Reinforced concrete infrastructure, Understanding the past, present and future

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

The construction industry is of critical importance to the UK economy and typically represents between 6-8% of the national GDP. But the large scale of this output comes at an environmental cost. The efficient design and lifetime extension of structures is therefore a social, environmental and economic priority.
The focus of this proposal is reinforced concrete where a major complication in delivering efficient, sustainable, low-maintenance solutions is that the performance of these structures reflects numerous factors including the initial design, the in-service conditions, the load history and any interventions during the service life. In service, one of the challenges is that there is an interaction between the concrete and the internal reinforcement and this behaviour is not currently well understood. This problem is exacerbated when considering how shear forces are transferred since questions still remain about how even a basic reinforced concrete structure carries these forces under static load conditions. Indeed, the 2006 collapse of the de la Concorde Overpass in Quebec is a tragic reminder of the impact of the initial design, in-service repairs and bridge management all contributed to the eventual collapse. It is therefore clear, considering the potential environmental and public safety issues, that a fundamental investigation to ascertain the types of structures and loadings which may be susceptible to time dependant changes in load sharing mechanisms that could be detrimental to the structural performance is overdue.
The situation becomes even more complex when interventions to increase or re-establish the strength of an existing structure are required. For example, the application of additional external fibre reinforced polymer (FRP) reinforcement has been found to be an effective means to achieve the capacity increases required to keep existing structures in service. FRPs have a high strength to weight ratio and are lighter and more durable than equivalent steel strengthening systems. However, this additional reinforcement changes the load-sharing behaviour of the structure. Furthermore, in many cases, the provision of the additional reinforcement addresses an immediate strengthening need where speed and ease of installation are primary considerations. However while the initial motivation may be for a short-term intervention, it is likely that, due to the disruption and costs associated with demolition and reconstruction, many of these FRP strengthening systems will be in service for a considerable period of time. To date, the longer term in-service performance of strengthened RC structures has not been adequately addressed. Cost-effective approaches for extending the life of existing infrastructure are becoming increasingly important in the current era of financial constraints.
This project seeks to address these identified gaps through the establishment of a high-level, enduring, international collaboration between the University of Toronto (U of T), Canada, Queen's University, Canada and the University of Cambridge, UK. The particular strength of this collaboration is that it brings together the necessary expertise to re-evaluate the time- and load-dependent baseline conditions in an existing reinforced concrete structure and to then assess and predict the long-term performance of both unstrengthened and FRP-strengthened structures. This enhanced understanding will inform asset owners and managers and lead to improved design and maintenance strategies.

Planned Impact

The main focus of the Overseas Travel Grant is the establishment of a high-level inter-disciplinary collaboration to investigate the design, assessment and in-service performance of reinforced concrete infrastructure. The proposal draws together a wealth of knowledge and experience. The opportunity for Dr Lees to work with Professors Collins, Bentz and Hoult to establish an International collaboration to address key challenges associated with civil engineering infrastructure will have notable academic, economic and societal impacts. Collectively there will be tremendous added-value in the synergy of the expertise of the project partners. Of particular significance are the potential repercussions of the outcomes for industry and governmental bodies in terms of a deeper understanding of how our critical, and extensive, reinforced concrete infrastructure assets perform throughout their lifetimes and the implications for the assessment of the residual strength capacity and any subsequent interventions.

The membership of the Advisory Committee has been targeted to represent industrial, academic and governmental interests. The Advisory Committee will provide a direct, high-level path for dissemination and feedback and will benefit from immediate access to the research findings. Their involvement will also be tremendously valuable in the context of understanding and translating the findings and improving relevant design practice. All the project partners have strong links with Industry and these links will also be used to transfer knowledge and experience between academia and industry.

The forum for discussion and collaboration with our North American colleagues will also bi-laterally enhance the awareness of International practices. The interaction between leading international research laboratories will also promote improved research practices and procedures and act as a catalyst for innovative testing protocols and ideas.
 
