Extending Span Ranges Of Precast Prestressed Concrete Girders

At head of title: National Cooperative Highway Research Program.

Introduction and Research Approach -- Findings -- Interpretation, Appraisal, and Application -- Interpretation, Appraisal, and Application -- References -- Appendixes.

This report establishes a user's manual for the acceptance, repair, or rejection of precast/prestressed concrete girders with longitudinal web cracking. The report also proposes revisions to the AASHTO LRFD Bridge Design Specifications and provides recommendations to develop improved crack control reinforcement details for use in new girders. The material in this report will be of immediate interest to bridge engineers.

Throughout the last decades, the increasing development of the urban metropolis and the need to establish fundamental infrastructure networks, promoted the development of important projects worldwide and several Multi-Span Large Bridges have been erected. Certainly, many more will be erected in the next decades. This international context undoubted

Over the past five decades, prestressed concrete bridge girders have evolved from traditional bulky shapes to efficient girder cross-sections with long spans and wide, thin top and bottom flanges. The objective of this research study is to provide the Kansas Department of Transportation (KDOT) with the information needed to make an informed decision about possible adoption of NU girders, including the data to determine whether or not wide-scale adoption is warranted. The investigation compared NU girders and Kansas K-girders in a parametric study of bridge superstructure designs using CONSPAN software, including evaluation of anticipated costs that include material, labor, and transportation. The bridge design procedure was based on the American Association of State Highway and Transportation Officials (AASHTO, 2012) Load and Resistance Factor Design (LRFD) Bridge Design Specifications (6th edition). Additional design guidelines were referenced from the Precast/Prestressed Concrete Institute's (PCI, 2014) Precast Prestressed Concrete Bridge Design Manual (3rd edition), and the KDOT (2015) Design Manual, Volume III – Bridge Section. The overall finding of this study is that K-girders should continue to be used instead of NU girders whenever normal spans and girder spacing allow, as this will likely result in the most economical superstructure. At longer spans (beyond 130–140 ft) NU girders are an excellent option and should become a standard design implementation to extend the applicable range of pretensioned girders to 200 ft and beyond. Additionally, the NU girder system can be used for the purpose of extending the span range (beyond K-girder capabilities) in specific situations where the maximum girder height is fixed. However, as shown previously through analyses, if K-girders can achieve the desired span at a normal spacing, then these will likely provide the most economical option.

This book contains the proceedings of the fib Symposium “High Tech Concrete: Where Technology and Engineering Meet”, that was held in Maastricht, The Netherlands, in June 2017. This annual symposium was organised by the Dutch Concrete Association and the Belgian Concrete Association. Topics addressed include: materials technology, modelling, testing and design, special loadings, safety, reliability and codes, existing concrete structures, durability and life time, sustainability, innovative building concepts, challenging projects and historic concrete, amongst others. The fib (International Federation for Structural Concrete) is a not-for-profit association committed to advancing the technical, economic, aesthetic and environmental performance of concrete structures worldwide.

This comprehensive and up-to-date reference work and resource book covers state-of-the-art and state-of-the-practice for bridge engineering worldwide. Countries covered include Canada and the United States in North America; Argentina and Brazil in South America; Bosnia, Bulgaria, Croatia, Czech Republic, Denmark, Finland, France, Greece, Macedonia, Poland, Russia, Serbia, Slovakia, and Ukraine in the European continent; China, Indonesia, Japan, Chinese Taipei, and Thailand in Asia; and Egypt, Iran, and Turkey in the Middle East. The book examines the use of different materials for each region, including stone, timber, concrete, steel, and composite. It examines various bridge types, including slab, girder, segmental, truss, arch, suspension, and cable-stayed. A color insert illustrates select landmark bridges. It also presents ten benchmark comparisons for highway composite girder design from different countries; the highest bridges; the top 100 longest bridges, and the top 20 longest bridge spans for various bridge types including suspension, cable-stayed, extradosed, arch, girder, movable bridges (vertical lift, swing, and bascule), floating, stress ribbon, and timber; and bridge construction methods.