Effectiveness of Alternative Reinforcing Strategies for Non-Contact Hooked Bar Lap Splices
| dc.contributor.author | Brown, Mason Kendall | en |
| dc.contributor.committeechair | Jacques, Eric Jean-Yves | en |
| dc.contributor.committeemember | Mokarem, David Wayne | en |
| dc.contributor.committeemember | Roberts-Wollmann, Carin L. | en |
| dc.contributor.department | Civil and Environmental Engineering | en |
| dc.date.accessioned | 2025-01-16T09:00:39Z | en |
| dc.date.available | 2025-01-16T09:00:39Z | en |
| dc.date.issued | 2025-01-15 | en |
| dc.description.abstract | Closure joints are used in precast bridge construction to join two pieces of precast concrete. The pieces of concrete are joined by a lap splice which consists of longitudinal steel sticking out of each precast element and overlapped over the minimum required development length. State departments of transportation find it desirable to make the width of closure joints short. To achieve this, bridge engineers have been using hooked bars in the closure joints in lieu of straight bars, with the assumption that this would allow for shorter splice lengths. Though engineers in practice are doing this, design guidance does not exist. One research project by Coleman (2024) tested 58 beam-splice specimens to investigate the impacts of a variety of parameters on bond and anchorage and develop design guidance for hooked bar lap splices. This project did not investigate three parameters: the number of lap splices, the placement of transverse reinforcement, and the addition of steel fibers in the closure joint. For this thesis, 15 beam-splice specimens were tested in 4 point-bending to investigate the impact of these parameters on bond and validate the descriptive equation developed by Coleman (2024) to determine the bar stress of a hooked bar lap splice. The findings of this study suggest that the number of splices and the placement of transverse reinforcement has minimal impact on the bar stress developed, and the equation by Coleman (2024) adequately predicts the bar stress when these parameters were varied. The addition of steel fibers to the closure joint had a substantial impact on increasing the splice strength. In the beams where steel fibers were added in a 1% fiber volume fraction, the descriptive equation by Coleman (2024) underpredicted the bar stress for both unconfined and confined beams with the addition of fibers. Thus, this thesis proposes a factor to multiply the descriptive equation by determining the bar stress when steel fibers are added. With these findings, using steel fibers in closure joints for precast concrete can be used to reduce splice length in non-contact hooked bar lap splices. | en |
| dc.description.abstractgeneral | Precast concrete is concrete that is cast off-site in a controlled environment and transported to the site to then be put together at the site of a project. In bridge construction, this is very beneficial to projects since it means that there is more quality control of the specimens and can allow for faster construction times since the components can have time to cure to strength off-site. To put together pieces of precast concrete to create continuous beams and other components, a closure joint is used. These closure joints consist of two precast pieces of concrete which have longitudinal steel sticking out of each precast element. The pieces of concrete are then joined by overlapping the longitudinal steel in a lap splice. Where a lap splice is used to develop the minimum development, length is required to provide the adequate bar strength such that load will be transferred from one beam to another to create a continuous beam. State departments of transportation find it desirable to make the width of closure joints short. Since closure joint width is typically controlled by the minimum development length required to connect the pieces of concrete, the main way to reduce the width is to reduce the minimum development length. To achieve this, bridge engineers have been using hooked bars in the closure joints in lieu of straight bars, with the assumption that this would allow for shorter splice lengths. Though engineers in practice are doing this, design guidance does not exist. One research project by Coleman (2024) tested 58 beam-splice specimens to investigate the impacts of a variety of parameters on bond and anchorage and develop design guidance for hooked bar lap splices. This project did not investigate three parameters: the number of lap splices, the placement of transverse reinforcement, and the addition of steel fibers in the closure joint. For this thesis, 15 beam-splice specimens were tested in 4 point-bending to investigate the impact of these parameters on bond and validate the descriptive equation developed by Coleman (2024) to determine the bar stress of a hooked bar lap splice. The findings of this study suggest that the number of splices and the placement of transverse reinforcement has minimal impact on the bar stress developed, and the equation by Coleman (2024) adequately predicts the bar stress when these parameters were varied. The addition of steel fibers to the closure joint had a substantial impact on increasing the splice strength. In the beams where steel fibers were added in a 1% fiber volume fraction, the descriptive equation by Coleman (2024) underpredicted the bar stress for both unconfined and confined beams with the addition of fibers. Thus, this thesis proposes a factor to multiply the descriptive equation by determining the bar stress when steel fibers are added. With these findings, using steel fibers in closure joints for precast concrete can be used to reduce splice length in non-contact hooked bar lap splices. | en |
| dc.description.degree | Master of Science | en |
| dc.format.medium | ETD | en |
| dc.identifier.other | vt_gsexam:42368 | en |
| dc.identifier.uri | https://hdl.handle.net/10919/124216 | en |
| dc.language.iso | en | en |
| dc.publisher | Virginia Tech | en |
| dc.rights | In Copyright | en |
| dc.rights.uri | http://rightsstatements.org/vocab/InC/1.0/ | en |
| dc.subject | lap-splice | en |
| dc.subject | hooked bar | en |
| dc.subject | steel fibers | en |
| dc.subject | number of splices | en |
| dc.subject | transverse reinforcement | en |
| dc.subject | precast bridge | en |
| dc.title | Effectiveness of Alternative Reinforcing Strategies for Non-Contact Hooked Bar Lap Splices | en |
| dc.type | Thesis | en |
| thesis.degree.discipline | Civil Engineering | en |
| thesis.degree.grantor | Virginia Polytechnic Institute and State University | en |
| thesis.degree.level | masters | en |
| thesis.degree.name | Master of Science | en |
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