Reinforced-concrete half-joint structures
Lead Research Organisation:
University of Cambridge
Department Name: Engineering
Abstract
A concrete half-joint is a structural component whose behavior is not well understood, it presents several problems related to safety of design methods, durability, accessibility for inspection and strengthening. Several bridges with half joints have collapsed in the past causing injuries and fatalities and the wide use of this component represents a serious risk for the community.
Experimental tests on large-scale specimens and numerical analysis will be carried out to study the structural behaviour of this type of joint under different types of loads, the effects of concrete degradation and reinforcement corrosion on the overall capacity, in order to develop analytical tools to better assess existing structures and design safer and more efficient new structures.
Experimental tests on large-scale specimens and numerical analysis will be carried out to study the structural behaviour of this type of joint under different types of loads, the effects of concrete degradation and reinforcement corrosion on the overall capacity, in order to develop analytical tools to better assess existing structures and design safer and more efficient new structures.
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509620/1 | 01/10/2016 | 30/09/2022 | |||
| 1791721 | Studentship | EP/N509620/1 | 05/01/2017 | 31/08/2020 | Michele Mak |
| Description | The initial findings of this research have led to an improved understanding of the fundamental mechanisms that cause a loss of overall structural capacity in ageing concrete infrastructure. Concrete bridges deteriorate and lose strength over time. This leads to significant rehabilitation costs. Infrastructure management is based primarily on visual inspections. However, corrosion of the internal steel reinforcement is among the main causes of deterioration and remains hidden. Evaluating its structural effects is therefore a major challenge. This research focused on correlating parameters that are visible and measurable on the outer concrete, such as surface cracks, to deterioration phenomena that are hidden within the structure, such as steel-to-concrete bond reductions. The results indicate that corrosion of the internal steel reinforcement and bond degradation may be only indirectly correlated. Instead of using measures of corrosion of the internal steel reinforcement as the key parameter for the evaluation of load-carrying capacity, concrete crack widths could potentially be better indicators to characterise bond strength degradation of the reinforcement. Crack widths were found to be a measure of the net amount of corrosion products that generate expansive effects and indicative of a reduction in the mechanical interlock between a reinforcement bar and concrete. Experiments were conducted on steel-reinforced concrete where significant general steel corrosion (up to average mass losses of 25.5%) was induced. It was found that under certain conditions expansive pressures did not build up. Conditions of limited oxygen and the presence of chlorides led to the development of liquid corrosion products. Before solidifying, these corrosion products flowed in the voids and porous structure of the concrete. Expansive pressures were therefore relieved. As a result, corrosion-induced cracking was delayed or did not occur at all. It was observed that accelerated corrosion techniques using an impressed current in the presence of chlorides can lead to non-uniform corrosion along the bar and localised pitting corrosion. The experimental results also highlighted that a specimen design that follows recommendations for concentric pull-out bond tests presents challenges if corrosion-induced cracking is also studied: the presence of a debonding sleeve induces a stress-free concrete zone adjacent to the corroded part, which reduces corrosion-induced crack widths. The results indicated the necessity to develop specifications and standardise accelerated corrosion testing methodologies for bond tests, with respect to both mechanical and chemical phenomena. These findings led to the development of a novel testing methodology. A new geometry and set-up were developed and validated experimentally, whereby the parasitic effects of external confinement from the support was removed. This new methodology was adopted in an experimental programme that investigated the effects of transverse reinforcement on the bond behaviour of deformed steel bars. The findings suggested that the presence of internal transverse reinforcement is beneficial to bond performance, but the enhancing effects are limited and may depend on the presence of cracks in the concrete cover surrounding the bars. This highlighted a critical aspect of a type of reinforced concrete component, called half-joint, that is very common in bridges. There are over 424 half-joint bridges within the Highways England Strategic Road Network alone, and many more worldwide. This structural configuration is characterised by a reduction in depth