Research On Dynamic Characteristics For Irregular Shaped Girder Bridge Based On Dynamic Substructure Method

Rapid economic development in China leads to the development of urban construction andthe prosperity of transportation infrastructure. The irregular shaped bridges gradually rise in theconstruction of urban overpasses and interchanges and play a good role in the flow of traffic.However, the study on the mechanical properties of irregular shaped bridges is still laggingbehind, and there is still no mature and effective method to calculate the static and dynamiccharacteristics. With respect to the structure static analysis, the dynamic characteristics analysistakes up more computer resources, especially for large and complex structures. The substructuremethod for the structural vibration analysis provides an effective way to solve the dynamiccharacteristics of complex structures. The substructure method is based on the idea ofdissociation. According to geometry features, the structure is divided into several substructures.The dynamic characteristics of the overall bridge can be obtained only by certain low-leveldynamic characteristics of each substructure combined with the substructure interfaces. Thisundoubtedly reduces the amount of memory and computation time, and is also easy introubleshooting, which reduces the possibility of failure in calculation. Focused on theapplications of dynamic substructure method into solving dynamic characteristics of irregularshaped bridge, the following researches are conducted in this paper:(1) The basic steps and methods by using the finite element method to solve the dynamicresponses of bridges are summarized and the basic principle and solution step details of severaltypes of substructure methods for solving the dynamic characteristics of structures areintroduced.(2) Two typical irregular shaped bridge models are selected as the research object, whichare respectively the relatively simple irregular shaped beam bridge and the bridge modelabstracted from the actual project out of the typical irregular shaped box girder bridges. First, thedynamic performances of the overall structure are analyzed by MATLAB, which are comparedwith ANSYS simulation results to verify and ensure the accuracy; then the dynamic characteristics of the structure under various dynamic substructure algorithms are calculated tovalidate the feasibility and accuracy of various dynamic substructure methods in dynamicanalysis of the irregular shaped bridge. And then, combined with the precision and thecomplexity of operation for all kinds of methods, their applicability in different types of irregularshaped bridge is discussed.(3) Design process is almost a repeated correction process. Rebuilding the model tochange certain design parameter is bound to increase the degree of design complexity. In order toachieve the purpose of rapid design, the typical irregular shaped box girder bridge is selected asthe research object to study the effects of the design parameters such as ramp radius, dark beamstiffness, main cross-section on the dynamic performances of the overall structure by means ofdual coordinate free interface modal synthesis method, which aims at providing analysisreference.