Structural assessment of ASR-affected concrete bridge deterioration

dc.contributor.advisorVan Zijl, Gideon P.A.G.en_ZA
dc.contributor.authorKirchner, Hugoen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.en_ZA
dc.date.accessioned2022-11-21T17:25:24Zen_ZA
dc.date.accessioned2023-01-16T12:53:37Zen_ZA
dc.date.available2022-11-21T17:25:24Zen_ZA
dc.date.available2023-01-16T12:53:37Zen_ZA
dc.date.issued2022-11en_ZA
dc.descriptionThesis (MSc) -- Stellenbosch University, 2022.en_ZA
dc.description.abstractENGLISH ABSTRACT: ASR has long been acknowledged as a key consideration that needs to be accounted for when designing structures in South Africa. The main purpose of this study was to inform industry practitioners of the influence of ASR on the structural behaviour of RC bridge structures within the Western Cape. It was found that the aggregate type and size plays a role in how the ASR develops over the life cycle of the structure. For this study the greywacke aggregate was found to be the most prominent component in ASR-affected structures within the Western Cape region and the structure investigated. From here, the influence of ASR on the three main mechanical properties namely, tensile strength, compressive strength, and E-modulus, were investigated and a decrease in all three properties over time was observed. A tool for decision making was developed in the form of the structural behavioural matrix, which was developed specifically for ASR-affected structures. It aims to quantify what components of the overall structural behaviour may be at risk due to ASR induced effects. This study focused on the effect of compressive strength at the ultimate limit state for the Sir Lowry’s Pass Viaduct. The overall condition of the bridge and the critical element were determined from existing reports and drawings. The South African STRUMAN BMS was utilized as a tool to form a better understanding of the service-life of a specific structure by making use of the routine field inspection reports. The critical bridge element was identified through obtaining the condition indices, crack widths, expansion index, and structural severity rating. The reduced material properties, due to the presence of ASR, were determined according to existing studies. ASR development curves for the affected elements were established. From these curves the extent of the ASR propagation could be determined. Through the available documentation the critical structural element is identified and investigated further through structural analysis. Three bridge design standards, namely the CPA (1977) and TMH7 (1981) along with the more novel WIM approach considered together with Eurocode provisions, were used to determine the maximum design bending moment and shear action and resistance. To develop a standardised approach that can be replicated on other bridge structures within the region it was decided to analyse a rectangular RC bridge deck slab. The slab was modelled according to the construction drawings along with the reinforcement detailing to subsequently obtain the ultimate shear and moment resistance of the actual element according to the CP110 (1974) code used for the initial bridge design, and current EN 1992-1-1 (2004) Eurocode standards. These designs were performed for the case of standard unaffected concrete and ASR-affected concrete respectively. Due to compressive strength being the least affected material property by ASR deterioration, the resistance to original design loads is found to be sufficient.en_ZA
dc.description.abstractAFRIKAANS OPSOMMING: ASR word vir baie jare al in die Suid-Afrikaanse konteks erken as ‘n belangrike aspek wat in die ontwerpsproses in ag geneem moet word. Die hoofdoel van hierdie studie was om die industrie bewus te maak van die invloed van ASR op die struktuurgedrag van gewapende betonbrugstrukture in die Wes-Kaap. Daar is gevind dat die aggregaatsoort en -grootte ‘n rol speel in hoe die ASR oor die struktuur se lewensduurte ontwikkel. In hierdie studie is die greywacke aggregaatsoort geïdentifiseer as die belangrikste komponent wat in ASR geaffekteerde strukture in die Wes-Kaap gevind is. Vervolgens is die invloed van ASR op die drie hoof materiaaleienskappe van beton naamlik, treksterkte, druksterkte en die E-modulus ondersoek en daar is gevind dat ASR al drie verlaag. ‘n Matriks van struktuurgedrag is ontwikkel as ‘n riglyn vir besluitneming spesifiek vir ASR geaffekteerde strukture. Dit beoog om te kwantifiseer watter komponente van die algehele struktuurgedrag die grootste risiko veroorsaak. Hierdie studie fokus op die effek van druksterkte by die uiterste limietstaat vir die Sir Lowryspas brug. Die algehele toestand van die brug en kritiese element word bepaal vanaf die bestaande verslae en tekeninge. Die Suid-Afrikaanse STRUMAN BMS is gebruik om ‘n beter idee te kry van die diensleeftyd van ‘n spesieke struktuur deur gebruik te maak van die bestaande verslae. Die kritiese brug element is geidentifiseer deur gebruik te maak van die toestand indekse, kraakwydtes, swellingsindeks, en die graad van erns vir die struktuur. Die verlaagde materiaaleienskappe, as ‘n gevolg van ASR, is bepaal volgense bestaande studies. ASR ontwikkelingskurwes vir die geaffekteerde elemente is bepaal. ASR ontwikkeling kan gevolgliks vanaf hierdie kurwes ontwikkel word. Die kritiese element is bepaal deur van die bestaande dokumentasie gebruik te maak en word vervolgens in verdere struktuuranalise ondersoek. Drie gestandardiseerde benaderings vir brugontwerp, naamlik die CPA (1977) en TMH7 (1981) tesame met die meer onlangse WIM bendaring en die hedendaagse Eurokode, is gebruik om die maksimum buigmoment en skuifkrag aksie en weerstand te bepaal. Om ‘n gestandardiseerde benadering te ontwikkel wat op ander strukture toegepas kan word is daar besluit om ‘n reghoekige gewapende beton dek te analiseer. Die blad is gemodelleer volgens die ontwerpstekeninge tesame met die bewapeningsinligting om gevolglik die maksimum skuif en buigmomentweerstand van die werklike element te bepaal. Hierdie proses is uitgevoer vir beide die CP110 (1974) en EN 1992-1-1 (2004) Eurokode benaderings. Vir elke kode is twee gevalle geanaliseer, naamlik die standaard ongeaffekteerde beton en die ASR geaffekteerde beton. Druksterkte van beton is die mins geaffekteerde meganiese eienskap deur ASR verwering, en voldoende brugweerstand is bevind vir die oorspronklike ontwerpsbelastings.en_ZA
dc.description.versionMastersen_ZA
dc.format.extentxv, 122 pages : illustrationen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/126169en_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectStructural engineeringen_ZA
dc.subjectConcrete construction -- Testingen_ZA
dc.subjectAlkali-Silica Reactionen_ZA
dc.subjectConcrete bridges -- Design and constructionen_ZA
dc.subjectConcrete bridges -- Crackingen_ZA
dc.subjectUCTDen_ZA
dc.titleStructural assessment of ASR-affected concrete bridge deteriorationen_ZA
dc.typeThesisen_ZA
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