Performance-Based Optimisation of Novel Lightweight Steel Frame Systems for Rapid, Economical and Sustainable Construction

Lead Research Organisation: University of Sheffield
Department Name: Civil and Structural Engineering

Abstract

Cold-formed steel (CFS) structures offer an economic and sustainable alternative to traditional construction techniques, and are increasingly adopted in modern building construction due to their light weight, speed of construction and recyclability. However, typical CFS wall-panel structures have the following limitations that should be addressed before they can be widely used in modern building construction: 1) Low buckling resistance and ductility in CFS members and joints; 2) No generic method for optimisation of CFS structural systems, capable of taking into account both manufacturing and construction constraints; 3) Extensive reliance on fixed load-bearing walls.

The main aim of the research is to develop a novel performance-based optimisation framework to address the challenging optimisation problems associated with complex CFS structural systems at both element and structural levels. The framework will be used to develop a new generation of high-performance dual wall-frame CFS systems, which are suitable for tall buildings and resilient to extreme load conditions. The overall objectives of the project are to:

1- Enhance strength and ductility of CFS structural systems to increase collapse resistance and overall safety under extreme events (such as blast and strong earthquakes), through the development of special connections and high-performance dual wall-frame systems.

2- Decrease structural weight and construction cost through advanced CFS section optimisation, accounting for dimensional and manufacturing limitations, and by developing a novel performance-based optimisation framework to obtain cost-effective CFS structures with better structural performance at serviceability and ultimate limit states.

3- Increase structural and architectural design flexibility by developing optimised CFS frame systems that eliminate (or reduce) the need for fixed CFS load-bearing wall panels.

The output of the proposed research will give a competitive advantage to the UK construction sector and will have a long term impact on UK economic growth by developing more efficient light-weight steel structural systems that can reduce overall construction costs and provide higher strength and ductility. The work will be conducted in partnership with key UK CFS industries. Industrial liaison and dissemination activities, including a project conference, are planned to ensure the take-up of the new technology and benefit international researchers and UK organisations.

Planned Impact

WHO WILL BENEFIT AND HOW?
The cold-formed steel (CFS) global market is growing very rapidly in China and North America (see section 2.6 for more information). This proposal will be an important step in tackling the gap in knowledge and tools for optimisation of CFS systems and will develop a new generation of high-performance dual wall-frame CFS systems. The main beneficiaries from the project will be:

- CFS industry: The project will provide the UK CFS industry with a framework to develop technology to increase and diversify their markets in the UK and abroad. The high-performance dual wall-frame systems will help CFS industries by enabling faster uptake of CFS structures.

- End users: Consultants, contractors, engineers, practitioners and governmental agencies will benefit from advanced optimisation tools, basic design recommendations and design examples. The performance-based optimisation framework can be directly used to optimise existing CFS structural systems and modular systems, and hence contribute to the competitiveness of UK consultants and contractors by providing more efficient design solutions.

- Academics: See section on Academic Beneficiaries.

- Professional bodies: SCI, IStructE, ICE, AISC, and NHBC will benefit from the novel performance-based optimisation approach for more efficient design of CFS structures, and high quality results derived from experimental tests and advanced FEA simulations.

- Society: The proposed project will improve the quality of life by developing more resilient and robust structures to cope with climate change as well as man-made and natural hazards.

- People: The research programme will train a highly skilled post-doctoral research assistant (PDRA) by providing him/her with the opportunity to work in partnership with a PhD student, the PI and an experienced technician at the University of Sheffield. The PDRA will attend an international conference and various UK workshops and seminars, and will be actively involved in engagement activities with industrial consultants and national and international research teams. Such training will have a direct economic impact via the provision of skilled workers who may subsequently be employed by any beneficiary organisation.

- Environment: The proposed project will help environment by reducing CO2 emissions and embodied energy, through decreasing structural weight and better use of material. It is estimated that if just 5% of the annual need of 4 billion m2 for new constructions worldwide were built from the new CFS system, it could save around 4 million tonnes of steel. This would result in about 3.5 million tonne reduction of CO2 emissions and 70,000 TJ embodied energy per year (see 'Pathways to Impact').

WHAT WILL BE DONE TO ENSURE THAT THEY HAVE THE OPPORTUNITY TO BENEFIT?
- Basic design recommendations and design examples will be prepared for use by engineers and practitioners (developed in close collaboration with members of the industrial steering committee).

- Improved optimisation design tools will be made available, for incorporation in software usable by engineers.

- Representatives of key Uk's CFS industry will participate on the project steering committee to ensure the impact of the work is maximized.

- Presentations will be made at professional meetings and key papers will be submitted to professional as well as academic journals.

- A workshop will be organised at Sheffield assembling related cross disciplinary researchers, project supporters and potential beneficiaries to ensure the take-up of the new technology and benefit international researchers and UK organizations.

