Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This study entails the appraisal of the constitutive models available for the non linear finite element analysis of reinforced concrete, using the DIANA finite element package and following generally accepted guidelines for non linear finite element analyses. The constitutive models considered are plasticity and total strain based (fixed and rotating crack) models. The appraisal consists of the analysis of various experiments performed on reinforced concrete beams that are governed by compressive, shear and tensile dominated failures. The investigation is not limited to the accuracy of the results obtained using these models but also of the consistency of the results obtained with regard to various mesh types and sizes, as well as a study of the individual influence of several material parameters. The intention of the study was to provide the reader with an indication of the performance capacity (accuracy and consistency) of the available constitutive models, where the notion of the use of the results obtained from non linear finite element analyses for design purposes is considered. The results obtained were varied. The models performed reasonably well in the compressive and tension dominated studies, with the importance of accurate material parameters being emphasized especially for the more advanced cementitious materials investigated. The total strain rotating crack model also showed a proclivity of simulating incorrect failure modes as well as exhibiting reluctance towards stress redistribution. All models used for the shear dominated study yielded mostly inaccurate and inconsistent results, but it was found that the four node quadrilateral element with selective reduced integration performed the best. The plasticity model did not capture shear failure well, and convergence was often not attained. The constant shear retention factor of the total strain fixed crack model was found to yield more detailed response curves for the smaller mesh sizes. The results of the tension dominated beams inspired more confidence in the models as quite accurate values were attained, especially by the plasticity model used. The ability of the available models to simulate realistic structural behaviour under various failure modes is very limited, as is evident from the results obtained. The development of a more advanced and robust model is required, which can provide consistently accurate results and failure modes, and even ‘anticipate’ potential failure modes not considered by the user.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Water flows required for fire protection (fire flows) from water distribution systems (WDS) in rural towns in the Western Cape Province, South Africa, were evaluated as part of this research project. The fire flow requirements specified in different South African guidelines, as well as a number of international standards, were compared. Various guidelines and codes used in South Africa, including the South African National Standards, specify fire flow requirements according to the risk category of the area concerned. Alternative methods of firefighting and new firefighting technologies that can reduce the reliance on potable water resources for firefighting were evaluated. The traditional method of designing a WDS to provide potable water for firefighting, commonly employed in South African municipal areas formed the focus of the study. The potential fire risk costs (potential costs of damages if a fire was to occur) should also be considered, in addition to the network construction costs, when designing a WDS, in order to determine the most economically feasible option. Data obtained from the fire departments of three municipalities in rural towns of the Western Cape, was analysed to determine the actual flow rates that were required to extinguish fires in these towns. The records considered covered approximately one year in each case and included a total of 564 fire incident reports suitable for this study. According to the data, a small fraction (11%) of the fires was extinguished using water from the WDS by connecting firefighting equipment directly to a fire hydrant. The majority of the fires were extinguished by means of water ejected from a firefighting vehicle. This method implies the use of water drawn from the potable network at a certain location; the water is shuttled by firefighting vehicles, from either the fire station or from a central abstraction point in the WDS. The location of the said abstraction point was found to have a notable impact on the WDS and this received attention in this study. The data showed that 99.8% of the flows required in rural towns were lower than the flows recommended for moderate