Description In 2008, the UK annual construction output was worth over £120 billion with expenditure on repair and maintenance representing approximately £55 billion/year. This EPSRC Overseas Travel Award (EP/J002887/1) was successful in establishing a high-level, enduring, inter-disciplinary collaboration between the University of Toronto, Canada, (Professors Collins and Bentz), Queen's University, Canada (Professor Hoult), and the University of Cambridge (Dr Lees) to understand the impact of initial design choices, and subsequent interventions, on the long-term performance of vital reinforced concrete infrastructure. Advances in these areas have extensive societal repercussions in the context of environmental impact mitigation, public safety, the avoidance of disruption, and economic prosperity by allowing for the more accurate assessment and efficient management of structures.
Dr Lees' research visits to North America have acted as a catalyst for engagement in a wide range of collaborative international research activity. A successful EPSRC research proposal - Reinforced concrete half-joint structures: Structural integrity implications of reinforcement detailing and deterioration (EP/K016148/1) - is a direct example of the benefit of this interaction. Professors Collins, Hoult and Bentz are international collaborators on the project and Professor Mitchell from McGill University, Canada has further expanded and strengthened the collaborative academic team. The opportunity to compare and reflect upon different design practices and experience in Canada and the UK has been incredibly valuable in the formulation of the project scope and direction. In addition, Professor Hoult successfully applied for funding for a student to work with Professor Hoult and Dr Lees to conduct experiments to validate theory developed at Cambridge as part of an ongoing research investigation. Dr Lees sat on the International Steering Committee for a NSERC Canada Strategic Grant - Protecting Canada's Concrete Bridges - led by Professor Hoult with colleagues from Queen's University in collaboration with the University of Toronto and University of Ottawa.
Knowledge transfer has been at the heart of the collaboration and our multi-institution collaboration has developed into an enduring two-way exchange of ideas and personnel. In 2014, Professor Hoult has visited Cambridge on two occasions and Professor Bentz spent three months here during a period of sabbatical leave. These visits, coupled with Dr Lees' stays in Canada, have enabled wider knowledge transfer amongst members of academic staff, research associates and graduate and undergraduate researchers at our respective Universities leading to an enhanced research capability.
Research projects relating to the time-dependent behaviour of reinforced concrete, the shear strength assessment of existing reinforced concrete structures, the measurement and analysis of crack propagation in concrete and the CFRP strengthening of reinforced concrete structures are underway at the University of Cambridge. These projects are taking advantage of the latest modelling developments emerging from the University of Toronto and also monitoring and measurement advances from Queen's University. The emerging research outcomes have the potential to make a real impact to the assessment and management of reinforced concrete infrastructure.
The remit of the Overseas Travel Grant Scheme is 'to visit recognised non-UK centres to study new techniques and to travel from the UK to start or develop international collaborations'. The securing of additional research funding for collaborative research projects, the undertaking of reciprocal exchange visits and the delivery of research to provide technical solutions for infrastructure challenges are evidence of the success of the scheme in meeting its aims.
Exploitation Route 1. Emerging publications and new research findings are leading to world-wide academic advancement
2. Benefits to the training of highly skilled researchers have already been realised and will continue through our enduring collaborative activity
3. Research leading to the lifetime extension of existing reinforced concrete infrastructure will result in more environmentally sustainable outcomes
4. Knowledge dissemination and interactions between the academic researchers and Industry and Governmental partners in the UK and Canada is enhancing the research capacity, knowledge and skills of the wider Construction sector.
Sectors Construction,Transport
 
Description The Overseas Travel Award was successful in acting as a springboard for collaborative research activity from which exciting research findings are now emerging.
First Year Of Impact 2014
Sector Construction,Transport
Impact Types Societal,Economic
 
Description EPSRC Established Career Fellowship
Amount £1,290,683 (GBP)
Funding ID EP/N017668/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 06/2017 
End 05/2022
 
Description Reinforced concrete half-joint structures: Structural integrity implications of reinforcement detailing and deterioration
Amount £385,153 (GBP)
Funding ID EP/K016148/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 09/2013 
End 09/2016
 
