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Structures Research Group

 

Biography

Dr Janet Lees is a Professor of Civil Engineering at the University of Cambridge and a Fellow of the Institution of Civil Engineers. Before embarking on a career in research, she spent time in Industry working both for a Consultant and for a Contractor. She received her PhD in Structural Engineering from the University of Cambridge.  She is the leader of the Concrete Infrastructure Research Group (CIRG) within the Civil Engineering Division.  The main research interests of her group relate to the development of more sustainable reinforced concrete infrastructure.  Ongoing project areas include the strength assessment of existing infrastructure, tailored reinforced concrete infrastructure and the use of high performance materials in construction. 

She is a Fellow of St John's College and a Director of the University of Cambridge EPSRC Centre for Doctoral Training in Future Infrastructure and Built Environment.  

Research

The overarching aim of the Concrete Infrastructure Research Group (CIRG) is to provide more sustainable infrastructure. This is achieved through an improved understanding of existing infrastructure assets, the use of new materials and the creation of innovative structural solutions.  Our priority is to investigate novel ways to combine these systems for further advantage.

Current project areas include:

Tailored Reinforced Concrete Infrastructure -  Concrete is the most widely used material in the world. Cement, the key constituent of concrete, is responsible for about 5% of global carbon emissions related to human activities. This makes the current use of concrete particularly hazardous for the environment. Hence, it is vital to develop technologies aimed at minimising the use of cement in concrete structures while preserving, or improving, their innate strength and durability properties. In this context, the concept of tailored reinforced infrastructure represents a promising approach to target specific structural performance while employing less cement. 

Existing Reinforced Concrete Infrastructure - Assessing the true capacity of deteriorated existing concrete structures represents a great challenge for engineers, since many controlling parameters are unknown. Unlike new design, assessors have no control on the design philosophy. The overestimation of the structural capacity can potentially put public safety at risk. However, overly conservative approaches can lead to onerous maintenance measures, sometimes unnecessary.  A better understanding of the behaviour of existing infrastructure helps to support decision-making about reinforced concrete structures in service.

Publications

Key publications: 

Selected Journal Publications (since 2013)*
* Links to papers in the DSpace@Cambridge repository are indicated, a full list of Journal Publications can be found elsewhere

