Numerical Simulations of Fully Encased Composite Columns under Gravity Loads

2016 ◽  
Vol 860 ◽  
pp. 140-145 ◽  
Author(s):  
Md Soebur Rahman ◽  
Mahbuba Begum
Keyword(s):  
Composite Structures ◽  
Numerical Study ◽  
Concrete Strength ◽  
Fe Model ◽  
Nonlinear Behaviour ◽  
Composite Columns ◽  
Axial Capacity ◽  
Concrete Confinement ◽  
Inelastic Behaviour ◽  
Steel Shapes

Composite structures is a combination of structural steel shapes and reinforced concrete and these two materials are combined in such a way to benefit each material characteristic. This paper investigates the behaviour and strength of axially loaded concrete encased steel composite columns. A nonlinear 3-D finite element (FE) model has been developed to analyse the inelastic behaviour of steel, concrete, and longitudinal reinforcement as well as the effect of concrete confinement on fully encased composite (FEC) columns. The model has been verified against the experiments conducted in the laboratory under concentric gravity loads. It has been found that the FE model is capable of predicting the nonlinear behaviour of the FEC columns up to failure with good accuracy. The capacities of each constituent of FEC columnssuch as steel-I section, concrete and rebars were also determined from the numerical study. Concrete is observed to provide around 57% of the total axial capacity of the column whereas the steel I-sections contributes to the rest of the capacity as well as to the ductility of the overall system. The nonlinear FE model developed in this study is also used to explore the effects of concrete strength on the behaviour of FEC columns under concentric loads. The axial capacity of FEC columns has been found to increase significantly by increasing the strength of concrete.

scholarly journals Behavior of an Advanced Bolted Shear Connector in Prefabricated Steel-Concrete Composite Beams

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2958 ◽  
Author(s):  
Jun Chen ◽  
Wei Wang ◽  
Fa-Xing Ding ◽  
Ping Xiang ◽  
Yu-Jie Yu ◽  
...  
Keyword(s):  
Composite Structures ◽  
Concrete Slab ◽  
Concrete Strength ◽  
High Strength ◽  
Fe Model ◽  
Building Structures ◽  
Shear Connector ◽  
Test Results ◽  
Shear Connectors ◽  
Bolt Pretension

The high-strength bolt shear connector in prefabricated concrete slab has advantages in applications as it reduces time during the construction of steel-concrete composite building structures and bridges. In this research, an innovative and advanced bolt shear connector in steel-concrete composite structures is proposed. To investigate the fundamental mechanical behavior and the damage form, 22 static push-off tests were conducted with consideration of different bolt dimensions, the reserved hole constraint condition, and the dimension of slab holes. A finite element (FE) model was established and verified by using test results, and then the model was utilized to investigate the influence of concrete strength, bolt dimension, yield strength, bolt pretension, as well as length-to-diameter ratio of high strength bolts on the performances of shear connectors. On the basis of FE simulation and test results, new design formulas for the calculation of shear resistance behavior were proposed, and comparisons were made with current standards, including AISC, EN 1994-1-1, GB 50017-2017, and relevant references, to check the calculation efficiency. It is confirmed that the proposed equation is in better agreement with the experimental results.

scholarly journals Seismic Behavior of Hybrid Frame Joints between Composite Columns and Steel Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Liusheng Chu ◽  
Qingze Li ◽  
Jun Zhao ◽  
Danda Li
Keyword(s):  
Crack Resistance ◽  
Seismic Behavior ◽  
Shear Failure ◽  
Numerical Study ◽  
Concrete Strength ◽  
Shear Resistance ◽  
Hysteretic Behavior ◽  
Cyclic Behavior ◽  
Shear Reinforcement ◽  
Composite Columns

This study presents experimental and numerical study on cyclic behavior of SRC composite columns-steel beam joints. The pseudostatic experiments were carried out on four samples with different axial loads. X-shaped shear reinforcement was added in the sample no. 4 in order to investigate its effect on the crack resistance in the joint core area. Low-frequency cyclic load was applied at beam ends to simulate the earthquake action. The failure characteristics, hysteretic behavior, stiffness degradation, shear resistance, and displacement ductility were investigated. Experimental results indicated that the failure mode of the joints was mainly shear failure, and the composite joints showed excellent seismic behavior with higher capacity and good ductility and energy dissipation ability. X-shaped shear reinforcement performed well to increase the concrete crack resistance. Shear forces from both experimental test and theoretical analysis were compared, and suggestions were given on modification of theoretical formulas. Simulation using the ABAQUS model showed good results that agreed well with the test results. Steel stress distribution and damage development were analyzed in the model. More parameters of web thickness, stiffener thickness, concrete strength, and stirrups and their influence on shear resistance were studied.

