Seismic and Service Life Assessment of Reinforced Concrete Structures and Novel Cementitious Materials Application for Durable and Resilient Construction

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The proposal addresses open issues in seismic and service life assessment and retrofit of existing reinforced concrete construction. The general framework is performance based, whereby the acceptance criteria are expressed in terms of Deformation Capacity estimates (DC) for the individual members and complete structural systems. Although the established Codes provide methods for estimation of DC, comparison with experimental evidence illustrate that this parameter is very poorly understood with unacceptably high margin of uncertainty to real values. For this reason the main objective of the study is to develop improved understanding of the mechanics that underly the DC of reinforced concrete, and to extend the performance based methods of assessment to corroded structures. In this context the project will also develop methods for service life estimation and performance criteria for corrosion affected structures. The available experimental evidence will be reviewed collectively after assembly of relevant databases, and additional tests will be undertaken in the lab and through advanced nonlinear finite element studies in order to clarify the physical significance of important parameters such as yield penetration, plastic hinge definition, axial load effects, and hierarchy of failure modes, on DC. This will be extended to include depth of corrosion penetration, steel area loss and embrittlement of the cover, for DC of corrosion affected members. Particular emphasis will be placed in improved representation of bond and the effects of bar yielding on strain development capacity of reinforcement; relevant experiments will be conducted to study its effect on DC, including the case of partially corroded anchorages/lap splices after simulated corrosion in the lab. Case studies of application of the improved estimates of DC, particularly when accounting for the important effects of yield spreading in the shear span of members, will be developed as model examples of performance based design and assessment. *** The structural performance of strain-hardening cementitious composites (SHCC) will be studied experimentally to resolve open issues in design of new structures (aiming for simpler construction through minimization of required stirrup reinforcement), and to implement them in innovative repair solutions of the systemic problems encountered in old structures. Functionalization of SHCC by engineering the nanostructure (through nano-additives) and combining different types of synthetic fibres and fibre coatings will be pursued for the various intended applications. Tests will explore the structural behavior of structural members constructed with SHCC so as to provide a basis for development of design rules to support their introduction in new construction but also in retrofitting methods, by taking advantage of the internal confinement afforded by SHCC due to their fiber content.**