EVALUATION OF LOAD CARRYING CAPACITY OF PC I-GIRDER AND STEEL I-GIRDER BRIDGE UNDER HEAVY VEHICLE

Abstract

This study comprehensively evaluates load-carrying capacity for two bridge types in Khammuan Province, Laos: a PC I-girder bridge (25m span) and a steel I-girder bridge (25.5m span). The investigation addresses a critical infrastructure challenge involving transporting hydropower equipment weighing up to 250 tons across bridges originally designed for 40-ton loads. The research revealed distinct performance characteristics between bridge types by integrating three-dimensional finite element modeling, full-scale testing, and real-time structural health monitoring. Results demonstrated that PC I-girders achieved superior deflection control with 28% lower deflections than steel I-girders, while steel I-girders exhibited more favorable load distribution patterns. Field measurements proved notably conservative compared to analytical predictions, with measured deflections reaching only 34% and 67% of predicted values for PC-I and Steel I-girders, respectively. The innovative 32-axle trailer configuration successfully distributed the 350-ton total weight, generating lower member forces than conventional highway trucks. The research contributes to bridge engineering practice through established methods for bridge evaluation in undocumented structures and safe heavy equipment transit procedures across existing infrastructure.