Numerical Modeling Techniques of High-Speed Rail Bridge Structures
AuthorStephenson, Andrew Wataru
AdvisorMoustafa, Mohamed A
Civil and Environmental Engineering
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High-speed rail (HSR) is a complex system incorporating various technical aspects such as infrastructure, rolling stock (specially-designed train sets), telecommunications, operating conditions, and equipment. The highly sophisticated technology combining these elements, as well as the elements themselves continue to evolve as the new transportation mode continues to expand and its intrinsic characteristics pose design issues unique to HSR systems. With the requirements for deflections, rotations, and natural frequencies of HSR bridge structures, comprehensive understanding of the HSR dynamic interactions is a topic of growing interest. Accordingly, many studies over the past few decades have been conducted, mostly internationally, with a focus on dynamic interaction between the different components of HSR train/bridge systems through sophisticated structural models. The focus of this research is to identify these modeling features and inherent characteristics of HSR bridges, and to provide guidance and demonstration examples on how to develop such models in OpenSees. Such models will aid researchers and designers in conducting parametric studies to test the static, modal, and dynamic performance of future HSR bridge designs to formulate a national standard for HSR infrastructure in the United States.The main objective of this study was to create a comprehensive modeling guideline for HSR bridge systems. To do so, a thorough literature review was conducted to synthesize various methods of numerical modeling techniques used to model HSR systems. Literature published from national and international sources were reviewed and compiled to demonstrate how the individual components within a train system, track system, and bridge system have been modeled in previous studies. The synthesis also identified the similarities and differences regarding the different finite element modeling techniques for different components. Based on the studies analyzed in the literature search, a prototype train system and track-bridge system were selected to construct a fully detailed example HSR bridge model. The prototypes were selected based on available information regarding the design of the prototype components to minimize assumptions necessary to model the prototype system. A step-by-step guide of the processes of formulating the model and analysis parameters from start to finish were documented, accompanied by snapshots from a sample OpenSees model input file for guidance and future use.To exemplify potential use of the developed model for informing future designs using OpenSees data output, sample static and dynamic analyses were performed with load cases without train loading and with train loading on the prototype HSR bridge. Additionally, a brief analytical study was performed to demonstrate the HSR bridge seismic performance using three different ground motions. The ground motions were retrieved from the PEER Ground Motion Database and were amplified to various degrees to perform nonlinear time history analysis. The nonlinear analysis considered four load cases for unloaded bridge and the bridge with a train on top in three sample load cases to observe the sensitivity of seismic analysis based on the addition and location of train loading. From the preliminary analysis results of the prototype HSR bridge modeled as a demonstration, the location of the train loading did not show significant influence on the local and global response of the bridge. At larger scale of ground motions, the bridge showed instances of higher nonlinearity with load cases with train loading which suggest that the train-bridge interaction better be considered when informing and optimizing future HSR bride designs in high-seismic areas.