Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
A new ultimate limit state approach to the design of prestressed concrete beams
The present approach to the design of prestressed beams is antiquated and time consuming. Neither SLS or ULS requirements are satisfied directly. There is a need for a new approach using plastic principles to design the prestressing requirements at ULS considering a whole span at a time, with checks...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Concrete Materials and Structural Integrity Research Unit (CoMSIRU)
2016
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613341917118464 |
|---|---|
| access_status_str | Open Access |
| author | Hallam, Grant Robert |
| author2 | Kratz, Rolf Dietmar |
| author_browse | Hallam, Grant Robert Kratz, Rolf Dietmar |
| author_facet | Kratz, Rolf Dietmar Hallam, Grant Robert |
| author_sort | Hallam, Grant Robert |
| collection | Thesis |
| description | The present approach to the design of prestressed beams is antiquated and time consuming. Neither SLS or ULS requirements are satisfied directly. There is a need for a new approach using plastic principles to design the prestressing requirements at ULS considering a whole span at a time, with checks made for SLS requirements afterwards. For a plastic design, the designer would need to know the limits of the bending moment redistribution for the beam under consideration. An equation is therefore necessary to assist the designer in this regard. Such an equation should take into account the cross-section shape of the beam and the prestress to reinforcing steel ratios. Many examples would have to be investigated using a rigorous plastic analysis to formulate such an equation. A computer program has been written as part of this thesis to perform such a rigorous analysis. It's accuracy has been evaluated by comparison with laboratory test beam results. The comparison was favourable, although more results would have to be compared to establish the accuracy that could be expected. A few examples were investigated and the observations noted. Two extreme cases were examined, those of a T-beam and I-beam. The redistribution of bending moments was similar in both cases, but the percentage of the central moment capacity reached was considerably less for the T-beam. For both beams it was impossible to reach the ultimate capacity at the centre before the strain capacity at the supports was exhausted. It was concluded that a plastic design procedure should be introduced, based on the ULS capacity of a span at a time. SLS requirements could then be checked afterwards. This approach would provide a design procedure corresponding to those used for other forms of modern structural design and would be much quicker, safer, more accurate and less costly that the existing design procedures. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/21967 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:34:36.552Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Concrete Materials and Structural Integrity Research Unit (CoMSIRU) |
| publisherStr | Concrete Materials and Structural Integrity Research Unit (CoMSIRU) |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/21967 A new ultimate limit state approach to the design of prestressed concrete beams Hallam, Grant Robert Kratz, Rolf Dietmar Prestressed concrete beams - Design and construction The present approach to the design of prestressed beams is antiquated and time consuming. Neither SLS or ULS requirements are satisfied directly. There is a need for a new approach using plastic principles to design the prestressing requirements at ULS considering a whole span at a time, with checks made for SLS requirements afterwards. For a plastic design, the designer would need to know the limits of the bending moment redistribution for the beam under consideration. An equation is therefore necessary to assist the designer in this regard. Such an equation should take into account the cross-section shape of the beam and the prestress to reinforcing steel ratios. Many examples would have to be investigated using a rigorous plastic analysis to formulate such an equation. A computer program has been written as part of this thesis to perform such a rigorous analysis. It's accuracy has been evaluated by comparison with laboratory test beam results. The comparison was favourable, although more results would have to be compared to establish the accuracy that could be expected. A few examples were investigated and the observations noted. Two extreme cases were examined, those of a T-beam and I-beam. The redistribution of bending moments was similar in both cases, but the percentage of the central moment capacity reached was considerably less for the T-beam. For both beams it was impossible to reach the ultimate capacity at the centre before the strain capacity at the supports was exhausted. It was concluded that a plastic design procedure should be introduced, based on the ULS capacity of a span at a time. SLS requirements could then be checked afterwards. This approach would provide a design procedure corresponding to those used for other forms of modern structural design and would be much quicker, safer, more accurate and less costly that the existing design procedures. 2016-09-28T19:00:39Z 2016-09-28T19:00:39Z 1990 Master Thesis Masters MSc (Eng) http://hdl.handle.net/11427/21967 eng application/pdf Concrete Materials and Structural Integrity Research Unit (CoMSIRU) Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Prestressed concrete beams - Design and construction Hallam, Grant Robert A new ultimate limit state approach to the design of prestressed concrete beams |
| thesis_degree_str | Master's |
| title | A new ultimate limit state approach to the design of prestressed concrete beams |
| title_full | A new ultimate limit state approach to the design of prestressed concrete beams |
| title_fullStr | A new ultimate limit state approach to the design of prestressed concrete beams |
| title_full_unstemmed | A new ultimate limit state approach to the design of prestressed concrete beams |
| title_short | A new ultimate limit state approach to the design of prestressed concrete beams |
| title_sort | new ultimate limit state approach to the design of prestressed concrete beams |
| topic | Prestressed concrete beams - Design and construction |
| url | http://hdl.handle.net/11427/21967 |
| work_keys_str_mv | AT hallamgrantrobert anewultimatelimitstateapproachtothedesignofprestressedconcretebeams AT hallamgrantrobert newultimatelimitstateapproachtothedesignofprestressedconcretebeams |