Hollow Flange Research Articles

Design rules and bending behaviour of assembling rivet-fastened rectangular hollow flange beams

Design rules and bending behaviour of assembling rivet-fastened rectangular hollow flange beams

Experimental Investigation and Design of Novel Hollow Flange Beams under Bending

In this paper, a new type of assembling rivet-fastened rectangular hollow flange beams (ARHFBs) is proposed. The cross-section of the ARHFB consists of two U-shaped and C-shaped components connected by self-locking rivets to form two rectangular hollow flanges. To study the performance and strength of the ARHFB as a flexural member, eight four-point bending tests and more than 40 simulation studies were carried out. The details, results, and comparison of the four-point bending tests, especially the characteristics of the test bench and the lateral support, are presented in this paper. ARHFB sections with varied rivet spacing, web depth, and flange width were experimentally studied. Additionally, a parametric study of ARHFB was conducted using finite element models verified by test results. The influence of span on the loading capacity of ARHFB was discussed. ARHFB can be used in large-span buildings. A more economical ARHFB component selection method was given. The depth of the flange, the strength of the web, and the thickness of the web are important parameters of ARHFB. The loading capacity obtained from the test was compared with the predicted values of the design formulas in the American Iron and Steel Institute (AISI) and the Chinese design standard for cold-rolled steel (GB50018). The calculation and verification of ARHFB flange buckling and lateral torsional buckling were also considered. It is recommended that GB50018 be used to predict the flexural capacity of ARHFBs.

Flexural Behavior of Rectangular Double Hollow Flange Cold-Formed Steel I-beam

This research experimentally investigates the flexural behavior of rectangular hollow flange cold-formed steel I-beam (RHFCFSIB) under two concentrated loads at the same distance from the support. All specimens were at a constant clear span of (L=1500mm), a constant beam specifications (t=4mm) web, flange thickness (h=300mm) for beam′s depth, and flange width of (bf=150mm). The connecting distance between the bolts, i.e., connects the web to the flanges, was (L/6), and eight stiffeners for each beam were placed under the load bearing points and at the support points on each side. The experimental program included assembling the parts to make beams and testing four specimens under two-point loads. The major parameters adopted in the current research included the flange depth, i.e., hf=30,60,90, and 120mm. The results showed that the beam with a flange depth of 30 mm had a higher ultimate load than other beams; however, it was the highest beam deflection. The beam with a flange depth of 120mm was the best section as a flexural member. The ultimate capacity of this beam increased by 15.34% and 6.4% compared to beams with flange depths of 60mm and 90mm and decreased by 12.9% compared to a beam with a flange depth of 30 mm. The maximum deflection at beam mid-span with a flange depth of 120 mm decreased by 53.8%, 44%, and 19.94% compared to beams with flange depths of 30 mm, 60mm, and 90mm, respectively. Therefore, the flange depth significantly influenced the flexural behavior by increasing the flange depth. Also, the ultimate capacity increased, and the deflection was reduced. The main conclusions drawn from the study were discussed and summarized. The research showed that the Hollow flanged sections gave the best results for flexural behavior.

Finite element modeling of assembling rivet-fastened rectangular hollow flange beams in bending

The assembling rivet-fastened rectangular hollow flange beam (ARHFB) is a new type of cold-formed steel beam. The ARHFB section has two rectangular hollow flanges formed by U-shaped and C-shaped components that connected by self-locking rivets. A finite element model is developed to simulate 16 four-point bending experiments. Details of the modeling including finite element meshing, loading and boundary conditions, contact and analysis methods are presented. The accuracy of the developed finite element model is verified by comparing the ultimate moment capacity, applied load versus deflection curves, bending moment versus deflection curves, strain versus deflection curves and failure modes obtained from the tests and the finite element analysis. Based on the validated finite element model, a parametric analysis is carried out to discuss the effects of rivet spacing, section depth, flange thickness, and web thickness on the bending performance of ARHFB. The moment capacities of these sections obtained from the parametric study are compared with predictions from Australia and New Zealand, Chinese design standards for cold-rolled sections and the DSM (Direct Strength Method). It is found that GB50018 can conservatively predict the bearing capacity of ARHFB with a large error, while AS / NZS 4600 and DSM (Direct Strength Method) cannot provide reliable prediction results.

