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
During their service life, existing structures may suffer a combination of ageing and reinforcement corrosion. The corrosion deterioration can significantly affect the durability of reinforced concrete (RC) elements causing premature concrete crushing, size reduction of reinforcement cross-section, degradation of mechanical properties of steel and concrete, and stirrups rupture. One of the main purposes related to durability reduction is the evaluation of the maintenance of adequate safety and residual capacity throughout the life of the structure. For this reason, a non-linear finite element approach (NLFEA), based on multi-layer shell elements and PARC_CL 2.1 crack model has been presented in this paper. The PARC_CL 2.1 model is a fixed crack model developed at the University of Parma and implemented in a subroutine UMAT for ABAQUS that incorporates cyclic constitutive laws of materials and the evolution of corrosion over time. In the present work, the crack model was improved by implementing the effects of exposure to environmental attack. Firstly, the effectiveness of the proposed model has been validated through comparison with experimental data available in literature. The residual capacity of corroded RC panels subjected to cyclic loads was then investigated over time considering different exposure classes. Based on the obtained results, the capacity reduction in terms of maximum shear stress and ductility have been estimated over time.
This article presents a simplified stress-strain relationship for the definition of the mechanical behavior of prestressing strands subjected to chloride-induced corrosion, named SCPS-model (Simplified Model for Corroded Prestressing Strands).The constitutive law adopts the equivalent spring model, that reproduces the overall behavior of a corroded strand by summing the contributions of each wire, assumed as a spring working in parallel to the others. The SCPS-model is designed for the application in the daily engineering practice; to this aim, it is based on a single input parameter that is the maximum penetration depth of the most corroded wire. Following a detailed description of the model formulation and parameters, the article shows the validation of the stress-strain relationship through several comparisons with experimental tensile test outcomes coming from scientific literature. Finally, a statistical analysis of the dimensionless ratio of experimental and analytical results in terms of ultimate corroded strength and strain is carried out to demonstrate the effectiveness of the SCPS-model. Concluding, the accurate and safe side prediction of the residual mechanical behavior of corroded prestressing strands is proposed using the SCPS-model.
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