Torelli G, Lees JM. (2019) Fresh state stability of vertical layers of concrete. Cement and Concrete Research. 120, 227-243. https://doi.org/10.1016/j.cemconres.2019.03.006
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
Jin, F. and Lees, J.M. (2019) "Experimental Behaviour of CFRP Strap Strengthened RC Beams Subjected to Sustained Loads". ASCE Journal of Composites for Construction (accepted version) (doi)
Desnerck, P.R.H, Lees, J.M. and Morley, C.T. (2018) "Strut-and-tie models for deteriorated reinforced concrete half-joints". Engineering Structures161 41-54. (published copy)(doi)
Desnerck P., Lees J.M., Valerio P., Loudon N., Morley C.T. (2018) "Inspection of RC half-joint bridges in England: Analysis of current practice". Proceedings of the Institution of Civil Engineers - Bridge Engineering, 1-30 (accepted version) (doi)
Fayyad, T.M. and Lees, J.M. (2018) "Integrated fracture-based model formulation for RC crack analysis". ASCE Journal of Structural Engineering, 144(7). (accepted version) (doi) 
Toumpanaki E., Lees, J.M. and Terrasi G.P. (2018) "Bond durability of carbon fiber-reinforced polymer tendons embedded in high-strength concrete". ASCE Journal of Composites for Construction, 22 (5). (accepted version) (doi)
Tzokova, P.S. and Seffen, K.A. and Lees, J.M. (2018) Ashby chart inspired design of tall modular buildings. Technical Report. Cambridge University Engineering Department, Cambridge
Desnerck, P.R.H, Lees, J.M. and Morley, C.T. (2017) "The effect of local reinforcing bar reductions and anchorage zone cracking on the load capacity of RC half-joints". Engineering Structures152 865-877. (published copy) (doi)
Fayyad, T.M. and Lees, J.M. (2017) "Experimental investigation of crack propagation and crack branching in lightly reinforced concrete beams using digital image correlation". Engineering Fracture Mechanics,  182:487-505 (accepted version) (doi)  
Foster, R.M., Brindley, M., Lees, J.M., Ibell, T.J., Morley C.T., Darby, A.P. and Evernden, M.C. (2017) "Experimental investigation of reinforced concrete T-beams strengthened in shear with externally bonded CFRP sheets " ASCE Journal of Composites for Construction 21(2) 10.1061/(ASCE)CC.1943-5614.0000743 (accepted version) (doi)
Foster, R.M., Haria, S., Morley, C.T. and Lees, J.M. (2017) "Shear capacity of reinforced concrete subjected to tension: Experimental results and analysis " J. Struct. Eng., 143 (9),04017085, (accepted version) (doi)   
Lees, J.M., Toumpanaki, E., Barbezat, M., & Terrasi, G. (2017) " Mechanical and durability screening test methods for cylindrical CFRP prestressing tendons " ASCE Journal of Composites for Construction 0.1061/(ASCE)CC.1943-5614.0000727, 04016080. (accepted version) (doi)
Desnerck, P., Lees, J.M. and Morley, C.T. (2016) "Impact of the reinforcement layout on the load capacity of reinforced concrete half-joints " Engineering Structures v. 27 Nov., pp. 227-239 (published copy) (doi)
Foster, R.M., Morley, C.T. and Lees, J.M. (2016) "Modified Push-off Testing of an Inclined Shear Plane in Reinforced Concrete Strengthened with CFRP Fabric" ASCE Journal of Composites for Construction, 20(3) (postprint), (doi)
Michels, J., Barros, J., Costa, I., Sena-Cruz, J., Czaderski, C., Giacomin, G., Kotynia, R., Lees, J., Pellegrino, C. and Zile, E. (2016) Prestressed FRP Systems. In: Pellegrino C., Sena-Cruz J. (eds) Design Procedures for the Use of Composites in Strengthening of Reinforced Concrete Structures. RILEM State-of-the-Art Reports, vol 19. Springer, Dordrecht
Desnerck, P., Lees, J.M. and Morley, C.T. (2015) "Bond Behaviour of Reinforcing Bars in Cracked Concrete" Construction and Building Materials v. 94, Sept., pp. 126-136 (open access) (doi)
Toumpanaki, E., Lees, J.M. and Terrasi, G.P. (2015) "Shear Modulus of Cylindrical CFRP Tendons Exposed to Moisture" ASCE Journal of Composites for Constructionv. 19 (3) 10.1061/(ASCE)CC.1943-5614.0000521, 04014059 (postprint) (doi)
Yapa, H.D. and Lees, J.M. (2015) "Optimisation of Shear Strengthened Reinforced Concrete Beams" Proceedings of the ICE - Engineering and Computational Mechanicsv. 167 (2) pp. 82–96 (published copy) (doi)
Yapa, H.D. and Lees, J.M. (2014) "Rectangular Reinforced Concrete Beams Strengthened with CFRP Straps"ASCE Journal of Composites for Construction v. 18 (1), 04013032 (postprint) (doi)
Dirar, S., Lees, J.M. and Morley, C.T. (2013) "Precracked RC T-beams Repaired in Shear with Externally Bonded CFRP Straps" ACI Structural Journal v. 110 (5) pp. 855-866 (postprint) (journal)
Dirar, S., Lees, J.M. and Morley, C.T. (2013) "Phased Nonlinear Finite Element Analysis of Precracked RC T-Beams Repaired in Shear with CFRP Sheets" ASCE Journal of Composites for Construction v. 17 (4) pp. 476–487 (postprint) (doi)
Scott, P. and Lees, J.M. (2013) "Water, salt water and alkaline solution uptake in epoxy thin films" Journal of Applied Polymer Science v. 130 (3) pp. 1898-1908 (postprint) (doi)

