Effect of variation of member stiffness on behavior to timber bridge floor systems

Abstract

This paper investigates the effects incurred in a bridge floor system resulting from variation in member stiffnesses. If the stiffness in one stringer is reduced, without reducing the stiffness in the other members, a higher load must be carried by the nonreduced members. The increased loading condition results in reduced capacity for the floor system. The study is accomplished using a computer simulation to analyze the member reactions in the floor system. Using a structural grid as a model for the bridge floor, a matrix solution based on the stiffness method is solved by computer. Figures are presented to show the effects on member reactions resulting from variation in stiffness and loading conditions. Results show the effects occurring in both exterior and interior stringers as well as in the floor planks. The governing effects from these members are combined to show the effects in the floor system. Reducing the stiffness in an exterior stringer results in a greater reduce tion in capacity of the floor system, compared to reduction in capacity due to reduction in an interior stringer.