Geometrically Nonlinear Static Behavior of Cable Structures

Geometrically nonlinear analyses are used to study the static structural behavior of three cable systems. All analyses and results are nondimensional and therefore valid for any scale. The behavior of a system that has a singular linear stiffness matrix is compared to that of a comparable system that has a nonsingular linear stiffness matrix. The actions considered include pretensioning, uniform dead load, asymmetric and antisymmetric vertical live loads and moving vertical live loads. There is no distinct improved static behavior associated with the system that has a nonsingular linear stiffness matrix. The nonlinear behavior of a cable stiffened by a girder is also studied. The behavior of the deck-stiffened system depends strongly on a nondimensional parameter defined by the moment of inertia of the girder divided by the area of the suspension cable times the square of its sag. A preliminary comparison of the relative effectiveness of stiffening with a girder versus stiffening by longitudinal pretensioning is made.