Cold-formed Steel Framing Research Articles

Sustainable Structural System Selection Using Hybrid Fuzzy Multi-Criteria Decision Model Based on Seismic Performance

In the rapidly evolving field of sustainable construction, this study aims to address the critical need for advancement in the building industry, focusing on vital indicators like energy efficiency and cost-effectiveness, as well as improving occupant comfort. This research introduces a novel approach to support the choice of suitable structural systems for mass housing projects, with a case study on Iran’s national housing scheme. This methodology involves a four-phase process, beginning with compiling a database from existing studies to outline primary and secondary indicators affecting structural system selection. It utilizes the fuzzy AHP method for criteria prioritization and the fuzzy TOPSIS technique for alternatives (LSF, 3DP, ICF, TRC, and RCCF). The study identified the light steel framing (LSF) system as the optimal choice for Iran’s housing needs based on various criteria. Then, in the final phase, the study evaluates the seismic performance of cold-formed steel (CFS) frames with various sheathing panel types (OSB, DFP, CSP, and GWB) under monotonic loads, examining key seismic parameters across 38 frame setups. The findings reveal that LSF structures can effectively withstand seismic events within the elastic behavior range, suggesting that this construction approach is viable for enhancing mass housing production in Iran’s construction sector.

Wind-induced creaking noise assessment of 3D full-scale assemblies of drywall system using multi-axis cyclic testing

The lateral wind load applied to high-rise buildings results in movements that can cause creaking noises in drywall partitions with suspended ceiling systems. These noises can be disruptive to the residents and impair the structure’s serviceability. In this study, a sequence of large-scale three-dimensional (3D) experiments was conducted on two assemblies of drywall partitions with a suspended ceiling system to address this serviceability issue. The goal was to explore the 3D response of these assemblies, with a key emphasis on validating the effectiveness of adhesives in mitigating noise introduced by screw fixings, not only for individual walls but also when interacting with neighbouring walls and ceilings, which represent the real-world conditions. The six-degree of freedom (6-DOF) Multi-Axis Substructure Testing (MAST) system at Swinburne University Technology was used to simulate realistic wind load conditions. Two sets of test specimens were constructed using different methods to fix the plasterboard wall lining to the cold-formed steel (CFS) frame, which was rigidly bolted to both the MAST crosshead and the floor below. The first set of specimens (Assembly 1) had the plasterboards screw-fixed to the steel frame, while the second set (Assembly 2) used adhesive-only or a combination of adhesive and screw-fixing methods. Additionally, the instrumentation employed for acoustic measurements was strategically chosen to capture the noise generated by the overall system-level response. This served as a means of validating the serviceability noise experienced by users/occupants. Sound pressure level measurements and an acoustic camera were used simultaneously to identify the noise sources. The creaking noise measurements were compared for different specimens of Assemblies 1 and 2 and the effects of different construction details (e.g. fixing method, plasterboard ceiling lining, etc.) on wind-induced creaking noises were discussed. The results of this study can provide valuable insights for manufacturers and designers to minimize creaking noises in drywall partition systems and propose new construction techniques to improve the serviceability of high-rise buildings.

Study on seismic performance of cold-formed steel frame structures based on software ABAQUS

Study on seismic performance of cold-formed steel frame structures based on software ABAQUS

Lateral load behavior of shear connections between steel storage racks and the spine bracing with posts

High-rise steel storage racks are cold-formed thin-walled steel frames, which achieve their lateral strength and stiffness by the use of a spine bracing system in the down-aisle direction commonly located at a short horizontal distance away from the main rack frames. The shear connections between the main rack frame and the spine bracing system play a dominant role in the effectiveness of the spine bracing system. This paper experimentally investigates the behavior of the shear connections used in industrial practice between a steel storage rack and the spine bracing system with posts using four groups of three nominally identical connection specimens. By employing a digital image correlation (DIC) system, the tests generate comprehensive data and establish the real-time deformation fields of individual components of such shear connections. Based on the component-based approach, a linear-elastic analytical model is developed for the type of shear connections under consideration. The proposed analytical model explicitly captures the behavior of the individual connection components, including the three-dimensional flexural bending of endplates, as well as the distortions of the open sections of the upright and the bracing post. Based on the proposed model, this paper quantifies the contribution of each component towards the total deformation of the shear connections. The investigation establishes that the cross-sectional distortion of the bracing post and the out-of-plane bending of the upright web are the most flexible components of such shear connections. Recommendations associated with the shear connections under consideration are proposed for the rack designers and manufacturers.

