Composite beams under fire loading: numerical modeling of behavior

2016 ◽  
Vol 7 (2) ◽  
pp. 142-157 ◽  
Author(s):  
Kristi L. Selden ◽  
Amit H. Varma
Keyword(s):  
Composite Beam ◽  
Failure Modes ◽  
Concrete Slab ◽  
Material Model ◽  
Composite Beams ◽  
Bottom Flange ◽  
Stress Strain ◽  
Content Type ◽  
Beam Deflections ◽  
Fire Loading

Purpose The purpose of this study was to develop a three-dimensional (3D) finite element modeling (FEM) technique using the commercially available program ABAQUS to predict the thermal and structural behavior of composite beams under fire loading. Design/methodology/approach The model was benchmarked using experimental test data, and it accounts for temperature-dependent material properties, force-slip-temperature relationship for the shear studs and concrete cracking. Findings It was determined that composite beams can be modeled with this sequentially coupled thermal-structural 3D FEM to predict the displacement versus bottom flange temperature response and associated composite beam failure modes, including compression failure in the concrete slab, runaway deflection because of yielding of the steel beam or fracture of the shear studs. Originality/value The Eurocode stress-strain-temperature (σ-ε-T) material model for structural steel and concrete conservatively predict the composite beam deflections at temperatures above 500°C. Models that use the National Institute of Standards and Technology (NIST) stress-strain-temperature (σ-ε-T) material model more closely match the measured deflection response, as compared to the results using the Eurocode model. However, in some cases, the NIST model underestimates the composite beam deflections at temperatures above 500°C.

Shear tab connection with composite beam subjected to transient-state fire temperatures

2019 ◽  
Vol 10 (4) ◽  
pp. 411-434 ◽  
Author(s):  
Mohammad Hajjar ◽  
Elie Hantouche ◽  
Ahmad El Ghor
Keyword(s):  
Composite Beam ◽  
Transient State ◽  
Composite Beams ◽  
Slab Thickness ◽  
Bottom Flange ◽  
Rational Model ◽  
Content Type ◽  
Geometrical Properties ◽  
Axial Forces ◽  
Shear Tab

Purpose This study aims to develop a rational model to predict the thermal axial forces developed in shear tab connections with composite beams when subjected to transient-state fire temperatures. Design/methodology/approach Finite element (FE) models are first developed in ABAQUS and validated against experimental data available in the literature. Second, a parametric study is conducted to identify the major parameters that affect the behavior of shear tab connections with composite beams in the fire. This includes beam length, shear tab thickness, shear tab location, concrete slab thickness, setback distance and partial composite action. A design-oriented model is developed to predict the thermal induced axial forces during the heating and cooling phases of a fire event. The model consists of multi-linear springs that can predict the stiffness and strength of each component of the connection with the composite beam. Findings The FE results show that significant thermal axial forces are generated in the composite beam in the fire. This is prominent when the beam bottom flange comes in contact with the column. Fracture at the toe of the welds governs the behavior during the cooling phase in most FE simulations. Also, the rational model is validated against the FE results and is capable of predicting the thermal axial forces developed in shear tab connections with composite beams under different geometrical properties. Originality/value The proposed model can predict the thermal axial force demand and can be used in performance-based approaches in future structural fire engineering applications.

scholarly journals Longitudinal shear capacity of the slabs of composite beams

1976 ◽  
Vol 3 (4) ◽  
pp. 514-522 ◽  
Author(s):  
M. N. El-Ghazzi ◽  
H. Robinson ◽  
I. A. S. Elkholy
Keyword(s):  
Composite Beam ◽  
Shear Failure ◽  
Concrete Slab ◽  
Compressive Force ◽  
Longitudinal Shear ◽  
Composite Beams ◽  
Shear Capacity ◽  
Slab Width ◽  
Two Parameters ◽  
Concrete Elements

