Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Bridges are amongst the most important structures of any highway network. Once the bridge
construction is complete and a bridge is put into service, it is subjected to deteriorations. An effective
condition assessment, as a component of bridge management system, is therefore necessary to keep
bridges in admissible conditions of safety and serviceability. In South Africa, some bridge authorities
do not have sufficient funds to carry out bridge inspections at required intervals. In the case where
bridge authorities have enough funds, a systematic inspection is performed, covering a number of
bridges that are not in need of inspection.
Inspection and maintenance for a limited number of bridges randomly chosen may result in an
increase of the number of bridges in critical conditions. A bridge inspection prioritisation method that
takes into account the need of inspection of bridges is therefore needed for South African highway
bridges.
This research provides a prioritisation method for concrete bridge inspections by integration of nonprofessional
inspectors, imagery inspection and deterioration models. To achieve the research
objectives of this study, a literature study has been carried out to understand bridge inspection practice
in general and South African practice in particular. The literature helped also to identify previous
works on bridge inspection prioritisation, the use of information from informal sources, imagery
inspection and involvement of non-professionals in bridge inspection and use of deterioration models
in bridge management. A survey has been conducted amongst South African bridge authorities in
order to fill the literature gaps. Inventory and inspection data of bridges managed by South African
National Roads Agency Limited (SANRAL) was used to develop a deterioration model by
considering bridge characteristics such as bridge age, number of spans, and bridge type.
Based on the literature review, results of surveys and estimated regression parameters, a bridge
inspection prioritisation method has been developed. This method comprises three phases. The first
phase is the initial screening that consists of an identification of bridges with critical defects that have
not been repaired yet. These bridges, to which are added bridges that have not been inspected in the
previous inspection, constitute the first inspection priority category. The second phase is an imagery
screening which is an analysis of digital photographs for detection of defects that need urgent
assessment by professional inspectors. The analysed photographs are taken by non-professional
inspectors and uploaded to the Bridge Management System. The third phase is a grouping of bridges
in inspection priority categories as a function of their physical characteristics and deteriorating factors
using deterioration modelling. The method has been applied on SANRAL bridges using inspection ratings of 2011-2012. 422
SANRAL bridges have been categorised in the first inspection priority group by considering
hydraulic related defects as critical. The third phase allowed to rank 522 possible combinations of
bridges based on their characteristics. The developed method would help bridge authorities where
inspection budget is limited, to prioritise bridge inspection as a function of needs of inspection. / AFRIKAANSE OPSOMMING: Brûe is ʼn belangrike deel van enige snelweg netwerk. Wanneer brugkonstruksie voltooi is en dit in
diens gestel word, is die brug onderhewig aan skade en verval . 'n Doeltreffende toestandsassessering,
as 'n komponent van ʼn brug bestuurstelsel, is dus nodig om brûe in ʼn toestand van veiligheid en
diensbaarheid te hou. In Suid-Afrika het sommige brugowerhede nie genoeg fondse om
bruginspeksies teen vereiste intervalle uit te voer nie. In die geval waar ʼn brugowerhede wel genoeg
fondse het, word stelselmatige reekse inspeksies uitgevoer, waar brûe wat nie lukraaknoodwendig op
daardie stadium inspeksie nodig het nie, ook soms ingesluit word. Inspeksie en onderhoud vir slegs
'n beperkte aantal brûe wat gekies word kan 'n toename veroorsaak in die aantal brûe wat in ʼn kritiese
toestand is. 'n Bruginspeksie prioritiseringmetode wat brûe identifiseer vir inspeksie is dus nodig vir
Suid-Afrikaanse brugowerhede.
Hierdie navorsing stel 'n metode voor wat bruginspeksies prioritiseer deur gebruik te maak van nieprofessionele
inspekteurs, inspeksie van foto’s en brugtoestandsvervalmodelle. Om die navorsings
doelwitte van hierdie projek te bereik, is 'n literatuurstudie uitgevoer oor die praktyk van
bruginspeksie in die algemeen, en meer spesifiek om die praktyk in Suid-Afrika te verstaan.. 'n
Opname is voorts onder Suid-Afrikaanse brugowerhede uitgevoer om gapings in die literatuur aan te
vul. Inventaris en inspeksie data van brûe wat bestuur word deur die Nasionale Padagentskap
(SANRAL) is daarna gebruik om 'n toestand agteruitgangsmodel te ontwikkel deur die eienskappe
soos brug ouderdom, aantal spanne en die tipe brug in ag te neem
Gebaseer op die literatuur, resultate van opnames en beraamde regressie parameters is 'n brug
inspeksie prioritiseringsmetode ontwikkel. Hierdie metode bestaan uit drie fases. Die eerste fase is
die aanvanklike siftingsproses wat bestaan uit die identifisering van brûe met 'n kritiese defek wat
nog nie herstel is sedert ʼn vorige inspeksie nie. Hierdie brûe, wat ingesluit word by ander brûe wat
nie geïnspekteer was in die vorige inspeksie nie, is die eerste kategorie van inspeksie prioriteit. Die
tweede fase is 'n ontleding van digitale foto's vir die opsporing van defekte wat dringende assessering
deur professionele inspekteurs nodig het. Die foto's word geneem deur nie-professionele inspekteurs
en dit word gelaai op die brug bestuurstelsel. Die derde fase is die groepering van brûe in inspeksie
prioriteit kategorieë as 'n funksie van hul fisiese eienskappe en vervalfaktore met die hulp van
agteruitgangsmodelle.
Die metode is toegepas op die SANRAL brûe met die hulp van inspeksie graderings van 2011-2012.
Deur die aanname van hidrouliese defekte as van kritiese belang, is 422 SANRAL brûe in die eerste
inspeksie prioriteit gegroepeer. Die derde fase prioritiseer 522 moontlike kombinasies van brûe op
grond van hul fisiese eienskappe. Die metode sal brugowerhede waar inspeksie begrotings beperk is,
help om bruginspeksies te prioritiseer as 'n funksie van die noodsaaklikheid van inspeksie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/96770 |
| Date | 03 1900 |
| Creators | Nsabimana, Placide |
| Contributors | Wium, Jan, Stellenbosch University. Faculty of Engineering. Dept of Civil Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xv, 131 pages : illustrations |
| Rights | Stellenbosch University |
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