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This study presents the first investigation into the use of glass fiber reinforced polymer GFRP to strengthen steel beams with web openings. Based on previous research about the strengthening of steel beams with web perforation using carbon fiber reinforced polymer (CFRP) conducted by one of the contributing authors of this paper, it was decided to investigate the ability of pultruded glass fiber reinforced polymer, which is less expensive than CFRP materials, to strengthen single rectangular web openings of steel beams. The previous published experimental test was used to validate the proposed numerical model developed with the finite element software ABAQUS, capable of acquiring important phenomena such as debonding between FRP and steel material. The validated simulation was then used to operate a parametric study involving four proposed GFRP strengthening techniques and three distinct pultruded GFRP product thicknesses to reinforce the same steel beam used in the earlier experimental test, having a single rectangular opening shape in two separate positions along the span. From these numerical models, an adequate GFRP strengthening arrangement was found and the possibility of using low-modulus FRP materials rather than the more expensive high-modulus FRP materials for strengthening steel beams with web penetration was confirmed. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) structural members retain their preferred position in the lightweight construction industry, which is due to their significant advantages. The optimization of these CSF elements will make it possible to construct buildings at very competitive prices, having in addition an increased load capacity, and thus obtaining a stable and economical construction. The main objective of this research being the evaluation of the effectiveness of these new sections in (CSF) and the estimation of the remarkable instabilities as well as the failure modes. This article deals with an experimental study on the behavior of CSF beams of delta and bi-delta shape, solicited by four-point bending loads. These cross section shapes are often used in floors as main and secondary beams. The properties of this type of sections are most often based on the method involving the effective width designated by the Eurocode 3 standard. A nonlinear analysis by finite elements (FE) using the ABAQUS calculation program is carried out, thus making it possible to compare the experimental results with the numerical ones as well as those which are given by the theory proposed by Eurocode 3. Finally, the results obtained essentially showed that the failure modes of the delta and bi-delta beams corresponded to the buckling modes local. [ABSTRACT FROM AUTHOR]

This research paper presents a new flexural design approach for cold-formed steel (CFS) built-up sections failing in local buckling, developed following an extensive numerical investigation involving two novel closed built-up sections. At first, a finite element (FE) model using the widely adopted ABAQUS software was constructed and carefully validated against pertinent experimental data available in the literature. A comprehensive validation process which included comparing flexural strengths, deformed shapes, moment-curvature, and moment-displacement curves was performed. Afterwards, the validated FE model was extended to a numerical parametric investigation comprising of 108 simulations involving both three-point and four-point bending cases. Key parameters, including cross-sectional shapes, slenderness, and screw spacing, were varied primarily to facilitate the formulation of the novel design method. The outcomes of this investigation revealed that the current direct strength method (DSM) available in the North American Specifications (NAS) underestimated the bending strength, particularly for the ultra-thin sections. Considering this observation which is consistent with the findings of past research on similar cross-sections, a Generalised Direct Strength Method (DSM-G) was developed by introducing a new mathematical model, which differs from the traditional slenderness limit equations, instead relying on a conservativeness degree-based approach used for modifying the original DSM equations. The DSM-G method demonstrated a better accuracy in predicting the flexural strengths of different built-up sections (including the ones investigated by other researchers), all failing by local buckling. Moreover, the reliability of DSM-G equations was assessed, satisfying the prescribed threshold index limit suggested in NAS. A comprehensive set of guidelines, along with a design example for implementing the DSM-G method, has been presented to facilitate practical application. • FE investigation on novel CFS closed built-up sections is carried out. • Key parameters like cross-sectional profiles/sizes and screw spacing are varied. • Current DSM predictions of the novel sections are inconsistent. • A new mathematical model is proposed for a new generalized DSM (DSM-G). • DSM-G is reliable and is verified against results from current and previous studies. [ABSTRACT FROM AUTHOR]

Currently, cellular steel beams are widely used by structural engineers and major companies due to their useful structural applications and serviceable performance. However, these types of steel beams are susceptible to different states of instability and failure mechanisms such as web postbuckling. The aim of this paper is to investigate the effectiveness of using externally bonded pultruded carbon fiber (CFRP) profiles for the strengthening of web post-buckling in thin webbed cellular beams as an alternative to the typical welding technique of reinforcement. A proposed numerical model created with the finite element software ABAQUS capable of capturing the de-bonding and fracture along the adhesive layer between steel and CFRP has been validated using published experimental results. The suggested numerical model is then used to simulate the parametric analysis of using pultruded CFRP T and U sections to strengthen six cellular beams of various sizes. It was found that this novel technique was able to prevent the web post-buckling failure mode or delay it to a grater load with a considerable strength enhancement comparable to control beams. [ABSTRACT FROM AUTHOR]

The wide use of cold-formed sections (CFS) in the field of steel constructions, favored by the multiple advantages they offer (lightness, ease of installation, etc.), has led us to reflect on a new process for manufacture of metal beams allowing the design of very large span hangars and a reduction in instability problems. This paper presents a study of the theoretical and numerical behavior of a large span CFS beam with different webs, a solid web, a triangular corrugated web, and a trapezoidal corrugated web. These beams are stressed by a concentrated bending load at mid-span. Numerical modeling was done using the finite element software ABAQUS. The numerical results have been validated by the analytical results those obtained based on Eurocode 3. The load capacity and failure modes of the beams were discussed. According to numerical and analytical analysis, corrugated web beams perform better than all other sections. [ABSTRACT FROM AUTHOR]