Strength and behavior of axially and eccentrically loaded built-up closed sections using four cold-formed steel open sections

Innovation in cold-formed steel framing systems is needed for opening flexibility and application in mid-rise buildings. Hence, this study proposes a closed built-up section using four cold-formed steel (CFS) open sections with a high load bearing capacity that potentially enables the development of high-performance cold-formed steel framing systems for these. The closed section by combining four open CFS sections using fasteners can effectively enhance the load capacity of the sections under axial loading. With a specially designed intersections gusset plate this built-up section offers more potential configurations of beam-column moment connections for CFS structures. First, a heuristic optimization was performed to identify a high-performance section based on the local and distortional buckling strengths using the finite strip method. Second, a test program was developed to investigate the load bearing capacity and failure behaviors of the optimized built-up closed section under axial and eccentric loading. Third, their load bearing capacities were compared with several other closed sections such as the rectangular hollow tube (RHS) of equal cross-sectional area or equal moment of inertia to highlight the high material efficiency. This study paved the groundwork for exploring high-performance cold-formed steel framing systems with this unique closed built-up section.

Time-dependent seismic reliability analysis of rocking cold-formed steel frame based on improved HOMM

Cold-formed steel structures are particularly sensitive to seismic loads due to their relatively low ductility and limited energy dissipation capacity. Moreover, the small thickness of cold-formed steel structures makes them more susceptible to environmental influences, leading to corrosion and material degradation. Therefore, it is essential to quantitatively assess the seismic reliability of cold-formed steel structures from a lifecycle perspective. Current structural reliability design standards often focus on the ultimate strength at the component level while neglecting the global safety of structures. Additionally, it tends to neglect the time-variant characteristic of structural resistance due to the corrosion and degradation of materials. Therefore, the time-dependent seismic reliability analysis framework was proposed at the global structural level based on an improved high-order moment method (HOMM). It directly addresses the objective failure probabilities at the global structural level and takes into account the resistance degradation of structures in the design reference period. A comparative analysis of the time-dependent seismic reliability between rocking cold-formed steel frames and rigid cold-formed steel frames is conducted, focusing on load-bearing capacity limit states and deformation capacity limit states. The investigation indicates that the differences between time-dependent and time-independent seismic reliability indexes are substantial. For cold-formed steel structures subjected to prolonged exposure to the corrosive environment, it is recommended to consider the time-dependent degradation of structures.

Seismic performance of cold-formed steel shear walls with a shear plate of low-yield steel

A novel cold-formed steel (CFS) sheathed and bare shear walls with a low-yield steel shear energy-dissipating plate is proposed by taking advantage of the plastic deformation generated by the shear plates to reduce the damage of CFS shear walls under earthquake. In this paper, the seismic performance of six CFS shear walls with shear plates using low-yield steel is experimentally studied through full-scale cyclic tests. Different configurations of energy dissipation segments and the replacement of the energy-dissipating shear plate after the earthquake (through two walls) are investigated. A list of influencing parameters on the performance of the shear walls is studied including the fixed conditions of the specimens, the type of built-up studs, the rigidity and strength of the shear plates, and the connection method between the shear plates and the walls. Overall, within a certain lateral displacement level, the damage of the shear wall is concentrated in the energy dissipation segment. The shear plate reaches the plastic stage before the CFS frame as designed. Meanwhile, the mechanical performance of repaired structures with the shear plate replacement after the earthquake is maintained well.

