Destructive Testing of Decommissioned Concrete Slab Bridge

Abstract

A destructive test was conducted on a decommissioned skew RC slab bridge. This bridge had severely deteriorated shoulder regions, where the top mat reinforcing bars were exposed. The test bridge was loaded using hydraulic cylinders arranged so as to simulate an HS‐20‐44 truck entering the bridge in one lane. The results indicate that the boundary conditions and the geometry of the bridge significantly influence bridge behavior. During the test, changes in the boundary conditions and yielding of the reinforcing bars caused the load path to shift twice. Failure of the slab occurred due to punching shear at a load of 3,200 kN (720 kips), equivalent to the axle load of 22 HS‐20‐44 trucks. Although the deterioration did not appear to affect flexural behavior, it did greatly reduce the punching‐shear capacity. Analysis indicates that simple modeling methods, such as strip models, overestimate structural demand and underestimate structural supply because they do not properly account for additional load‐carrying mechanisms, such as slab action. Better estimates of structural supply and demand are found using nonlinear finite‐element models.