A new ultimate limit state approach to the design of prestressed concrete beams

Simple item page
dc.contributor.advisorKratz, Rolf Dietmaren_ZA
dc.contributor.authorHallam, Grant Roberten_ZA
dc.date.accessioned2016-09-28T19:00:39Z
dc.date.available2016-09-28T19:00:39Z
dc.date.issued1990en_ZA
dc.description.abstractThe 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.en_ZA
dc.identifier.apacitationHallam, G. R. (1990). <i>A new ultimate limit state approach to the design of prestressed concrete beams</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Concrete Materials and Structural Integrity Research Unit (CoMSIRU). Retrieved from http://hdl.handle.net/11427/21967en_ZA
dc.identifier.chicagocitationHallam, Grant Robert. <i>"A new ultimate limit state approach to the design of prestressed concrete beams."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Concrete Materials and Structural Integrity Research Unit (CoMSIRU), 1990. http://hdl.handle.net/11427/21967en_ZA
dc.identifier.citationHallam, G. 1990. A new ultimate limit state approach to the design of prestressed concrete beams. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Hallam, Grant Robert AB - 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. DA - 1990 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1990 T1 - A new ultimate limit state approach to the design of prestressed concrete beams TI - A new ultimate limit state approach to the design of prestressed concrete beams UR - http://hdl.handle.net/11427/21967 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/21967
dc.identifier.vancouvercitationHallam GR. A new ultimate limit state approach to the design of prestressed concrete beams. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Concrete Materials and Structural Integrity Research Unit (CoMSIRU), 1990 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/21967en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentConcrete Materials and Structural Integrity Research Unit (CoMSIRU)en_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherPrestressed concrete beams - Design and constructionen_ZA
dc.subject.otheren_ZA
dc.titleA new ultimate limit state approach to the design of prestressed concrete beamsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
thesis_ebe_1990_hallam_grant_robert..pdf
Size:
2.14 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Masters