The aim of this work is to provide new contributions in order to define more accurately the structural robustness concept, particularly when applied to corroded reinforced concrete (RC) structures. To fulfill such task, several robustness indicators are analyzed and discussed with special emphasis on structural performance based measures. A new robustness definition and a framework to assess it are then proposed, based on the structural performance lost after damage occurrence. The competence of the proposed methodology is then tested comparing the robustness of two reinforced concrete foot bridges under corrosion. The damage considered is the longitudinal reinforcement corrosion level and load carrying capacity is the structural performance evaluated. In order to analyze corrosion effects, a finite element based on a two step analysis is adopted. In the first step a cross section analysis is performed to capture phenomenons such as expansion of the reinforcement due to the corrosion products accumulation; damage and cracking in the reinforcement surrounding concrete; steel-concrete bond strength degradation; and effective reinforcement area reduction. The results obtained are then used to build a 2D structural model, in order to assess the maximum load carrying capacity of the corroded structure. For each foot bridge, robustness is assessed using the proposed methodology.

Currently, decisions on infrastructural assets maintenance and repair, in particular on structures, are based, mostly, on the results of inspections and the resulting condition index, neglecting systems robustness, and, therefore, not making optimal use of the limited available funds. This paper presents a definition and a measure of structural robustness in the context of deteriorating structures, compatible with asset management systems for optimal maintenance and repair planning. The proposed index is used in defining the robustness of existing RC structures to rebar corrosion. Structural performance and the corresponding reliability index are assessed using combined advanced reliability and structural analysis techniques. Structural analysis explicitly includes deterioration mechanisms resulting from corrosion such as reinforcement area reduction, concrete cracking and bond deterioration. * Corresponding authorEmail address: joan.ramon.casas@upc.edu (Joan R. Casas) Preprint submitted to Structural Concrete July 8, 2016The First Order Reliability Method, combined with a Response Surface algorithm, is used to compute the reliability index for a wide range of different corrosion levels, resulting in a fragility curve. Finally, structural robustness is computed and discussed based on the obtained results. Robustness comparison of different structures can then be used to determine structural types more tolerant to corrosion and these results can be used for maintenance and repair planning.

The flexural behavior of slender (1/40) long‐span precast high‐strength concrete girders was experimentally investigated as a competing solution to steel alternatives for highway overpasses. Half‐scale specimens were produced using an economical and high‐strength (120 MPa) concrete mixture, non‐fiber reinforced, designed only with conventional raw materials, currently available at Portuguese precast companies. Two girder specimens were subjected to quasi‐static short‐term loading up to structural failure in bending. Results have shown the typical behavior of conventional reinforced concrete members in bending, despite the brittle behavior of non‐fiber‐reinforced high strength concretes. Results also showed acceptable ductility (2.6) and the ability of the girder specimens to experience large deformation without significant softening. An analytical approach, based on plane sections and short‐term stress–strain constitutive model recommended by the Eurocode 2 for concrete up to the C90/105 strength class, showed to predict accurately the behavior of girders in bending, both to ultimate and serviceability limit states, including cracking, yielding, maximum loads, and ultimate deflections.

The effectiveness of masonry infill wall on behavior of a Reinforced Concrete (RC) frame subjected to a column failure is studied experimentally. For this reason, one full scale RC frame designed according to Eurocode is statically tested to investigate the behavior of the frame with and without masonry infill wall. The obtained results show that infill wall can significantly increase the load carrying capacity of RC frame and thus serve as an important robustness reserve in the case of unpredictable extreme events (i.e. local impact, blast or earthquake). A photogrammetry analysis is carried out to study the behavior of the structure. Results give valuable information about the alternative load path, transfer of the applied load to the column and beams, and interaction forces between RC frame and infill wall. At the end, the experimental program is simulated by the OpenSees software to study the behavior of the frame. After having demonstrated that this model can predict the load deflection with good accuracy, a parametric study is conducted to evaluate the effect of the percentage of longitudinal reinforcement ratio of beams and columns on the load carrying capacity of the infilled RC frame.