WHEN?
The academic and professional benefits of the research will start arising just before the end of the project, and as soon as the first experimental data are processed and published. Major benefits to CFS industry should start to be realised within 1 to 2 years of completion of the research.

Publications

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Becque J (2014) Structural optimization of a cold-formed steel channel section for compression and bending in Engineering and Applied Sciences Optimization (OPT-i)

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Becque J (2014) An Optimization Framework for Optimum Design of Cold-Formed Steel Compression and Bending Elements in The 7th International Conference on Thin-Walled Structures (ICTWS 2014)

 
Description •A novel shape optimisation method is developed to obtain optimised cold-formed steel (CFS) elements based on buckling and post-buckling behaviour as well as manufacturing and construction constraints. The results are CFS beam and column sections with up to 30% higher flexural and axial strength compared to existing standard sections.

•Based on the proposed optimisation methodology, a computer programme (open source) is developed to obtain optimum CFS sections for practical design purposes. This programme can be efficiently used by engineers and practitioners.

•For the first time, optimum CFS sections are obtained for 10 different standard prototypes using different design parameters (e.g. length, coil width and sheet thickness). These standard elements can be used by structural engineers as 'off-the-shelf' elements or as part of optimised CFS structural systems.

•The results of this study showed that a folded flange section can provide better design solutions by satisfying all manufacturing and construction constraints. This novel cross section can be efficiently used in the construction of CFS modular structures and can reduce the total structural weight by up to 25%.

•The optimised sections developed in this study can considerably decrease the structural weight and construction cost of CFS structures and provide higher load resistance, which makes them suitable for tall buildings and resilient to extreme load conditions. This can also reduce the CO2 emissions and embodied energy for new constructions.
Exploitation Route UK CFS industry, consultants, contractors, engineers, practitioners and governmental agencies are the most likely non-academic beneficiaries of the results of this research. Special efforts have been made to ensure these parties have full opportunity to benefit from the research undertaken. To help the findings of this research be taken forward:

•The practical outcomes of the project have been presented to a few key potential industrial beneficiaries in the UK. More direct visits will be arranged in future.

•The preliminary results of this study have been presented in three conference papers. More publications are planned in scientific journals as well as professional journals widely read by engineers and practitioners.

•A design tools has been developed for engineers and practitioners. The PI and the industrial partners will encourage incorporation of the developed optimisation methods in commercial software applications by alerting the developers of CFS software.

•Short technical presentations will be given at events which are attended by engineers and representatives of UK consultants (e.g. SCI, ICE, and IstructE events).

•Leaflets and posters will be distributed and displayed at University Open Days, Headstart Engineering Summer School (a four day residential course for year 12 students) and Researchers' Night events, using the assistance of school liaison office of the University of Sheffield.

•One day workshop will be held at the University of Sheffield at the end of the project by inviting the project's supporters, engineers, CFS software developers, and prominent researchers from UK, EU and US to discuss outcomes of this research and to map future research directions. As a part of the programme, the efficiency of the developed optimum design tool will be demonstrated by using practical example, followed by an open discussion.
Sectors Construction,Environment

URL https://www.istructe.org/downloads/near-you/yorkshire/istructe-yorkshire-16-may-2016-2nd.pdf
 
Description The results of this study have been already used by BW Industries (one of the industrial partners) and WElink Group (specialised renewable energy company) to make more cost-effective cold-formed steel (CFS) sections. Using the same amount of material, the optimised sections developed in this project have up to 40% higher flexural and axial strength compared to existing standard sections.
First Year Of Impact 2015
Sector Construction
Impact Types Economic

 
Description Training researchers
Geographic Reach National 
Policy Influence Type Influenced training of practitioners or researchers
Impact The preliminary results of this study have been presented in my lecture materials at The University of Sheffield. This could help our MEng and MSc graduates in Structural Engineering use light-weight cold-formed steel (CFS) structural systems as sustainable and cost-effective alternatives to conventional hot-rolled steel structures.
 
Description PhD Studentship
Amount £55,000 (GBP)
Organisation University of Sheffield 
Sector Academic/University
Country United Kingdom
Start 03/2014 
End 02/2018
 
Title CFS optimised sections 
Description A new algorithm is developed to optimise complex cold-formed steel (CFS) beam and column sections based on Eurocode-3 by taking into account the manufacturing and construction constraints. The optimisation algorithm is used to produce a complete catalogue of optimum CFS sections, which can be directly used in the practical design of resilient CFS structural systems. 
Type Of Material Computer model/algorithm 
Year Produced 2015 
Provided To Others? Yes  
Impact The developed optimisation methodology and practical optimum CFS sections can lead to up to 30% less structural weight and construction cost. 
 