The longitudinal shear failure of the slab of composite beams is constrained to occur at a predetermined shear surface. A method for calculating the longitudinal shear capacity of the slab of simply-supported steel–concrete composite beams is presented. The method is based on analyzing the stresses at failure of the concrete elements located at the slab shear surface.A design chart based on estimating the transverse normal stress required within the concrete slab to achieve the full ultimate flexural capacity of the composite beam is proposed. Alternatively, using elastic–plastic stress distribution across the concrete slab, the longitudinal compressive force due to bending and hence the applied moment can be predicted for any longitudinal shear capacity of the slab. The proposed design and analysis when compared to previous tests and analysis showed good agreement.The slab width and the shear span of the composite beam are found to be two important parameters which cannot be neglected when estimating the longitudinal shear capacity of the slab. These two parameters have been neglected in the empirical solutions previously adopted.

scholarly journals Experimental Study on Mechanical Performance of U-Shaped Steel-Encased Concrete Composite Beam-Girder Joints

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhangqi Hu ◽  
Ran He ◽  
Yukui Wang ◽  
Weirong Lv ◽  
Jingchao Li
Keyword(s):  
Composite Beam ◽  
Mechanical Performance ◽  
Concrete Slab ◽  
Bottom Flange ◽  
The Novel ◽  
Test Results ◽  
Construction Period ◽  
Failure Patterns ◽  
Loading Tests ◽  
Two Sides

This paper proposes a novel U-shaped steel-encased concrete composite beam-girder joint (referred to herein as the novel composite beam-girder joint), in which the U-shaped beams at two sides (L and R) are inserted into a shaped sleeve, and the U-shaped girder and two U-shaped beams are connected by the shaped sleeve through welding. Compared with the traditional beam-girder joints, the novel composite beam-girder joints take advantage of easy construction, light weight, and short construction period. The failure patterns, load-strain and load-deflection curves, and strain distributions of the novel composite beam-girder joints were investigated through the static loading tests on two full-scale specimens, denoted as GBJ1 and GBJ2. The two specimens were varied in beam section reinforcements. Specimen GBJ2 was equipped with 3Ф16 additional bars in the U-shaped beams based on Specimen GBJ1. Test results show that the two specimens failed as the through arc cracks developed at the concrete slab interfaces. The additional bars can increase the bearing capacity slightly but will also increase the stress concentration on the bottom flange of the shaped sleeve, leading to the decrease of ductility for Specimen GBJ2. The slab effect is considered in the test and can thus reflect the actual stress state of the beam-girder joints well. This study can provide a reference for the design and application of beam-girder joints.

scholarly journals Study on Behaviour of Stud Type Shear Connector in Composite Beam Using ANSYS

2018 ◽  
Vol 7 (3.10) ◽  
pp. 54
Author(s):  
T Subramani ◽  
A Periasamy
Keyword(s):  
Composite Beam ◽  
Composite Structures ◽  
Numerical Models ◽  
Concrete Slab ◽  
Composite Beams ◽  
Vital Role ◽  
Shear Connector ◽  
Structural Behaviour ◽  
Shear Connectors ◽  
High Rise

Composite plays a vital role in replacing the existing mild steel in reinforcement and exterior truss structure. This study proposed to design shear connector for joining concrete slab and steel section. Shear connectors has analyzed and predict the best connector for a particular composite beam with respect to static load and the amount of steel in the connector as a common aspect. The use of composite structures is increasingly present in civil construction works nowadays. Composite beams, especially, are structures which include substances, a metal phase placed in particular inside the tension region and a concrete phase, positioned in the compression go sectional location, both are related with the aid of steel gadgets called shear connectors. The main features of this connector are to permit the weight for the joint the beam-column, to restriction longitudinal slipping and uplifting on the factors interface the shear forces. Our project paper presents 3D numerical models of steel-concrete composite beams to simulate their structural behaviour, with emphasis on the beam column interface using Simulations software ANSYS 18.1 based on the Finite Element Method. Mostly these type of structures are widely used in the dynamic loading structures like bridges and high rise buildings.  

scholarly journals Experimental study of Steel-Concrete Composite Beams comprised of Fly ash based Geopolymer concrete

