A Critical Review on Optimization of Cold-Formed Steel Members for Better Structural and Thermal Performances

The construction and building sectors are currently responsible globally for a significant share of the total energy consumption and energy-related carbon dioxide emissions. The use of Modern Methods of Construction can help reduce this, one example being the use of cold-formed steel (CFS) construction. CFS channel sections have inherent advantages, such as their high strength-to-weight ratio and excellent potential for recycling and reusing. CFS members can be rolled into different cross-sectional shapes and optimizing these shapes can further improve their load-bearing capacities, resulting in a more economical and efficient building solution. Conversely, the high thermal conductivity of steel can lead to thermal bridges, which can significantly reduce the building’s thermal performance and energy efficiency. Hence, it is also essential to consider the thermal energy performance of the CFS structures. This paper reviews the existing studies on the structural optimization of CFS sections and the thermal performance of such CFS structures. In total, over 160 articles were critically reviewed. The methodologies used in the existing literature for optimizing CFS members for both structural and thermal performances have been summarized and presented systematically. Research gaps from the existing body of knowledge have been identified, providing guidelines for future research.

Bending and flexural-buckling strength of steel members considering strain-rate-effects at elevated temperatures

PurposeIn this study, the bending strength, flexural buckling strength and collapse temperature of small steel specimens with rectangular cross-sections were examined by steady and transient state tests with various heating and deformation rates.Design/methodology/approachThe engineering stress and strain relationships for Japan industrial standard (JIS) SN400 B mild steels at elevated temperatures were obtained by coupon tests under three strain rates. A bending test using a simple supported small beam specimen was conducted to examine the effects of the deformation rates on the centre deflection under steady-state conditions and the heating rates under transient state conditions. Flexural buckling tests using the same cross-section specimen as that used in the bending test were conducted under steady-state and transient-state conditions.FindingsIt was clarified that the bending strength and collapse temperature are evaluated by the full plastic moment using the effective strength when the strain is equal to 0.01 or 0.02 under fast strain rates (0.03 and 0.07 min–1). In contrast, the flexural buckling strength and collapse temperature are approximately evaluated by the buckling strength using the 0.002 offset yield strength under a slow strain rate (0.003 min–1).Originality/valueRegarding both bending and flexural buckling strengths and collapse temperatures of steel members subjected to fire, the relationships among effects of steel strain rate for coupon test results, heating and deformation rates for the heated steel members were minutely investigated by the steady and transient-state tests at elevated temperatures.

Vehicle Body and Roll Cage Assessment involving Frontal, Side and Roll-over Crash Analysis by FEA using LS-Dyna

Simulating the vehicle collision has gained importance in the automotive sector due to its accuracy, cost effectiveness and enhanced reliability. It aids in improving the safety of driver and passenger and also examine the cause of crash or collision. This numerical analysis investigates the materials capability to enhance safety. A three-dimensional vehicle model was developed along with its roll cage using solid work tool. Hypermesh work bench was employed to discretise the sensitive parts of the body and roll cage using beam 189 element having six degree of freedom at each node. The existing structural steel members were replaced with reinforced carbon fibre in all the sensitive part of the body and roll cage and its structural stability was assessed using the frontal, side and roll over crash simulation using LS Dyna. This investigation also reveals the change in internal energy, kinetic energy absorption and momentum transfer for both structural steel and carbon fiber under all the crash scenarios. The outcomes of this numerical investigation proved that the reinforced carbon fiber can be effectively replaced with the structural steel to enhance safety.