Comparison of dynamic behaviour of cable stayed bridges which are modeled as 2 and 3 dimensional

In this thesis, it is aimed to compare natural frequencies and mode shapes of cable stayed bridges obtained from modal analysis for 2 and 3 dimensional finite element computer models and to evaluate the closeness of the results to real life structural behavior.Quincy Bayview Bridge is taken as a real life structure and 2 and 3 dimensional models are performed by considering the masses and rigidities of structural elements. First model is considered as 2 dimensional and the other two are modeled as 3 dimensional. While in the first model of 3 dimensional models, the deck is modeled by frame elements and connecting rigid links to reflect the deck behavior, in the other model the deck is defined by shell elements. In this thesis, not only comparison of 2 and 3 dimensional models are performed but also it is examined that how effectively the rigid links can reflect the real structural behavior. Models are analyzed with SAP2000 computer analysis program, and also an additional 3 dimensional model is prepared with ADINA finite element program for comparison of the results.At the end of the study, even though the 2 dimensional and 3 dimensional models have yielded close results, it is observed that with the developing computer technologies, 3 dimensional models yield more effective and close solutions to real life structural behavior.