Highway Bridge Vibration Studies

Abstract

The attached Final Report "Highway Bridge Vibration Studies" is submitted as a summary of the extensive research conducted on this project. The research has provided considerable new information and clearer understanding of the bridge vibration problem and advanced capability toward the use of a dynamic-based design criterion for highway bridges. Such use should provide more effectively for the comfort of users of bridges in an economic and beneficial manner.This research in our opinion has been very productive and we are hopeful the State Highway Department can utilize some of the findings in designing and building a highway bridge and that further confirmation of the findings of this project can be the subject of a new research project on such implementation.The acceptance of this report as fulfilling the objectives of the Study will terminate this research. The general objectives of this research have been to obtain a better understanding of the dynamic performance of highway bridges and of the vibrations sensed by bridge users in order to aid in the development and implementation of a dynamic-based design criterion which can more effectively ensure the comfort of pedestrians, maintenance workers, cyclists, etc. Because the human body is primarily sensitive to changes in motion, the investigations have focused on accelerations.Special purpose computer programs were used for parametric studies of the bridge vehicle system. Significant parameters were found to be span length, weight and speed of the vehicle, and the roughness of the bridge deck. Maximum accelerations were only moderately increased by reductions in girder stiffness.Dynamic responses of some 62 steel and concrete beam bridges under actual highway traffic were measured in the field. Bridges were instrumented with midspan accelerometers and one deflection transducer, all mounted on the curbes of the deck.Differentiated deflection records were used to check corresponding acceleration records. More than 900 crossing records were analyzed for maximum deflection, velocity, acceleration, jerk, and frequency content. Only 5 of the crossing records contained accelerations which exceeded the comfort limit proposed by Wright and Walker.

Dynamic responses of a three-span continuous girder bridge with variable cross-section based on vehicle–bridge coupled vibration analysis

“…Psychological discomfort results from unexpected motions, but physiological discomfort results from a low frequency, high amplitude vibration such as sea sickness (Roeder, Barth and Bergman 2002). Some of the earliest measurements concerning human sensitivity to vibrations were carried out by Mallock in 1902 (Gaunt and Sutton 1981). Investigating complaints of unpleasant vibration caused by passing traffic to certain house near Hyde Park, Gaunt and Sutton (1981) concluded that the acceleration caused noticeable discomfort is one per cent of the gravitational acceleration.…”

Two degree of freedom vibration based electromagnetic energy harvester for bridge health monitoring system

“…The target of this work is small and medium span bridges (up to 50 m) on most of the highways which are concrete beam structures. An extensive study was conducted by Gaunt and Sutton (1981) and reported bridge frequency and acceleration levels for 62 bridges. The bridges were of span less than 30 meters.…”

Investigation of deflection and vibration criteria for road bridges

“…Among them, deflection limits are the most commonly used by design engineers because calculation of deflection is easier and more convenient than calculation of the other studied characteristics. However, many previous studies have found that humans are more sensitive to acceleration than to displacement (Gaunt, 1981), that deflection limits alone are a poor method for controlling bridge vibrations or ensuring human comfort (Wright and Walker, 1971), that vibration cannot be consistently prevented by a simple deflection limit alone (Oehler, 1970), and that deflection limits do not mitigate the vibration and acceleration that induce human reactions (Fountain and Thunman, 1987). In recent years, significant research has occurred on serviceability of bridges.…”