Anchorage System in Old Post-Tensioned Precast Bridges

The first precast post-tensioned bridges in Slovakia are approaching 60 years of their service life. Facing an aging infrastructure, it is necessary to assess their present structural condition and residual life expectancy. Different types and methods of anchorage system were developed and available for first post-tensioned bridges around the world. The reliability and functionality of anchorages contribute to the proper behaviour of post-tensioning system. The considerable effect of aggressive environment (frost, chloride salts, humidity) and environmental load (CO2) leads to corrosion of anchorages and prestressing steel with the risk of a sudden unexpected damage to bridge. The research work deals into finding more details of this structural part. During the demolition of damaged post-tensioned bridges built in 1960s several anchorages were removed and analysed. The material properties, size parameters and performed tensile tests of a wedge anchorage system are summarised in this paper. The findings from this study can be used as input parameters for numerical simulation and durability assessment of similar aged existing post-tensioned bridges.

Influencing Factors and Shear Capacity Formula of Single-Keyed Dry Joints in Segmental Precast Bridges under Direct Shear Loading

This article investigates the nonlinear behavior of single-keyed dry joints in segmental precast bridges under direct shear loading on the basis of nonlinear finite element analysis on lots of specimens with concrete plastic damage considered. Through detailed discussion on existing research, influence factors of the ultimate shear capacity of the keyed dry joint are analyzed, a new shear capacity formula was proposed and evaluated. The feasibility and correctness of the FE simulation method were verified by comparison with the existed experimental results. Concrete tensile strength at the key root is critical to the ultimate bearing capacity of the single-keyed dry joint under the direct shear loading. Friction on the joint interface and dimension parameters of the key do not have much effect on the ultimate shear capacity. However, reasonable key inclination (tanθ) would be suggested as 0.7~0.9. In comparison with the predicted results obtained by other existed formulas, the proposed formula is demonstrated to be in perfect consistency with both tests and the FE simulation results.

Proposal of Sustainability Indicators for the Design of Small-Span Bridges

The application of techniques to analyze sustainability in the life cycle of small-span bridge superstructures is presented in this work. The objective was to obtain environmental and economic indicators for integration into the decision-making process to minimize the environmental impact, reduce resource consumption and minimize life cycle costs. Twenty-seven configurations of small-span bridges (6 to 20 m) of the following types were analyzed: steel–concrete composite bridges, cast in situ reinforced concrete bridges, precast bridges and prestressed concrete bridges, comprising a total of 405 structures. Environmental impacts and costs were quantified via life cycle environmental assessment and life cycle cost analysis following the boundaries of systems from the extraction of materials to the end of bridge life (“from cradle to grave”). In general, the results indicated that the environmental performance of the bridges was significantly linked to the material selection and bridge configuration. In addition, the study enabled the identification of the products and processes with the greatest impact in order to subsidize the design of more sustainable structures and government policies.