RILEM 287-CCS: Early age and long-term crack width analysis in RC structures скачать в хорошем качестве

RILEM 287-CCS: Early age and long-term crack width analysis in RC structures

Even though reinforced concrete (RC) is one of the most used manmade materials in the world, and adequate models exist for the prediction and design of the ultimate capacity of RC structures, the prediction of service life behaviour is still not mature enough for actual design purposes. This may lead to immediate repair needs, inadequate service life behaviour even when regulatory prescriptions for design are strictly followed, or at other times to unnecessary overdesign of reinforcement, which has negative consequences on both sustainability and economic aspects. This is amplified by development of new more sustainable cements and supplementary materials since the range of material properties needed for SLS-design is considerably wider than for ULS design. The problem stems to a more fundamental set of mutually influencing factors that clearly require further development and integration: (i) lack of proper understanding of the fundamental mechanisms involved in the processes of hydration-induced temperature, shrinkage, creep and herewith caused cracking; (ii) lack of integrative developments combining material scientists and structural engineers for the relevant concerns in research; (iii) lack of definitions/recommendations for collaborative developments of field-involved stakeholders towards better behaviour (material technologists, structural designers, contractors, material suppliers); (iv) lack of integration of experimental developments for restrained behaviour in complex reinforced systems with predictive/simulation methodologies; (v) lack of benchmarking and integration of existing methodologies for simulation/prediction of stresses and crack widths during service life, including simplified code-based approaches and advanced simulations (e.g. backed by FE method), which are able to cope with the combined effects of applied load (sustained) and restrained deformation at both early ages and in the longer term. This lecture explains how these challenges are addressed within RILEM TC 287-CCS, gives a retrospective view of the accumulated knowledge and research in the field and paves the way towards future anticipated research in this topic and anticipated outcomes.  Dr Miguel Azenha is a member of the permanent staff of the Structural Division in the Department of Civil Engineering, University of Minho. His research interests comprise: 1) numerical and experimental study of concrete at early ages regarding phenomena such as thermo-hygral-mechanical couplings, concrete properties evolution during hydration, creep and shrinkage; 2) use of digital processes in construction, namely Building Information Modelling. He is the Director of the ERASMUS+ Master Course in Building Information Modelling, Deputy Coordinator of Marie Sklodowska-Curie Action European Training network – Innovative Training Network (ETN ITN) – SUBLime – Sustainable Building Lime Applications Via Circular Economy and Biomimetic Approaches. He is the current Chair of RILEM TC 287-CCS “Early age and long-term crack width analysis in RC Structures”, past deputy-chair of RILEM TC 254-CMS “Thermal cracking of massive concrete structures” and past Chair of COST Action TU1404 “Towards the next generation of standards for service life of cement-based materials and structures”. He is also a member of the Editorial Board of the Journal of Advanced Concrete Technology.  Dr Fragkoulis Kanavaris is ARUP’s leading concrete materials specialist based in London in the Specialist Technology and Research practice of the Advanced Digital Engineering group. He provides global expert advice related to concrete technology and materials, durability, cracking, low carbon concrete and testing and monitoring concrete and concrete structures with involvement in over 200 projects worldwide including medium and high-rise buildings, tunnels, highways & bridges, railways structures, wind turbines, nuclear structures, offshore & on-shore structures, maritime structures. Fragkoulis is co-ordinating concrete materials related research within ARUP and is an ambassador of industry-academia collaborative efforts towards understanding concrete behaviour and producing robust and sustainable concrete solutions. He is currently involved in more than 5 industry-academia research projects looking into concrete cracking, sustainable materials and durability. He is the current Deputy Chair of RILEM TC 287-CCS “Early age and long-term crack width analysis in RC Structures” and Convener of the fib TG 4.6 “Constitutive laws for concrete with supplementary cementitious materials. He is an active member of several other RILEM and fib committees and standard drafting committees. He is a member of the steering group for C766 guidance document on Control of cracking by restrained deformation in concrete and him and his team served as principal reviewers and technical editors of the document during its update.