Cellular Steel Research Articles

Neural Network-Based Formula for the Buckling Load Prediction of I-Section Cellular Steel Beams

Cellular beams are an attractive option for the steel construction industry due to their versatility in terms of strength, size, and weight. Further benefits are the integration of services thereby reducing ceiling-to-floor depth (thus, building’s height), which has a great economic impact. Moreover, the complex localised and global failures characterizing those members have led several scientists to focus their research on the development of more efficient design guidelines. This paper aims to propose an artificial neural network (ANN)-based formula to estimate the critical elastic buckling load of simply supported cellular beams under uniformly distributed vertical loads. The 3645-point dataset used in ANN design was obtained from an extensive parametric finite element analysis performed in ABAQUS. The independent variables adopted as ANN inputs are the following: beam’s length, opening diameter, web-post width, cross-section height, web thickness, flange width, flange thickness, and the distance between the last opening edge and the end support. The proposed model shows a strong potential as an effective design tool. The maximum and average relative errors among the 3645 data points were found to be 3.7% and 0.4%, respectively, whereas the average computing time per data point is smaller than a millisecond for any current personal computer.

Simplified analysis method for catenary action of restrained cellular steel beams at elevated temperature considering strain reversal

A Simplified Analysis Method (SAM) for predicting catenary action of restrained Cellular Steel Beams (CSB) at elevated temperature, as an alternative of finite element method, was proposed in this paper. A finite element model was developed and validated by existing test results and numerical results first. The temperature distribution along the section height was assumed to be linear based on available research results. Then the simplified analysis method was developed based on equilibrium equations, constitutive equations and geometric equations. The approach considered non-uniform temperature, geometric non-linearity, material non-linearity, as well as strain reversal when calculating section stresses. A series of parametric study using verified numerical model were then carried out to assess the accuracy of the proposed method. It was found that the simplified method yielded results which agreed well with those obtained from Finite Element Analysis (FEA). A lower compressive force and catenary tension were predicted when the web at perforated section was not considered. And the ignorance of strain reversal in the SAM would lead to a larger deflection prediction. The simple approach could also be used to predict the behavior of the beam subjected to non-uniform temperature distribution across the section in the latter stage of a fire, which may not always be obtained from FEA due to convergence problem.

Load Distribution Factors for Composite Multicell Box Girder Bridges

Cellular steel section composite with a concrete deck is one of the most suitable superstructures in resisting torsional and warping effects induced by highway loading. This type of structure has inherently created new design problems for engineers in estimating its load distribution when subjected to moving vehicles. Indian Codes of Practice does not provide any specific guidelines for the design of straight composite concrete deck–steel multi-cell bridges. To meet the practical requirements arising during the design process, a simple design method is needed for straight composite multi-cell bridges in the form of load distribution factors for moment and shear. This work presents load distribution characteristics of straight composite multi-cell box girder bridges under IRC trains of loads.

Three-dimensional printed cellular stainless steel as a high-activity catalytic electrode for oxygen evolution

Three-dimensional printed cellular stainless steel exhibits a high electrochemical surface area and electronic conductivity, which deliver excellent oxygen evolution reaction activity.

Optimized design of cellular steel beams

Optimized design of cellular steel beams

Structural system and buckling design of cellular steel silos

Large steel silos are widely used to store huge quantities of granular solids in industry and agriculture. In the present analysis, a novel type of silo structure, designated the cellular silo, is proposed and discussed. The performance advantage of the cellular silo is the clustered construction of individual hexagon silos, which can be formed by different numbers and arrangements of cell silos. The structural system is firstly determined for the cell silo by comparison between the plate model and 3D-stiffened plate models, and it is shown that the 3D-stiffened plate assembly composed of shell elements and beam elements is feasible for the cell silo, which is quite distinct from the shell structure fit for circular silos. The horizontal solid pressure, which is beneficial to circular silos, is unfavourable to the buckling of cell silos, and the buckling design is governed mainly by the horizontal pressure rather than the vertical frictional pressure. The buckling behaviour of group silos is investigated by considering load cases defined by the number of working cell silos and their relative position in the group. The common features of group silos during buckling are summarized, and it is referential for structural design of a cellular silo. An illustrative example of a cellular silo is presented at the end to demonstrate the design procedure, and it is concluded that the buckling design of the cellular silo is governed by the full loading condition and can be completed by optimization of the cell silos and their combinations.

