Date of Award


Document Type


Degree Name

Master of Science (MS)


Civil Engineering


In this investigation a comparative study is made of the dynamic behavior of rigid and elastomeric bearings of a model bridge subjected to eccentric vibratory loading.

Bor the experimental portion, static and vibration tests were conducted using an approximate one-third scale model bridge 25 ft long and 10 ft wide, with a composite section of steel girders and concrete bridge deck slab. A counterrotating eccentric weight oscillator was used to produce oscillatory loads on the bridge. Tests were conducted with three types of bearing conditions: curved steel sole plates, 64 durometer and 49 durometer hardness neoprene pads.

A theoretical analysis was also made and the values obtained for natural frequencies and deflections were compared with those obtained experimentally.

Some of the conclusions are: (a) for a statically applied load the total midspan deflection is greater for neoprene than steel supports; (b) neoprene bearing pads add to the damping of the bridge; (c) in general, though not always, the maximum strain and also the total and the net deflection /' in the girders, at the respective natural frequency for each bearing condition, are greater for steel bearings; (d) the dynamic stress and deflection, and also their amplification factors, of a loaded bridge are less than those of an unloaded bridge; (e) at low and high frequencies the magnitudes of strain and deflection are quite close for different bearing conditions.