Highway Bridge Vibration Studies : Interim Report

Abstract

The report is titled "Highway Bridge Vibration Studies". This Interim Report is of some of the activity which has been in progress on this research in the Joint Highway Research Project at Purdue University.It is an investigation of those parameters which affect bridge accelerations and human response. The findings indicate that the parameters which affect the human pedestrian are predominately span length, weight and speed of the vehicle, and surface roughness.The Report is presented to the Board for acceptance as partial fulfillment of the objectives of the research. It The results of the investigation indicated that, for simple span bridges, the amplitudes of accelerations which psychologically disturbed the pedestrian were predominately affected by the span length of the bridge, the weight and speed of the vehicle, and the surface roughness.The parameters that provided the minor effects were the girder flexibilities and the transverse position of load.For two and three span continuous bridges, the magnitudes of acceleration were larger than the recommended limit of comfort only when the surface roughness of the bridges was taken into account.Deflection limitations and maximum girder span-depth ratios used in present bridge design codes do not assure the bridge users' comfort.Present bridge design criteria have limited the use of high strength steel although the dynamic characteristics of the bridge may be satisfactory.Some reports indicate that bridge acceleration was significant in producing psychological effects.The results of this study indicate high strength steel girders could be used for highway bridges since the effect on bridge accelerations of flexibility of the steel was relatively Insignif 1 cant.

Highway Bridge Vibration Studies

“…The following response characteristics were determined: (1) maximum deflection from the deflection gage data, (2) maximum acceleration indicated by the data from each accelerometer (3) damping ratio from the free vibration portion of the data from each transducer, (4) maximum velocity and deflection from integrated acceleration data, (5) maximum velocity, acceleration, and jerk from smoothed and differentiated deflection data, and (6) maximum jerk from differentiated acceleration.…”

“…Experiments have been of two types: (1) people subjected to the vibration of actual structures in the field, and (2) people subjected to controlled "shake Lenzen (26) in a later study of the vibration of steel joistconcrete slab floors, suggested using the Reiher and Meister curves with the tolerance limits increased by a factor of ten if the amplitude decays to less than 10 percent of its initial magnitude in 5 to 12 cycles.…”

“…Both two and three span symmetric continuous girder bridges have been studied extensively (2) ; however because the results are similar only two span bridges will be discussed herein. Bridge data again has been taken from Reference (7) and the study is restricted to steel continuous beam bridges with reinforced concrete decks.…”

“…Perhaps a satisfactory level of comfort can be provided by more flexible bridges. identification through analytical studies of the parameters of the bridge-vehicle system which are most significant in their effect upon the dynamic response of the bridge, 2) measurement and analysis of the dynamic performance of typical bridges under actual traffic in the field, 3) comparison of field measurements with analytical predictions, 4) identification of reasonable quantitative dynamic criteria for user sensitivity to Vibrations, and 5) investigation of a simple dynamic-based design criterion for controlling bridge vibrations.…”

“…The first phase of the research, reported by Aramraks (2), consisted primarily of analytical studies of the effects of varying some of the parameters of the structure-vehicle system. Somewhat surprisingly, the most significant effect was found to be the roughness of roadway.…”