CALIBRATION OF DESIGN FORMULA FOR BUCKLING STRENGTH OF BUILT-UP BACK-TOBACK COLD-FORMED STEEL MEMBERS IN COMPRESSION (original) (raw)
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COLD-FORMED STEEL COMPRESSION MEMBERS: A REVIEW
IRJET, 2022
The cold-formed steel structural or nonstructural members usage has increased in the past few years in various constructional activities. It is used due to its lightweight, easy installations, erection and economy. A builtup column is composed of two or more channels together to form a single entity that is connected either by battens or lacings. The three fundamental buckling modes, local, distortional and global are depended on the cross-sectional shape of the cold-formed steel members. Many experimental and numerical analyses have been done on differently shaped channels like single-channel sections, back-to-back channels, face-to-face channels, and Z-shape by various researchers. Different parametric studies were conducted on the effect of slenderness ratio, spacing of channels, batten width, channel spacings, screw spacings, and lacing slenderness on the ultimate capacity of columns under axial compression. In most cases, the experimental results are compared with the numerical results that are obtained from the finite element models developed in software like Abaqus and Ansys. The obtained buckling capacities of the column are compared with American iron and Steel Institute (AISI), Australian Standards (AS) or New Zealand Standards (NZ) and Eurocode standards.
BUCKLING ANALYSIS OF COLD FORMED STEEL CHANNEL SECTIONS WITH AND WITHOUT STIFFENERS
IJTIMES, 2019
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.
Materials
The practice of utilizing cold-drawn steel for structural and non-structural elements has expanded nowadays due to it being lighter in weight, economic section, desirable in fabrication, and its preferred post-buckling behavior over hot rolled sections. The cold-drawn steel section back to the back-lipped channel section has a wide application as a structural member. The fasteners are provided at regular intervals for the long-span structure to prevent individual failures. This study is concerned with the inadequacy of research addressing the behavior of built-up columns. The relevant built-up column section is chosen based on the AISI-S100:2007 specification. Thirty-six specimens were designed and tested by varying web, flange, lip dimensions, spacing between the chords, and battened width experimentally subjected to an axial compression. Comparing 36 experimentally buckled specimens with the model generated by Finite Element Method accompanied with ASI-recommended two direct stren...
CFS Section is widely used in structural system. As we know that the CFS is light gauge steel section. Also cold formed steel sections are economic due to its low weight than the hot rolled section. There is need of checking buckling behavior of cold formed section. So, economic section can develop by considering these different conditions. For this study buckling mode is observed for different length by keeping section thickness and cross section constant. Also the load carrying capacity is calculated by using abaqus software for different length of section.
Buckling Analysis of Cold Formed Steel Compression Members at Elevated Temperatures
Cold-formed steel members have been widely used in residential, industrial and commercial buildings as primary load bearing structural elements due to their advantages such as higher strength to weight ratio over the other structural materials such as hot-rolled steel, timber and concrete. However, they are susceptible to various buckling modes including local and distortional buckling. Fire safety design of building structures has received greater attention in recent times as fire events can cause loss of property and lives. Therefore it is essential to understand the fire performance of light gauge coldformed steel structures under fire conditions. The buckling behavior of cold-formed steel compression members under fire conditions is not well investigated yet and hence there is a lack of knowledge on the fire performance of cold-formed steel compression members. Therefore, this paper deals with behavior of cold formed steel compression member under fire and to analyze the effect of fire on critical buckling load of compression member. Eigen value analysis for Lipped channel sections made of various thicknesses and both low and high strength steels was carried out through finite element method. The ultimate load carrying capacity results from experimental investigation and finite element analyses were then compared
The paper presents the investigation on cold formed steel lipped channel columns experiencing distortional and global buckling interaction under axial compression. Five cross sections are chosen based upon the limitations given in the draft IS 801 code. The cross section dimensions and length ensures equal distortional/global critical buckling loads, thus maximizing the distortional/global mode interaction effects through elastic buckling analysis using CUFSM software. The plate slenderness ratio (b/t) is within the limit to avoid local buckling. The ends of the columns are considered as Pinned-Pinned. The Numerical analysis are carried out by the finite element package ANSYS. Finite element model include the geometric and material non-linearities. Geometric imperfections are incorporated in the model by extracting distortional and global modes obtained from buckling analysis. Parametric studies are carried out by varying the yield stress as 250,350 and 550 N/mm2.Theoretical Analysis are carried out by Direct Strength Method DSM-AISI 100-2007 and Australian Standard AS/NZS:4600-2005.The results are compared and the effect of distortional and global interaction on ultimate strength is discussed.
2019
Built-up columns composed of multiple cold-formed steel (CFS) sections are often used as structural members to carry the high axial force demand as they are considered as economical and efficient. Though built-up CFS columns with intermediate lacing plates are widely adopted in the practice, very limited studies have been conducted in the past to investigate their performance under various loading conditions. This study presents an experimental investigation on the built-up CFS column specimens with double-lacing configuration and large flat width-tothickness ratio. Pin-ended support conditions allowing uniaxial bending are adopted in this study. The main parameters varied in this study are the sectional compactness of chord sections, the column slenderness ratio, and the slenderness ratio of lacing elements. The slenderness ratio of the unbraced chord elements is kept constant in all test specimens. The design strengths of builtup CFS columns are computed using North American and E...
Compression tests on cold-formed steel built-up box sections
2019
Built-up box sections are becoming increasingly popular as column members in cold-formed steel (CFS) structures; uses of such sections include CFS trusses, space frames, and portal frames. In this paper, the built-up box sections are fabricated by two identical lipped channel-sections connected at their flanges with self-drilling screws. This paper presents an experimental investigation on the axial capacity of CFS built-up box sections. Compression tests were conducted for different values of slenderness’s covering stocky to slender columns. In total 8 built-up box columns were tested. For comparison, 8 single channel sections were also tested and reported herein. Prior to the compression tests, material properties and initial imperfections were measured for both the single channel and CFS built-up box sections. Load-axial shortening relationship, failure modes, and deformed shapes at failure are discussed for CFS built-up box columns. Test results show that all short columns faile...