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Target reliability of concrete structures governed by serviceability limit state design
Thesis (MEng)--Stellenbosch University, 2018.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2018
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| _version_ | 1867614114757476352 |
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| access_status_str | Open Access |
| author | Van Nierop, Stacey C. |
| author2 | Viljoen, Celeste |
| author_browse | Van Nierop, Stacey C. Viljoen, Celeste |
| author_facet | Viljoen, Celeste Van Nierop, Stacey C. |
| author_sort | Van Nierop, Stacey C. |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2018. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/103558 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:53.692Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/103558 Target reliability of concrete structures governed by serviceability limit state design Van Nierop, Stacey C. Viljoen, Celeste Lenner, Roman Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Target costing Maintainability (Engineering) Serviceability (Engineering) Water Retaining Structures Reliability UCTD Thesis (MEng)--Stellenbosch University, 2018. ENGLISH ABSTRACT: Structures are typically designed for the ultimate limit state (ULS) while the serviceability limit state (SLS) is checked. However, in many cases the design is governed by SLS requirements. The target reliability for the ULS ßt,ULS is recommended based on cost optimisation and back calibration of existing practice. The current recommendation in ISO2394 is ßt,SLS = 1:5 for the irreversible SLS, although, it is unclear how this value was obtained. The aim of this research is to determine reasonable ßt,SLS values for all serviceability requirements with a focus on concrete structures governed by SLS design. The approach taken, by this thesis, is based on reliability-based economic optimisation in a generalised context, taking into account a range of failure consequences and cost classes. A generalised framework is established to perform a reliability analysis. The limit state function g for the SLS is generalised to g = 1 -πE. This equation is based on the assumption that the design limit is deterministic and the action-resistance effect E is the only random variable. From the generic limit state equation, a generalised decision parameter d is determined, and the reliability level ß(d) is determined through a FORM analysis. Through economic optimisation of the generalised ß(d) values, a parametric table of ßt,SLS values is obtained. The table accounts for a range of cost ratios C1=Cf = [0:5 - 100] (relating the failure costs Cf to the costs per unit of the decision parameter C1) and coefficient of variation of the action-resistance effect VE = [0:05 - 0:50]. ßt,SLS is observed to systematically increase as the cost ratio increases and VE decreases. The current recommendation of 1.5 seems reasonable from a practical perspective for relatively low cost ratios. Two examples of the application of ßt,SLS, from the generic development,are provided. ßt,SLS of a water retaining structure, governed by cracking, and ßt,SLS of a simply supported beam, for de ections, are investigated. E is the product of either the mean-maximum crack width wm;max or mean-maximum deflections δm,max and the model factor Ø VE is then determined through Monte Carlo analysis and Cf/C1 is quantified for the two structures. Once VE and Cf-C1 are known, ßt,SLS is obtained from the generic development. Through economic optimisation of the specific ß(d) values, ßt,SLS is obtained for the same costs. These target values are compared to ßt;SLS from the generic development. The discrepancy identified in the ßt,SLS values for the examples is due to the inefficiency of the generic decision parameter to increase the reliability level of the structure compared to the efficiency of the specific decision parameters. AFRIKAANSE OPSOMMING: Strukture word tipies vir die grenstoestand van swigting (ULS) ontwerp terwyl die grenstoestand van diensbaarheid (SLS) slegs geverifieer word. In baie gevalle is die SLS