scholarly journals Experimental and Numerical Investigation of Octagonal Partially Encased Composite Columns Subject to Axial and Torsion Moment Loading

2017 ◽  
Vol 3 (10) ◽  
pp. 939 ◽  
Author(s):  
Mehdi Ebadi Jamkhaneh ◽  
Mohammad Ali Kafi
Keyword(s):  
Numerical Study ◽  
Compressive Loading ◽  
Compressive Load ◽  
Thickness Ratio ◽  
Composite Columns ◽  
Deformation Curves ◽  
Concrete Confinement ◽  
Different Types ◽  
Analytical Phase ◽  
Partially Encased Composite Columns

This paper includes experimental and numerical study of the octagonal partially encased composite (PEC) columns specimens under axial and torsion loading. The major difference between them was the concrete reinforcement details. The parameters investigated in the experimental and numerical study were the type of reinforcement details, the failure mode, width-to-thickness ratio of flange, transverse links spacing and diameter. The results were presented as load-deformation curves. Numerical model was validated using finite element method and the results indicated acceptable accuracy with tests results in the form of capacity and ductility. In the analytical phase, the experimental results in the compressive loading were compared with those obtained from CSA S16-14 and EN 1994-1-1 equations. Also, the new concrete confinement factor in proportion to the web width to thickness ratio was presented to octagonal PEC columns under pure compressive load. Furthermore, different types of retrofit of cross-shaped steel column including concrete encasement, use of stiffener plates and transverse links were investigated in this research. Results revealed that concrete confinement and use of transverse links had respectively the most and the least effect on increasing torsional capacity of the specimens.

Numerical modelling of concrete-filled stainless steel slender columns loaded eccentrically

2020 ◽  
Vol 17 (5) ◽  
pp. 697-707
Author(s):  
Majid M.A. Kadhim
Keyword(s):  
Stainless Steel ◽  
Axial Load ◽  
Fe Model ◽  
Nonlinear Behaviour ◽  
Content Type ◽  
Composite Columns ◽  
Small Width ◽  
Strength Capacity ◽  
Simulation Results ◽  
Slender Columns

Purpose This paper is aimed at clarifying the behaviour of concrete-filled stainless steel tube (CFSST) slender columns. Based on the review of previous works, it can be found that the pieces of research on the behaviour of CFSST slender columns are very rare and the existing studies, to the author’s knowledge, have not covered this topic in greater depth. The purpose of this paper is to investigate the structural response and strength capacity of eccentric loaded long CFSST columns. Design/methodology/approach In this paper, a new finite element (FE) model is presented for predicting the nonlinear behaviour of CFSST slender columns under eccentric load. The FE model developed accounts for confinement influences of the concrete in-filled material. In addition, the initial local and overall geometric imperfections were introduced in the numerical model in addition to the inelastic response of stainless steel. The interaction between the stainless section and concrete in-filled was modelled using contact pair algorithm. The FE model was then verified against an experimental work presented in the literature. The ultimate strengths, axial load–lateral displacement and failure mode of CFSST slender columns predicted by the FE model were validated against corresponding experimental results. Findings The simulation results show that the improvement in the column strengths (compared to hollow section) is less significant when the composite columns have small width-to-thickness ratio. Finally, comparisons were made between the results obtained from FE simulation and those computed from the Eurocode 4 (EC4). It has been found that the EC4 predictions in most analysed cases are conservative for composite columns analysed under a combination of axial load and uniaxial or biaxial bending. However, the conservatism of the code is reduced with a higher slenderness ratio of the composite columns. Practical implications The simulation results throughout this research were compared with the corresponding Eurocode predictions. Originality/value This paper provides new findings about the structural behaviour of CFSST columns.

scholarly journals Bond Behaviour of Near-Surface Mounted Strips in RC Beams—Experimental Investigation and Numerical Simulations

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4362
Author(s):  
Renata Kotynia ◽  
Hussien Abdel Baky ◽  
Kenneth W. Neale
Keyword(s):  
Concrete Strength ◽  
Element Model ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Experimental Program ◽  
Fe Model ◽  
Bond Behaviour ◽  
Near Surface ◽  
Cfrp Laminates ◽  
Near Surface Mounted

This paper presents an investigation of the bond mechanism between carbon fibre reinforced polymer (CFRP) laminates, concrete and steel in the near-surface mounted (NSM) CFRP-strengthened reinforced concrete (RC) beam-bond tests. The experimental program consisting of thirty modified concrete beams flexurally strengthened with NSM CFRP strips was published in. The effects of five parameters and their interactions on the ultimate load carrying capacities and the associated bond mechanisms of the beams are investigated in this paper with consideration of the following investigated parameters: beam span, beam depth, longitudinal tensile steel reinforcement ratio, the bond length of the CFRP strips and compressive concrete strength. The longitudinal steel reinforcement was cut at the beam mid-span in four beams to investigate a better assessment of the influence of the steel reinforcement ratio on the bond behaviour of CFRP to concrete bond behaviour. The numerical analysis implemented in this paper is based on a nonlinear micromechanical finite element model (FEM) that was used for investigation of the flexural behaviour of NSM CFRP-strengthened members. The 3D model based on advanced CFRP to concrete bond responses was introduced to modelling of tested specimens. The FEM procedure presents the orthotropic behaviour of the CFRP strips and the bond response between the CFRP and concrete. Comparison of the experimental and numerical results revealed an excellent agreement that confirms the suitability of the proposed FE model.

