'n Koste vergelykende studie tussen konvensionele ongewapende beton en spanbeton pakhuisvloere wat vir puntlaste ontwerp is
- Authors: Vilonel, Jacobus Philippus
- Date: 2014-11-17
- Subjects: Prestressed concrete construction , Floors, Concrete - Design and construction
- Type: Thesis
- Identifier: uj:12842 , http://hdl.handle.net/10210/12730
- Description: M.Ing. (Civil Engineering) , Please refer to full text to view abstract
- Full Text:
- Authors: Vilonel, Jacobus Philippus
- Date: 2014-11-17
- Subjects: Prestressed concrete construction , Floors, Concrete - Design and construction
- Type: Thesis
- Identifier: uj:12842 , http://hdl.handle.net/10210/12730
- Description: M.Ing. (Civil Engineering) , Please refer to full text to view abstract
- Full Text:
Concrete filled double skin circular tubes : a review
- Essopjee, Yoosuf, Dundu, Morgan
- Authors: Essopjee, Yoosuf , Dundu, Morgan
- Date: 2014
- Subjects: Prestressed concrete construction , Columns, Concrete , Plates, Iron and steel
- Type: Article
- Identifier: uj:5083 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13654
- Description: A review of the research conducted on the compressive strength of concrete filled double skin circular tubes (CFDSCT) columns is conducted. Variables of the CFDSCT considered in this review include the concrete strength, steel strength, inner and outer tube diameter, steel thickness and length of the stub columns. Test results show that the composite columns had compressive strengths of up to 41% higher than the sum of the individual strengths of the section. All the outer tubes of these composite columns by failed local buckling. A review of the design equations proposed are presented and discussed. The paper also identifies gaps for further research for these types of columns.
- Full Text:
- Authors: Essopjee, Yoosuf , Dundu, Morgan
- Date: 2014
- Subjects: Prestressed concrete construction , Columns, Concrete , Plates, Iron and steel
- Type: Article
- Identifier: uj:5083 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13654
- Description: A review of the research conducted on the compressive strength of concrete filled double skin circular tubes (CFDSCT) columns is conducted. Variables of the CFDSCT considered in this review include the concrete strength, steel strength, inner and outer tube diameter, steel thickness and length of the stub columns. Test results show that the composite columns had compressive strengths of up to 41% higher than the sum of the individual strengths of the section. All the outer tubes of these composite columns by failed local buckling. A review of the design equations proposed are presented and discussed. The paper also identifies gaps for further research for these types of columns.
- Full Text:
Limits of elongation variation of tenadons in post-tensioning
- Dundu, Morgan, Rupieper, Sebastian
- Authors: Dundu, Morgan , Rupieper, Sebastian
- Date: 2014
- Subjects: Tendons (Prestressed concrete) , Prestressed concrete construction , South African Design Standards
- Type: Article
- Identifier: uj:5069 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13640
- Description: This paper analyses tensioning data obtained from a variety of projects that have been completed in South Africa in recent years in order to determine the causes of variation in elongation and suggest practical elongation limits. Current limits, prescribed by the South African standards (SANS 2001-CC1 and COLTO), of elongation variation limit of ±6% and an average elongation variation limit of ±3% are causing huge problems to the post-tensioning industry. The scatter of tendon elongation results is often greater than the range prescribed by these standards. This usually requires the contractor to re-tension the tendons at huge financial costs. In most cases the results obtained after re-tensioning are the same.
- Full Text:
- Authors: Dundu, Morgan , Rupieper, Sebastian
- Date: 2014
- Subjects: Tendons (Prestressed concrete) , Prestressed concrete construction , South African Design Standards
- Type: Article
- Identifier: uj:5069 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13640
- Description: This paper analyses tensioning data obtained from a variety of projects that have been completed in South Africa in recent years in order to determine the causes of variation in elongation and suggest practical elongation limits. Current limits, prescribed by the South African standards (SANS 2001-CC1 and COLTO), of elongation variation limit of ±6% and an average elongation variation limit of ±3% are causing huge problems to the post-tensioning industry. The scatter of tendon elongation results is often greater than the range prescribed by these standards. This usually requires the contractor to re-tension the tendons at huge financial costs. In most cases the results obtained after re-tensioning are the same.
