Cold-formed sections (CFS) fabricated using high strength steel have recently been utilised in construction due to their numerous advantages, such as higher load-to-weight ratio, flexibility of shape, and availability in relatively long spans. High strength CFS channel sections can be used as purlins and joists in structural systems; thus, they are vulnerable to different buckling instabilities, including web crippling. Predicting their web crippling capacity using the current design guidelines may be insufficient due to their empirical nature. This study, therefore, aims to investigate the web crippling capacity of high strength unlipped CFS sections under End-Two-Flange (ETF) loading conditions. Numerical simulations were carried out using nonlinear finite element (FE) analysis. The developed models were first validated against available experimental data and then used as a base for conducting an extensive parametric study. The ultimate web crippling capacity obtained from the parametric study was used to assess the accuracy of the available design equations in the standards and those proposed in the relevant studies. The assessment revealed that the existing design equations are not suitable for predicting the ultimate web crippling capacity for high strength CFS channel sections under the ETF loading condition. Thus, a modified design equation was proposed, following the same technique of current design standards, and a new Direct Strength Method (DSM) approach was developed.

The use of 3D printing in modular building connections is a novel and promising technique. However, the performance of 3D printed steel modular building connections has not been investigated adequately to date. Therefore, this paper presents a three-dimensional finite element model (FEM), using the multi-purpose software Abaqus, to study the effect of different geometrical and material parameters on the ultimate behaviour of modular building connections (herein named 3DMBC) using a wire and arc additive manufacturing (WAAM) method, as part of the UK’s 3DMBC (3D Modular Building Connections) project. The proposed model considers material and geometrical non-linearities, initial imperfections, and the contact between adjacent surfaces. The finite element results are compared with the currently available experimental results and validated to ensure developed FEM can be used to analyse the behaviour of 3DMBC with some adjustments. Case studies were investigated using the validated model to analyse the ultimate behaviour with different nominal and WAAM-produced materials under various loading arrangements. Based on the results, it is recommended to conservatively use the treated or untreated WAAM material properties obtained in θ = 90° print orientation in the finite element modelling of 3DMBCs considering the complex component arrangements and multi-directional loading in the modular connections. It is also noted that the thickness of beams and columns of fully 3D printed connections can be increased to achieve the same level of performance as traditional modular connections. For the 3DMBCs printed using untreated WAAM, the thickness increment was found to be 50% in this study.

Stainless steel is a high‐performance construction material that combines the strength and stiffness associated with ferrous alloys with the corrosion resistance derived principally from the high chromium content. Its unique combination of properties usually comes at a cost, which puts increased emphasis on ensuring that the material is utilized to the upmost in structural applications. Consequently, in the recent years, an increase in the use of stainless steel in the construction industry has been witnessed, more specifically in exposed architectural applications and where total life economics, durability, improved resistance to aggressive environment, etc. are prime deciding criteria. However, the shear behaviour and capacity of cold‐formed stainless steel beams has not been investigated adequately in the past. Hence, detailed finite element analyses (FEA) were undertaken to investigate the shear behaviour and strength of stainless steel lipped channel beams (LCBs). The developed finite element models were first validated using the shear test results. They were then used in a detailed parametric study to investigate the effects of various influential parameters such as section thickness, depth and grade. Moreover, a parametric study was conducted to emphasize the beneficial effect of strain hardening of stainless steel on shear capacity of LCBs, in particularly for compact sections. FEA results showed that currently available design equations (EN1993‐1‐4) are inadequate to capture the available inelastic reserve capacity of compact stainless steel LCBs, thus suitable equations were proposed to enhance the predictions. This paper presents the details of finite element modelling and analyses of stainless steel LCBs and the development of these new shear design rules.