Forced vibration of continuous highway bridges

Abstract

A CORRELATION IS PRESENTED OF FORCED VIBRATION THEORY WITH DYNAMIC IMPACT TESTS FOR THREE CONTINUOUS HIGHWAY BRIDGES AND A SIMPLE SPAN HIGHWAY BRIDGE. THE EXPERIMENTAL IMPACT WAS DETERMINED AT THE CENTERLINE OF THE SINGLE SPAN HIGHWAY BRIDGE AND IN THE OUTER AND INNER SPANS AND AT THE INTERIOR SUPPORTS FOR THE THREE TYPES OF CONTINUOUS FOUR-SPAN HIGHWAY BRIDGES. THE EFFECT OF THE VEHICLE IS ASSUMED TO BE AN OSCILLATING FORCING FUNCTION WHOSE FREQUENCY IS THE FREQUENCY OF AXLE REPETITION AND WHOSE FORCE IS THE OSCILLATING LOAD EFFECT OF A CONSTANT FORCE TRAVERSING A BEAM. THE CORRELATION OF THE THEORETICAL AND EXPERIMENTAL IMPACT INDICATES THAT THE SIMPLIFICATIONS MADE IN THE EFFECT OF THE VEHICLES ARE JUSTIFIED FOR THE BRIDGES TESTED AND THE EXPERIMENTAL VEHICLE VELOCITIES USED. THESE RESULTS SHOW QUALITATIVELY THAT THE AMOUNT OF IMPACT IS A FUNCTION OF THE RATIO OF THE FREQUENCY OF AXLE REPETITION TO THE LOADED NATURAL FREQUENCY OF THE STRUCTURE. /AUTHOR/