Research on Long-Span Old Bridge's Dynamic Reliability Under Vehicular Load

From an analysis of random process with modal analysis method, formulas of related parameters for an analysis of structural dynamic reliability have been deduced first in the paper, accordingly, prepares "the PMDK dynamic reliability analysis program" by Fortran programming language. Next, Some parameters for vehicular load probability distribution model have been derived by a method of unconstrained planning, Combining with an observation data for vehicle distribution at a long-span old bridge, the author has obtained the model in this paper. Finally, author has calculated a dynamic reliability for the long-span old bridge under a specific vehiclar load by the program and studied a relationship between dynamic reliability and displacement as well as sectional position and influences of damping and elastic modulus on its dynamic rerliability. Meanwhile the author also has studied a relationship between dynamic reliability and time and influences of structural unilateral and bilateral reliability. At last all aboved conclusions have been confirmed by Monte Carlo method. With the increasing of traffic volume and speed as well as axle load, there are many neglected diseases for old bridges. More reasons about it, a important one is that design load which put on old bridges is small, So carrying performances are influenced by that seriously. Currently, the relative information about dynamic reliability of highway is less, so it is particularly important to research on rules of vehicular load distribution and dynamic reliability under the load.