at the supports. The underside of the full-depth section does not benefit from support confinement in the anchorage zone of the longitudinal tensile reinforcement. Moreover, leakage of contaminated water often causes corrosion of the internal steel reinforcement and cracking of the concrete cover. Thus, half-joints are particularly vulnerable to bond degradation due to corrosion and cracking. To develop an improved understanding of deterioration in reinforced concrete half-joints structures and to study the consequences of anchorage degradation on the overall behaviour of the component, an experimental investigation was carried out on scaled half-joint beams where anchorage deterioration was simulated. The specimens were tested to failure. The results highlighted the inadequacy of current design-based predictive models when used for the strength assessment of structures in the presence of deterioration. Analytical predictions based on the lower bound theorem of plasticity were found to be overly conservative and did not capture the behaviour observed experimentally. This was attributed to a combination of local effects of greater anchorage capacity than predicted and global effects relating to alternative load-paths not taken into account by the predictive models. It was concluded that local deterioration led to a premature local failure of the half-joints, whilst the rest of the structural component was far from its ultimate behaviour and little redistribution had occurred. These conditions undermine the assumptions that underpin plasticity-based models for new design, thus reducing their accuracy when used for the assessment of existing structures in the presence of deterioration. The findings suggest further research directions towards the development of more accurate assessment of existing infrastructure. |
| Exploitation Route | The results of the project have been presented and discussed with international academics during scientific conferences and workshops, representatives of governmental asset management agencies (Highways England) and engineering consultants (Arup). The findings can lead to the development of a new and potentially more accurate approach for the structural assessment of deteriorated reinforced concrete structures. Improved and more accurate assessments can reduce the maintenance costs of the infrastructure network by limiting onerous interventions such as repairs, strengthening or replacement of entire bridges. |
| Sectors | Construction,Transport |
| Description | Our research findings are informing strategies for the assessment of existing reinforced concrete half-joint infrastructure. |
| First Year Of Impact | 2017 |
| Sector | Construction,Transport |
| Impact Types | Societal,Economic |
| Description | Cambridge Philosophical Society Travel Grant |
| Amount | £250 (GBP) |
| Funding ID | S54/111/18 |
| Organisation | Cambridge Philosophical Society |
| Sector | Charity/Non Profit |
| Country | United Kingdom |
| Start | 11/2018 |
| End | 11/2018 |
| Description | Cambridge Philosophical Society Travel Grant |
| Amount | £300 (GBP) |
| Funding ID | S54/058/19 |
| Organisation | Cambridge Philosophical Society |
| Sector | Charity/Non Profit |
| Country | United Kingdom |
| Start | 05/2019 |
| End | 05/2019 |
| Description | Cambridge University Engineering Society Individual Grant |
| Amount | £300 (GBP) |
| Organisation | Cambridge University Engineering Society |
| Sector | Learned Society |
| Country | United Kingdom |
| Start | 11/2018 |
| End | 11/2018 |
| Description | Sidney Sussex College Graduate Fund |
| Amount | £500 (GBP) |
| Organisation | University of Cambridge |
| Department | Sidney Sussex College, Cambridge |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 11/2018 |
| End | 11/2018 |
| Description | Sidney Sussex College Graduate Fund |
| Amount | £500 (GBP) |
| Organisation | University of Cambridge |
| Department | Sidney Sussex College, Cambridge |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 05/2019 |
| End | 05/2019 |
| Title | Data supporting: Corrosion-Induced Cracking and Bond Strength in Reinforced Concrete |
| Description | Dataset contains results from an experimental programme that investigated the structural effects of corrosion of the internal steel reinforcement embedded in concrete. It includes information on concrete mix composition, results from standard material characterisation tests (i.e. compressive strength on cubes and cylinders, indirect tensile splitting strength), predicted and measured levels of steel corrosion from accelerated corrosion testing using an impressed current, measurements of corrosion-induced concrete surface crack widths, bond strength from concentric pull-out tests, and bond stress-slip curves. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2018 |
| Provided To Others? | Yes |
| Impact | The data was used for the publication Mak, M.W.T., Desnerck, P. and Lees, J.M. (2019) Corrosion-induced cracking and bond strength in reinforced concrete. Construction and Building Materials, 208:228-241. https://doi.org/10.1016/j.conbuildmat.2019.02.151 |