An Experimental Behaviour of Cellular Lightweight Concrete-Filled Steel Square Tube Columns under Axial Compression

The axial load behavior of cellular lightweight concrete-filled tube (CLCFT) columns subjected to concentric axial compression is experimentally investigated. In the study, the maximum compressive loads obtained from the experiment were compared with the values calculated using Eurocode 4 design equation. The dimension of the square column specimens 150 mm in width and 750 mm in height. The effects of the ultimate compressive strengths and wall thicknesses of the steel tubes were observed. A total of 24 specimens, including 18 CLCFT columns and 6 reference cellular lightweight concrete (CLC) columns, were tested under monotonic axial compression. From the tests, it was found that the response curves of the CLCFT columns have a linear elastic behavior up to approximately 80-90% of their maximum compressive load. The nonlinear behavior of the columns has a ductile-like with strain-softening type. Tests also showed that the maximum compressive load and ductility of the CLCFT columns are increased significantly compared to the reference columns, depending mainly on the ultimate compressive strength of the concrete and the wall thickness of the steel tube. In addition, good agreement was observed between the predicted values using the Eurocode 4 design equations for the composite column and the experimental results.

Performance of unprotected and protected cellular beams in fire conditions

This paper describes an experimental study at elevated temperatures on the behaviour of full-scale composite floor unprotected and protected cellular steel beams with intumescent coating having different size and openings shape. All beams were designed for a full shear connections between the steel beam and the concrete flange using headed shear studs in order to fail in by web-post buckling. In fire, the temperature distribution across a composite member is non-uniform, since the web and bottom flange have thin cross-sections and a greater exposed perimeter than the top flange. The deterioration of the material properties of the web will therefore become an important effect on the overall performance of the member in the event of fire. Fire resistance and protection of cellular beams has been very controversial concerning their behaviour in elevated temperatures, the fire protection material and the required thickness. Two failure temperatures were observed in the fire tests indicated that cellular beams failed by web post buckling and Vierendeel bending associated with the buckling of the web posts of the steel section. The finite element modelling software TNO-Diana was used to complete the numerical investigation. Comparison of the experimental and FEM results is presented and both are in good agreement. However the Euro code approach can be improved by using the correct material specification of the intumescent coating used.

Design Optimization Shape Web Opening of Cellular Steel Beams

Design Optimization Shape Web Opening of Cellular Steel Beams

FIRE RESISTANCE PERFORMANCE OF CELLULAR STEEL BEAM (CSB) AT ELEVATED TEMPERATURES

Cellular steel beam (CSB) is getting more and more popular to be used as the main structural member for steel building structure in the United Kingdom (UK). Despite quite costly to erect and assemble a steel structure member compared to concrete, it has several advantages in terms of lightweight material, higher strength, easy to assemble and aesthetic value. Even though the use of CSB is quite significantly positive, the negative side also needs to be addressed. Any steel structures are prone to fire exposure scenario. The strength of CSB will be significantly decreased when exposed to elevated temperature due to fire. Large deformation from experimental procedure will be clearly seen after the time-temperature curve reach critical stage. Vierendeel bending mechanism and web-post buckling are some of the drawbacks of the CSB at elevated temperature. In this paper, general purpose ABAQUS Finite Element (Version 6.14) on large deformation of protected and unprotected CSB at elevated temperature is proposed. Performance based approach is introduced to validate the numerical analysis with the experimental results from the available Compendium of UK Standard Fire Test Data produced by British Steel Corporation Research Services, Swinden Laboratories, UK.

Web-post buckling of fully and partially protected cellular steel beams at elevated temperatures in a fire

Web-post buckling behaviors of fully and partially protected cellular steel beams at elevated temperatures in a fire were investigated through verified finite element models. The partially protected cellular steel beam represented a protected cellular steel beam with the hole edge left unprotected. The temperature distribution in the web-post was non-uniform, even for the unprotected CSB and the fully protected CSB. The fire resistance time of a CSB increased linearly with the increase in fire coating thickness. However, for the partially protected cellular steel beam, the temperature gradient in the web-post becomes greater with the increase in the fire protection thickness. And with the increase in the fire protection thickness, the increment in the fire resistance time decreased. Additional thermal stress occurred due to the non-uniform thermal strain in the web-post. When web-post buckled, the principle compression stress in the web-post decreased suddenly. The stress at the center of the web-post could change from compression to tension due to the membrane action caused by the large buckling deformation.