Investigating seismic behaviour of cold-formed steel moment frames with the welded through-plate flexural connection

The Cold-Formed Steel (CFS) construction in seismic regions requires carefully selecting and designing an approved seismic-force resisting system. Among the available seismically-resistant structural systems, the bolted CFS moment frames have recently gained some attention. However, given the currently existing design issues associated with the bolted connections in CFS moment frames, this paper seeks to conduct a numerical investigation into the potential substitution of bolt fasteners with the weld materials in CFS frames. The objective is to explore the possibility of including the welded connection as an alternative to bolted connections in subsequent editions of the ASCE 7 code. To this end, finite element models, consisting of two built-up CFS beams and twenty-three flare-bevel-groove and fillet weld specimens, are initially validated against the cyclically and monotonically loaded tests with data available in the relevant literature. Subsequently, the verified weld and CFS beam models are incorporated in the simulation of thirty-four CFS beam-to-column welded moment connections, each differing in beam dimension, weld length and size, and gusset plate thickness. The built-up beams comprise back-to-back and lip-to-lip double C-section profiles. Stress variations along the weld lines, derived initially from nonlinear finite element analyses and then computed from the theoretical elastic analysis, are compared to establish a basis for categorizing stress distribution patterns in the longitudinal welds. Finally, six CFS frames assembled with the welded moment connection and subjected to a combined column axial compression and cyclic lateral drift are examined, resulting in an estimated seismic modification coefficient, R, equal to 3.8. Overall, the welded moment connections demonstrate a stable seismic response with an average ductility ratio, μ, of 2.7. The dominant failure mode is a locally developed ductile fracture in the two end segments of the longitudinal welds, identified as critical regions.

Enhancing Energy Efficiency of Cold‐formed Steel Framed Walls with Vacuum Insulation Panels

AbstractIn the current evolving building construction sector, the use of cold‐formed steel frames (CSF) has gained popularity due to their fast, clean, and flexible constructability. On the other side, in terms of the energy efficiency of a building, the use of CSF has raised concerns due to their high thermal conductivity, especially in the case of external wall panels. Hence, it is crucial to examine the thermal performance of such wall configurations and find solutions to reduce heat loss through walls by lowering the thermal transmittance, which would ultimately enhance the energy efficiency of the buildings. Accordingly, this study focuses on analysing the thermal performance of external wall panels made of cold‐formed and thin‐walled steel‐lipped channel studs with plasterboard linings and vacuum insulation panels (VIP). 2D and 3D finite element models developed in ABAQUS were used to analyse the effect of using VIP, oriented strand board and plasterboard, and their positions on the thermal transmittance of the CSF walls. 70 numerical analyses were conducted on 35 wall configurations and the results obtained were checked against the U‐value requirements set by UK building standards. It was found that replacing oriented strand boards with plasterboards does not substantially affect the thermal transmittance of the wall. However, adopting VIP as an insulation material has shown a U‐value reduction of up to 77%. But again, the change in position of VIP in the wall cross section has no notable effect on the U‐value.

Experimental Investigation of the CFS-PU Composite Wall Panel under Axial Compression

This study presents an innovative design for a cold-formed steel polyurethane (CFS-PU) composite wall panel, combining a cold-formed steel frame, a polyurethane foam infill, and a gypsum fibreboard sheathing. The foam filling process, in which the foam is injected under pressure, ensures uniform distribution, bonding, and interaction of all panel components. The aim of the study is to evaluate the behaviour of the CFS-PU composite panels and the influence of the PU foam and sheathing on the performance of the CFS frame structure. For this purpose, a comprehensive test programme was conducted with nine full-scale specimens, including four CFS-F specimens without infill and sheathing and five CFS-PU specimens with infill and sheathing on both sides. The study examined various aspects of the specimens, including failure modes, stability, stiffness, load-bearing capacity, and ductility index. By analysing these parameters, valuable insights were gained into the performance characteristics of the composite wall panels. The load-bearing capacity of the CFS-PU test specimens was improved by 2.34 times and the stiffness by 1.47 times compared to the CFS-F test specimens. The positive results highlight the potential of foam and sheathing in improving the axial compression performance of CFS walls.

