David Conciatori

Analysis and Design of Straight and Skewed Slab Bridges

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 prop...

Calculation of reinforced concrete corrosion initiation probabilities using the Rosenblueth method

The Rosenblueth method is used to analyse stochastic parameters in a numerical model to calculate the solution for independent variables. By replacing all or a part of the independent variables with random variables, the solution becomes itself random. The Rosenblueth method simplifies this passage, while being limited to dichotomous random variables. This avoids the complex and computer-intensive Monte Carlo simulation method. A specific example is developed in this article using a non-linear transport model to simulate chloride ion penetration into reinforced concrete and to predict the development of corrosion in the civil structure. The taking into consideration of complex physical chemical processes and a reconstituted climate increases considerably the simulation time, making impossible the usual use of the Monte Carlo method. The two numerical examples show that the exposure degree affects in a dominating way the appearance of structural damage.

Brine absorption in concrete at low temperature: Experimental investigation and modeling

An experimental campaign supports a model named TransChlor for bringing liquid water moved by capillary suction and chloride ions into concrete. The principal objective of the experimental campaign is to represent conventional concretes under real conditions of a local microclimate. Capillarity tests were performed on specimens of three different types of concrete dried at different levels of relative humidity at low temperatures (to -20 degrees C) to represent the effect of a real climate in winter. This article shows that low temperatures decrease water absorption by capillarity. The use of TransChlor to simulate liquid water and chloride ion penetration into concrete is presented with an emphasis on the faster transport mode of chloride ions by convection when water is in contact with concrete. DOI: 10.1061/(ASCE)MT.1943-5533.0000238