Behaviour of partly stiffened cold-formed steel built-up beams: Experimental investigation and numerical validation

Abstract

To address the various instability problems in cold-formed steel members, many researchers have mainly focused on developing innovative sectional profiles wherein geometry of the section plays a vital role in enhancing the inherent resistance of such sections against premature buckling. However, the process of forming such innovative shapes is not only complex and time-consuming but sometimes such sections fail to mobilize their complete reserve strength. Hence, a stiffening arrangement of weaker zones for mobilizing the untapped reserve strength is suggested. The contribution of this simple, effective and partly stiffening arrangements, aimed at eliminating/delaying the premature local buckling, is studied both experimentally and numerically and also compared with existing codes. Experimental study was carried out on different simply supported cold-formed steel beams with judiciously proposed stiffening arrangements under four-point loading. An equivalent hot-rolled steel beam was also tested to compare the efficiency of the cold-formed steel beams. The cold-formed steel beams investigated had different width-to-thickness ratio, different geometries and different stiffening arrangements. The test strengths, failure modes, deformed shapes, load versus mid-span displacements and geometric imperfections were measured and reported. The test strengths of the beam models are also compared with the design strength predicted by North American Standards and Eurocode for cold-formed steel structures. To validate the test results further, a numerical study was carried out on such stiffened cold-formed steel beams using finite element software ABAQUS. All these results show that the proposed strengthening system is efficient and economical and allow cold-formed steel beams to reach greater load carrying capacity.

Numerical investigation of the cold-formed I-beams bending strength with different web shapes

“…Fig. 16 shows the failure mode of the single web beam modeled with the ABAQUS software which was chosen because of its high performance and precision [19][20][21][22]24]. It is noted that the beam I has undergone a local buckling in the upper flange at the level of the zone of application of the load in addition to a distortional lateral buckling.…”

“…The basic concept of finite element analysis is that a structure is divided into a finite number of elements having finite dimensions and reducing the structure having infinite degrees of freedom to finite degrees of freedom [18]. For finite element analysis, the advanced ABAQUS software was used for our numerical simulation [2,[19][20][21][22]. The goal of our project is the design of beam models on two supports subjected to bending.…”

Development of an efficient steel truss system using CFS sections: a comparative study with a hot-rolled steel truss

“…Figure 5 shows the semi-log load-displacement trend of HRSTS. At times, the test data may not be clearly interpretable, and semi-log graphs are adopted as a tool of extrapolation (Dar et al , 2019b, 2018b). The peak displacement noted at the other dial gauge location was 46.72 mm.…”

Assessment on the Behaviour of Cold-Formed Steel Built-up Beams

“…Open sections from I sections [1,[4][5][6][7], lipped channels [8][9][10][11][12], C sections [2,[13][14][15][16] are presented. Research works of an open section from I section were assembled by screws [4,6,7] and bolts [5].…”

“…Wang and Young [9] investigation showed that design equations were progressive for lipped channels connecting back to back for design strength prediction. Dar et al [10] on doing a study using lipped channel assembled back to back with angle stiffeners found that design strength computed as per North American specification [17]and European Code are conservative. Manikandan and Thulasi [11]on investigating lipped channel stiffened at intermediate web revealed that the provision of intermediate web and edge stiffeners will improve the behaviour and increase the strength of the section.…”