Large-scale shaking table tests of a six-story floor-by-floor assembled CFS frame-framing shear wall structure

To study the seismic performance of a proposed multi-story floor-by-floor assembled structure using cold-formed steel (CFS) frame with square columns and double-channel beams connected by novel joints, and CFS framing walls as shear walls, shake table tests were conducted on a 2:3 scaled six-story CFS frame-framing shear wall structure (CFSF-FSWS) using bidirectional seismic inputs. A prefabricated concrete floor slab was proposed utilizing the channel section beams as the molds during prefabricating processes. The CFS framing shear walls were designed with various configurations researched before: framed or trussed skeleton, single or double side sheathing, flat or corrugated steel sheathing sheet. The observed damages, dynamic properties, seismic responses and failure mechanisms of the CFSF-FSWS under different peak ground accelerations (PGAs) were analyzed. The CFS frame carried gravity load, and the horizontal earthquakes were mainly resisted by CFS framing shear walls. The results indicated a good deformation capacity and seismic performance of the CFSF-FSWS building. The damping ratio of the test model gradually increased with the accumulation of damage, varying between 3.30%∼6.95%. After all seismic loading, the CFS frame remained intact and the damages were concentrated on the CFS framing shear walls, achieving the design objective of “separated gravity and lateral resisting systems”.

Study on seismic behavior of double leg C-type cold-formed thin-walled steel frame

The cold-formed steel (CFS) frame has the advantages of high strength, light weight, high construction efficiency, so it has been widely applied in building structures. However, the research on the seismic performance of multistory frames, especially those with braces, is rarely reported, the design method is also incomplete. In view of this, a pseudo static experiment of a three story double leg C-section CFS frame with brace is carried out. The bearing capacity, ductility, stiffness degradation and energy dissipation performance of the specimens are studied. The finite element analysis (FEA) method is used to simulate the failure process of the CFS frame and the design suggestions are proposed. The experiment result show that the failure process of the cold-formed thin-walled frame without braces has satisfactory ductility and energy dissipation performance; For framed CFS frame, the lateral stiffness and bearing capacity of the CFS frame increases, but the ductility decreases. Replacing double angle steel brace by steel plate strip brace can improving the seismic performance of structures, but there is an optimal width thickness ratio of steel plate strip. In this paper, the optimal width thickness ratio of brace is 5.0. When the design suggestions proposed in this paper are met, the CFS frame can achieve “strong structure, weak brace”, so as to improve the seismic performance of the frame.

Effect of wall sheathings on seismic behaviour of phosphogypsum-filled CFS shear walls

To improve the seismic behaviour of cold-formed steel (CFS) walls, a novel infilled CFS wall covered with different wall sheathings (gypsum wallboard, oriented strand board and fibre cement board) was assessed. Four full-scale specimens were tested under cyclic lateral loads to investigate the impacts of the wall sheathings on the seismic performance of the CFS wall. The failure process, failure mode, load–displacement curve, strength degradation, stiffness degradation, energy dissipation, deformation and strain variation of the walls were investigated. The failure modes of the walls were found to be failure of the connections between the CFS frame and the sheathing as well as crushing of the infill material. Compared with a specimen without sheathing, the peak load and lateral stiffness of the walls with sheathing were increased by 1.25–1.72 times, indicating that the sheathings played an important role in the lateral resistance of the wall. An analysis model and formulas for predicting wall lateral stiffness were developed. Comparisons between the calculations and experimental data showed that the proposed theoretical method was able to predict the lateral stiffness of the infilled CFS walls accurately.

Effect of System Reliability on Design of Metal Building Roof Purlins

This paper provides a framework to incorporate structural system reliability effects in the design of roof purlins in a typical metal building. Today, every roof purlin is considered as a separate component, and the effect of spatial variation in the demand loads and potential redistribution and load sharing in the roof system capacity is ignored in design. Component reliability is established by first-order reliability methods implemented through load and resistance factor design. Based on recent work in load-bearing cold-formed steel framing systems, the load and resistance factor design framework is extended from components to systems through an additional resistance factor to account for system influence. An archetypical metal building is designed and selected for this study. Monte Carlo simulations of a segment of the metal building roof are performed with consideration of both randomness in the demands and capacity and employing geometric and material nonlinearity in the response model of the roof. The simulations indicate that the system effect in metal building roofs is beneficial, and increases in the design capacity when evaluated against demands may be justified. Sensitivity to the target reliability (allowed probability of failure), deflection limits, and modeling assumptions are observed and discussed. Preliminary factors to account for roof system reliability are provided.