- Full Text:
Mechanical properties of green concrete with Palm Nut Shell as low cost aggregate
- Agbenyeku, Emem-Obong Emmanuel, Okonta, Felix Ndubisi
- Authors: Agbenyeku, Emem-Obong Emmanuel , Okonta, Felix Ndubisi
- Date: 2014
- Subjects: Sustainable construction , Prestressed concrete construction , Concrete - Testing , Building materials , Palm Nut Shell
- Type: Article
- Identifier: uj:5077 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13648
- Description: The cost saving benefits of aggregate replacement in concrete works are well documented. The utilization of Supplementary Aggregate Materials (SAMs) in concrete engineering without compromising standards in concrete works remain very attractive to both infrastructure developers and design engineers. However, there is continual search for low cost beneficial substitute materials. The mechanical properties of green concrete produced from Palm Nut Shell (PNS) as coarse aggregate was investigated. The abundance of PNS (light weight waste product of palm oil production) in West Africa created the impetus for the study. Series of laboratory tests such as; Slump, Compaction factor, Density, Schmidt hammer and Compressive strength tests were conducted on specimens of 10, 20, 30, 40 and 50% replacements of dry weight of PNS as coarse aggregate and specimens of natural aggregate as control sample. The specimens were cured at relative humidity (RH) of 95-100% and temperature (T) of 22-25oC in a chamber for periods of 7, 14, 21 and 28 days. The results showed the PNS samples to have relatively medium to high workability ranging from 24-47 mm for slump height and values of 0.85 to 0.90 for compaction factors. A general strength development was observed across the different samples with the PNS sample reaching strength of 48.7 N/mm2 at 28 days curing. The 50% replacement specimens which mobilized UCS of 28.7 N/mm2 met the requirement for lightweight concrete however, 30% is the optimum for a partial aggregate replacement in green concrete as UCS of 39.2 N/mm2 was mobilized in 28 days. Thus PNS is a suitable concrete constituent and can be a major cost reduction factor especially in low cost rural projects with streamlined loading requirements.
- Full Text:
- Authors: Agbenyeku, Emem-Obong Emmanuel , Okonta, Felix Ndubisi
- Date: 2014
- Subjects: Sustainable construction , Prestressed concrete construction , Concrete - Testing , Building materials , Palm Nut Shell
- Type: Article
- Identifier: uj:5077 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13648
- Description: The cost saving benefits of aggregate replacement in concrete works are well documented. The utilization of Supplementary Aggregate Materials (SAMs) in concrete engineering without compromising standards in concrete works remain very attractive to both infrastructure developers and design engineers. However, there is continual search for low cost beneficial substitute materials. The mechanical properties of green concrete produced from Palm Nut Shell (PNS) as coarse aggregate was investigated. The abundance of PNS (light weight waste product of palm oil production) in West Africa created the impetus for the study. Series of laboratory tests such as; Slump, Compaction factor, Density, Schmidt hammer and Compressive strength tests were conducted on specimens of 10, 20, 30, 40 and 50% replacements of dry weight of PNS as coarse aggregate and specimens of natural aggregate as control sample. The specimens were cured at relative humidity (RH) of 95-100% and temperature (T) of 22-25oC in a chamber for periods of 7, 14, 21 and 28 days. The results showed the PNS samples to have relatively medium to high workability ranging from 24-47 mm for slump height and values of 0.85 to 0.90 for compaction factors. A general strength development was observed across the different samples with the PNS sample reaching strength of 48.7 N/mm2 at 28 days curing. The 50% replacement specimens which mobilized UCS of 28.7 N/mm2 met the requirement for lightweight concrete however, 30% is the optimum for a partial aggregate replacement in green concrete as UCS of 39.2 N/mm2 was mobilized in 28 days. Thus PNS is a suitable concrete constituent and can be a major cost reduction factor especially in low cost rural projects with streamlined loading requirements.
- Full Text:
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