 

 

 

 

Other publications: 

Selected Conference Papers/Technical Publications (since 2013)*

*A full list of Conference/Technical Publications can be found elsewhere

Mak, M.W.T. and Lees, J.M. (2019) Development of a novel bond test set-up for concrete with transverse reinforcement. 2019 fib Symposium: Concrete - Innovations in Materials, Design and Structures. 27-29 May 2019, Kraków, Poland [Accepted Feb 2019]
Torelli G, Lees JM. (2019) Functionally graded concrete elements composed of vertical layers of different mixes. IABSE Symp., Guimaraes (Portugal).
Toumpanaki, E, Lees JM, Terrasi GP (2019) Effect of bond in the development length of CFRP pretensioned beams, IABSE Symposium 2019 Guimarães Towards a Resilient Built Environment - Risk and Asset Management, March 27-29, 2019, Guimarães, Portugal, IABSE, Swizerland, pp. 635-642
Desnerck,P., Valerio, P., Lees, J.M. and Loudon, N.  (2018) "Suggestions for improved reinforced concrete half-joint bridge inspection in England" 5th International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2018, Cape Town, South Africa 
Mak, M., Desnerck, P. and Lees, J.M. (2018) "Correlation between surface crack width and steel corrosion in reinforced concrete" 5th International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2018, Cape Town, South Africa 
Foster, R.M, Morley, C.T. and Lees, J.M. (2017) "An upper-bound plastic approach to the capacity of reinforced concrete slab-on-beam structures strengthened in shear with externally bonded CFRP" Proceedings of the 8th Biennial Conference on Advanced Composites In Construction, ACIC 2017 Sheffield, UK, Sept 2017 
Gibbons, N., Lees, J. M. and Al-Tabbaa, A. (2017) "Next generation doctoral training for future infrastructure and built environment" Proceedings of the International Symposium for Next Generation Infrastructure, ISNGI 2017 London, UK, Sept 2017 
Jin, F. and Lees, J.M. (2017) "Experimental investigation of time-dependent shear deformation in RC beams strengthened with CFRP straps" SMAR 2017 Switzerland, Sept 13-15, 2017 
Desnerck, P., Lees, J.M. and Morley, C.T. (2016) "Reinforcement lay-out implications for reinforced concrete half-joint structures" fib Symposium 2016 South Africa, Nov 21-23, 2016 
Sivanendran, S. and Lees, J.M. (2016) "The effects of moisture and stress on CFRP-concrete interactions in CFRP pre-stressed concrete " fib 11th International PhD Symposium in Civil Engineering, Tokyo, Japan, Aug 29-31, 2016
Sivanendran,S., Lees, J.M. (2015) " Durability of CFRP pre-stressed concrete subjected to stress and moisture exposure" Proceedings of the 12th International Symposium on Fiber Reinforced Polymers for Reinforced Concrete Structures (FRPRCS-12) & The 5th Asia-Pacific Conference on Fiber Reinforced Polymers in Structures (APFIS-2015) Joint Conference, Dec 14-16 2015. (to appear)
Fayyad, T.M. and Lees J.M. (2015) "Evaluation of a minimum flexural reinforcement ratio using fracture-based modelling" Proceedings of the IABSE2015 Conference: Providing solutions to global challenges, Geneva, Switzerland pp. 735-742
Fayyad, T.M. and Lees J.M. (2015) "Integrated fracture-based model for the analysis of cracked reinforced concrete beams" Proceedings of the Concrete2015 conference, 27th Biennial National Conference of the Concrete Institute of Australia in cojunction with the 69th RILEM Week conference, Melbourne, Australia, pp. 1233-1242