Experimental investigation on the seismic performance of phosphogypsum-filled cold-formed thin-walled steel composite walls

Cold-formed steel (CFS) is generally used in the construction industry for low-rise and multi-story buildings. In such structures, CFS walls are the main load-carrying elements. The traditional CFS wall has a low load-carrying capacity and poor seismic performance, which is the main reason for structural damage under natural disasters and also restricts the application of CFS structures in medium- and high-rise buildings. In this study, to improve the shear capacity and seismic performance of CFS walls, an innovative CFS wall filled with phosphogypsum (PG), called phosphogypsum-filled cold-formed thin-walled steel (PFCFS) composite wall, is presented. Taking the axial compression ratio, PG strength, and steel tube’s wall thickness as the study parameters, seven full-scale specimens have been fabricated and tested under cyclic lateral loads. The failure processes, failure modes, load–displacement response, strength and stiffness degradations, and energy absorption capacities of all the specimens are comprehensively investigated. The test results indicate that the specimen with a low axial compression ratio exhibits a connection failure between the CFS frame and hold-downs. For other specimens, the damage to the component materials leads to the final specimen failure. The axial compression ratio and the wall thickness of steel tubes have a significant influence on the seismic performance of the composite walls, while the PG strength has a much lower impact on the seismic performance. In addition, an analytical model and calculation formulas are proposed for predicting the shear capacities of the PFCFS walls. The effectiveness and accuracy of the proposed formulas are verified by comparing the calculated and test values.

Study on the seismic performance of cold-formed thin-walled steel frame with K-shaped braced shear panel

This study investigates the seismic behavior of an innovative cold-formed thin-walled (CFTW) steel frame with a K-shaped braced shear panel (BSPK). This new structural system is expected to improve the energy dissipation capacity of traditional CFTW steel structures. Eight full-scale one-story one-bay CFTW steel frames with BSPKs (CFTW-BSPKs) were subjected to lateral cyclic loads to examine the influence of the shear panel width-to-thickness ratio, aspect ratio, stiffening ribs, and slotted holes. The damage evolution, yield sequence, hysteresis curve, skeleton curve, load-carrying capacity, ductility, energy dissipation capacity, and stiffness degradation were analyzed. The test results demonstrated that all specimens exhibited stable hysteretic performance as well as a high load-carrying capacity. The seismic behavior consisting of energy dissipation and load-carrying capacity can be improved by increasing the shear panel width-to-thickness ratio or decreasing the aspect ratio. The stiffening ribs can significantly improve the load-carrying capacity and stiffness degradation of the specimens, while the slotted holes have a negative effect on the seismic behavior of the specimen.

Research on the Simplified Method of Nonlinear Finite Element Analysis for CFS-SPR Connections

This study reviewed some simplified methods of finite element analysis (FEA) for connections in cold-formed steel (CFS) structure, and summarized eight simplified methods divided into three categories. Shear performance tests were performed for six groups of self-piercing riveted (SPR) connection in CFS. A constitutive model of shear behavior for SPR connections was proposed, which was simplified from the load–displacement curve of shear performance test results. The models of SPR connection were established in ABAQUS by the eight simplified methods, and then the FEA results and the test results were compared. The applicable scope of each simplified model was explored, and a simplified method of FEA that was most suitable for the shear behavior of the CFS-SPR connection was proposed. Moreover, the shear performance test of the CFS shear wall with SPR was conducted by considering the rivet spacing, and failure modes and load–deformation curves were obtained. On this basis, numerical models of the CFS-SPR connection shear wall were established. By comparing the test results and the FEA results for the CFS-SPR connection shear wall, the feasibility of a simplified method of FEA applied to the CFS-SPR connection was verified. The main failure modes of the CFS-SPR connection were that the rivet tail pulled out from the bottom sheet and the rivet head pulled over from the top sheet. The SPR connection of the CFS frame could be simplified with a pin or a fastener element, and the SPR connection between the steel frame and the sheathing could be simulated by a Cartesian connector or a Spring2 element. The FEA results were highly similar to the test results for the CFS-SPR shear wall.