2018 ◽  
Author(s):  
Balbir Singh ◽  
Ee Loon Tan ◽  
Zhu Pan ◽  
Olivia Mirza ◽  
Julius Boncato
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Composite Beam ◽  
Concrete Slab ◽  
Composite Beams ◽  
Full Potential ◽  
Geopolymer Concrete ◽  
Moment Capacity ◽  
Green Concrete ◽  
Structural Applications

To combat the present situation of greenhouse gases emission from cement production, a promising solution is to utilise supplementary cementitious by-product materials such as fly ash to produce green concrete known as Geopolymer concrete (GPC). However, despite fly ash based concrete is a promising substitute for ordinary Portland cement (OPC) concrete, it is not yet being utilised to its full potential for structural applications.  And so, to utilise green concrete to its full potential, this paper aim is to conduct an experimental study that will integrate fly ash based concrete within steel-concrete composite beams. The research will include casting of composite beams with GPC mix, and an OPC concrete as a reference mix designed according to British Standards. To determine the ultimate moment capacity, a total of Four (4) composite beams comprised of coventional and Bondek steel profile concrete slab are designed and tested according to Australian Standards. From the test results, it was found that composite beam with conventionalconcrete slab outperformed the beams with Bondek profile sheeting. Also, regarding of ultimate bending moment capacity, the composite beam with geopolymer concrete experienced almost identical to OPC composite beam.

scholarly journals Flexural Design and Analysis of Composite Beams with Inverted-T Steel Girder with Ultrahigh Performance Concrete Slab

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Wonchang Choi ◽  
Youngcheol Choi ◽  
Sung-Won Yoo
Keyword(s):  
Composite Beam ◽  
Steel Fiber ◽  
Concrete Slab ◽  
Composite Beams ◽  
Flexural Behavior ◽  
Slab Thickness ◽  
Horizontal Shear ◽  
Steel Girder ◽  
Beam Combining ◽  
Ductile Behavior

This study intends to improve the efficiency of the composite beam combining a slab made of steel fiber-reinforced ultrahigh performance concrete (UHPC) and a steel girder without top flange. To that goal, the experiment is conducted on 24 composite beams fabricated with varying compressive strength of UHPC, steel fiber content, stud spacing, and slab thickness to evaluate the behavior of the studs and the flexural behavior of the composite beam combining the UHPC slab and the inverted-T steel girder. The experimental results show the test members developed sufficient ductile behavior with respect to the slip limit of 6 mm stipulated in Eurocode-4 and regardless of the considered test variables. The experimental ultimate horizontal shear force is seen to be clearly larger than the static strengths of the stud predicted by Eurocode-4 and AASHTO-LRFD. Improved design formulae for the composite beam shall be derived to reflect the UHPC slab thickness.

Spectral finite element method for wave propagation analysis in smart composite beams containing delamination

2020 ◽  
Vol 92 (3) ◽  
pp. 440-451
Author(s):  
Namita Nanda
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Composite Beam ◽  
Spectral Element ◽  
Equation Of Motion ◽  
Composite Beams ◽  
Piezoelectric Composite ◽  
Content Type ◽  
Propagation Analysis ◽  
Spectral Finite Element

Purpose The purpose of the study is to present a frequency domain spectral finite element model (SFEM) based on fast Fourier transform (FFT) for wave propagation analysis of smart laminated composite beams with embedded delamination. For generating and sensing high-frequency elastic waves in composite beams, piezoelectric materials such as lead zirconate titanate (PZT) are used because they can act as both actuators and sensors. The present model is used to investigate the effects of parametric variation of delamination configuration on the propagation of fundamental anti-symmetric wave mode in piezoelectric composite beams. Design/methodology/approach The spectral element is derived from the exact solution of the governing equation of motion in frequency domain, obtained through fast Fourier transformation of the time domain equation. The beam is divided into two sublaminates (delamination region) and two base laminates (integral regions). The delamination region is modeled by assuming constant and continuous cross-sectional rotation at the interfaces between the base laminate and sublaminates. The governing differential equation of motion for delaminated composite beam with piezoelectric lamina is obtained using Hamilton’s principle by introducing an electrical potential function. Findings A detailed study of the wave response at the sensor shows that the A0 mode can be used for delamination detection in a wide region and is more suitable for detecting small delamination. It is observed that the amplitude and time of arrival of the reflected A0 wave from a delamination are strongly dependent on the size, position of the delamination and the stacking sequence. The degraded material properties because of the loss of stiffness and density in damaged area differently alter the S0 and A0 wave response and the group speed. The present method provides a potential technique for researchers to accurately model delaminations in piezoelectric composite beam structures. The delamination position can be identified if the time of flight of a reflected wave from delamination and the wave propagation speed of A0 (or S0) mode is known. Originality/value Spectral finite element modeling of delaminated composite beams with piezoelectric layers has not been reported in the literature yet. The spectral element developed is validated by comparing the present results with those available in the literature. The spectral element developed is then used to investigate the wave propagation characteristics and interaction with delamination in the piezoelectric composite beam.

