Structural Behaviour of Shear-Connected Adjacent Precast Concrete Box Beam Bridges Subjected to AASHTO Truck Loading

Abstract

<p>Shear-connected box beam bridges have been extensively used in North America for their reduction in construction times and life cycle cost. Literature review revealed that the applied transverse vertical shear force, Vy, required to design the shear keys between beams subjected to AASHTO truck loading is yet unavailable. As such, a parametric study was carried out, using the Orthotropic Plate Theory, to obtain reliable Vy to design the shear keys. Although AASHTO-LRFD Bridge Design Specifications provide equations for the fraction of truck loading carried by box beams, these equations do not cover the case of one-lane bridge cross-section, nor the effect of the concrete traffic barrier, built integrally with the exterior box beams. Therefore, a parametric study was conducted to determine the fraction of truck loading carried by the beams to evaluate such equations. The key parameters in the parametric study included bridge span and width, cross-sectional geometric properties, truck loading conditions and barrier stiffness. Results led to the development of design charts for Vy values in addition to alternative empirical equations. The study on the fraction of truck loading carried by beams showed that AASHTO-LRFD equations are conservative for bridges of two and more traffic lanes but not for one-lane bridges. As such, an empirical equation was developed for such bridge configuration. The study also showed that the fraction of truck loading carried by beams decreases significantly due to barrier stiffness. Thus, empirical equations for the effect of the barrier were deduced to assist engineers in economical design of new bridges and bridge rating.</p>