Dynamic Analysis Of Vehicle-Bridge Coupling For Multi-beam Concrete Skew Girder Bridges

Skew bridges are widely used in bridge construction, because of the land-form’s restriction or the linear requirements of highway. So far, the skew bridge’s static behaviors have been researched thoroughly, whereas its dynamic behaviors under vehicle load are still to be studied, thus the design basis for reference have not be provided yet. What’s more, the regulations of its impact coefficients defined by the current Highway Bridge Code for Design in China are to be discussed as well. Hence, the multi-beam concrete skew bridges with typical section form are investigated in this thesis to study the impact effect and its calculate formula of impact coefficient could be obtained. The main study achievements in this paper are as follows:1. Based on the previous studies, the modified grillage model applied for skew bridge’s dynamic analysis is adopted. After comparing with the simulation entity model, the static and dynamic analysis results verify the reliability of the model. Then, according to highway bridge and culvert General Standard drawings, single-span skew girder bridge’s finite element models (including skew T girder bridge, skewed hollow slab beam bridge and skew small box girder bridge which are widely used in domestic highway) are built by general finite element software ANSYS, thus typical examples are provided for dynamic characteristics parameters analysis and vehicle-bridge coupling vibration analysis.2. The influencing rules of parameters (like span, skew angel, and span to width ratio) on the characteristic frequency are surveyed. The results indicate that:skew girder bridge’s mass and stiffness are changed with the variation of each design parameter, furthermore, affecting its characteristic frequency. Each parameter has different extents of impact, and span dominates top among all.3.Considering the road roughness, the vehicle’s three-dimensional computational model with 12 degrees of freedom is adopted to compile the vehicle-bridge coupling analysis program. Compiled analysis program is applied to the parameter ana-lysis of single span and multi-span skew girder bridge, so the impact effects to different important parameters(traveling position of vehicle, road roughness, vehicle speed, bridge span, skew angle, span to width ratio, bridge structure’s damping ratio and spans of bridge) could be surveyed. The study conslusions come to that:impact effect is influenced greatly by deterioration of road condition; speed, span, damping ratio and skew angle all have strong influence on the impact effect while the traveling position and span to width ratio is relatively small, among them the impact effect will decline as the incline of skew angle.4. After these parameters having being analised, practical formulas of multi-beam concrete skew girder bridge’s impact coefficient under different road roughness levels are obtained, consequently provide a reference for its dynamic engineering and operation maintenance.