Title: Field Testing to Failure of a Skewed Solid Concrete Slab Bridge
Author(s): Fabien Lagier, Bruno Massicotte, David Conciatori, Jean-François Laflamme
Publication: Symposium Paper
Appears on pages(s): 40-59
Keywords: solid slab bridges, field testing, load rating, shear failure, nonlinear finite element analysis
In 2006 in Quebec, a skewed cantilever solid concrete slab bridge without shear reinforcement collapsed
due to a shear failure, which highlighted the need to improve the assessment of this type of structure. A large
experimental program was carried out to test three decommissioned solid slab bridges to failure. In parallel, an
extensive nonlinear finite element analysis study was performed with the aim of better understanding the failure
mechanisms, the degree of load redistribution, and to gain insight into the ultimate shear capacity of these structures.
A beam shear failure mode was expected for the first two bridge tests, but a flexural failure mode was observed. This
paper focusses mainly on the last field test of a simply supported solid slab bridge having a 40 degree skew. The load
position and the loading protocol were established with the objective of causing a shear failure at the obtuse corner of
the slab where high shear forces develop. The main test motivation was to illustrate that simply supported solid slab
bridges would normally not be prone to shear failure due to an intrinsic redundancy. The paper presents experimental
techniques that could help bridge owners in assessing the performance of their bridges. The test results also provide
valuable information for calibrating nonlinear element models that can be used for assessing the carrying capacity of
existing concrete bridges.
Although the actual bridge conditions were worse than anticipated, a global shear failure mode occurred near the
obtuse corner at a maximum load of 1400 kN, which significantly exceeded the factored shear force due to the
maximum traffic load. The failure was followed by a gradual load redistribution toward undamaged portions of the
slab. This field test confirmed the assumption of non-fragility for this type of bridge, where support conditions enable
development of an intrinsic redundancy. Despite these observations, nonlinear analyses carried out in parallel to the
testing program indicated that this beneficial effect diminishes with an increase of slab thickness.