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

scholarly journals Drops bouncing off macro-textured superhydrophobic surfaces

2017 ◽  
Vol 824 ◽  
pp. 866-885 ◽  
Author(s):  
Ali Mazloomi Moqaddam ◽  
Shyam S. Chikatamarla ◽  
Iliya V. Karlin
Keyword(s):  
Contact Time ◽  
Numerical Study ◽  
Three Dimensional ◽  
Superhydrophobic Surfaces ◽  
Nonlinear Behaviour ◽  
Textured Surfaces ◽  
Texture Density ◽  
Wide Range ◽  
Quantitative Manner ◽  
The Impact

Recent experiments with droplets impacting macro-textured superhydrophobic surfaces revealed new regimes of bouncing with a remarkable reduction of the contact time. Here we present a comprehensive numerical study that reveals the physics behind these new bouncing regimes and quantifies the roles played by various external and internal forces. For the first time, accurate three-dimensional simulations involving realistic macro-textured surfaces are performed. After demonstrating that simulations reproduce experiments in a quantitative manner, the study is focused on analysing the flow situations beyond current experiments. We show that the experimentally observed reduction of contact time extends to higher Weber numbers, and analyse the role played by the texture density. Moreover, we report a nonlinear behaviour of the contact time with the increase of the Weber number for imperfectly coated textures, and study the impact on tilted surfaces in a wide range of Weber numbers. Finally, we present novel energy analysis techniques that elaborate and quantify the interplay between the kinetic and surface energy, and the role played by the dissipation for various Weber numbers.

scholarly journals Detection of Material Degradation of a Composite Cylinder Using Mode Shapes and Convolutional Neural Networks

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6686
Author(s):  
Bartosz Miller ◽  
Leonard Ziemiański
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Composite Structures ◽  
Vibration Mode ◽  
Numerical Study ◽  
Mode Shapes ◽  
Zone Size ◽  
Composite Cylinder ◽  
Material Degradation ◽  
Damaged Zone

This paper presents a numerical study of the feasibility of using vibration mode shapes to identify material degradation in composite structures. The considered structure is a multilayer composite cylinder, while the material degradation zone is, for simplicity, considered a square section of the lateral surface of the cylinder. The material degradation zone size and location along the cylinder axis are identified using a deep learning approach (convolutional neural networks, CNNs, are applied) on the basis of previously identified vibration mode shapes. The different numbers and combinations of identified mode shapes used to assess the damaged zone size and location were analyzed in detail. The final selection of mode shapes considered in the identification procedure yielded high accuracy in the identification of the degradation zone.

scholarly journals Numerical Study on Surface Roughness Measurement Based on Nonlinear Ultrasonics in Through-Transmission and Pulse-Echo Modes

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4855
Author(s):  
Maodan Yuan ◽  
Anbang Dai ◽  
Lin Liao ◽  
Yan Chen ◽  
Xuanrong Ji
Keyword(s):  
Surface Roughness ◽  
Numerical Study ◽  
Material Model ◽  
Nonlinearity Parameter ◽  
Fe Model ◽  
Roughness Measurement ◽  
Monitoring Method ◽  
Surface Roughness Measurement ◽  
Nonlinear Ultrasonics ◽  
Pulse Echo

Ultrasonic is one of the well-known methods for surface roughness measurement, but small roughness will only lead to a subtle variation of transmission or reflection. To explore sensitive techniques for surfaces with small roughness, nonlinear ultrasonic measurement in through-transmission and pulse-echo modes was proposed and studied based on an effective unit-cell finite element (FE) model. Higher harmonic generation in solids was realized by applying the Murnaghan hyperelastic material model. This FE model was verified by comparing the absolute value of the nonlinearity parameter with the analytical solution. Then, random surfaces with different roughness values ranging from 0 μm to 200 μm were repeatedly generated and studied in the two modes. The through-transmission mode is very suitable to measure the surfaces with roughness as small as 3% of the wavelength. The pulse-echo mode is sensitive and effective to measure the surface roughness ranging from 0.78% to 5.47% of the wavelength. This study offers a potential nondestructive testing and monitoring method for the interfaces or inner surfaces of the in-service structures.

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