The behavior of steel beams with triangular welded hollow flange

The behavior of steel beams with triangular welded hollow flange

Parametric Study on Cold-Formed Stainless Steel Triangular Hollow Flange Section and I Section under Shear

Parametric Study on Cold-Formed Stainless Steel Triangular Hollow Flange Section and I Section under Shear

Assessment of Eurocode shear design provisions for cold-formed steel sections

Cold-formed steel (CFS) sections are widely used in structural systems and are particularly prone to shear failure in short span applications. Therefore, accurate shear strength estimation is essential for the design. However, while there exists an abundance of research studies investigating the shear behaviour of CFS sections, there is a clear need for the assessment of Eurocode 3 shear design provisions. Towards meeting this need, the design of CFS sections subjected to shear is studied herein. Existing experimental data on CFS lipped channels and hollow flange sections were assembled from the literature. The collected experimental data was then used to assess the accuracy of the current Eurocode 3 shear design provisions. The current Eurocode 3 design provisions are shown to provide overly conservative shear strength predictions against the experimental data. Modifications, including the slenderness of the cross-section to reflect the shear buckling coefficient were proposed. The proposed modifications to the current design provisions offer substantially improved accuracy in shear strength predictions.

Finite Element Investigation of the Ultimate Capacity of Hollow-Flange Steel Girders with Web Openings

The goal of structural design is to select member sizes that are proportional to thestructural geometry in order to achieve the most cost-effective design. Steel girders weretypically made of webs, flanges and a number of internal stuffeners, the main objectiveof this research is to develop a finite element model to study the effect of the shapes andlocations of openings on the behavior of hollow flange steel plate girders. In this study,seven models were analyzed in two groups. The first group study the effect of webopenings shape openings on the behavior of hollow flange steel plate girders, while thesecond group study the effect of web openings location on the behavior of hollow flangesteel plate girders. The girders are analyzed until the final failure has occurred. Theresults obtained from finite element analysis showed that that the absence of openinghad an important effect on the ultimate load capacity. The ultimate capacity of hollowflange steel plate girder with four squares opening decreased about 5% compared tohollow flanges steel plate girder without openings.

Shear performance of lightweight concrete filled hollow flange cold-formed steel beams

Concrete-infilled hollow flange cold-formed steel (CF-HFCFS) beams have gained attention in the construction practices owing to many benefits in terms of their structural performances and applicability. The concrete infill ensures better structural performance by restraining the buckling instabilities of thin-walled cold-formed steel elements. However, the shear strength characteristics of CF-HFCFS are not systematically explored yet and hence there is a lack of understanding on the shear strength characteristics of CF-HFCFS beams. Therefore, in this research, shear characteristics were investigated through numerical studies by establishing and analysing three-dimensional finite element (FE) models of CF-HFCFS beams. The developed FE models were verified against the experimental data in terms of failure modes, ultimate shear capacities, and load-displacement characteristics. Then a series of parametric analyses were carried out to investigate the shear behaviour of CF-HFCFS beams against the effects of geometrical (steel thickness, beam depth) and mechanical (yield strength of steel and compressive strength of concrete) properties to further verify the shear characteristics of CF-HFCFS. Lightweight normal and lightweight high strength concrete materials were considered as infill. Also, the influence of the concrete infill on the ultimate shear capacity of the CF-HFCFS beams was evaluated through parametric studies. The ultimate shear capacities were compared against the already available design provisions. Consequently, based on the data established through of parametric analyses, modified design provisions are developed to estimate the ultimate shear capacity of CF-HFCFS beams.

Effect of web stiffeners on the lateral distortional buckling of channel section with hollow flanges

Hollow Flange Channels (HFC) have been known for their higher capacity when compared to open flange C-sections. On the other hand, the small stiffness of HFC slender web compared to their flanges limits the bending capacity to the lateral distortional buckling (LDB) strength. Welding web stiffeners can limit the web distortion and enhance the bending capacity. This paper investigates how to alleviate LDB capacity of HFCs using transverse web stiffeners. Stiffener’s spacing, depth and thickness are the parameters, modeled with different beam lengths. It is found that using the right spacing and depth of stiffeners can greatly increase the HFC capacity. Adding full depth stiffener to 4000 mm span increases the capacity by 32%. However, this percentage decreases for longer spans with partial depth stiffeners. Increasing the stiffener thickness have been found insignificant in enhancing the performance. A new formula is proposed to predict the bending capacity of stiffened HFC.

