A new analytic solution to determine internal load of small span suspension bridge

Abstract

Until now, no available analytic solution considering suspender deformation was given to determine cable tension load at the middle of cable and suspender internal load of suspension bridge. Firstly, the classical theory without suspender deformation was taken to study the sag effect on the internal load of suspension bridge. Results indicate that the tension load at all cable points decreases when the sag increases. A procedure using Muller-Breslau principle to determine the moment and shear force influence line of the stiffening girder in the wire suspension bridge was given, and validated by the influence line given by the classical theory. Secondly, a new analytic solution considering suspender deformation was given to determine cable tension load at midpoint and the internal load of suspenders. The new analytic solution is more reasonable than the classical theory in theory. According to the new analytic solution, the cable tension load gets peak value when the unit live load Pi applies at the middle of stiffening girder, while the internal tension loads in all suspenders reach equal maximum value. Then a linear static model was built in ANSYS ignoring large displacement, initial strain and Ernst’s modulus of elasticity. Results using the new analytic solution compare well with benchmark simulations from ANSYS. So, the proposed analytic solution is a quick and easy way to approximately determine the internal load of small span suspension bridge.