Research On The Bridge Traffic Loads Based On The Monitoring Record And CA Traffic Model

For short-and medium-span bridge structures, their design traffic load is caused by theextra-heavy trucks in highway transportation; and for long-span bridge structures, theproportion of the vehicle types and the traffic operation status should also be taken intoconsideration. Based on the long-term monitoring traffic load data in two regions of China,the characteristics of those two regions’ traffic flow parameters were analyzed; the internalforce distributions of short-and medium-span simply supported beams under the monitoringtraffic loads were calculated and were made a contrast with the effects under design trafficloads. The main traffic flow parameters those affect the long-span bridges’ traffic loadmagnitudes were discussed using the CA traffic model. The following major works weredone:Firstly, according to the WIM data for a period of30days and180days collected from104state road and Xuan-Da freeway separately, the proportion, weight and speed distribution,and the actual over-loaded transportation proportion of different type vehicles in each lane ofthose two regions were analyzed and were made a comparison. The fatigue truck models indifferent lanes of two regions were calculated and contrasted based on the principle of fatigueequivalence.Secondly, the internal force distributions of short-and medium-span simply supportedbeams under the actual traffic loads in each lane of those two regions were calculated basedon the influence line loaded principle. The overrun ratios of each simply supported beam’sinternal forces were analyzed. The maximum traffic load effects in the design reference periodof each simply supported beam were extrapolated using the Rice formula. The relationshipsbetween the span of simply supported beam and the ratios of the maximum traffic load effectsand the design traffic load effects were analyzed. The differences of traffic load effects in eachlane were discussed.Thirdly, the long-span bridge traffic loads under different vehicle type proportions anddifferent traffic flow densities were analyzed using CA traffic model. The main traffic flowparameters those affect the long-span bridges’ traffic load distribution were discussed. Thetraffic loads distributions of different loaded length under the traffic operation of crowedstatus or congested status were modeled in different regions, and were made a contrast withthe traffic loads under design code.