bepalend vir die ontwerp. Die teiken betroubaarheid vir ULS, ßt,ULS is gebaseer op koste optimisering en kalibrasie na bestaande praktyk van bestaande praktyk. Die huidige aanbeveling in ISO2394 is ßt,SLS = 1:5 vir die onomkeerbare SLS, alhoewel die oorsprong van hierdie waarde onbekend is. Die doel van hierdie studie is om redelike ßt,SLS waardes vir alle diensbaarheid vereistes te bepaal met die klem op betonstrukture wat deur die SLS ontwerp bepaal word. Die benadering, wat deur hierdie studie gevolg word, is gebaseer op ekonomiese optimisering binne 'n algemene konteks met betrekking tot betroubaarheid, met inagneming van 'n verskeidenheid swigting gevolge en kosteklasse. 'n Algemene raamwerk om 'n betroubaarheidsanalise uit te voer word bevestig. Die grenstoestandsfunksie, g, vir die SLS word veralgemeen na g = 1 - πE. Hierdie vergelyking is gegrond op die aanname dat die limiet deterministies is en die aksie-weerstand-effek, E, is die enigste ewekansige veranderlike. Vanuit die generiese limietstaatvergelyking word 'n algemene besluitparameter d bepaal, en die betroubaarheidsvlak, ß(d), word bepaal deur middel van 'n EOBM (Eerste Orde Betroubaarheid Metode) analise. Deur ekonomiese optimisering van die algemene ß(d) waardes, word 'n parametriese tabel van ßt;SLS waardes verkry. Die tabel neem 'n verskeidenheid kosteverhoudings C1=Cf = [0:5 - 100] (Wat die falingskoste Cf tot die koste per eenheid van die besluitparameter C1 vergelyk) en koffisint van variasie van die aksie-weerstand effek VE = [0:05 - 0:50] in ag. Dit word opgemerk dat ßt,SLS stelselmatig toeneem namate die kosteverhouding toeneem en VE afneem. Die huidige aanbeveling van 1.5 blyk redelik vanuit 'n praktiese perspektief vir relatief lae koste verhoudings te wees. Twee voorbeelde van die toepassing van ßt,SLS, vanaf die generiese ontwikkeling, word verskaf. ßt,SLS van 'n waterhoudende struktuur, beheer deur kraking, en ßt,SLS van 'n eenvoudig ondersteunde balk, vir de eksie, word ondersoek. E is die produk van die gemiddelde-maksimum kraakwydte wm;max of gemiddelde-maksimum de eksie δm,max en die modelfaktor Ø. VE is dan deur middel van 'n Monte Carlo analise bepaal en Cf=C1 word gekwantifiseer vir die twee tipes strukture. Sodra VE en Cf=C1 bekend is, word ßt,SLS vanuit die generiese ontwikkeling verkry. Deur ekonomiese optimisering van die spesifieke ß(d) waardes, word ßt,SLS verkry vir dieselfde koste. Hierdie teiken waardes word vergelyk met ßt,SLS van die generiese ontwikkeling. Die teenstrydigheid tussen die ßt,SLS waardes vir die twee voorbeelde word toegeskryf aan die ondoeltreffendheid van die generiese besluitparameter om die betroubaarheidsvlak van die struktuur te verhoog in vergelyking met die doeltreffendheid van die spesifieke besluitparameters. 2018-02-22T18:16:21Z 2018-04-09T07:00:44Z 2018-02-22T18:16:21Z 2018-04-09T07:00:44Z 2018-03 Thesis http://hdl.handle.net/10019.1/103558 en_ZA Stellenbosch University 135 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Target costing Maintainability (Engineering) Serviceability (Engineering) Water Retaining Structures Reliability UCTD Van Nierop, Stacey C. Target reliability of concrete structures governed by serviceability limit state design |
| title | Target reliability of concrete structures governed by serviceability limit state design |
| title_full | Target reliability of concrete structures governed by serviceability limit state design |
| title_fullStr | Target reliability of concrete structures governed by serviceability limit state design |
| title_full_unstemmed | Target reliability of concrete structures governed by serviceability limit state design |
| title_short | Target reliability of concrete structures governed by serviceability limit state design |
| title_sort | target reliability of concrete structures governed by serviceability limit state design |
| topic | Target costing Maintainability (Engineering) Serviceability (Engineering) Water Retaining Structures Reliability UCTD |
| url | http://hdl.handle.net/10019.1/103558 |
| work_keys_str_mv | AT vannieropstaceyc targetreliabilityofconcretestructuresgovernedbyserviceabilitylimitstatedesign |