This article presents a comprehensive modeling of temperature, carbonation, water and chloride ions transport in cover concrete using the transport model "TransChlor". The TransChlor transport model employs weather data and chloride ion concentrations present on the concrete surface to predict the temporal and spatial evolution of the presence of chloride
A numerical approach, named TransChlor, is proposed to simulate transport phenomena of various substances in concrete. This approach is a theoretical model based on finite elements and finite differences methods. The model consists of coupled nonlinear partial differential equations based on Fick's diffusion law and on kinematics equations. Simulation results from
Results of an investigation aimed at determining bending moments and shear forces, required to design skewed concrete slab bridges using the equivalent-beam method are presented in this paper. Straight and skewed slab bridges were modeled using grillage and finite-element models to characterize their behavior under uniform and moving loads with the objective of determining the most appropriate modeling approach for design. A parametric study was carried out on 390 simply supported slabs with geometries covering one to four lane bridges of 3-to 20-m spans and with skew angles ranging from 0 to 60°. The analyses showed that nonorthogonal grillages satisfactorily predict the amplitude and the transverse distribution of longitudinal bending moments and shear forces, and can be used for the analysis of skewed slab bridges. Results of the parametric study indicated that shear forces and secondary bending moments increase with increasing skew angle while longitudinal bending moments diminish. Equations are proposed to include, as part of the equivalent-beam method for skew angles up to 60°, the increase of shear forces and the reduction of longitudinal bending moments. Equations are also given for computing secondary bending moments. A simplified approach aimed at determining the corner forces for straight and skewed bridges is proposed as an alternative to a more-refined analysis. The analyses indicated the presence of high vertical shear stresses in the vicinity of free edges that justifies suggesting to provide shear reinforcement along the slab free edges.
Accelerated migration tests which are commonly used to measure chloride diffusion in ordinary cement-based materials cannot be directly applied to composite with very low permeability, such as Ultra High-Performance Fiber Reinforced concretes (UHPFRC). In order to assess the UHPFRC enhancement on the structural durability, there is a critical need to accurately assess the permeability level of the material to chloride ions. The objective of this work is to adapt an existing set-up of accelerated chloride migration test in order to (i) better characterize the resistance of chloride ion penetration in UHPFRC; and (ii) to compare the resistance of chloride ion penetration between UHPC and UHPFRC. The material characterization, the set-up modifications of the existing accelerated migration test, the results are presented. In conclusion, the modification of the test-set-up allowed to accurately measure chloride transport of very low permeability UHPFRC and to shed light on the effect of the fiber reinforcement.
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