Out-of-plane flexural behaviour tests and numerical analysis of LEM-infilled CFS walls

With carbon neutrality gradually becoming the global focus, employing the energy-saving wall in structure has become the development trend of energy-efficient buildings. This paper focuses on a novel type of cold-formed steel (CFS) wall in which lightweight expanded polystyrene (EPS) mortars (LEM) are filled in the space of CFS framing. The CFS framing and LEM are formed into a whole to resist the bending moment demands. To explore the flexural response of the LEM-infilled CFS wall, six specimens were designed and tested. These specimens included two specimens without wall sheathing and four specimens sheathed with various panel types. The specimens were subjected to gradually increased uniformly distributed loads. Failure patterns, load–deflection relationships, capacities and strain distribution of typical points were also analyzed. Test results illustrated that the flexural bearing capacities of the specimens were 9.69–13.14 times their self-weight. Specimens with sheathings exhibited better flexural response, and specimens with cement-based LEM exhibited higher flexural stiffness and capacities than that of specimens with gypsum-based LEM. Subsequently, finite element (FE) models of LEM-infilled CFS walls were developed and validated by the test data. Effects of steel yield strength, steel thickness, LEM compressive strength and wall panel type on the flexural behaviours of LEM-infilled CFS walls were explored by parametric studies. The transformed cross-section method was employed to calculate the mid-span deflection and the results were validated by test and FE analytical results. The analysis in this research could provide reasonable references for design and application.

Experimental research on seismic performance of cold-formed thin-walled steel frames with braced shear panel

The traditional cold-formed thin-walled (CFTW) steel sheathed walls are prone to have misalignment at the joints of wall panels and the damage of self-tapping screw connections under earthquake, resulting in obvious pinching of the hysteretic curves. In order to improve the energy dissipation and shear bearing capacity of the lateral resisting member in CFTW steel structures, an innovative structure called CFTW steel structure with braced ductile shear panel (CFTW-BSP) was proposed in this paper. Four full-scale one-story one-bay CFTW-BSP specimens containing two X-shaped and two K-shaped brace specimens were designed and tested under horizontal cyclic loads. The effects of configuration types, shear panel aspect ratios and slotted holes were investigated by comparing the lateral performance. In addition, the replaceability of the shear panel damper was analyzed. In general, the specimens performed well with a stable and plump energy dissipation capacity. The plastic deformation concentrated on the shear panel before 2% interstory drift, and then the end stud bases yielded and cracks propagated near the hold-downs at the ultimate stage. The braces always remained elastic during the tests. For X-shaped brace specimens, the slotted holes on shear panel can improve the ductility but decrease the energy dissipation capacity of the structure. For K-shaped brace specimens, the lateral resistance of the structure can be improved by decreasing the shear panel aspect ratio.

Behavior of CFS shear walls infilled with lightweight ceramsite concrete under cyclic loading

To meet the lateral resistance requirement for cold-formed steel (CFS) shear walls in multistory buildings, a novel CFS shear wall filled with lightweight ceramsite concrete is proposed in this paper. Three full-scale specimens were conducted under cyclic loading to evaluate their failure mode, bearing capacity, lateral stiffness, ductility, and energy dissipation. The experimental results showed that the main failures of the walls were bond-slip cracks between the CFS framing and fillers, cracking of sheathings, and compression failure at the corners of the fillers. The bearing capacity and energy dissipation of the infilled walls were superior to that of unfilled wall. Increasing the stud section area could improve the lateral behavior of the wall. Finite element (FE) models were introduced to simulate the shear performance of the test specimens. The numerical simulation results were in good agreement with the experimental results; hence, the FE models for simulating CFS shear walls were validated. Subsequently, a parametric study was performed by varying the parameters, including the ceramsite concrete strength, wall thickness, aspect ratio, steel strength, and sheathing material. Furthermore, a calculation method was proposed to determine the bearing capacity of the CFS shear walls. The calculated results agree well with the experimental results. A comparison between the proposed CFS shear walls and existing CFS shear walls showed that the lateral performance of the proposed walls was higher than that of CFS shear walls.