Excitation of Arch and Suspension Bridges by Subwires

Noriaki Hiwatashi,Itio Hirai,Yutaka Ishihara,Yoji Mizuta

doi:10.1155/1993/408367

Abstract

A force generation method using a subwire for arch and suspension bridges is proposed. The subwire is connected to the arch or the cable of the bridge through rollers. The uniform force produced by pulling and releasing the pretensioned subwires acts on the bridge as an externalforce. A new device called “the resonance force generator” is also developed to excite the bridges by applying a small force. To verify the proposed concept, a stress ribbon bridge was excited with the resonance force generator.

Highlights

This article proposes an approach to generate a uniform force by the use of a subwire for fullscale vibration tests of long-span arch and suspension bridges
The pretensioned subwire with many rollers placed along the parabolic main cable of a suspension bridge produces a uniform force by the action of pulling or releasing the pretensioned subwire
The vibration system adjusted in this way is the proposed "resonance force generator" and can efficiently produce larger driving uniform force with the lowest natural frequency of the bridge

Summary

INTRODUCTION

This article proposes an approach to generate a uniform force by the use of a subwire for fullscale vibration tests of long-span arch and suspension bridges. The vibration of some beams and buildings is controlled by means of a tendon mechanism [e.g. Camotim and Roorda, 1991; Chung, Reinhorn, and Soong, 1988; Roorda, 1975; Yang and Giannopoulos, 1979] It seems that this kind of uniform load produced by a parabolic subwire on many rollers, which is continuous over the elastic main cable (or arch) of a suspension (or arch) bridge, has not been developed. For the validation of the proposed concept, a stress ribbon pedestrian bridge instead of a suspension bridge was oscillated at resonance by pulling and releasing the subwire connected to the slab surface of the bridge through rollers Structures such as arch and suspension bridges are treated as beams stiffened with parabolic axial force members. M (or two cables) is able to cause torsional vibration for these bridges

RESONANCE FORCE GENERATOR

Pl a n

DISCUSSION

CONCLUSIONS