The Study To Load Standard Of Live Load In Longspan Multi-line Bridge

In recent years, the study of multi-line load standard of live load has relatively lagged behind with the wide application of multiple line railway bridge, highway-railway bridge and double-decked railway bridge in China. Most research about multi-line load standard of live load in our country is combination loading based on their own specified lateral reduction factor lack of the consideration to the probability models of live load and the probability that two trains can meet, so it is of great important to study multi-line load standard of live load.Based on the statistics of various vehicles (trucks, trains and cars), firstly, the paper takes the lateral reduction factor of live load as the research object. Secondly, It simulates the respective probability distribution density function of the load and conducts the goodness of fit test through kolmogorov-smirnov test of probability theory. At last,the paper builds the relationship between lateral reduction factor and correlation variable according to the method which highway bridge calculates lateral reduction factor and repeated independent trials and calculate the proposed value of lateral reduction factor in single-line live load (such as railway line for freight traffic or passenger railway) with probabilistic method. At the same time, this text innovatively takes freight line and highway lanes into consideration, calculate the proposed value of respective lateral reduction factor of live load in different lanes on the basis of probability theory and apply it to the calculation of double-deck railway bridge and highway-railway bridge.The results as follows:(1) When single-line live load affect the bridge, the relationship of lateral reduction factor of live load is:railway line for freight traffic>passenger railway> highway lanes.(2) When there is only passenger railway lane or freight line load, the transverse reduction factor in the paper decrease gradually along with the number of line increasing and is greater than the specified lateral reduction factor, except two passenger railway lines.(3) When three-line live load affect the bridge, the relationship of lateral reduction factor of live load is:railway line for passenger railway> freight traffic> highway lanes.(4) According to the transverse reduction factor in this paper, the maximum response of the highway-railway bridge appears when the number of line is four and for the double-decked railway bridge the number is six, but on the basis of the specified lateral reduction factors the maximum response appears when all live loads work on the bridge, at the same time, it is greater than the former.