Study On Dynamic Performance Of A Pedestrian Bridge In Da Qing

Human being's oldest bridge is a single-plank pedestrian bridge,the first perception of bridge vibration is caused by human."One step single-plank bridge will shake three times",is the single-plank bridge the description of vibration is caused by human.With the development of urban traffic,the city appeared more and more the steel pedestrian bridge.But the calculation and practice show that pedestrian bridge first-order natural frequencies close to the normal people walking frequency,highly cause resonance,structural displacement,stress will greatly exceed the value of static analysis,pedestrian will also feel the powerful vibration and panic,if things continue this way,will affect the structural safety and proper use.Civil engineering structure dynamic design concept can be generalized include seismic design, wind resistant design,and vehicles,pedestrians and assess environmental vibration due to power machinery and shock absorption design.Narrowly speaking, the main means structural dynamic design is analysis and modification of structural dynamic characteristics.In this paper,a 29.8m span steel pedestrian bridge dynamic design as an example,with finite element method analysis of load on the steel pedestrian bridge affected,carry out dynamic characteristics analysis and time history analysis.Work and research as follows:1.According to the characteristics of the pedestrian load,we studied the pedestrian load model,and determined the loading function of the Human-induced load.2.Use finite element software ANSYS,with beam elements Beam4,flexible shell element Shell63 establish an accurate finite element model analysis of dynamic characteristics,got pedestrian bridges of the top ten natural frequencies and mode shapes.3.With beam elements Beam4 build pedestrian bridge simplified finite element model,using the transient analysis conducted on the steel pedestrian bridge dynamic response.Analysis of the pedestrian bridge in the Human-induced load, the structure dynamic response under moving harmonic load and concentrated loads on the midspan the (displacement,velocity and acceleration),and then compared the results to determine a reasonable way of loading.4.Finally,the application of the national pedestrian bridge vibration comfort evaluation method has been introduced and example of the comfort conditions has been evaluated.