Description BW 
Organisation BW Industries
Department Research and Development
Country United States 
Sector Private 
PI Contribution An advanced software is developed by my research team at The University of Sheffield to obtain more efficient cold-formed steel (CFS) beam and column sections with significantly higher ultimate capacity compared to existing standard sections. This has led to high-performance CFS dual wall-frame structural systems, which can be efficiently used in modular construction.
Collaborator Contribution The BW Industries has provided access to valuable data and information on manufacturing process of CFS sections and construction constraints. They also provided the CFS sections required for the beam and column testing specimens.
Impact - Advanced software to optimise complex cold-formed steel (CFS) sections based on Eurocode-3 by taking into account the manufacturing and construction constraints. -More efficient and cost-effective CFS beam and column sections. -More resilient CFS systems for new generation of modular structures.
Start Year 2014
 
Title CFS optimisation software 
Description User-friendly software is developed by my research team at The University of Sheffield to find more efficient cold-formed steel (CFS) beam and column sections with significantly higher ultimate capacity compared to existing standard sections. The software is developed in MATLAB. 
Type Of Technology Software 
Year Produced 2014 
Open Source License? Yes  
Impact The developed optimisation software can be efficiently used by engineers and practitioners to design more efficient and resilient cold-formed steel (CFS) structural systems. 
 
Description European workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Actively participated in a workshop on resilient structures for seismic regions as a part of European Conference on Earthquake Engineering in 2014. The discussions with the experts and prominent researchers helped the development of ideas for more resilient cold-formed steel structural systems suitable for high seismic regions.

I received very positive feedback from both academics and practitioners. After the conference, I received several PhD applications, who are all interested in working on the areas directly related to this project. I also received to requests from international colleagues to have a sabbatical period in my research group to work with me on the new generation of cold-formed steel structures.
Year(s) Of Engagement Activity 2014
 
Description Four Conference presentations 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact The preliminary results of this research have been presented in three international conferences (see publication section). The presentations and the follow-up questions could help the academic and professional audience learn the principals of a new practical optimisation method to obtain more efficient Cold-Formed Steel (CFS) structural elements.

The audience showed a lot of interest in the methodology and results presented in the conference presentations. The optimisation method developed in this research can be efficiently used to optimise complex non-linear systems (impact on knowledge). The results of this study can improve the quality of life by developing more resilient and sustainable structures and better use of material (impact on economy and society).
Year(s) Of Engagement Activity 2014,2015
 
Description Half day seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Supporters
Results and Impact This half day seminar/presentations was organised by the PI at The University of Sheffield for UK Cold-Formed Steel (CFS) industry, consultants, contractors and engineers. The results of this meeting and the following open discussion led to several innovative and practical ideas to improve the resilient and efficiency of CFS forming process and final products. Some of these ideas will be developed further by applying for new UK and EU funding programmes.

After these talks, my research group received several requests from Cold-Formed Steel (CFS) industry to develop more efficient CFS forming process and structural systems. This can create cost effective structural systems with less structural weight and rapid assembly and enable the faster up take of CFS structures by introducing high-performance systems.
Year(s) Of Engagement Activity 2014
 
Description Half day seminar 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact This half day seminar was organised at The University of Sheffield for UK Cold-Formed Steel (CFS) industry, consultants, contractors and engineers as an IStructE regional event. The results of this EPSRC funded project on the development of more efficient CFS structural systems was presented by Dr Iman Hajirasouliha (PI). The results presented at this seminar and the following open discussions led to several innovative and practical ideas to improve the resilient and efficiency of CFS forming process and final products. Some of these ideas will be developed further by applying for new UK and EU funding programmes with the support from CFS industry.
Year(s) Of Engagement Activity 2016
URL https://www.istructe.org/downloads/near-you/yorkshire/istructe-yorkshire-16-may-2016-2nd.pdf
 
Description Visit BW Industries 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Supporters
Results and Impact I had a visit to BW Industries (one of industrial partners) with two of my PhD students working on new generation of cold-formed steel (CFS) structural systems. The discussions after the visit from the factory helped us understand the manufacturing and construction constraints to produce CFS sections in modular structures.

After this visit, BW Industries approached my research team to help them develop more efficient moment-resisting connections for typical CFS structures, which is a new are area of research related to my project.
Year(s) Of Engagement Activity 2014
 
Description Visit Hadley industries 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact A team from University of Sheffield (including three members of staff and two PhD students working in this field) visited Hadley Hadley Industries (The UK largest cold roll-forming company). It was a formal working group meeting to discuss the outcomes of this EPSRC funded project and map the future activities to support cold-formed steel industry in the UK. A few novel ideas were discussed and potential national and international funding bodies were identified.
Year(s) Of Engagement Activity 2017