Dynamic assessment of curved cable stayed bridge by model updating
Through comparison, the characteristics of the two simulation methods can be known.By this study, the bridge bearing simulation model of the bridge has an obvious impact on the frequency of bridge model.Updating an existing but inaccurate structural dynamics model with measured data can be mathematically reduced to the problem of the best approximation to a given matrix pencil in the Frobenius norm under a given spectral constraint and a submatrix pencil constraint.In this paper, a direct method and the associated mathematical theories for solving this problem are proposed.In the past few years this issue attracted great public attention. The excessive lateral sway motion caused by crowd walking across the infamous Millennium Bridge in London is the prime example of the vibration serviceability problem of footbridges.
Comparison of the frequencies of model before and after applying the secondary dead load make us know that applying dead load will lead to the lower frequency of bridge. Updating of the analytical models of two footbridges based on modal testing of full-scale structures.
The literature survey identified humans as the most important source of vibration for footbridges. Warnitchai, Synchronization of humanwalking observed during lateral vibration of a congested pedestrian bridge, Earthquake Engineering and Structural Dynamics 22 (1993), pp.
However, modelling of the crowd-induced dynamic force is not clearly defined yet, despite some serious attempts to tackle this issue in the last few years. Taylor, Damper retrofit of the Millennium Footbridge—a case study in biodynamicdesign, in: Proceedings of the 73rd Shock and Vibration Symposium, Newport, USA, November18–22, 2002. H. Ammann, Vibrations in Structures—Induced by Man and Machines, Structural Engineering Documents, Vol.
The problem of influence of walking people on footbridge vibration properties, such as the natural frequency and damping is not well understood, let alone quantified.
Finally, there is not a single national or international design guidance which covers all aspects of the problem comprehensively and some form of their combination with other published information is prudent when designing major footbridge structures. The overdue update of the current codes to reflect the recent research achievements is a great challenge for the next 5–10 years.