Failure Mode and Ultimate Strength of Precast Concrete Barrier

Abstract

This study examines the validity of design formulas adopted from the yield line theory of American Association of State Highway and Transportation Officials load and resistance factor design (AATSHTO LRFD) specifications for precast concrete barriers with a potential longitudinal discontinuity and for barrier sections with a slope discontinuity. A full-scale static test was performed on newly-developed type of precast concrete barrier system. Protruded reinforcements and a mortar filling were used to combine the barrier and deck. Five specimens were fabricated with different test variables that simulate the cantilevered part of the deck and a series of precast barriers. Test levels and the corresponding loading patterns simulating a vehicle crash were adopted from AASHTO LRFD specifications. Findings show that the new precast concrete barrier system had an ultimate capacity equivalent to that of a conventional barrier. The longitudinal continuity of a series of precast barrier segments significantly affected the ultimate strength of the whole barrier system. The shapes of the yield liens obtained in the static test were different than those presented in the AASHTO specifications. An alternative failure mode and corresponding predictive equations of the strength based on actual yield lines were proposed. The proposed theories may be applicable to barriers with a tapered section with some points of slope discontinuity.