Periodic Reporting for period 1 - ConCatenaTion (Novel CONnection design and modelling idealisations utilising CATENAry acTION in the disproportionate collapse resistance mechanism of cold-formed steel panelised structures)
Periodo di rendicontazione: 2022-03-09 al 2024-03-08
The problem:
Cold-formed steel (CFS) panelised structures are an increasingly used offsite modern method of construction (MMC) with high strength-to-weight ratio, durability, speed of construction and reduced carbon footprint. Despite these advantages, their robustness under accidental loss of support is poorly understood. Recent developments enabling longer spans, lighter sections and open-plan layouts can reduce robustness and increase vulnerability.
While substantial research exists on CFS element design and standard connections, there is limited understanding of structural interactions and resistance to disproportionate collapse under loss of support, particularly the ability to develop catenary action. The absence of reliable test data and guidance has led to conservative designs, excessive material use, limited industry confidence and restricted uptake of CFS MMC. Current European standards inadequately address their robust design, hindering safe and economic implementation.
Why is it important for society:
Housing need: The significant deficit in housing supply and the need for more responsible and efficient construction policies underscores the need for MMC in general, and CFS panelised systems in particular, to deliver rapid, resilient and cost-efficient housing solutions. This research supports the uptake of MMC, helping governments address societal needs and providing affordable dwellings, including social housing and emergency or disaster response structures.
Environmental benefit: There is an obligatory requirement for more sustainable construction solutions to meet UN SDGs. CFS panelised structures are material-efficient, highly recycled, and adaptable, reducing embodied carbon emissions. Their wider adoption supports a greener economy, “low carbon, resource efficient and socially inclusive”, by delivering safer, more affordable and more sustainable buildings with reduced waste.
Economic/industry benefit: Limited design guidance for CFS robustness leads to excessive material use, high design costs and low industry confidence. This research develops guidance, improving connection detailing, modelling and reducing waste, enabling safer, more efficient construction and wider MMC adoption.
Overall objectives:
The aim of the Concatenation project is to evaluate the behaviour of cold-formed panelised (CFS) structures under accidental loss of support and develop connection performance criteria to enable floor catenary action as a collapse resistance mechanism under accidental loading. This fellowship undertakes:
- First-of-its-kind large-scale testing of industry-standard CFS connections under loss-of-support conditions to understand connection ductility, rotation and tensile behaviour.
- Development of validated analytical and numerical models
- Assessment and refinement of existing design guidelines in line with European standards
- Simplified modelling recommendations to imrpove safety, efficiency and sustainability
The output of this research improves safety and confidence in structural robustness of CFS structures, enhances resource efficiency, and increases the competitiveness of CFS MMC sector, which will ultimately reduce costs and support the safe uptake of CFS MMC in construction.
Cold-formed steel (CFS) panelised structures are an increasingly used offsite modern method of construction (MMC) with high strength-to-weight ratio, durability, speed of construction and reduced carbon footprint. Despite these advantages, their robustness under accidental loss of support is poorly understood. Recent developments enabling longer spans, lighter sections and open-plan layouts can reduce robustness and increase vulnerability.
While substantial research exists on CFS element design and standard connections, there is limited understanding of structural interactions and resistance to disproportionate collapse under loss of support, particularly the ability to develop catenary action. The absence of reliable test data and guidance has led to conservative designs, excessive material use, limited industry confidence and restricted uptake of CFS MMC. Current European standards inadequately address their robust design, hindering safe and economic implementation.
Why is it important for society:
Housing need: The significant deficit in housing supply and the need for more responsible and efficient construction policies underscores the need for MMC in general, and CFS panelised systems in particular, to deliver rapid, resilient and cost-efficient housing solutions. This research supports the uptake of MMC, helping governments address societal needs and providing affordable dwellings, including social housing and emergency or disaster response structures.
Environmental benefit: There is an obligatory requirement for more sustainable construction solutions to meet UN SDGs. CFS panelised structures are material-efficient, highly recycled, and adaptable, reducing embodied carbon emissions. Their wider adoption supports a greener economy, “low carbon, resource efficient and socially inclusive”, by delivering safer, more affordable and more sustainable buildings with reduced waste.
Economic/industry benefit: Limited design guidance for CFS robustness leads to excessive material use, high design costs and low industry confidence. This research develops guidance, improving connection detailing, modelling and reducing waste, enabling safer, more efficient construction and wider MMC adoption.
Overall objectives:
The aim of the Concatenation project is to evaluate the behaviour of cold-formed panelised (CFS) structures under accidental loss of support and develop connection performance criteria to enable floor catenary action as a collapse resistance mechanism under accidental loading. This fellowship undertakes:
- First-of-its-kind large-scale testing of industry-standard CFS connections under loss-of-support conditions to understand connection ductility, rotation and tensile behaviour.
- Development of validated analytical and numerical models
- Assessment and refinement of existing design guidelines in line with European standards
- Simplified modelling recommendations to imrpove safety, efficiency and sustainability
The output of this research improves safety and confidence in structural robustness of CFS structures, enhances resource efficiency, and increases the competitiveness of CFS MMC sector, which will ultimately reduce costs and support the safe uptake of CFS MMC in construction.
Following an extensive review of the relevant literature, a comprehensive multi-scale experimental program was undertaken. Six large-scale subassemblies of industry-standard CFS connections were tested under simulated static loss-of-support with vertical displacements up to 700mm. These connections were selected to represent practical, cost-effective solutions aligned with established off-site manufacturing and on-site manufacturer practices, ensuring direct relevance to both the industry and society. Technical challenges were mitigated through bespoke refinements to the rig, restraints, supports and instrumentation to ensure reliability, stability and repeatability. Finite element (FE) models were developed and validated against the experimental results and the formulation of design recommendations is currently ongoing. Findings and valuable insights are being disseminated through conferences, stakeholder events, and several peer-reviewed journal publications under preparation, with follow-on testing and analysis ongoing to expand the project’s impact.
While substantial research exists on the fundamental behaviour of CFS elements and connections, little research has explored their interaction under accidental loss-of-support. To develop catenary action, structural panels must accommodate large rotations with significant axial tensile forces, the combination of which has not been investigated experimentally in CFS systems. This project provides a first-of-its-kind experimental database capturing the behaviour of industry-standard CFS connections under loss-of-support conditions. These results provide a critical foundation for the calibration of numerical models and development of innovative, optimised connections and European design guidance.
This research delivers significant socio-economic and societal benefits including:
- Improved safety and structural robustness in CFS panelised structures
- More cost-effective, resource-efficient design with reduced embodied carbon and costs
- Increased industry confidence and reduced over-design
- Wider adoption of MMC to support construction policies and sustainability targets
- Enhanced competitiveness of the European CFS/MMC sector
- Faster, safer and more affordable housing delivery
This research delivers significant socio-economic and societal benefits including:
- Improved safety and structural robustness in CFS panelised structures
- More cost-effective, resource-efficient design with reduced embodied carbon and costs
- Increased industry confidence and reduced over-design
- Wider adoption of MMC to support construction policies and sustainability targets
- Enhanced competitiveness of the European CFS/MMC sector
- Faster, safer and more affordable housing delivery