Development of Stainless Steel (SS316L) Foam with Different Composition Using Compaction Method

<span><span style="font-family: Times New Roman; font-size: medium;" face="Times New Roman" size="3"> </span> <p><span style="font-size: medium;" size="3"><span style="font-family: Times New Roman;" face="Times New Roman">Powder metallurgy stainless steels are retains unique benefits in preparation of porous metals due to its low cost, better wear, precise size control and corrosion resistance which are significant quality displays. In this study, the fabrication of open cellular stainless steel (SS316L) foams by using a crystalline sugar via compaction method was investigated. In this work, we show a promising method of SS316L preparation with crystalline sugar as space holder particles. Then, the foams will be given to consider the properties of SS316L foam after sintering process. Powder metallurgy process needs to go through the mixing, pressing, sintering and analysis. The selected composition of SS316L was 50 wt % and 55 wt % SS316L while the remaining percentages are foaming agent or binder. Then, sintering process was conducted in the tube furnace. The SS316L foams were characterised using X-Ray Diffraction (XRD) and Energy Diffraction X-ray (EDX). The results of this study indicate that, the XRD was detected Austenite stainless steel. Then, the detected elements in the SS316L foam were O, K, Mn, Cr, Fe, Mo and Al.</span></span></p> <span style="font-family: Times New Roman; font-size: medium;" face="Times New Roman" size="3"> </span>

Practical method for calculating the buckling temperature of the web-post in a cellular steel beam in fire

Buckling behaviors of web-posts in a cellular steel beam at elevated temperatures in a fire were studied using the Finite Element Method (FEM) analysis and available analytical models. The buckling temperatures obtained by the analytical models differed greatly to those obtained from the FEM simulation. Among these analytical models, the buckling temperature obtained through the strut model based on BS5950-1 agreed with the FEM result the best. It is more reasonable to take the width of the compression stress band in the web-post as the effective width of the strut. Numerical parametric studies showed that the width of the compression stress band varied with the opening diameter, the opening distance and the web thickness. A simplified method was proposed to calculate the effective width of the strut. The accuracy of the strut model integrating the new effective width was validated against the FEM simulations. The obtained buckling temperature of the web-post using the modified strut model agreed well with the FEM simulation result.

Analysis of Seismic Performance of the Joint of Cellular Steel Column and Steel Beam in Different Axial Compression Ratio

This article researches seismic performance of the joint of cellular steel column and steel beam through simulation of the finite element software. With the change of axial force, we can attain the load-displacement hysteretic curves, skeleton curves under the different axial compression ratio, and then analyze their bearing capacity, ductility, energy dissipation and other mechanical properties. Results show that, the decrease of axial compression ratio is helpful to improve the bearing capacity of specimens. The joints of cellular steel column and steel beam have full hysteretic curve, good ductility and seismic performance.

Influence on Seismic Performance of Joints of Cellular Steel Column and Steel Beam due to the Opening Rate

The article researches seismic performance of joints of cellular steel column and steel beam by finite element simulation. Finite element model is established by using the finite element software reasonably. Considering about the hole position and the distance of center of hole as invariant moments, under low cyclic loading we can attain hysteretic curves and skeleton curves etc. which are compared and analyzed in different opening rate by simulated software. The results show that for a certain axial compression ratio (n=0.45) of joints of cellular steel column and beam, the reasonable opening rate can improve the seismic behavior of the joints.

Moment gradient factor of cellular steel beams under inelastic flexure

The flexural capacity of cellular steel beams is influenced by both local and global instabilities. In the current paper, the finite element method is employed to investigate the inelastic behavior of cellular steel beams under combined buckling modes. A three-dimensional non-linear finite element model, that takes into consideration possible interaction between lateral torsional/distortional buckling modes and localized deformations of the cross section is developed and validated against available results in the literature. The study considers simply supported beams subjected to three different load configurations; mid-span load, uniformly distributed load and end moments. An extensive parametric analysis is conducted to assess the impact of various geometrical parameters on the inelastic stability of cellular steel beams. These parameters include the dimensions of the beam cross-section; flange width and thickness, web height and thickness, and hole size and spacing. The moment gradient factors that correspond to various buckling modes experienced by the wide range of dimensions considered in the simulation study are reported. The outcomes of the this study are expected to provide more insight into the behavior of cellular steel beams and enable accurate prediction of the moment gradient factor and consequently the flexural capacity of this special type of steel beams.