scholarly journals Numerical analysis of the effect of partial interaction in the evaluation of the effective width of composite beams

2018 ◽  
Vol 11 (4) ◽  
pp. 757-778
Author(s):  
A. R. SILVA ◽  
L. E. S. DIAS
Keyword(s):  
Composite Beam ◽  
Concrete Slab ◽  
Composite Beams ◽  
Interface Element ◽  
Steel Beam ◽  
Real Problem ◽  
Effective Width ◽  
Plate Element ◽  
Technical Standards ◽  
Partial Interaction

Abstract Most of the engineering problems involving structural elements of steel-concrete composite beam type are approximations of the structural problem involving concrete plates connected by connectors to steel beams. Technical standards allow the replacement of the concrete plate element by a beam element by adopting a reduction in the width of the plate element known as effective width. The effective width is obtained, in most technical norms, taking into account only the parameters of beam span length and distance between adjacent beams. Numerical and experimental works found in the literature show that this effective width depends on several other parameters, such as the width and thickness of the concrete slab, and the type of loading. The objective of this work is to verify the influence of the partial interaction in the evaluation of the effective width of composite beams formed by a concrete slab connected to a steel beam with deformable connection, being used in numerical simulation three types of finite elements: a plate element for nonlinear analysis of the concrete slab; a bar element for non-linear analysis of beams with cross-section defined by a polygon; and an interface element which connects the plate and beam elements, simulating the deformation effect of the shear connectors. In the studied examples, it was found that the reduction of the shear connection stiffness at the interface between the concrete slab and the steel beam leads to a decrease in the shear lag effect and, consequently, makes the effective width of the concrete slab closer to the its real width. In another example, curves are constructed to define the effective width of a composite beam with medium stiffness. Considering maximum stresses and maximum displacements, these curves are obtained by forcing the equivalence of the approximate model with the model closest to the real problem.

scholarly journals Effect of Shear Connector Layout on the Behavior of Steel-Concrete Composite Beams with Interface Slip

2019 ◽  
Vol 9 (1) ◽  
pp. 207 ◽  
Author(s):  
Xinggui Zeng ◽  
Shao-Fei Jiang ◽  
Donghua Zhou
Keyword(s):  
Composite Beam ◽  
Concrete Slab ◽  
Composite Beams ◽  
Triangular Distribution ◽  
Shear Connector ◽  
Optimal Method ◽  
Shear Connectors ◽  
Appreciable Increase ◽  
Partial Interaction ◽  
Distribution Type

In a steel-concrete composite beam (hereafter referred to as a composite beam), partial interaction between the concrete slab and the steel beam results in an appreciable increase in the beam deflections relative to full interaction behavior. Moreover, the distribution type of the shear connectors has a great impact on the degree of the composite action between the two components of the beam. To reveal the effect of shear connector layout in the performance of composite beams, on the basis of a developed one-dimensional composite beam element validated by the closed-form precision solutions and experimental results, this paper optimizes the layout of shear connectors in composite beams with partial interaction by adopting a stepwise uniform distribution of shear connectors to approximate the triangular distribution of the shear connector density without increasing the total number of shear connectors. Based on a comparison of all the different types of stepped rectangles distribution, this paper finally suggests the 3-stepped rectangles distribution of shear connectors as a reasonable and applicable optimal method.

