Evaluation of the effective slab width for composite cable-stayed bridge design

Modern cable stayed bridges have become popular with designers and the public all over the world. They represent an efficient way to bridge medium and long spans in a cost effective, efficient and aesthetic manner. As with any new technology, there are questions as to how to properly address certain design issues. The determination of effective slab width for composite cable-stayed bridge decks, which carry large compressive forces in addition to the usual bending and shear forces of conventional structures, is a case in point.; This question of effective slab width has historically been addressed in design by “borrowing” approaches and methods from other bridge types with rigid vertical supports. As such, one can question how accurately these borrowed methods predict the real situation in a bridge deck where additional compression forces are present. The answer to this question is important, since the economic and efficient design of these structures depends on indenturing the interaction between the deck and its supporting structure. Moreover, the safety of the public also is of paramount importance; the design process must predict accurate results.; Accordingly the study described here evaluated the deck participation with the supporting structure in a way so as to identify the fundamental relationship between the deck, span and bridge geometry. The results of the study in slab participation and resulting stress distribution in the concrete deck of composite cable-stayed bridge systems are presented. Analytical models developed using the ANSYS® finite element analysis package are displayed for typical span arrangements, similar to those being designed and constructed in the United States. Particular attention is given to the longitudinal stress distribution across the deck section and the resulting effective slab width. Recommendations for the implementation of the first specific modified Effective Slab Width procedure for composite cable stayed bridges are outlined. The results using this modified effective slab width procedure used in a direct stiffness analysis are compared to those from detailed finite element studies, and other traditional means. The results show excellent agreement between the proposed method and the more detailed current method. In addition the results show that accurate results can be achieved in mere hours as compared to weeks using traditional approaches. Future research topics that will also make significant contribution to this field of engineering are also presented.*; *Please refer to dissertation for diagrams.