Performance of Fiber Reinforced High-strength Concrete with Steel Sandwich Composite System as Blast Mitigation Panel

The study investigated the response of steel-concrete composite panels subjected to air-blast loading. The composite panels consist of fiber-reinforced high-strength concrete on the incident face, together with a specially configured steel sandwich as the distal layer, which functions to dissipate the imparted blast energy. The performance of the novel composite panel is compared to a conventional steel concrete steel (SCS) panel and an ordinary reinforced concrete panel. The dynamic response of the composite panel is obtained numerically using finite element analysis adopting a simplified modeling approach. Parametric studies are carried out by varying the charge weight, the concrete type, and a number of steel sandwich core structures. Furthermore, the energy absorption capacity is found by calculating the area under the resistance-deflection curve of the proposed composite panel. The relationship between the steel sandwich core structure and the energy absorption capacity, as well as the core design and total panel deflection subjected to various blast charges, are then derived. The combination of fiber reinforced high-strength concrete and cellular steel sandwich demonstrated good potential for use as blast mitigation panel due to the high weight-to-performance ratio and the high energy absorption properties of the composite system.

The Influence of Tensile Membrane Action on Fire-exposed Composite Concrete Floor-steel Beams with Web-openings

On the basis of a series of the full-scale fire tests carried out on the composite frame at Cardington, a design method is now well established to calculate the performance of composite flooring systems subject to fire. The method models in a simplified fashion the influence of tensile membrane action in composite floor slabs which are formed as an array of composite beams using solid-web steel downstand beams which are largely unprotected. The development of membrane action depends on the conditions of vertical support maintained around the boundaries of the fire-affected slab panels by protected beams. Cellular beams can achieve the same strength as unperforated I-beams of the same depth, with significantly reduced steel mass, and the ability to accommodate service ducts within the beam depth, and therefore the use of composite cellular beams as floor members is becoming increasingly popular in construction. Due to the general lack of research on perforated sections, the guidance about their design for fire conditions remains rather primitive. Moreover, tensile membrane action in composite floor slabs with cellular steel downstand beams could exhibit very different behaviour in fire from that when solid-web sections are used. A parametric study has been carried out as an initial investigation into the fire performance of cellular beams within composite slab systems, including the effects of tensile membrane action in enhancing the load-carrying capacity. The effects of changes to the edge support conditions are also investigated. The results show the protected perimeter beams maintained their load-carrying capacity and were subject only to small vertical displacements, although web-post buckling was observed to occur on the protected secondary beam near to a support. This suggests that maintenance of vertical support is not sufficient for a slab panel with cellular beams. Web-post buckling or the Vierendeel mechanism may govern the mode of structural failure, indicating that the sizes of openings and their positioning necessitate careful design.

Nonlinear analysis of cellular steel beams under combined buckling modes

This paper discusses the nonlinear analysis of normal and high strength cellular steel beams under combined buckling modes. A nonlinear 3-D finite element model has been developed, which accounted for the initial geometric imperfection, residual stresses and material nonlinearities of flange and web portions of cellular steel beams. The nonlinear finite element model was verified against tests on cellular steel beams having different lengths, different cross-sections, different loading conditions and different failure modes. Failure loads, load–mid-span deflection relationships and failure modes of cellular steel beams were predicted from the finite element analysis. An extensive parametric study involving one hundred and twenty cellular steel beams was performed using the verified finite element model to study the effects of the change in cross-section geometries, beam length and steel strength on the strength and buckling behaviour of cellular steel beams. The results of the parametric study has shown that cellular steel beams failing due to combined web distortional and web-post buckling modes exhibited a considerable decrease in the failure loads. It is also shown that the use of high strength steel offers a considerable increase in the failure loads of less slender cellular steel beams. The failure loads predicted from the finite element model were compared with that predicted from Australian Standards for steel beams under lateral torsional buckling. It is shown that the Specification predictions are generally conservative for normal strength cellular steel beams failing by lateral torsional buckling, unconservative for cellular steel beams failing by combined web distortional and web-post buckling and quite conservative for high strength cellular steel beams failing by lateral torsional buckling.

Experimental and Numerical Modelling of Cellular Beams with Circular and Elongated Web Openings at Elevated Temperatures

This paper describes an experimental and numerical study at elevated temperatures on the behaviour of full scale composite floor cellular steel beams with circular and elongated web openings. A total of three specimens, comprising three different steel geometries and loading conditions were tested at elevated temperatures. Finite element models were established with both material and geometrical non-linearity to compare with the experimental results. This paper also demonstrates the capability of a developed simple design approach in comparison with numerical modelling, experimental tests and existing design software used by the Steel Construction Institute (SCI).