Lumped system model for elastic steel-concrete beams with partial interaction

2019 ◽  
Vol 16 (1) ◽  
pp. 121-133
Author(s):  
Ahmed M. Ellakany ◽  
Mohamad Ali ◽  
Mohamed A. El-Gohary ◽  
Mohamed Elkholy
Keyword(s):  
Numerical Model ◽  
Shear Layer ◽  
Transfer Matrix ◽  
Composite Beam ◽  
Composite Beams ◽  
Elastic Support ◽  
Dynamic Responses ◽  
Content Type ◽  
Elastic Composite ◽  
Lower Beam

Purpose The purpose of this paper is to introduce a numerical model to investigate static response of elastic steel-concrete beams. The numerical model is based on the lumped system with the combination of the transfer matrix and the analog beam methods (ABM). The beams are composed of an upper concrete slab and a lower steel beam, connected at the interface by shear transmitting studs. This type of beam is widely used in constructions especially for highway bridges. The static field and point transfer matrices for the element of the elastic composite beam are derived. The present model is verified and is applied to study the static response of elastic composite beams with intermediate conditions. The intermediate condition is considered as an elastic support with various values of stiffness. The elastic support can be considered rigid when the stiffness has very high values. The influence effect of shear stiffness between the upper slab and lower beam, and the end shear restraint on the static behavior of the composite beams is studied. In addition, the change in the stiffness of the elastic support is also highlighted. Design/methodology/approach The objective of this study is to introduce a numerical model based on lumped system to calculate the static performance of elastic composite bridge beams having intermediate elastic support by combining the ABM with the transfer matrix method (TMM). The developed model is applicable for studying static and dynamic responses of steel-concrete elastic composite beams with different end conditions taking into account the effect of partial shear interactions. The validity of the lumped mass model is checked by comparing its results with a distributed model and good agreements are achieved (Ellakany and Tablia, 2010). Findings A model based on the lumped system of the elastic composite steel-concrete bridge beam with intermediate elastic support under static load is presented. The model takes into consideration the effect of the end shear restraint together with the interaction between the upper slab and the lower beam. Combining the analogical beam method with the TMM and analyzing the behavior of the elastic composite beam in terms of shear studs and stiffness, the following outcomes can be drawn: end shear restraint and stiffness of the shear layer are the two main factors affecting the response of elastic composite beams in terms of both the deflection and the moments. Using end shear restraint reduces the deflection extensively by about 40 percent compared to if it is not used assuming that: there is no interaction between the upper slab and the lower beam and the beam is acting as simply supported. As long as the shear layer stiffness increases or interaction exists, the deflection decreases. This reduced rate in deflection is smaller in case of existence of end shear restraint. The effect of the end shear restraint is more prevailing on reducing the deflections in case of partial interactions. However, its effect completely diminishes in case of complete interaction. Presence of the end shear restraint and shear layer stiffness produces almost the same variations in the components of the bending moments of the composite beam. Finally, for a complete interaction, comparing the case of using end shear restraint or the case without it, the differences in the values of the deflections and moments are almost negligible. Research limitations/implications The following assumptions related to the theory of ABM: shear studs connecting both sub-beams are modeled as a thin shear layer, each sub-beam has the same vertical displacement and the shear deformation in the sub-beams is neglected. Practical implications The developed model can be effectively used for a quick estimation of the dynamic responses of elastic composite beams in real life rather than utilizing complicated numerical models. Social implications The applications of this model can be further extended for studying the behavior of complex bridge beams that will guarantee the safety of the public in a quick view. Originality/value Previous models combined the TMM with the ABM for studying the static and free-vibration behaviors of elastic composite beams assuming that the field element is subjected to a distributed load. To study the dynamic response of elastic composite beams subjected to different moving loads using transfer matrix ABM, it was essential to use a massless field element and concentrate the own weight of the beam at the point element. This model is considered a first step for studying the impact factors of elastic composite beams subjected to moving loads.

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