Laboratory and Field Testing of Precast, Three Sided Arch Culverts

Abstract

The use of precast, three-sided arch culverts has become fairly popular for new short-span bridges and bridge replacements due to their rapid construction time, aesthetic appeal, and minimal impact to the waterway, but little research has been performed into the strength of these structures. It has been thought that, due to arching action, large lateral earth pressures can be developed in the backfill behind the legs, and that these pressures allow the bridge to achieve strengths much larger than possible without the confinement of the backfill soil. The research detailed in this thesis sought verify the behavior of this bridge system through field testing of an existing bridge, as well as two ultimate load tests on individual bridge units. It was concluded that the test bridges were too stiff to cause enough lateral deflection to activate passive earth pressures in the backfill, and the earth pressures had a minimal effect. Furthermore, it was found that non-ductile shear failures can occur in certain bridge designs, and the ductility of the steel used for reinforcement was not sufficient to allow flexural hinges to form.