| URL | https://www.repository.cam.ac.uk/handle/1810/290909 |
| Title | Data supporting: Corrosion-Induced Cracking and Bond Strength in Reinforced Concrete |
| Description | Research data supporting the journal paper: Mak, M.W.T., Desnerck, P., Lees, J.M. (2019). Corrosion-induced cracking and bond strength in reinforced concrete. Construction and Building Materials, 208, 228-241. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2019 |
| Provided To Others? | Yes |
| Impact | Evidence for improved understanding of the impact of corrosion-induced cracking on the bond behaviour of internal steel reinforcement in concrete. |
| Description | Highways England |
| Organisation | Department of Transport |
| Department | Highways Agency |
| Country | United Kingdom |
| Sector | Public |
| PI Contribution | Knowledge transfer, delivery of research advances and sharing of research findings |
| Collaborator Contribution | Highways England 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 with Arup on Reinforced Concrete Design & Assessment |
| Organisation | Arup Group |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Ongoing engagement with ARUP team regarding research findings Hosting of a Cambridge/ARUP meeting in Cambridge on Feb 1, 2019 on recent research findings in relation to the strength assessment of reinforced concrete bridges, and tailored reinforced concrete structures |
| Collaborator Contribution | Technical advice and feedback |
| Impact | Closer collaboration, knowledge transfer |
| Start Year | 2017 |
| Description | Cambridge/Highways England Roadmapping Workshop |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | This was a high-level workshop facilitated by the Cambridge Institute for Manufacturing Education and Consultancy Services. It drew together professionals from Highways England and researchers from the Concrete and Composites Research Group led by Janet Lees to discuss and formulate fruitful and collaborative research areas and directions . |
| Year(s) Of Engagement Activity | 2017 |
| Description | Industry/Academia Workshop for knowledge exchange - University of Cambridge, University of Toronto, Queen's University, Highways England and Atkins |
| 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 | A workshop to showcase emerging University of Cambridge research findings relating to the lifetime extension of existing infrastructure and carbon efficient concrete, recent advances at the University of Toronto and Queen's University in the context of reinforced concrete infrastructure and structural health monitoring, and the latest challenges, findings and developments from the perspectives of Highways England and Atkins was an excellent platform for knowledge exchange and further collaboration. |
| Year(s) Of Engagement Activity | 2019 |
| Description | Keynote presentation (Lees) - 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures - 27 - 29 August 2019 in Potsdam, Germany |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Professor Lees presented a keynote lecture on: Mismatches between design and condition assessment in reinforced concrete with or without FRP strengthening |
| Year(s) Of Engagement Activity | 2019 |
| URL | https://www.smar2019.org/ |
| Description | Masterclass in Civil Engineering |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Schools |
| Results and Impact | I delivered a masterclass in Civil Engineering to year 12 pupils about the structural design of bridges, tall buildings and domes. |
| Year(s) Of Engagement Activity | 2018 |
| Description | Online magazine interview about doctoral studies in the UK |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Media (as a channel to the public) |
| Results and Impact | I have been interviewed by an international journalist about doctoral studies in the United Kingdom. |
| Year(s) Of Engagement Activity | 2018 |
| Description | Pecha Kucha presentation at Science Festival |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Schools |
| Results and Impact | One of our research team, Michele Mak, presented a talk at the Cambridge Science Festival - Hidden secrets of concrete bridges - about his research with 20 slides where each slide is shown for 20 seconds. |
| Year(s) Of Engagement Activity | 2017 |
| Description | Podcast interview about the environmental sustainability of concrete and concrete structures |
| Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | Michele has been invited to participate in a podcast named 'Parole in Connessione' (Italian) [Words in Connection] on an episode about cities, sustainability, construction and transports. He has been interviewed by an academic from TU Delft on the topic of structural safety, concrete sustainability, circular economy and the reduction of the environmental footprint of infrastructure through lifetime extension. |
| Year(s) Of Engagement Activity | 2021 |
| URL | https://open.spotify.com/episode/4imMtWf17Cz36Cit7dGGR2 |
