Overload and Ultimate Load Behavior of Posttensioned Slab Bridge

Abstract

A three-tenths-scale model of a posttensioned slab bridge is constructed in a laboratory and tested in the overload and ultimate load ranges. Dimensions of the slab are 16.9 × 5.33 × 0.23 m. In addition to uniformly distributed longitudinal posttensioning, a band of tendons is located in a narrow region directly above the supporting columns. A large array of strain gauges, linear variable differential transformers, and load cells serve to gather data for each loading configuration. Results are presented for a series of overloads that are placed on the slab in a variety of critical locations. Ultimate positive bending moment is imposed on one span and an ultimate negative moment is applied to the slab in the region of the supporting columns. Complementary nonlinear finite-element analyses of the overload and ultimate loadings are also presented. Results show that the posttensioned slab bridge supported a load-causing moment equivalent to 4.8 times the factored moment of an AASHTO MS 18 loading.