Computer Analysis of Highway Bridge Girders

A computational procedure is presented for computer analysis of continuous highway bridge girders with unlimited number of spans and variable moment of inertia with or without floor beams. The length of the girder is subdivided into many elements. Then, by using the Moment Area method of analysis, the influence lines for deflection, reactions, moment, and shear are determined. For automatic computation of impact effects, a new method is proposed which uses impact modified influence lines. The influence lines are then loaded with dead loads and standard AASHO live loads. The loading of influence lines with moving loads can be formulated as a mathematical programming problem consisting of optimization of the effects of moving loads subject to constraints and limitations between the spacing of axles and vehicles. The envelope of maximum, minimum, and absolute maximum effects are obtained and the stresses are determined. This computational procedure is programmed in ALGOL-60 Compiler for an 1107-Univac Digital Computer. A numerical example is presented.