Light gauge steel roofing systems of low rise buildings are made of high strength steel roof cladding, battens and purlins/rafters/trusses and fastened with self-drilling screws. Localised failures ...occurring at these screw connections under wind uplift loading often lead to catastrophic losses of steel roofing systems during severe storm events. Pull-out failures occurring at the two bottom flanges of roof batten to purlin/rafter screw connections is one of them. Multiple screw fasteners connecting the bottom flanges of roof battens to purlins/rafters pull out prematurely from the light gauge steel purlins/rafters. Since the structural behaviour of multiple screw connections differs significantly from the behaviour of single screw connections, the pull-out capacity of multiple screw connections cannot be calculated directly based on the number of screw fasteners. Hence a series of 80 small scale pull-out tests was conducted to investigate the pull-out capacities of two and four-screw fastener connections in roof battens. The pull-out failure loads from the tests were first compared with the pull-out capacities predicted using the design equations in the current cold-formed steel design standards. Suitable design modifications were then proposed to accurately calculate the pull-out capacities of roof battens with two and four-screw connections. This paper describes the details and the results of this study.
•Conducted an experimental study on the pull-out failures of multiple screw connections in steel roof battens•The load sharing mechanism of multiple screw connections was investigated in the tests.•Demonstrated the inadequacy of current pull-out capacity design equations•Proposed suitable design modifications for the multiple screw connections in steel cladding systems•Highlighted the significant reduction in pull-out capacity per fastener for multiple screw connections
Cold-formed steels (CFS) or light gauge steels (LGS) are steel sections created through processes without heat application, such as roll forming or press-braking. In the past few decades, the ...utilization of CFS as a structural material has expanded due to its advantages over the other materials used in the construction industry, consequently increasing the number of studies conducted by many researchers. CFS studies have focused on many research areas, including designing, and analyzing members and systems, connections, sustainability, residual stresses, and post-fire data. As a result, several authors have also conducted a literature review involving these areas. However, a literature review for more recent studies involving elevated temperature exposure of CFS has not been conducted. This paper seeks to compile and review the recent publications regarding CFS behavior and performance at high temperatures events. Sixty-nine (69) journal articles published from 2017 to 2023 were retrieved from the Scopus database and systematically reviewed through text mining with the aid of VOS Viewer. Prior studies utilizing finite element analysis and experimental methods to investigate the performance at elevated temperature events of varying CFS sections, systems, and steel grades have been summarized. In addition, this paper also briefly discussed the findings of the recent research works involving member connections of CFS. Key points from the literature review have been emphasized such as the outcome of experimental and numerical validation of existing design rules from different codes such as American Iron and Steel Institute (AISI), Eurocodes, and Australian codes which could vary depending on the CFS section and steel grades. Important points of previous studies regarding the CFS walls, insulations, and screwed connections have also been noted in this paper. Based on the review, research gaps in the prior studies involving elevated temperature exposure of CFS have been identified, such as lack of CFS investigation under fatigue and cyclic loading. These were then recommended as future direction and concentration of CFS at elevated temperatures research works.
Purpose. Design, manufacture and test the assembly tools for the self-drilling screws. Devices meet the requirements of hard location the screw, based on the outer diameter of the thread, the inner ...diameter of the thread or jig bushing, while at the end of the screwing, holding elements pass the head of the screw. Design/methodology/approach. In a paper it is shown that thread-forming screws, known as self-tapping screws capable of forming or rolling a matching thread into the material into which they are installed requires a hard location of the screw in device to prevent action the radial component of the cutting force. And at the same time devices, that meet the requirements of hard location the screw in the locator, at the end of the screwing let the screw head through them. The presented devices hold the screws for the outer diameter of the thread, the inner diameter of the thread or jig bushing. A device designed to align hex parts, such as screw heads, is also described. Such devices are designed for automated production. Findings. The developed devices were manufactured and tested. Self-drilling screws drilled holes under the action of axial load, maintaining the correct position and with a free passage of the screw head at the end of drilling. Two of the devices presented are protected by copyright. Originality/value. In the presented devices assembly with the use of self-drilling forming screws consists in the sequential execution of two diverse operations - first drilling, and then rolling the thread under the action of axial load. In this case, the device rigidly bases the screw, but let the screw head pas sat at the end of drilling. Developed devices can be used in assembly automation
Cold-formed steel (CFS) elements have gained significant attention in the field of structural engineering due to their numerous advantages, including high strength-to-weight ratio, ...cost-effectiveness, and ease of assembly and prefabrication. This review paper presents a comprehensive state-of-the-art analysis of the design and analysis of CFS structures, with a specific focus on columns and beams. The primary objectives and aims of this review paper are to provide a detailed assessment of the factors influencing the behavior and performance of CFS elements, including partial composite action, fastener spacing, bolt arrangement, web aperture, stiffeners, and connection spacing, to propose and present various formulas and methodologies that accurately estimate critical buckling loads, strength, and moment resistance for CFS members, and to emphasize the significance of proper screw and bolt placement in preventing premature failure and enhancing the overall load-carrying capacity of CFS structures. Additionally, the impact of temperature on the mechanical properties and performance of CFS members is discussed. The review paper proposes different formulas and methodologies to accurately estimate critical buckling loads, strength, and moment resistance for CFS members. Moreover, the paper highlights the importance of proper screw and bolt placement to prevent early failure and improve the overall load-carrying capacity of CFS structures. The discussion also emphasizes the need for revisions in existing standards and codes to provide more practical guidelines for designers and engineers. Overall, this state-of-the-art review paper provides valuable insights and recommendations for researchers and practitioners involved in the design and analysis of CFS elements.
