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This study investigated the structural behavior of a beam–slab member fabricated using a steel C-Purlins beam carrying a profile steel sheet slab covered by a dry board sheet filled with recycled aggregate concrete, called a CBPDS member. This concept was developed to reduce the cost and self-weight of the composite beam–slab system; it replaces the hot-rolled steel I-beam with a steel C-Purlins section, which is easier to fabricate and weighs less. For this purpose, six full-scale CBPDS specimens were tested under four-point static bending. This study investigated the effect of using double C-Purlins beams face-to-face as connected or separated sections and the effect of using concrete material that contains different recycled aggregates to replace raw aggregates. Test results confirmed that using double C-Purlins beams with a face-to-face configuration achieved better concrete confinement behavior than a separate configuration did; specifically, a higher bending capacity and ductility index by about +10.7% and +15.7%, respectively. Generally, the overall bending behavior of the tested specimens was not significantly affected when the infill concrete’s raw aggregates were replaced with 50% and 100% recycled aggregates; however, their bending capacities were reduced, at −8.0% and −11.6%, respectively, compared to the control specimen (0% recycled aggregates). Furthermore, a new theoretical model developed during this study to predict the nominal bending strength of the suggested CBPDS member showed acceptable mean value (0.970) and standard deviation (3.6%) compared with the corresponding test results.

The use of cold-formed sections (CFS) in construction is growing quickly in spite of the difficulty facing the designer in choosing the optimum sections’ proportions of any CFS in order to acquire the most economical section. In this paper, the optimization of CFS C-lipped channel beam will be carried out with respect to their flexural strength calculated using the direct strength method (DSM) given by the American specifications (AISI). The optimization will be carried out by developing an accurate and effective optimization code using particle swarm optimization (PSO). The mathematical model and the optimization technique used in this paper will help in finding the most optimum ratios between the different elements of the C-lipped channel beam that are studied in three groups. Nonlinear regression analysis is performed to obtain proposed equations that predict the flexural capacity of the cross section in two modes of failure: the local buckling mode and the distortional buckling mode. These proposed equations are used as objective functions in the optimization process as they showed that they are capable of predicting the moment capacity of the C-lipped channel effectively. It was found that the most suitable group of the three studied groups is the ratios between different elements of the cross section lies between 15 and 50%.

Light gauge elements for integrated beams were used, and thin webs are typically needed in constructed beams’ economical design. However, the buckling problem may arise if the Web is fragile. This risk may be reduced by using thicker panels, web reinforcements, or web enhancements. The use of corrugated Web is a possible means of achieving adequate rigidity and shear resistance without hardeners. Analytical studies were conducted in this present work to study the bending behavior of the conventional beam and light-weight steel beam with corrugated, concrete enclosed Web. Analyzes of finite elements have been conducted using the ANSYS beam software. The results present the capacity for load carrying and the deformation of the concrete-covered corrugated web beams. This study’s main objective is to acquire a better knowledge of a concrete embedded steel beam’s behavior.

In this study, the flexural performance of a new composite beam–slab system filled with concrete material was investigated, where this system was mainly prepared from lightweight cold-formed steel sections of a beam and a deck slab for carrying heavy floor loads as another concept of a conventional composite system with a lower cost impact. For this purpose, seven samples of a profile steel sheet–dry board deck slab (PSSDB/PDS) carried by a steel cold-formed C-purlins beam (CB) were prepared and named “composite CBPDS specimen”, which were tested under a static bending load. Specifically, the effects of the profile steel sheet (PSS) direction (parallel or perpendicular to the span of the specimen) using different C-purlins configurations (double sections connected face-to-face, double separate sections, and a single section) were investigated. The research discussed the specimens’ failure modes, flexural behavior, bending capacity, bending strain relationships, and energy absorption index of specimens. Generally, the CBPDS specimens with the PSS slab placed in a parallel direction achieved approximately a 13–40% higher bending capacity compared with the corresponding specimens with a perpendicular PSS direction (depending on the configuration of the beam). Fabricating the beam of the CBPDS specimen with double C-purlins (face-to-face) led to more effective concrete confinement behavior compared with the double separate C-purlins beam. The related specimen recorded a 10% higher bending capacity. Finally, the suggested composite CBPDS system exhibited a sufficient energy absorption capability of the static bending load because it demonstrated high strength and high ductility.

Cold-formed sections (CFS) fabricated using high strength steel have recently been utilised in construction due to their numerous advantages, such as higher load-to-weight ratio, flexibility of shape, and availability in relatively long spans. High strength CFS channel sections can be used as purlins and joists in structural systems; thus, they are vulnerable to different buckling instabilities, including web crippling. Predicting their web crippling capacity using the current design guidelines may be insufficient due to their empirical nature. This study, therefore, aims to investigate the web crippling capacity of high strength unlipped CFS sections under End-Two-Flange (ETF) loading conditions. Numerical simulations were carried out using nonlinear finite element (FE) analysis. The developed models were first validated against available experimental data and then used as a base for conducting an extensive parametric study. The ultimate web crippling capacity obtained from the parametric study was used to assess the accuracy of the available design equations in the standards and those proposed in the relevant studies. The assessment revealed that the existing design equations are not suitable for predicting the ultimate web crippling capacity for high strength CFS channel sections under the ETF loading condition. Thus, a modified design equation was proposed, following the same technique of current design standards, and a new Direct Strength Method (DSM) approach was developed.