Description Highways Agency 
Organisation Department of Transport
Department Highways Agency
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Public 
PI Contribution Knowledge transfer, delivery of research advances and sharing of research findings
Collaborator Contribution The Highways Agency have supported a number of funded EPSRC projects including (EP/K016148, GR/S55101/01, EP/I018972/1 and EP/J002887/1). This support has included technical guidance, access to data relating to reinforced concrete infrastructure, sharing of experience in managing the strategic road network in the UK and guidance regarding the main challenges faced on the network. This has ensured the long-term relevance of our research and extensive knowledge exchange.
Impact Knowledge transfer, revision of design guidance, formulation of research proposals for funding, improved understanding of reinforced concrete infrastructure assets
Start Year 2006
 
Description Knowledge exchange between the University of Cambridge and Queen's University 
Organisation Queen's University, Kingston
Country Canada 
Sector Academic/University 
PI Contribution As a result of Dr Janet Lees' overseas travel award for research visits to Canada (EP/J002887/1), Dr Lees and Professor Hoult from Queen's University have strengthened existing collaborations and forged new collaborations. They are currently collaborating on a MSc student project at Queen's University which is based on research conducted at Cambridge investigating crack propagation. Professor Hoult and his team are providing fibre optic sensor results which will help validate models developed at Cambridge. Dr Lees has provided strategic technical guidance through her membership of the Steering Committee of a Canadian NSERC Strategic grant led by Professor Hoult in collaboration with the University of Toronto and the University of Ottawa.
Collaborator Contribution Professor Hoult is a member of the International Steering Committee for our Cambridge-based EPSRC funded research project (EP/K016148/1) to investigate reinforced concrete half joints. During two recent visits to Cambridge Professor Hoult has been working with the project team on collaborative aspects. We also collaborate through SKYPE meetings.
Impact Additional research funding, international research collaboration, knowledge transfer, student training
Start Year 2010
 
Description Knowledge exchange between the University of Cambridge and University of Toronto 
Organisation University of Toronto
Department Civil and Mineral Engineering
Country Canada 
Sector Academic/University 
PI Contribution As a result of Dr Janet Lees' overseas travel award for collaborative research visits to Canada (EP/J002887/1), a number of new and exciting research projects have been instigated in collaboration with the University of Toronto (U of T) . A PhD project started at the University of Cambridge in Oct 2012 to undertake research to investigate the time-dependent behaviour of reinforced concrete. The Cambridge PhD student is applying an analytical approach developed at the University of Toronto (U of T) and linking this to experiments undertaken in Cambridge. The collaboration with U of T is also benefiting an EPSRC funded project relating to the CFRP shear strengthening of reinforced concrete T-beams (EP/J002887/1) where the Cambridge team is building on analytical work undertaken by the University of Toronto which we feel can be adapted to a new class of problems. Professors Bentz and Collins are International Collaborators on a EPSRC project on reinforced concrete half joints (EP/K016148/1) where our two Institutions are actively sharing and discussing research findings.
Collaborator Contribution Under the aegis of EP/J002887/1 Professors Bentz and Collins hosted Dr Lees in Toronto during Spring/Summer 2012 and subsequently on short term repeat visits during 2013/2104. Dr Lees worked with Professors Bentz and Collins during her stays and was not charged a bench fee. As a result of these visits and discussions, Dr Lees submitted a successful EPSRC proposal - Reinforced concrete half-joint structures: Structural integrity implications of reinforcement detailing and deterioration (EP/K016148/1). Professors Bentz and Collins are International Collaborators on this grant. To further develop our collaboration, Professor Bentz spent a three month period of sabbatical leave at the University of Cambridge in 2014.
Impact Additional research funding, international research collaboration, new approaches to reinforced concrete design, analysis and assessment, student training
Start Year 2012
 
Description Parsons Brinckerhoff 
Organisation Parsons Brinckerhoff
Country United States of America 
Sector Private 
PI Contribution Knowledge transfer, delivery of research advances and sharing of research findings
Collaborator Contribution Chairing/membership of steering committees for a number of EPSRC funded grants, technical advice and support
Impact Knowledge transfer, incorporation of research findings into design guidance and Industry practice
Start Year 2010