TUNED MASS DAMPER EFFECTS ON DYNAMIC CHARACTERISTICS OF THE EXISTING FOOTBRIDGE BY STATIONARY PERSONS LYING ON THE BRIDGE SURFACE

Abstract

 Although it is recognized that the structural damping of the footbridge increases for both the posture standing and sitting in a chair close to the center span, the dynamic characteristics has not been verified when stationary persons lied on the bridge surface. This paper deals with tuned mass damper effects of stationary persons lying on the existing footbridge surface. It is known that much of the human body is made of water, a full scale measurement for the footbridge with a fundamental frequency of about 7.9Hz is carried out by putting the added mass water in the container on the bridge surface. Excitation experiments were also conducted for the same bridge occupied by stationary standing and lying persons on the bridge surface. Based on these experimental results, it is found that the added mass water on the bridge surface acts as to decrease the frequency of the footbridge in the same function as sand bags. It is also revealed that the structural damping in the state of lying on the bridge surface increases to almost the same extent as the result of stationary standing persons according to the increase of number of stationary lying persons due to tuned mass damper effects.