial compression and confined by CFRP with various initial compressions. The different initial compressions’ influence on ultimate stresses and strains are investigated. The decrease of CFRP reinforcing effect due to pre-compression are analyzed. The research results provide experimental datum for reinforced design of existing concrete columns.

Experimental Research on Axially Loaded Circular Concrete Columns Confined by CFRP under Preload

2011 ◽  
Vol 255-260 ◽  
pp. 694-698 ◽  
Author(s):  
Yi Pan ◽  
Shuang Yin Cao ◽  
Deng Hu Jing ◽  
Shi Chun Zhao
Keyword(s):  
Uniaxial Compression ◽  
Experimental Research ◽  
Concrete Strength ◽  
Peak Stress ◽  
Concrete Columns ◽  
Confinement Effect ◽  
Confined Concrete ◽  
Stress And Strain ◽  
Circular Section ◽  
Cfrp Sheet

A total of 32 circular-section concrete columns confined by CFRP sheet were tested in uniaxial compression involved in different preload ratio, concrete strength and CFRP plies. The failure characteristic and mechanics behavior of confined concrete columns were presented, and the descending of the peak stress and strain of confined concrete due to preload were analyzed. The experimental results indicated that the confinement effect of CFRP was influenced by preload ratio observably. The second stiffness, the peak stress and strain declined with preload ratio ascending, and the extent developed with the enhancement of CFRP ply.

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 Experimental Behavior of Concrete Columns Confined by Transverse Reinforcement with Different Details

2020 ◽  
Vol 14 (1) ◽  
pp. 250-265 ◽  
Author(s):  
Mariateresa Guadagnuolo ◽  
Alfonso Donadio ◽  
Anna Tafuro ◽  
Giuseppe Faella
Keyword(s):  
Reinforced Concrete ◽  
Concrete Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Eurocode 8 ◽  
Strength Increase ◽  
Existing Buildings ◽  
Concrete Confinement

Introduction: Most of the existing reinforced concrete buildings often have columns with poor transverse reinforcement details. Models for computing the confined concrete strength were developed using experimental tests performed on specimens with transverse reinforcement typical of seismic design. The paper presents the results of an experimental program performed to investigate the effect of type, amount and pitch of transverse reinforcement on the behavior of confined concrete. Aim: The paper is also aimed at evaluating whether the current code models are suitable for estimating the confined strength of concrete in existing buildings. Methods: A total of 45 reinforced concrete columns with four volume ratios of transverse reinforcement were tested under axial loads. Type and pitch of transverse reinforcement typical of existing r/c buildings not designed according to seismic standards were considered. Therefore, columns reinforced by spiral and hoops with 135° or 90° hooks at the end are investigated for comparing their behavior. The confinement of spirals and hoops to core concrete is discussed as the amount of transverse and longitudinal reinforcement varies. Small increases in strength due to the concrete confinement were measured for hoop pitch of 150 mm (ranging between 2% and 7%), but also for hoops with 90° hook and pitch of 75 mm. Greater increments were obtained by spirals and hoops with 135° hook in the case of 75 mm pitch and when rhomboidal hoops or cross-ties were arranged in addition to the perimeter hoops. A comparison with some similar experimental results is also performed, achieving quite similar results. The mean experimental stress-strain curves are also analyzed. Results: The results show how the increase in concrete strength due to the confinement is more dependent on the transverse reinforcement pitch than the type and detail of transverse reinforcement or even less diameter of longitudinal bars. Finally, the experimental strength of confined concrete is then compared with the values provided by Eurocode 8 and the new Italian Building Code, showing that the higher the volumetric percentage of transverse reinforcement, the greater the overestimation of code models. Conclusion: An overestimation of codes up to 30% is assessed, systematically lower in the case of spirals, and higher in the case of hoops with 90° hooks at the end. The results highlight the need to develop specific equations to determine the strength increase due to the concrete confinement in the case of existing buildings with poor transverse reinforcement.

scholarly journals Experimental Study on CFRP-Confined Circularized Concrete-Filled Square Steel Tube Short Columns

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yuchuan Wen ◽  
Zhongjun Hu ◽  
Anningjing Li ◽  
Quanheng Li ◽  
Xuepeng Li ◽  
...  
Keyword(s):  
Concrete Strength ◽  
Concrete Columns ◽  
Steel Tube ◽  
Confined Concrete ◽  
Test Results ◽  
Stress Strain ◽  
Short Columns ◽  
Reinforced Polymer ◽  
Square Steel Tube ◽  
Strain Model

This study investigates the suitability of the circularization technique for strengthening square concrete-filled square steel tube (CFSST) short columns. A total of 16 specimens were tested under axial compression. The main parameters under investigation were concrete strength, the thickness of arc cement mortar layer components (CAM), and the layers of carbon fiber-reinforced polymer (CFRP) sheets. Test results indicated that the failure mode of CFRP-confined circularized CFSST (C-C-CFSST) columns was similar to that of CFRP-confined concrete columns. The CFRP-confined circularized strengthening method can increase confinement efficacy and reduce the stress concentration at the corners of CFSST columns. Three existing CFRP-confined concrete stress-strain models were evaluated using the test results. The predictions of the Lam and Teng stress-strain model agree well with the test data.

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