Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Structural design standards based on the principles of structural reliability are gaining
worldwide acceptance and are fast becoming the new basis of structural safety verification.
The application of these principles to establish a standardised basis for structural design using
partial factor limit states design procedures is done in the European Standard for the Basis of
Structural Design EN 1990 from which it is adapted to the South African Basis of Design
Standard for Building and Industrial Structures SANS 10160-1. The basis of design
requirements stipulated in EN 1990 and SANS 10160-1 apply to all aspects of structural
design: This includes reliability levels of structural performance and their differentiation and
management; identification of various limit states and design situations; the specification of
all the basic variables; separate treatment of actions and material-based resistance. However,
application of these requirements is then primarily focused on actions whilst the provision for
structural concrete is then left to the materials based design standards.
This two-part thesis describes a systematic assessment of the degree to which the application
of the reliability framework presented in the basis of design requirements has been achieved
in the present generation of structural concrete design standards. More importantly, attempts
are made to identify ways in which the process can be advanced. Special attention is drawn
to issues that are specific to South African conditions and practice in structural concrete.
Part One of the thesis focuses on the key elements of the reliability framework presented in
EN 1990 and traces to what extent the requirements have been propelled through the design
stipulations of the Eurocode Standard for Design of Concrete Structures EN 1992-1-1. The
implications of the different reference level of reliability between the Eurocode default value
of ß = 3.8 and that characteristic of South African practice ß = 3.0 through various issues
are highlighted. The use and advantage of explicit treatment of reliability performance on
reliability management related to some aspects of quality control are explored. A critical
aspect is the shear prediction model providing unconservative estimates of shear resistance.
Part Two of the thesis focuses on characterising the model factor of the EN 1992-1-1 shear
prediction model for members requiring design shear reinforcement. This is done by a
comparison to a compiled experimental database with special focus on situations with high
reinforcement ratios. The significance of the modelling uncertainty in shear prediction is verified by this comparison. The use of the more conceptually rational modified compression
field theory (MCFT) to improve on the quality of shear predictions is investigated and proves
to yield more precise values with lower scatter hence making it a more reliable tool for
predicting shear. The MCFT can then be used as reference for the reliability calibration and
possible improvement for the Eurocode procedure. / AFRIKAANSE OPSOMMING: Strukturele ontwerpstandaarde gebaseer op die beginsels van strukturele betroubaarheid
verkry wêreldwye aanvaarding en word vinnig die nuwe basis van strukturele veiligheid
bevestiging. Die toepassing van hierdie beginsels om ʼn gestandaardiseerde basis vir
strukturele ontwerp is bevestig deur gebruik te maak van gedeeltelike-faktorbeperkende
stadiums ontwerpprosedures in die Europese Standaard vir die Basis van Strukturele
Ontwerp EN 1990 waarvandaan dit herbewerk is na die Suid-Afrikaanse Basis van Ontwerp
Standaarde vir Bou en Industriële Strukture SANS 10160-1. Die basis van ontwerpvereistes
bepaal in EN 1990 en SANS 10160-1 is van toepassing op alle aspekte van strukturele
ontverp: Dit sluit inbetroubaarheidsvlakke van struktureele prestasie en hul diversifikasie en
bestuur; identifikasie van verskeie beperkende state en ontwerpsituasies; die spesifikasie van
al die basiese veranderlikes; afsonderlike behandeling van aksies en materiaal-gebaseerde
weerstand. Desnieteenstaande, die toepassing van hierdie voorwaardes is dan hoofsaaklik
gefokus op aksies terwyl die voorsiening van strukturele beton is dan gelaat op die materiaalgebaseerde
ontwerpstandaarde.
Hierdie tweeledige verhandeling beskryf ʼn stelselmatige beoordeling van die graad waartoe
die toepassing van die betroubaarheidsraamwerk aangebied word in die basis van
ontwerpvereistes bereik in die huidige generasie van strukturele beton-ontwerp standaarde is.
Meer belangrik, pogings is aangewend om die maniere hoe die proses bevorder kan word te
identifiseer. Spesiale aandag word gevestig op kwessies wat spesifiek op Suid-Afrikaanse
toestande en praktyke in strukturele beton toepaslik is.
Deel Een van die verhandeling fokus op die sleutel-dele van die betroubaarheidsraamwerk
aangebied in EN 1990 en skets die mate waartoe die vereistes aangespoor word deur die
ontwerp voorskrifte van die Eurocode Standard for the Design of Concrete Structures EN
1992-1-1. Die implikasie van die verskillende verwysingsvlakke van betroubaarheid tussen
die Eurocode standaardwaarde van ß = 3.8 en die eienskap van Suid-Afrikaanse praktyk
ß = 3.0 deur verskillende kwessies word uitgelig. Die gebruik en voordeel van spesifieke
behandeling van betroubaarheidsuitvoering op betroubaarheidsbestuur verwantskap met
sekere aspekte van kwaliteit kontrole word ondersoek. ʼn Kritiese aspek is die model vir die
voorspelling van skuif-weerstand wat die onkonserwatiewe beramings vir skuif-weerstand
gee. Deel Twee van die verhandeling fokus op karakterisering die modelfaktor van die EN 1992-
1-1 skuif-weerstand voorspellings-model. Dit word gedoen deur ʼn vergelyking na ʼn
saamgestelde eksperimentele databasis met spesifieke fokus op situasies met hoe
herbevestigingsvergelykings. Die oorheersing van die modellering- onsekerheid in skuifweerstand
voorspelling is bevestig deur hierdie vergelyking. Die gebruik van ʼn meer
konseptuele rasionele gemodifiseerde druk-veld teorie (bekend as MCFT) om die kwaliteit
van skuif voorspelling te verbeter is ondersoek en verskaf ‘n meer presiese waarde met laer
verspreiding wat lei tot ʼn meer betroubaree instrument om skuif mee te voorspel. Die MCFT
word dan gebruik as verwysing vir die betroubaarheid-samestelling en moontlike verbetering
van die Eurocode prosedures.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/19967 |
| Date | 03 1900 |
| Creators | Mensah, Kenneth Kwesi |
| Contributors | Retief, J. V., Barnardo-Viljoen, C., Stellenbosch University. Faculty of Engineeering. Dept. of Civil Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | Stellenbosch University |
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