Experimental Investigation of High Strength Cold-Formed C-Sections in Combined Bending and Shear (original) (raw)

The Light gauge cold-formed steel sections being used extensively in residential, industrial and commercial building as secondary load bearing members since last three decadez. In this context a study is being made to analyses C Sections with and without stiffeners to arrive at design strength criterion in compression. The direct strength method of design for cold formed steel sections has been validated over the years through research and the same has been incorporated in the standard codes of practice in the countries like USA and Australia. ABAQUS and CUFSM has been extensively used to perform Finite Element analysis and Finite Strip method of thin walled cold formed steel sections and the results are compared to each other. The analysis is being done on CUFSM and ABAQUS. The design strength curves will be arrived at using direct strength method. This is because cold-formed steel sections have a very high strength to weight ratio compared with thicker hot-rolled steel sections, and their manufacturing process is simple and cost-effective. In this context, a study is being made to analyze C sections with and without stiffeners to arrive at design strength criterion in compression members. In this study, the behavior of C sections with and without stiffeners under the action of axial loads has been carried out with various thickness and depths. In ABAQUS, the loads are applied on both ends. The clamped end conditions are considered.

In the field of structural engineering the design of cost efficient structure is highly important. This led to development of cold-formed steel structures. Cold formed steel members have been widely used in residential and commercial buildings as primary load bearing structural elements. They are often made of thin steel sheets and hence they are more susceptible to local buckling. The present study focuses on understanding the importance of “lip” in cold formed steel sections. As per IS: 801 - 1975, design solution is developed for flexure member design. An experimental program is performed, to gain information on flexural capacity and buckling behaviour of member. Suitable finite element models are then developed to simulate the behaviour of tested beams and are validated using test results. All the ultimate load capacity results for local buckling are compared with codal provisions as well as results obtained by experimental program. This paper mainly focuses on to investigate load carrying capacity and buckling behaviour of two different cold formed steel channel sections i.e., with lip and without lip, by analytically(by developing design solutions),experimentally as well as by finite element analysis(by using ABAQUS software).The „lip‟ is not taking part anywhere in calculation of bending moment capacity. It is important regarding to buckling behaviour of cold formed steel sections. All the specimens are tested under Universal Testing Machine (UTM) and subjected to two point load system. Results are showing that members subjected to pure bending, with „Lip‟ channel section is subjected to web buckling. Channel sections with 'lip' is showing 28.7% higher than without 'lip' sections. In contrast, without „Lip‟ channel section is subjected to flange buckling. With „lip‟ channel section has high load carrying capacity compared to without „Lip‟ channel section. Analytical, experimental and finite element results are showing close to each other.

A R T I C L E I N F O Keywords: Finite element modelling Cold-formed stainless steel Shear strength Lipped channel beam Circular web openings New design rules A B S T R A C T : Cold-formed stainless-steel (CFSS) sections are increasingly popular for architectural and structural applications, especially in the corrosive environment due to its resistance to corrosion and other various benefits. The combination of stainless-steel material properties and the lightweight section properties makes the CFSS section the right choice for offshore steel structures. The demand for the stainless-steel sections in the construction industry is limited to a certain extent due to the higher cost; thus, the optimal use of stainless steel is vital. Openings to the web of CFSS Lipped Channel Beams (LCB) are introduced to facilitate the building services to reduce the floor height. Subsequently, the shear capacity is reduced due to the reduction of the web area. However, only very limited researches have been conducted so far to predict the reduced shear capacity of CFSS LCBs with circular web opening. Hence, this paper addresses a numerical study to investigate the shear behaviour and strength of cold-formed austenitic grade 1.4301 and duplex grade 1.4462 stainless steel LCB sections with unreinforced circular web openings. A detailed parametric study was carried out by developing 180 Finite Element Analyses (FEA) models to establish a wide-ranging shear strength database following the validation process with available shear test results. The analysis of the numerical results showed that the currently available reduction factor equations are either conservative or unsafe to use for the CFSS LCBs with circular openings. Hence, three sets of equations with different approaches to predict the shear capacity of CFSS LCBs with circular web opening are developed and presented in this paper.

The paper describes the recently balloted Direct Strength Method (DSM) of design for shear of the North American Specification for Cold-Formed Steel Structural Members NAS S100. The method requires the shear buckling load V cr of the complete section to be computed. Shear buckling examples of channel sections in pure shear using both the semi-analytical and spline finite strip buckling analyses are presented. Recent work on the buckling and strength of channel sections in pure shear with rectangular and triangular web stiffeners is also described.

This paper investigates on flexural behaviour for cold-formed steel beam. Cold-formed steel is getting popular over the years in construction industry. However, due to its thin-walled behaviour, cold-formed steel is prompt to have buckling failure. Previous research were done to provide stiffener in order to overcome this problem. Furthermore, as addressed in this paper, curved section is introduced and studied to determine its behaviour compare to straight member in handling deformation. Both straight and curved cold-formed steel were tested under flexural with different length as the investigation variable. The results were analysed for comparison. Curved section of cold-formed steel behave differently in beam and column compared to straight section. Curved section has an advantage in reducing the deflection for structural members for flexural behaviour.

This paper is concerned with distortional buckling of cold-formed steel channel sections by the semi-analytical complex finite strip method. The main purpose of this paper is to study the buckling behavior of cold-formed channel sections with extra longitudinal stiffeners at the end of flanges and also on the web. One of the most important purposes of this study is to investigate the optimum width of extra longitudinal flange stiffeners in cold-formed channel sections. Furthermore, the optimum position of longitudinal web stiffeners is calculated to maximize the distortional as well as local buckling strength of cold-formed channel sections. For validation purposes, complex finite strip method results are compared with those obtained by Generalized Beam Theory (GBT) analysis. Using the semi-analytical complex finite strip method, a comparison on the buckling behavior of unstiffened and stiffened cold-formed channel sections in local, distortional and global modes will be done.