In order to meet the requirement of the growing global construction market, various new construction technologies have been introduced in the past few years that not only have tremendous advantages in terms of safety, durability, and restorability when compared to traditional construction but also ensure sustainable development. One such technology is light gauge steel frame structure (LGSF) that has several advantages such as lightweight, enabling fast construction, less labour cost, no usage of formwork, and reducing wastage of building material, over the traditional construction like masonry and reinforced concrete construction. However, LGSF prefabricated technology has not yet been studied in depth. The present study is focussed on the performance evaluation of LGSF structure using different seismic methods, namely linear static analysis, nonlinear static analysis, and nonlinear dynamic analysis. To perform the analysis, an analytical model of an under-construction structure was formulated using cold-formed steel (CFS) profile-89 and the same model with CFS profile-150. The performance was evaluated in terms of displacement, storey/base shear, and performance levels. From the linear static analysis, it was observed that the response of the structure for both the profiles was within permissible limits as per relevant Indian standards. Based on the nonlinear static and nonlinear dynamic analysis as per ASCE/SEI 41-13 2014, it was obtained that performance of both the structures was at life safety level.

PurposeSigma cross-section profiles are often chosen for their lightness and ability to support large spans, offering a favourable bending resistance. However, they are more susceptible to local, distortional and lateral-torsional buckling, as possible failure modes when compared to common I-sections and hollow cross-sections. However, the instability phenomena associated to these members are not completely understood in fire situation. Therefore, the purpose of this study is to analyse the behaviour of beams composed of cold-formed sigma sections at elevated temperatures.Design/methodology/approachThis study presents a numerical analysis, using advanced methods by applying the finite element software SAFIR. A numerical analysis of the behaviour of simply supported cold-formed sigma beams in the case of fire is presented considering different cross-section slenderness values, elevated temperatures, steel grades and bending moment diagrams. Comparisons are made between the obtained numerically ultimate bending capacities and the design bending resistances from Eurocode 3 Part 1–2 rules and its respective French National Annex (FN Annex).FindingsThe current design expressions revealed to be over conservative when compared with the obtained numerical results. It was possible to observe that the FN Annex is less conservative than the general prescriptions, the first having a better agreement with the numerical results.Originality/valueFollowing the previous comparisons, new fire design formulae are analysed. This new methodology, which introduces minimum changes in the existing formulae, provides at the same time safety and accuracy when compared to the numerical results, considering the occurrence of local, distortional and lateral-torsional buckling phenomena in these members at elevated temperatures.

The main purpose of this paper is to study the structural behavior of cold-formed steel connections. Five specimens of cold-formed beam to column connections are studied. The beams are connected to the columns by using two different shapes of gusset plates and self-drilling screws. Experimental tests on these cold-formed connections are carried out to obtain their ultimate capacities. A numerical analysis is performed on the same tested specimens and the finite element model is verified. The ultimate loads obtained from the numerical analysis as well as the load-strain curves and buckling modes are compared with those obtained from the experimental tests and are found to be in good agreement. The finite element model well predicts the stress and deflection values, as well as the buckling modes of the specimens. Some recommendations are concluded to help researchers and designers choose the optimum type of beam to column connection.

This paper aims to evaluate the web crippling capacities of cold-formed Z-sections under two-flange load cases defined in the AISI Specification. The design specification provides an empirical equation to determine the web crippling strength. However, the results from this equation for different loading and support conditions are not consistent as it predicts unconservative for certain cases and over-conservative for some other cases. In this study, web crippling capacities of Z-sections are determined using validated finite element models and compared with the AISI Specification. The comparison showed that the empirical equation predicts adequate strength for fastened support conditions and conservative strength for unfastened support conditions under End-Two-Flange (ETF) load case. For the Interior-Two-Flange (ITF) load case, the empirical equation predicts unconservative strength for fastened support conditions and over-conservative strength for unfastened support conditions. Therefore, a detailed numerical study is carried out to recommend new web crippling coefficients using a parametric study under both loading cases for fastened and unfastened support conditions. The parametric study is based on 540 finite element models. Based on the results of this study new web crippling design equations are proposed for both load cases and support conditions using the direct strength method.

Cold-formed steel section (CFS) is broadly utilised in structural elements such as compression members, flexural members and tension members. Owing to its commendable properties such as light weight, easy handling, faster installation, aesthetic appearance and high strength to weight ratio, this study investigates the impact of lip depth and web depth on the flexural strength of light gauge steel C-sections. Specifically, it examines the flexural strength, including the strength-to-weight ratio, of C-sections with varying lip depths, and comparing these trends across different web depths. A finite element analysis was carried out to determine the optimum dimension of the depth of the lip by using the software ABAQUS. Load–deflection behaviour, failure modes, strength to weight ratio and changes in the load carrying capacity were discussed in this paper. The paper explores the load–deflection behaviour, failure modes, strength-to-weight ratio variations and corresponding differences in bending carrying capacity. The analysis reveals that the strength-to-weight ratio of C-sections increases gradually with lip depth. Moreover, an increase in lip depth positively influences the load carrying capacity of lipped channel sections in CFS structures.