Flexural behaviour and design of hollow flange cold-formed steel beam filled with lightweight normal and lightweight high strength concrete

A comprehensive investigation of the flexural behaviour of concrete-infilled hollow flange cold formed steel (CF-HFCFS) beams with lightweight normal and lightweight high strength concrete is presented in this paper. These are new generation of complex members, and their enhanced structural capacity is governed by inter-related parameters including composite action. However, the knowledge surrounding the flexural performance of lightweight concrete infilled hollow flange cold formed steel (HFCFS) beam is limited. This work aims to study the influence of key parameters on flexural behaviour of CF-HFCFS through numerical analysis and is followed by developing a simplified design approach. A non-linear finite element (FE) model of HFCFS beams with and without lightweight concrete infill was developed. The developed FE model was validated against the experimental results available in the literature. The validated model was subsequently used to conduct a parametric study. The parametric study also included the HFCFS beams without concrete infill for comparison purposes. It was found that the concrete infill contributes to up to 55% of flexural capacity enhancement compared to the bare HFCFS beams. The suitability of the existing design approach available in the literature for the concrete infilled structural steel tubes under flexure was assessed and modifications are proposed. In addition, using the numerically derived data, a novel simplified design approach was developed based on the capacity improvement factor method to estimate the moment capacity. The developed equations have shown to be accurate in estimating the moment capacity of concrete infilled hollow flange beams.

Shear behaviour of screw fastened rectangular hollow flange beams with web openings

Cold-formed screw-fastened Rectangular Hollow Flange Channel Beam (RHFCB) is considered as an alternative steel section to welded LiteSteel beam. The simple fabrication procedure of attaching two Rectangular Hollow Section (RHS) as flanges to a web plate with intermittently spaced screws allows for a selection of a wide range of dimensional parameters for optimum design. Generally, web openings are made on such Cold-Formed Steel (CFS) sections to allow for building services. These web openings influence the shear behaviour and cause a reduction in their structural performances. On the other hand, hardly any investigations have been done on the shear behaviour of screw-fastened RHFCB with square/ rectangular/ elliptical web openings. Therefore, to investigate the shear behaviour and capacity of screw-fastened RHFCB with non-circular web openings, a series of experimental shear tests and a detailed numerical study was conducted. The laboratory shear test results were used to validate the developed Finite Element (FE) models of CFS RHFCBs with and without web openings. The influence of different parameters was investigated in a detailed parametric study using developed FE models. The analysis of FE results showed that a significant reduction (max 70%) in the shear capacity observed due to the web openings. The results indicated that the existing shear design equations to predict the shear capacity of CFS screw-fastened RHFCBs are either conservative or unsafe. Hence, a new series of shear design equations for the accurate estimation of the shear strength of screw-fastened RHFCB with unreinforced square, rectangle and elliptical web openings are proposed.

Web crippling design of modular construction optimised beams under ETF loading

In recent times, modular construction is considered as one of the most effective construction methods. It is necessary to understand the structural behaviour of modular construction elements for possible improvements. Modular Construction Optimised (MCO) beam is one of the innovative profiles and can be categorised into hollow flange Cold-Formed Steel (CFS) sections. The hollow flanges encourage bending stiffness and flexural performance, in contrast, slender web causes web crippling failure as these members are often subjected to concentrated loads and reactions. Even though research studies regarding MCO beams are very limited, the structural performance of other types of hollow flange beams has been covered in previous studies. However, to date, web crippling behaviour of MCO beams is still unknown and should be investigated to enhance the commercial aspects of MCO beams as this is an innovative section in the modular construction area. To address this research gap, this paper investigates the web crippling capacity of MCO beams under End-Two-Flange (ETF) load case with flanges unfastened to support condition using numerical analysis. Numerical models were developed and validated against the web crippling test results of hollow flange beams available in the literature. Subsequently, parametric numerical analysis (162 models) was conducted for MCO beams with varying key controlling parameters on web crippling capacity. The web crippling capacities of MCO beams were compared with existing codified (AISI S100, AS/NZ 4600) predictive equations and new design equations were developed to accurately predict the web crippling capacity of MCO beam under ETF load case with flanges unfastened condition. • Investigated web crippling behaviour of Modular Construction Optimised (MCO) beams under ETF load case. • The effect of section depth, web thickness, yield strength, bearing length, effective depth of the beam was identified. • Corner radius effect on web crippling behaviour of Modular Construction Optimised beams was investigated. • Web crippling design equations for Modular Construction Optimised beams under ETF load case are not available in standards. • Web crippling design equations for Modular Construction Optimised beams under ETF load case was proposed.

