Serviceability criteria for decompression in prestressed concrete bridge girders

The structural design process is a complex procedure involving optimization of the engineering concept to satisfy multiple goals. An Engineer is expected to find a healthy balance between the functionality, economy, appearance and safety. Tremendous progress in engineering technology over the last two decades allowed designers to create lighter, bigger and stronger structures. Improvement of numerical and analytical methods enhanced the accuracy of the resistance estimates. Design concept in which none of the components would ever fail can be very expensive, and often not even possible. Therefore, this dissertation presents formulation of new serviceability design criteria, allowing the designer to create a better bridge that will last longer. The objective of this study is to identify the load and resistance parameters, develop analysis procedure to estimate the number of decompressions and corresponding reliability, and formulate a basis for the analysis procedure to assess the reliability of the bridge as a structural system within the framework of finite element method. The major steps in the presented research included formulation of new serviceability limit state function for selected representative structures, development of the load and resistance model, development of the analysis procedure, analysis of the selected bridges, formulation of the recommendations for the consistent serviceability design, and development of the reliability analysis procedure for the numerical model of the bridge structural system. Reliability methods are used to form a conceptual framework for the development of code provisions providing satisfactory and consistent structural serviceability and safety. Presented probabilistic finite element method numerical procedure can be applied to perform probabilistic performance based design of prestressed concrete bridges. The presented research demonstrates that for consistent serviceability design, site specific load characteristics need to be incorporated into the design procedure