Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Middle East Technical University, Turkey
Approval Date: 2020
Student: Aynur Şeyma Bulduk
Supervisor: ÖZGÜR KURÇ
Abstract:Skewed and horizontally-curved steel I-girder bridges show complicated behavior due to the torsional action they exhibit under standard bridge loads, particularly during construction. The restrained warping response of girders can play a critical role in the analysis and design of these structures. In finite element analysis, the restrained warping behavior of girder can be considered through detailed 3D shell models or alternative methods such as utilizing an effective torsion constant in the analysis with conventional beam elements. However, there is still a need for an intermediate modeling approach for practical purposes, that is time-saving, reliable, and will provide specific analysis output parameters with sufficient accuracy. This study investigates different modeling approaches involving shell elements, beam elements with warping behavior, and the combination of shell-beam elements. Then, it evaluates to what extent a modeling approach that utilizes beam elements with an additional warping degree of freedom can produce accurate results compared to the other modeling approaches. For this purpose, a 3D frame analysis program is developed in MATLAB and different beam element formulations are implemented vi into the program. Under construction loads, a straight I-girder, a horizontally-curved I-girder, and a horizontally-curved I-girder bridge are analyzed through the frame analysis program. Equivalent 3D shell models are constructed and analyzed in LARSA 4D finite element analysis software. The accuracy of twist angles, vertical deflections, major-axis and lateral bending moments, associated stresses, and crossframe forces are discussed in a comparative manner. The main conclusion drawn from this study is that the beam element with an additional warping degree of freedom is capable of producing essential analysis output parameters with sufficient accuracy. Moreover, using shell and beam elements for modeling the web and flanges of an I-section, respectively, can be considered as an alternative and practical way of modeling such bridges.