Deterioration of bridges is a common issue in the nation's aging infrastructure system. One of the most common problem is concrete deck degradation, which when left untreated can lead to spalling, exposure and corrosion of the reinforcement, and eventually reduced capacity of the bridge. Use of ultra-high performance concrete (UHPC) as a bridge deck overlay has the potential to reduce the deck degradation in these situations and extend the service life of the deck. However, reliable bond between the UHPC overlay and the normal concrete (NC) deck interface must be ensured, which may be affected by time depended behavior of UHPC, temperature variations, and seasonal freeze-thaw cycles. This paper presents a method to assess condition of the interface between the UHPC overlay and NC deck. The potential delamination between UHPC and NC is evaluated using infrared imaging, which is a non-destructive technique. A delaminated deck interface area may consist of a complex region comprising of cementitious material, steel fibers, moisture, and air voids. A thermal radiation gradient is expected due to the different thermal conductivities of each material. It is shown that this concept can be used to evaluate delamination of the UHPC layer placed on top of NC deck.
Although live load is well known to have a dynamic effect on bridge response in addition to its self-weight, the significance of these effects on seismic response is unclear. In addition, most bridge design specifications have few requirements concerning the inclusion of live load in their seismic design provisions. The main objective of this study is therefore to investigate and obtain insight into the effect of vehicle-bridge interaction during earthquake shaking. The study consists of both experimental and analytical investigations. This paper focuses on the experimental work, which includes shake table testing of a 2/5-scale model of a horizontally curved steel girder bridge loaded with a series of representative vehicles. Preliminary experimental results show that the presence of the live load had a clear beneficial effect on performance for small amplitude motions, but that this improvement diminished with increasing amplitude of shaking. Parameters used to measure performance include column displacements, abutment shear forces, abutment uplift, and concrete spalling.
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