Dynamic characteristics of the crowchild trail bridge

This paper presents the results of a study on the dynamic characteristics o f the Crowchild Trail Bridge in Calgary, Alberta. This bridge is currently being monitored by members of the Intelligent Sensing for Innovative Struct ures Network (ISIS Canada). The effects of various modeling assumptions on the computed dynamic characteristics of the bridge are investigated and dis cussed in this paper. The dynamic characteristics of the bridge were determ ined by means of ambient vibration measurements and were used to calibrate a number of computer models developed by four different groups of engineers . The results of this study showed that in order to properly calibrate a mo del of the bridge for structural dynamic analysis, it is necessary to have not only a good match of experimental and analytical natural frequencies bu t also a good match of experimental and analytical mode shapes. Improper de termination of dynamic characteristics of a bridge using analytical models could lead to erroneous conclusions on its expected behaviour under dynamic loading.