New prefabricated lightweight structures made of solid wood with connections for joining and building metal screws for wood are proposed. Manufacture and assembly of basic elements-bars with a ...cross-section of 15x15 cm can be carried out in line conditions on the simplest woodworking equipment. The use of local tim-ber material has a number of advantages (ecological, economic and operational). The description of structures with manufacturing process, examples of buildings with vaulted and hipped roofing, connection arrangement, preparation of experimental samples with the use of new equipment of the National Research Moscow State University of Civil Engineering are given. The method of analysis with allowance for plastic deformations is under consideration. It provides additional economic advantages. The analysis is carried out by the method of integral estimates developed by Prof. V.M. Bondarenko for reinforced concrete structures and adapted to wooden structures by Prof. K.P. Pyatikrestovsky. Special strength criteria are used for the analysis of decks working together with the ribs (in a combined stressed state). It is planned to build buildings for various purposes in the ar-eas of development of the Far North of Russia.
► Modelling hysteretic behaviour of CFS wall panels and screw connections. ► Smoothly varying Bouc–Wen–Baber–Noori model is used to model the hysteretic behaviour. ► Nelder and Mead’s simplex ...algorithm to estimate the BWBN model parameters.
Cold-formed steel shear wall panel (CFSSWP) is a main lateral load resisting system in the CFS wall panel building system. It consists of CFS framing members attached to sheathing with screw connections. The hysteretic behaviour of a properly designed CFSSWP is dictated essentially by the hysteretic behaviour of the screws connecting the sheathing to the CFS framing. A numerical model of the hysteretic behaviour of such panels is necessary to study the system behaviour under various earthquake loading. In this paper, Bouc–Wen–Baber–Noori (BWBN) model is used to capture the deteriorating behaviour, such as the strength and stiffness degradation with severe pinching, observed in the screw connections between the CFS framing members and sheathing, as well as the full wall panels under cyclic loading. The system identification technique based on Nelder and Mead’s simplex algorithm is used to identify the unknown parameters of the model. The representation of the constitutive relationship, both under static and cyclic loading of the screw connections and the wall panel sub-system, is demonstrated using the BWBN model.
Load-bearing cold-formed steel (CFS) walls sheathed with double layers of gypsum plasterboard on both sides have demonstrated good fire resistance and attracted increasing interest for use in ...mid-rise CFS structures. As the main connection method, screw connections between CFS and gypsum sheathing play an important role in both the structural design and fire resistance of this wall system. However, studies on the mechanical behavior of screw connections with double-layer gypsum sheathing are still limited. In this study, 200 monotonic tests of screw connections with single- or double-layer gypsum sheathing at both ambient and elevated temperatures were conducted. The failure of screw connections with double-layer gypsum sheathing in shear was different from that of single-layer gypsum sheathing connections at ambient temperature, and it could be described as the breaking of the loaded sheathing edge combined with significant screw tilting and the loaded sheathing edge flexing fracture. However, the screw tilting and flexing fracture of the loaded sheathing edge gradually disappear at elevated temperatures. In addition, the influence of the loaded edge distance, double-layer sheathing and elevated temperatures is discussed in detail with clear conclusions. A unified design formula for the shear strength of screw connections with gypsum sheathing is proposed for ambient and elevated temperatures with adequate accuracy. A simplified load-displacement model with the post-peak branch is developed to evaluate the load-displacement response of screw connections with gypsum sheathing at ambient and elevated temperatures.
Cold-formed steel (CFS) wall panels with different board materials are used extensively in residential and commercial buildings to resist lateral loads by in-plane shear, in addition to helping the ...studs resist gravity loads. Generally the screw connection between the board and CFS skeleton frame, which experience shear, dictates the behaviour and strength of such panels. In this paper, details of an experimental study on behaviour and strength of the screw connections between the cold-formed steel profiles and calcium silicate boards, under monotonic and cyclic shear loading, are presented. The objectives of the experimental study are: (a) to develop a new test procedure that realistically represents the behaviour and failure of screw connections in CFS wall panels; (b) to investigate the effect of edge distance of the screws and thickness of the boards on behaviour and strength; (c) to study behaviour under monotonic and cyclic loading; (d) to develop the values of the important parameters that determine the load–deformation behaviour of the screw connection in such wall panels under in-plane shear; and (e) to develop design equation to evaluate the ultimate shear strength and its resistance factor required in load resistance factor design (LRFD).
Thin-film-based smart telemetric sensors coated onto the surface of washers were developed for the measurement of normal forces in screw connections for industrial applications.
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