The Research On Impact Factor Spectrum Of Bridges Based On Measured Ramdom Traffic Flow Data

Dynamic characteristic of bridge structure is an important aspect in the evaluation ofbridge design parameters, while the impact factor is one of the important parameters ofdynamic characteristic of bridge structure. Based on the random vehicle-bridge coupledvibration analysis system, researching on the influence of impact factor under differentvehicles running in different speeds and typical models running in different loads. A six spancontinuous T beam bridge modle has been used to calculate the impact coefficient spectrumof bridge strcture under random traffic flow. In order to analysis the impact coefficientspectrum of extra heavy traffic loads, selected five typical simple supported T beam highwaybridges and calculated both the static and dynamic response of structures, and then putforward a more reasonable way to calculate the impact factor after considerding the roadsurface index.The major researches are as follows:Firstly, according to the collected24hours data of random traffic flow, divide thecommon vehicle models of highway into17types, and the statistical analysis of vehiclespeed, vehicle weight, and driving horizontal position parameters has been done. Calculate thestatic and dynamic response of a six span continuous T beam bridge to get the impactcoefficient spectrum of the structure,and then analysis the relationship between the spectraldistribution and its impact factor between speed, weight, the internal force of the main beam.Secondly, analysis how the impact factors change when different vehicles running indifferent speeds, also several typical models of great influence on the bridge impactcoefficient have selected and traffic cases of different loads simulated to calculate the effect tothe impact factor.Thirdly,build five typical simple supported T beam highway bridges modles, andcalculated both the static and dynamic response of structures,and then form the impactcoefficient spectrum of extra heavy traffic loads. Do research on the relationship between theimpact coefficient spectrum and static effect of bridge strcture under traffic loads, and makecontrast to design load effects.At the end of this paper, a more reasonable calculation methodto calculate the impact factor have been put forward, taking the road surface index intoconsideration.