Aerodynamic Response of a Bridge Girder Segment during Lifting Construction Stage

Abstract

Investigations on the wind loads and aerodynamic responses of the bridge girder segment during the lifting construction stage are limited. Free vibration tests of a lifting girder segment of a kilometer-span cable-stayed bridge were carried out in a wind tunnel to study its aerodynamic performance. Large aerostatic displacements were observed in the wind velocity range of concern. Large-amplitude limit cycle oscillations (LCOs) around the horizontal axis perpendicular to the bridge span occurred when the full-scale velocity exceeded 25.3 m/s. The analytical expression of the eigenfrequency of the dangerous mode of a lifting girder segment was derived, and the analytical result was compared with those determined by using the finite-element analysis (FEA) and testing results. The characteristics of the large-amplitude LCOs under different conditions were thoroughly analyzed. For various testing cases, the influences of the angle of attack, wind velocity, and vibration amplitude on the vibration frequency and aerodynamic damping ratio were comprehensively investigated and the parameter identification accuracies were verified. It was demonstrated that more attention should be paid to assessing the wind-resistance of lifting girder segments to ensure the construction safety of long-span bridges. The results of the present work can provide beneficial reference for evaluating the wind-resistance performances of similar types of lifting girder segments.