Shear behaviour of doubly symmetric rectangular hollow flange beam with circular edge-stiffened openings

Cold-Formed Steel (CFS) sections are evolved through the last two decades compromising various aspects of construction needs. Doubly symmetric Rectangular Hollow Flange Beam (RHFB) is one of the innovative CFS sections, which was introduced to eliminate the drawbacks of conventional open CFS sections such as prone to complex buckling and torsional effects. Edge-stiffened web holes are recently recommended and available for extensive usage in the floor beams. Even though previous studies conducted researches on various kinds of stiffeners, there is no definite design equation or findings that were presented on shear behaviour. Therefore, this study focuses on the effect of edge-stiffened circular web openings on the shear capacity of doubly symmetric RHFB. Non-linear numerical models were developed using the ABAQUS software package for validation purposes and then comprehensive parametric studies were carried out for doubly symmetric RHFB with edge-stiffened openings. A total of 558 models consisting of edge-stiffeners, un-stiffened openings and plain webs were analysed in this study. Parametric results of with edge stiffeners exhibited shear capacity increment (1–90%) compared to unstiffened web openings. Hence, new design equations were proposed in the form of reduction factor and based on Direct Strength Method (DSM). Finally, optimum edge-stiffener length of 15 mm was recommended regardless of web opening size.

Sequentially coupled structural modelling of LSF floor-ceiling systems

Fire resistance levels provide a standardised measurement of building elements' fire resistance under structural, integrity and insulation criteria, and are usually obtained from standard full-scale fire tests. However, these tests consume excessive time and money and thus the use of validated advanced numerical models is preferred. This paper presents the details of a sequentially coupled structural modelling study of LSF floor-ceilings made of Lipped Channel beam (LCB) and rivet fastened Rectangular Hollow Flange Channel beam (RHFCB) section joists used in eight different floor-ceiling configurations, and its results. Ambient temperature structural finite element (FE) models of LCB and RHFCB joists were developed first and validated using experimental results. Full scale fire test results of LCB floor system were then used to validate a structural FE model developed and analysed using a sequentially coupled approach utilising the time-temperature profiles from the same fire test. Finally, using the validated sequentially coupled structural FE models, the effects of a range of influential parameters such as joist types and floor-ceiling configurations were investigated. The results of structural fire resistance/failure times versus load ratio showed that the new RHFCB joists gave only minor improvements, however, they provided superior load bearing capacities. Fire resistance improved significantly when more gypsum plasterboard layers were used. The use of thin steel sheathing also improved the failure times, and is recommended as the fire exposed layer due its ability prevent plasterboard fall-off. Finally, suitable critical mid-web temperatures are proposed for predicting the structural fire resistance times of LSF floor-ceiling systems.

Numerical study of cold-formed steel frame walls under compression loading

Bearing walls in cold-formed steel buildings act as a transmitter of vertical loads of the building and as a retainer of the exterior of the building and also absorb the lateral loads of the building such as wind and earthquake loads. In this article, the behaviour of cold-formed steel frame walls under compressive axial load has been investigated numerically. First, the finite element model of the cold-formed steel wall was developed using ABAQUS software, and then, structural analysis was performed, taking into account the effects of geometric and materials nonlinearities. The results of the numerical model were compared with the experimental results to confirm the accuracy of the numerical model. In the following, parametric studies have been carried out considering some parameters affecting the behavior and the ultimate load of cold-formed steel frame walls such as type of sheathing, stud web depth, stud flange width and stud cross-section shape. The results of the structural analysis showed that the type of wall sheathing did not have a significant effect on the ultimate load of the wall, but increasing the web depth of the stud, has led to a decrease in the load-bearing capacity of the steel wall. The wall with hollow flange studs has a higher ultimate load than other sections, and also, the use of web stiffened stud leads to an increase in the final bearing capacity of the wall compared to typical sections.

