dc.contributor.advisor | Viljoen, Celeste | en_ZA |
dc.contributor.advisor | Day, P. W. | en_ZA |
dc.contributor.author | De Koker, Nico | en_ZA |
dc.contributor.other | Stellenbosch University. Faculty of Engineering. Faculty of Civil Engineering. | en_ZA |
dc.date.accessioned | 2018-10-22T13:36:03Z | |
dc.date.accessioned | 2018-12-07T06:48:09Z | |
dc.date.available | 2018-10-22T13:36:03Z | |
dc.date.available | 2018-12-07T06:48:09Z | |
dc.date.issued | 2018-12 | |
dc.identifier.uri | http://hdl.handle.net/10019.1/104862 | |
dc.description | Thesis (PhD)--Stellenbosch University, 2018. | en_ZA |
dc.description.abstract | ENGLISH ABSTRACT: Current standards used in South African geotechnical design practice follow the partial factor limit states design approach. Although partial factors
used in this approach are calibrated for standardised target reliability levels, the approach does not take direct account of the probability of failure. Probabilistic reliability analysis provides additional insight to practitioners, making
for potentially more optimal geotechnical structures.
The technical committee responsible for drafting the South African geotechnical design standard has been requested by representatives of the geotechnical community to consider including standardised guidelines to reliability based geostructural design. As background research towards compiling the pre-normative report for such a set of guidelines, the use of reliability analysis
in geostructural design needs to be considered in the context of the following problems.
Firstly, the reliability analysis techniques appropriate to different geostructural
design problems – a design standard can only be successful if the analysis
methods are sufficiently accurate, robust, and practical to apply. Secondly,
the appropriate statistical descriptions of the various model parameters – reliability
analysis of civil structures is extrapolatory by nature, and so is very
sensitive to the choice of functional form (distribution) and the values used to
constrain its parameters. Thirdly, the minimum requirements on sample quality
– sophisticated reliability analysis techniques have little value if parameter
values are based on biased samples that are not representative of the material
upon which the structure is to be founded.
This thesis presents a number of studies associated with the issues listed
above, from which it is concluded that geostructural design to a target reliability
is possible, provided that the resistance model and the statistics describing
its parameters are accurate and unbiased. However, it is shown that for this
to be achieved, samples consisting of a greater number of specimens than currently
used in routine geotechnical practice would be required, while the distribution
types used to represent the various geotechnical material parameters
should be standardised. Of the range of reliability analysis techniques available,
the variants of the first order reliability method (FORM), in combination
with an analytical surrogate performance function (response surface) where required,
are shown to provide the best balance of transparency, economy, and
accuracy. | en_ZA |
dc.description.abstract | AFRIKAANS OPSOMMING: Geostrukturele ontwerpstandaarde wat tans in die Suid Afrikaanse praktyk
gebruik word, volg die parsiële faktor limietstaatontwerp benadering. Hoewel
die faktore in dié benadering teen gestandaardiseerde teikenbetroubaarheidsvlakke
gekalibreer is, word die faalwaarskynlikheid nie direk in ag geneem nie.
Betroubaarheidsanalise en -ontwerp met ’n direkte waarskynlikheidsgrondslag
bied die praktisyn dieper stogastiese insig, wat potensieel meer optimale geotegniese
struktuurontwerp kan bewerkstellig.
Die tegniese komitee verantwoordelik vir die opstel van die Suid Afrikaanse
geotegniese ontwerpstandaard, is deur verteenwoordigers van die geotegniese
ingenieursprofessie versoek om die insluiting van gestandaardiseerde riglyne vir
betroubaarheidsontwerp te oorweeg. As grondslag vir die verwante konsepverslag
is dit nodig om geostrukturele betroubaarheidsontwerp in die konteks van
die volgende probleme te oorweeg.
Eerstens, die metodes vir betroubaarheidsanalise van verskeie geostrukturele
ontwerpsprobleme – ’n ontwerpstandaard kan slegs suksesvol wees met
akkurate, veelsydige, toepasbare analise metodes. Tweedens, die gepaste statistiese
beskrywings vir die verskeie modelparameters – betroubaarheidsanalise
van siviele strukture is uiteraard ekstrapolerend, en dus baie sensitief vir die
keuse van verdelingstipe en parameterwaardes. Derdens, die vereiste steekproefgrootte
en -kwaliteit – gevorderde betroubaarheidsanalise is van min nut
wanneer parameterwaardes sydig en nie verteenwoordigend van die struktuur
se onderliggende grondlaag is nie.
Hierdie tesis bevat ’n stel navorsingstudies gemik op dié vrae, en bevind
dat geostrukturele ontwerp teen ’n teikenbetroubaarheidsvlak uitgevoer kan
word, mits die weerstandsmodel én die statistiese beskrywing van parameters,
akkuraat en onsydig is. Dít is egter slegs moontlik met meer steekproefwaardes
as wat tans die norm in die praktyk is, terwyl verdelingstipes vir
die verskeie geotegniese parameters gestandaardiseer behoort te word. Uit
die verskeidenheid metodes vir betroubaarheidsanalise is bevind dat die verskillende
vorme van die lineêre betroubaarheidsmetode (‘first order reliability
method’, FORM), waar nodig gekombineer met ’n vervangde limietstaatfunksie
(responsoppervlak), die optimale balans van duidelikheid, doeltreffendheid,
en akkuraatheid bied. | af_ZA |
dc.format.extent | 171 pages : illustrations | en_ZA |
dc.language.iso | en_ZA | en_ZA |
dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
dc.subject | Geotechnical Engineering | en_ZA |
dc.subject | UCTD | en_ZA |
dc.subject | Structural design -- Reliability (Engineering) | en_ZA |
dc.subject | Structural design | en_ZA |
dc.subject | Structural Engineering | en_ZA |
dc.title | Reliability-Based Design in Geostructural Engineering | en_ZA |
dc.type | Thesis | en_ZA |
dc.rights.holder | Stellenbosch University | en_ZA |