The aim of this research is to compare the predictions of the design load‐carrying capacity of slabs obtained with simplified analytical and numerical procedures which can be readily used by analysts in the current design process. The research fits into a research programme initiated by the Dutch Ministry of Infrastructure and the Environment for the re‐examination of the load‐carrying capacity of existing bridges and viaducts, and the beams and slabs they include, through the use of non‐linear finite‐element analyses. The behaviour of reinforced concrete slabs subjected to concentrated loads close to their supports is investigated in this contribution. Three tests from a series of 18 slabs with a total of 108 tests, tested at Delft University of Technology, were selected as case studies and analysed with non‐linear finite‐element analyses and analytical models either proposed by design codes or available in the literature. The research agrees well with the philosophy of the fib Model Code for Concrete Structures 2010, which offers different analytical and numerical calculation methods for evaluating the design shear resistance of reinforced concrete members according to different levels of approximation. For the three slabs investigated in this study, it indeed pays to use higher levels of approximation. The highest level (level IV) based on non‐linear finite element analysis gives the highest design load resistance, but still well below the resistance obtained experimentally.
An experimental campaign was carried out on full-scale naturally corroded prestressed concrete (PC) beams without transverse reinforcement to investigate the corrosion effects on failure modes, shear capacity, and ductility. The analyzed PC beams, structural members of a thermal power plant, were subjected for 10 years to refrigerating wetting cycles with marine water. In this paper, the experimental results of four-point bending tests, carried out at the Institute "Eduardo Torroja" in Madrid, are described. Before tests, a visual inspection was conducted to detect the damages induced by corrosion. During the tests, displacements and strains were measured by using linear variable displacement transducer (LVDT) and digital image correlation (DIC). After the tests, strands were removed from beams and cut in pieces, which were weighed to measure the mass loss. Last, it was proved that the residual life of PC beams, exposed to chloride attack, is strongly affected by corrosion, whose effects reduce the shear capacity in terms of both resistance and ductility. K E Y W O R D S digital image correlation, natural corrosion, prestressed concrete beams, shear capacity 1 | INTRODUCTION In the last years, corrosion has been considered as one of the main factors that causes detrimental effects on durability and resistance of reinforced concrete (RC) and prestressed concrete (PC) structures and infrastructures. After the recent bridge collapses occurred worldwide, such as the Ynys-y-gwas Bridge in 1985 in
Corrosion of prestressed concrete structures causes size reduction of strands, degradation of mechanical properties of steel, cracking of the surrounding concrete, and bond decay at steel-to-concrete interface. In this paper, a numerical approach able to take into account all the effects involved in the corrosion process by using nonlinear finite element analysis (NLFEA) and membrane or shell elements modeling is proposed. Two different strategies are adopted to model strands: the smeared and the discrete approaches. The results obtained using these latter strategies are validated by comparing NLFEA results with experimental measurements of a naturally corroded prestressed beam tested at the "Instituto de Ciencias de la Construcción Eduardo Torroja" in Madrid. Finally, pros and cons of the proposed modeling approach are critically analyzed, demonstrating that considering the actual spatial corrosion distribution is necessary to predict the position where failure occurs.
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