A Study Of Dynamic Characteristics Of Recent Footbridges In Ube City

With the progress of ever-increasing span of footbridges and the application of modern light and high strength materials,as well as the pursuit of bridge aesthetic in urban areas,the fundamental frequency of modern flexible footbridges decreases significantly.Since the event of London Millennium Bridge which was closed due to excessive pedestrian-induced lateral vibration,considerable efforts have been devoted to pedestrian-induced vibration analysis,particularly the lateral vibration,and its mitigation for modern footbridges.In the present study,the fundamentals of pedestrian-induced vibration theory and dynamic design of footbridges are described.The emphasis is placed on three existing methods for analyzing the large amplitude lateral vibration,namely the direct resonance method,the pedestrian-bridge interaction method and the parametric resonance method.In this study,the stress and deformation of a superstructure and abutment under lateral movement is examined and an adequate analytic model of these states is considered in the dynamic analysis of the whole bridge system.The improvement of the bridge’s seismic performance is inspected based on the analytic results.In this case,the input seismic wave is set as a level 2 earthquake,and two types seismic wave were used.Type1 has numerous repetitions at an accelerations of approximately 300 gal and maximums acceleration is 675 gal.while Type2 has fewer repetitions but stronger acceleration at 687 gal.In the scientific field,researchers are asked to make predictions of earthquake probability and severity.In the engineering field,researchers are tasked with preventing loss of life and property by ensuring the safety of structures during future earthquakes and the tsunamis they induce.If both seismologic science and earthquake engineering execute their individual obligations and collaborative roles,a safe and risk-free society in the face of earthquakes and tsunamis would be achieved.The purpose of earthquake engineering is to analyze the response of structures such as buildings,bridges and surface ground to earthquake motions,and ensure their safety.The ultimate goal of this engineering is to create safer and more secure societies,based on the design and construction of structures.Natural frequency of footbridge,earthquake response of footbridge due to actual earthquake,a method of analysis of footbridge be give,discussed and summarized at the conclusion in this paper.