| Description | Presentation at 1st fib Italy YMG Symposium on Concrete and Concrete Structures, Parma, Italy |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on 'Bond degradation and reduced cover in concrete with transverse reinforcement' during 1st fib Italy YMG Symposium on Concrete and Concrete Structures, Parma, Italy |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presentation at 5th International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2018, Cape Town, South Africa |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on 'Correlation between surface crack width and steel corrosion in reinforced concrete' during 5th International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2018, Cape Town, South Africa |
| Year(s) Of Engagement Activity | 2018 |
| Description | Presentation at Adam Neville Centre of Excellence in Cement and Concrete Symposium 2020 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on `Deterioration and cracking in reinforced concrete bridges' during Adam Neville Centre of Excellence in Cement and Concrete Symposium 2020 |
| Year(s) Of Engagement Activity | 2020 |
| Description | Presentation at Concrete and Earthquake Engineering Seminar, University of Sheffield, UK |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on `Assessment of bond deterioration in concrete bridges - Towards a splitting crack-based approach' during Concrete and Earthquake Engineering Seminar Series at the University of Sheffield, United Kingdom. |
| Year(s) Of Engagement Activity | 2021 |
| Description | Presentation at IABSE Congress 2020 - Resilient Technologies for Sustainable Infrastructure |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on `Assessment of corrosion-induced bond deterioration in reinforced concrete - Towards a splitting crack-based approach' |
| Year(s) Of Engagement Activity | 2021 |
| Description | Presentation at IStructE Young Researchers Conference 2020 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Presentation by a team member (Mak) on `Assessment of bond deterioration in reinforced concrete bridges: Towards a splitting crack-based approach' during IStructE Young Researchers Conference 2020. |
| Year(s) Of Engagement Activity | 2020 |
| URL | https://www.istructe.org/resources/news/2020-young-researchers-conference-report/ |
| Description | Presentation at SPP Italy 2019 Conference - Science Policy Public, Cambridge, UK |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on 'Towards an effective data based infrastructure management system' during SPP Italy 2019 Conference - Science Policy Public, Cambridge, UK |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presentation at Sidney Sussex College Graduate Seminars, Cambridge, UK |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on historical bridge failures and forensic engineering during Sidney Sussex Collage Graduate Seminars, Cambridge, UK |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presentation at fib Symposium 2019 on Concrete - Innovation in Materials, Design and Structures, Krakow, Poland |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on 'Development of a novel bond test set-up for concrete with trans-verse reinforcement' during fib Symposium 2019 on Concrete - Innovation in Materials, Design and Structures, Krakow, Poland |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presentation at fib Symposium 2020 - Concrete Structures for Resilient Society |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Presentation by a team member (Mak) on `Effects of anchorage deterioration on the shear behaviour of reinforced concrete half-joint beams' |
| Year(s) Of Engagement Activity | 2020 |
| Description | Publication of a technical news web-article to disseminate research findings to professional audience |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Michele W.T. Mak is a PhD candidate working on the assessment of deteriorated reinforced concrete bridges. Further to being awarded the fib Italy YMG Award for Best Research Advances in Concrete and Concrete Structures 2019, a Technical News article about his doctoral research has been published on the website of the Collegio dei Tecnici della Industrializzazione Edilizia (CTE), the Italian Board of Building Industry Specialists. The title of the dissemination article is 'Il degrado del calcestruzzo e la valutazione della sicurezza di ponti: un approccio basato sulla apertura di fessura' (Italian) [Concrete degradation and bridge assessment: a crack-based approach]. |
| Year(s) Of Engagement Activity | 2021 |
| URL | https://www.cte-it.org/il-degrado-del-calcestruzzo-e-la-valutazione-della-sicurezza-di-ponti-un-appr... |
| Description | Reinforced concrete half-joints - Workshop hosted by Cambridge University |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | The workshop drew together a number of diverse stakeholders from Highways England, Heriot-Watt University, Cambridge University and a representative from one of Highways England's Framework providers to discuss and share the latest findings and developments relating to reinforced concrete half-joint structures. |
| Year(s) Of Engagement Activity | 2017 |