Evaluation of the Design of Simple-Span Precast Prestressed Bridge Girders Made Continuous for Composite Dead and Live Loads. State of the Art

摘要

A detailed investigation was undertaken to study the time-dependent behavior and relevant design criteria for simple-span precast prestressed bridge girders made continuous. A survey of different DOTs across the country was conducted by circulating questionnaires to determine the current practice of analysis and design of this type of bridge. Creep and shrinkage tests were conducted on steam cured concrete at an early age since this type of concrete is used in most precast girders. Computer simulations were carried out using the programs PBEAM and WALL HINGE to investigate the effects of time-dependent material behavior and design parameters on the effective continuity for live load plus impact. The results indicate that positive moment connections in the diaphragms at the piers are not required as they have no structural advantages. The results also indicate that the effective continuity for live load plus impact can vary from 0 to 100% depending on the design parameters and sequence of construction. The computer analysis was used to determine an upper limit for the amount of negative moment reinforcement over the supports to ensure full moment redistribution and strength.