Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Civil and Environmental Engineering

Supervisor

Dr. F. Michael Bartlett

Abstract

Current provisions in CSA S6-06 “Canadian Highway Bridge Design Code” for computing second-order effects in slender concrete beam-columns were derived for columns in buildings, where these effects can often be neglected, so their applicability to extremely slender cable-stayed bridge decks warrants investigation. The research reported in this thesis first reviews the provisions in CSA S6-06, as well as eight equations proposed by others, for computing the flexural rigidity, EI, of slender concrete beam-columns. Methods for quantifying the rotational restraint provided at deck slab supports by steel or concrete floorbeams are presented and validated: steel floorbeams provide negligible restraint but concrete floorbeams can provide sufficient restraint to reduce markedly the effective length factor. A rational method is presented and validated for analyzing continuous beam-columns subjected to transverse loads applied between their supports. A sensitivity analysis demonstrates that the variables that influence the moment magnification of cable-stayed bridge decks are: the applied axial load, the slenderness ratio, the concrete compressive strength, and the rotational restraint provided at the deck slab supports. Lastly, the deficiency of the provisions in CSA S6-06 for designing a simplified three-span cable-stayed bridge deck is demonstrated and recommendations are given to facilitate design office practice.


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