Flexural Capacity Formulae of Steel Cold-Formed I-Beam with Strengthened Hollow Tubular Flanges. (Dept. C)

This research presents a new approach formula that predicts the flexural behavior of steel cold-formed I-beam with strengthened hollow tubular flanges. Rectangularity aspect ratio and strength of the strengthening material effect on the flexural behavior of steel cold-formed I-beam with strengthened hollow tubular flanges were studied and analyzed. A wide range of investigations was carried to figure out the effect of the hollow flanges rectangularity aspect ratio and its strengthening material. Eighty-eight numerical models were created and analyzed using the finite element technique. Three-dimensional nonlinear finite element models were prepared using eight nodes solid element with three degrees of freedom per node. Material nonlinearity and geometric effects have been considered in the model analysis. A good agreement between the experimental work done by the authors [1] and FE-model results was achieved and presented. The ultimate load values of the strengthened models were presented and compared with non-strengthened models. The increase of rectangularity aspect ratio and strength of the strengthening material lead to an increase in the section capacity of the studied models. Finally, new equations for the values of the section capacity of the strengthened sections were deduced, taking into account the factors described in this study.

Shear behaviour and design of doubly symmetric hollow flange beam with web openings

Cold-Formed Steel (CFS) sections are extensively used in structural engineering applications replacing the conventional hot-rolled sections due to their inherent advantages. Web openings are generally placed in CFS floor joists and bearers to accommodate the building services, which leads the reduction of floor height. The web openings significantly influence the shear behaviour and reduce the shear capacity. However, very limited research studies have been conducted on hollow flange CFS beams with web openings under shear load. Therefore, this study presents a detailed Finite Element (FE) investigation of the shear behaviour of CFS doubly symmetric Rectangular Hollow Flange Beams (RHFBs) with unreinforced circular web openings. Non-linear FE models were created and validated using the laboratory shear test results. A detailed parametric study was then carried out by extending the validated FE models for doubly symmetric RHFBs with circular web openings. In total,126 FE models were investigated with different geometric parameters including section depth, thickness, material strength and web opening sizes to observe their behaviour on shear strength. The results showed that the existing shear strength design equations are either unsafe or conservative for doubly symmetric RHFBs with unreinforced circular web openings. Therefore, new Direct Strength Method (DSM) based shear design rules are proposed to estimate the shear strength of doubly symmetric RHFBs with unreinforced circular web openings in conjunction with proposed shear reduction factor (qs).

Effect of circular holes on the web crippling capacity of cold-formed LiteSteel beams under Interior-Two-Flange load case

Lite Steel Beams (LSB) are innovative cold-formed formed steel sections, made of two rectangular hollow flanges with a web, and introduced in Australia claiming of flexural capacity enhancement. However, these sections are vulnerable to web crippling under concentrated loads and support reactions because of their slender webs when used as bearers and joists in floor systems. Limited research studies have been performed to investigate web crippling behaviour of these sections with fastened and unfastened supports under all four load cases, but without considering web hole effects. Recently few research studies indicated that the web crippling capacity of these sections reduced with the introduction of centred beneath and offset web holes under the End-Two-Flange load case, and hence it is critical. However, no investigations have been performed to explore the web hole effect of these sections under the Interior-Two-Flange load case. Therefore, this paper investigates the web crippling behaviour of LSB sections with three types of web holes: centred beneath, one offset, and two offset web holes, under Interior-Two-Flange (ITF) load case. The FE validations have been performed using four different experimental data sets from past research studies to generate accurate finite element models in ANSYS. In addition, a parametric study has been performed using validated FE models. A parametric study using 1126 FE models has proposed suitable capacity reduction equations for LSBs for centred beneath, one-side offset and both-side offset web holes. The results showed that the proposed equations provide accurate web crippling strength compared to design standards.

Flexural behaviour and design of modular construction optimised beams

The use of modular construction shows continuous growth leading to cost-effective and fast construction methods. Modular Construction Optimised (MCO) beams are employed in steel-framed modular units owing to their enhanced structural performance. MCO beams fall under the hollow flange beam family and can be produced using roll forming techniques, with lesser cost compared to general built-up beams. However, there is no dominant research on the design approach to predict the section moment capacity of MCO beams. To bridge this knowledge gap, this paper aims to investigate the section moment capacity of MCO beams using numerical analysis. Numerical models were developed as simply supported four-point bending arrangement in ABAQUS. The validity of the numerical models in terms of failure capacity prediction and failure modes were ensured comparing the experimental results of the hollow flange and lipped channel beams. Subsequently, a comprehensive parametric study was conducted including various dimensional and strength parameters to generate a section moment capacity results database. The results were compared with the codified Direct Strength Method (DSM) predictions and appropriate design recommendations were proposed. Based on the results, a simplified calculation method to predict the critical elastic buckling capacity of the MCO beams was also developed. New findings arising from this study would enhance the applicability of MCO beams in steel modular structures.