This paper provides a description and design developments of the extradosed prestressed bridge concept. The development of the extradosed prestressed bridge concept is discussed, drawing upon the differences with a cable-stayed bridge type. Proportioning parameters used for initial concept development or verification are provided. This includes recommendations on span ranges, structure depth, tower height and multi-span applicability. Stay cable design considerations are discussed. These proportioning parameters are applied to a prototype design, the Pearl Harbor Memorial Bridge. Aesthetic opportunities for this new bridge type are discussed.

Due to increased traffic loads and changes in the code provisions many highway bridges in Germany exhibit deficits in shear capacity according to current codes. The majority of these bridges’ structures comprises continuous concrete beams whose calculatory shear capacity is often exceeded by now. However, the actual shear capacity of prestressed concrete continuous beams is usually underestimated since the design procedures have been derived on the basis of single-span beam tests and neglect significant shear transfer mechanisms. In order to extend the service life of existing bridges, the reserves in the design procedures can be partially taken advantage of by the application of refined design approaches. For this reason, five shear tests on prestressed concrete continuous beams have been performed at the Institute of Structural Concrete of RWTH Aachen University in Germany. Within these tests, the influence of cross-section type (rectangular and I-shaped cross-section), load distribution (concentrated and distributed loads) and the shear reinforcement ratio are investigated. In this paper, the test results of three beams under concentrated loads will be presented.

This is a case study involving an aging parking structure that deteriorated to the point where the structural floor slab failed. The lines of responsibility between parties involved with owning, managing and repairing the existing, exposed structures are not always clear, based on contractual language. This case ended in litigation to determine who was responsible for repair costs when the structural slab reached the end of its service life, taking into account the root cause of the slab failure. In this case study, we review the field and background information obtained for this case as well as the court interpretation of lines of responsibility and contract language regarding parking structure maintenance and normal wear and tear.

This paper presents an on-going research program to develop an effective strengthening method using post-tensioned near-surface-mounted (NSM) carbon fiber reinforced polymer (CFPP) composites for constructed bridges girders. Various technical aspects associated with strengthened girders are examined through computational modeling, laboratory experiments (small- and full-scale tests), and a field project that is the world’s first site application of post-tensioned NSM CFRP. The flexural behavior of the bridge girders is improved by strengthening (that is, cracking, yield, and ultimate loads, as well as serviceability) relative to unstrengthened control girders, and the post-tensioned NSM CFRP should cover at least 60% of the girder length. The influence of CFRP post-tensioning on the girder concrete adjacent to the anchorage exponentially decays and becomes negligible beyond a distance of 800 mm (31 in.), irrespective of girder size. The presence of initial damage in the girder does not affect the efficiency of the strengthening system until failure occurs. The site application is dedicated to upgrading the design live load capacity of a 56-year old bridge in South Korea from 318 kN (72 kips) to 424 kN (95 kips). Step-by-step procedures are detailed for the technology transfer. Long-term performance monitoring for this upgraded bridge is underway and corresponding results will be reported when sufficient data are available.

The span length of precast prestressed concrete girder bridges is typically limited to 140–160 ft (43–49 m) due to handling and transportation restrictions on individual girder segments. Span lengths may be doubled by splicing individual girder segments within the spans to form a continuous bridge. A design for a three-span continuous prototype bridge with a 240 ft (73 m) main span and 190 ft (58 m) end spans using modified Tx70 precast concrete girders has been developed. A full-scale experimental study investigated the performance of the prototype bridge details in the splice region under service and ultimate loads. The tested splice connection details were selected to represent critical design parameters. The splice connections performed well under service level loads. However, the lack of continuity of the pretensioning through the splice connection region had a significant impact on the behavior at higher loads approaching ultimate conditions. Moderate ductility was observed for positive bending with low ductility for negative moment. Ideally, spliced connections should be located in regions of low moment demands, away from the peak positive or negative moments. Improved connection behavior at ultimate conditions is expected through enhanced connection details, and several detailing suggestions are discussed.