Retief, Johannes Verster (2015-12)
Thesis (DEng)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Implementation of the principles of structural reliability widely impacted on recent improvements in structural performance. Improvements in the rational basis for the design of structures in turn have a bearing on the ability of structural engineers to contribute to the safety, functionality and economy of structures to accommodate the activities and infrastructure serving society. This dissertation presents a number of investigations that can broadly be classified to explore and advance the implementation of reliability concepts and procedures in standardized structural design. The context of the investigations is provided by various activities on the development of revised or new South African standards for structural design, utilising international standards as reference base. The principles of reliability provide the common basis for the harmonization of national and international standards, unification between various standards which are common to specific structures and reliability assessment for classes of design variables and performance functions.
Specific investigations considered the general basis of structural design required for a suite of standards; the reliability modelling of actions and their combinations, including wind loading, imposed roof loads and crane induced loads; structural resistance, including structural concrete shear and cracking performance, the reliability performance of pile foundations. Generalisation of the detailed investigations consists of the identification of the attributes of structural design standards that could serve as the basis for meta-standard drivers for standards development and their management. A common theme in many investigations is the consideration of model uncertainty and the need for its proper quantification for use in reliability assessment. Accordingly generalisation consists of the compilation of a classification scheme for classes of model uncertainty and systematic procedures for the investigation and implementation of model uncertainty. The scheme can also be used to provide a basis for planning of research activities on which model development can be based.
The investigations confirm the potential for value to be added at the interface between reliability theory and design practice, despite the maturity of the field. Examples presented in the dissertation include detailed investigations on design variables such as South African strong wind characteristics and wind load reliability models, extensive investigations on concrete shear resistance models and their uncertainties, and pile foundation reliability calibration. General investigations on the reliability basis of design contributed to demonstrate the achievement of harmonisation between the new South African Loading Code SANS 10160:2010 and Eurocode to the extent that the South African standard serves as an example of the application of Eurocode beyond Europe. A common basis also serves to unify national standards for the design of various structural materials ranging from steel to geotechnical materials, having widely diverse origins ranging from adoption to local development.
Finally the investigations reveal both remaining topics begging further investigation and a methodology for prioritisation and integrating the outcomes into the general reliability framework.
AFRIKAANSE OPSOMMING: Die implementering van die beginsels van struktuurbetroubaarheid het oor ŉ wye front tot onlangse verbeterings in die verrigting van strukture bygedra. Die verhoogde rasionele basis vir die ontwerp van strukture stel struktuur-ingenieurs in staat om beduidende bydraes te maak tot die veiligheid, funksionaliteit en kostes van strukture wat bydra om gemeenskaps-aktiwiteite en infrastruktuur te huisves. ŉ Aantal ondersoeke word in hierdie verhandeling aangebied, wat breedweg geklassifiseer kan word as ŉ verkenning en bevordering van die implementering van konsepte en prosedures van betroubaarheid in gestandaardiseerde struktuur-ontwerp. Die konteks waarin die ondersoeke uitgevoer is, is die ontwikkeling van nuwe of hersiene Suid-Afrikaanse standaarde vir struktuur-ontwerp, waartydens internasionale standaarde as verwysingbasis aangewend word. Die beginsels van betroubaarheid dien as gemeenskaplike basis vir die harmonisering van nasionale en internasionale standaarde, die unifikasie tussen die onderskeie standaarde wat gebruik word by die ontwerp van spesifieke strukture, sowel as die assessering van die betroubaarheid van klasse van ontwerp-veranderlikes en verrigtingsfunksies.
Benewens ondersoeke na die algemene betroubaarheidsbasis vir struktuur-ontwerp soos van toepassing op ŉ stel van standaarde; is ondersoek uitgevoer op aksies wat inwerk op strukture en hul kombinasies, insluitende windbelasting, opgelegde dakbelastings en belastings wat deur oorhoofse hyskraan-installasies geïnduseer word; struktuur-weerstand, insluitend dié van beton teen skuifkragte en kraak-vorming; die betroubaarheidsverrigting van heipaal fondamente. Veralgemening van die ondersoeke behels die identifikasie van die attribute van standaarde vir struktuur-ontwerp wat dien as meta-standaard aandrywing vir die ontwikkeling van standaarde en bestuur van die proses. Die noodsaak daarvan om voldoende voorsiening te maak vir die bydrae van model-onsekerheid in die assessering van betroubaarheid is ŉ gemeenskaplike tema tot vele van die ondersoeke. ŉ Veralgemeende skema vir die hantering van model-onsekerheid is op grond van hierdie ondersoeke opgestel, waardeur hierdie klas van ondersoek sistematies beplan en uitgevoer behoort te word, self ook vir model-ontwikkeling.
Die ondersoeke bevestig die potensiaal vir verdere toevoeging van waarde deur ondersoeke oor die tussenvlak tussen betroubaarheidsteorie en ontwerp-praktyk, ten spyte van vordering wat reeds gemaak is. Voorbeelde van spesifieke detail ondersoeke sluit die gemelde karakterisering van wind-belasting, omvattende ondersoeke na modelle vir beton skuifweerstand en heipaal betroubaarheids-kalibrasie in. Algemene ondersoeke sluit in die demonstrasie van die harmonisering van die nuwe Suid-Afrikaanse Las-kode SANS 10160:2010 en Eurocode, tot so ŉ mate dat die nasionale standaard beskou kan word as die implementering van Eurocode buite Europa. ŉ Bydrae word ook gelewer tot die unifikasie van die diverse nasionale struktuur-standaarde.
In die finale instansie lê die verhandeling ŉ aantal onderwerpe bloot wat met vrug verder ondersoek kan word, asook ŉ metodologie vir die prioritisering en integrasie van sodanige ondersoeke in ŉ oorhoofse raamwerk vir struktuurbetroubaarheid.
Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/97800
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