Foster, R.M., Lees J.M. and Morley, C.T. (2015) "An Experimental Investigation into the Effect of Externally Bonded CFRP Fabrics on the Shear Behaviour of Reinforced Concrete T-beams" Proceedings of the 7th Biennial Conference on Advanced Composites In Construction, Cambridge, Sept 9-11 2015. Eds J. Lees and S. Keighley
Jin, F., Lees, J.M. (2015) "Time-Dependent Load-Sharing in RC Beams Strengthened with CFRP Straps" Proceedings of the 7th Biennial Conference on Advanced Composites In Construction, Cambridge, Sept 9-11 2015. Eds J. Lees and S. Keighley
Brault, A., Hoult, N.A. & Lees, J.M. (2015)"Development of a Relationship between External Measurements and Reinforcement Stress"Proc SPIE 9435, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, 943519 (March 27, 2015); doi:10.1117/12.2175830 (published copy) (doi)
Sivanendran, S. & Lees, J.M. (2015) "Interaction between CFRP tendons and concrete when subjected to long-term moisture exposure" fib symposium 2015, Copenhagen
Desnerck, P., Lees, J.M. and Morley, C. (2015) "Impact of Material Deterioration on the Strength of Reinforced Concrete Half Joint Structures," Proceedings of the 2015 IABSE Workshop on Safety, Robustness and Condition Assessments of Structures, Helsinki, Finland,p. 8 (postprint)
Desnerck, P., Lees, J.M. and Morley, C.T. (2014) "Assessment of Reinforced Concrete Half-joint Structures: Dealing with Deterioration"Proceedings of the 2014 PCI Convention and National Bridge Conference, Washington DC, United States [CD-ROM]
Foster, R.M., Morley, C.T. and Lees, J.M.(2014) "Relating Shear Transfer Experiments to FRP Strengthened Beam Behaviour in Shear." 7th international Conference on Fiber Reinforced Polymer (FRP) Composites in Civil Engineering (CICE 2014).
Jin, F. and Lees, J.M.(2014) "Time - Dependent Shear Transfer in Reinforced Concrete Beams Strengthened with CFRP Straps" 7th international Conference on Fiber Reinforced Polymer (FRP) Composites in Civil Engineering (CICE 2014).
Toumpanaki, E., Lees, J.M. and Terrasi, G.P. (2014)."Measurement of the Sand Coating Layer in CFRP Tendons through Image Processing"7th international Conference on Fiber Reinforced Polymer (FRP) Composites in Civil Engineering (CICE 2014).
Fayyad, T.M. and Lees, J.M. (2014) "Application of Digital Image Correlation to Reinforced Concrete Fracture" Procedia Materials Science - 20th European Conference on Fracture, Eds Z. Zhang, B. Skallerud, C. Thaulow, E. Østby and J. He, Elsevier v. 3 , pp. 1585–1590 (published copy)(doi)
Foster, R.M., Morley, C.T. and Lees, J.M. (2013) "Shear Transfer Across a Diagonal Crack in Reinforced Concrete Strengthened with Externally Bonded FRP Fabric"Advanced Composites in Construction (ACIC) 2013 Conference Proceedings, September 10-12, pp. 181-192.
Toumpanaki, E., Lees, J.M. and Terrasi, G.P. (2013) "Effect of Moisture Uptake on the Shear Stiffness of CFRP Tendons and the Role of the Manufacturing Route" FRPRCS-11 -11th International Symposium on Fibre Reinforced Polymer Reinforcement for Concrete Structures

Teaching and Supervisions

Professor of Civil Engineering
Director, EPSRC Future Infrastructure of the Built Environment
Professor Janet  Lees

Contact Details

Cambridge University
Engineering Department
Trumpington Street
Cambridge CB2 1PZ
+44 1223 332678
Takes PhD students
Not available for consultancy

Affiliations