Abstract: The National Bridge Inventory (NBI) includes more
than 600,000 bridges within the United States of America.
Prestressed concrete girder bridges represent one of the most widely
used bridge systems. The majority of these girder bridges were
constructed using 0.5 and 0.6 inch diameter strands. The main
impediments to using larger strand diameters are: 1) lack of prestress
bed capacities, 2) lack of structural knowledge regarding the transfer
and development length of larger strands, and 3) the possibility of
developing wider end zone cracks upon strand release.
This paper presents a study about using 0.7 inch strands in girder
fabrication. Transfer and development length were evaluated, and
girders were fabricated using 0.7 inch strands at different spacings.
Results showed that 0.7 inch strands can be used at 2.0 inch spacing
without violating the AASHTO LRFD Specifications, while attaining
superior performance in shear and flexure.
Abstract: This article presents the analysis of experimental values regarding cracking pattern, specific strains and deformability for reinforced high strength concrete beams. The beams have the concrete class C80/95 and a longitudinal reinforcement ratio of 2.01%, respectively 3.39%. The elements were subjected to flexure under static short-term and long-term loading. The experimental values are compared with calculation values using the design relationships according to Eurocode 2.
Abstract: This paper in essence presents comparative
experimental data on the mechanical performance of steel and
synthetic fibre-reinforced concrete under compression, tensile split
and flexure. URW1050 steel fibre and HPP45 synthetic fibre, both
with the same concrete design mix, have been used to make cube
specimens for a compression test, cylinders for a tensile split test and
beam specimens for a flexural test. The experimental data
demonstrated steel fibre reinforced concrete to be stronger in flexure
at early stages, whilst both fibre reinforced concrete types displayed
comparatively the same performance in compression, tensile splitting
and 28-day flexural strength. In terms of post-crack controlHPP45
was preferable.