risk areas in typical South African guidelines. Hydraulic modelling of a hypothetical WDS model was conducted to illustrate that the provision of fire flows according to commonly used South African fire flow standards leads to higher costs. The latter hypothetical case study illustrates that designing a network to provide fire flows according to the referred standards resulted in 15% higher costs, compared to designing a network that would have provided for the actual recorded fire flows according to the data set obtained from the selected rural towns compiled for this study. The hypothetical case study also showed that the cost for a WDS, where sufficient pressure is required at all hydrants during peak fire flows, is 2.4% higher than the cost for a distribution system where water is supplied via predetermined hydrants for refilling firefighting vehicles. A WDS with central, predetermined abstraction points for refilling firefighting vehicles offers a solution to providing fire flows in areas where the distribution systems may be inadequate. The revision of the current fire flow standards of South Africa would, therefore, be a logical next step along with the reassessment of methods used for supplying fire flows. / AFRIKAANSE OPSOMMING: Water vloei vir brandbestryding (brandvloei) uit waterverspreidingstelsels (WVS) in plattelandse dorpe in die Wes-Kaap, Suid Afrika, is as deel van hierdie navorsingsprojek geëvalueer. Die brandvloei soos gespesifiseer in verskillende Suid-Afrikaanse riglyne, asook ʼn aantal internasionale standaarde is vergelyk. Verskeie riglyne en kodes wat in Suid-Afrika gebruik word, insluitende die Suid-Afrikaanse Nasionale Standaarde, spesifiseer brandvloei-vereistes op grond van die risiko-kategorie van ʼn spesifieke gebied. ʼn Verskeidenheid alternatiewe metodes vir brandbestryding en nuwe brandbestrydings-tegnologieë is ondersoek, om sodoende die afhanklikheid van ons beperkte drinkbare waterbronne vir brandbestryding te verminder. Die tradisionele metode om water aan munisipale areas te voorsien, die gebruik van ʼn WVS, is ook geassesseer. Hierdie metodes dui daarop dat die potensiële brandgevaar-kostes (potensiële koste van skade indien ʼn brand sou plaas vind) ook in ag geneem moet word, tesame met die konstruksie kostes van ʼn WVS, om sodoende die mees ekonomies haalbare netwerk te bepaal. Data wat verkry is vanaf die brandweer departement van drie plattelandse munisipaliteite in die Wes-Kaap is ontleed om die werklike vloei-tempos vas te stel wat nodig was om brande te blus in hierdie dorpe. Die data is verkry vir ʼn tydperk van een jaar en 564 brandverslae was bruikbaar vir die doeleindes van hierdie studie. Volgens die data was ʼn lae aantal (11%) van die brande geblus vanuit die WVS deur die koppeling van brandbestrydingstoerusting direk aan ʼn brandkraan. Die meeste van die brande is geblus met behulp van water wat voorsien is deur ʼn brandbestrydingsvoertuig. Met hierdie metode word water deur die brandbestrydings-voertuie aangery vanaf die brandweerstasie of onttrek vanuit ʼn sentrale ontrekkingspunt in die WVS. Daar is gevind dat die ligging van laasgenoemde ontrekkingspunt ʼn beduidende impak op die WVS het – hierdie aspek is daarom verder ondersoek. Die data het getoon dat 99.8% van die vloei-tempo’s wat nodig is om brande te blus in plattelandse dorpe, laer is as die brandvloei riglyne vir matige risiko-areas volgens tipes Suid-Afrikaanse standaarde. Hidrouliese modellering van ʼn hipotetiese WVS is uitgevoer om te illustreer dat die verskaffing van brandvloei volgens die standaarde wat algemeen gebruik word, hoër kostes tot gevolg het. Die laasgenoemde hipotetiese gevallestudie illustreer dat ʼn netwerk ontwerp om brandvloei te verskaf volgens die huidige standaarde 15% duurder is as vir netwerke wat ontwerp is om die werklike aangetekende brandvloei te voorsien soos getoon deur die veld-data wat vir hierdie studie verkry is. Die hipotetiese gevallestudie het ook getoon dat die koste vir ʼn WVS, waar voldoende drukke gehandhaaf moet word by alle brandkrane terwyl piek brand vloeie voorsien word, 2.4% duurder is as vir ʼn WVS waar die brandvloei verskaf word by voorafbepaalde brandkrane vir die hervulling van brandbestrydingsvoertuie. ʼn WVS met sentrale onttrekkingspunte vir die hervulling van brandbestrydingsvoertuie, bied ʼn metode om brandvloei te voorsien in gebiede waar die WVS onvoldoende is, bv. informele nedersettings. Die hersiening van die huidige brandvloei standaarde van Suid Afrika sou dus ʼn logiese volgende stap wees, tesame met die herevaluering van die metodes wat gebruik word vir die verskaffing van brandvloei.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The development of mass housing is an excellent example of multi-disciplinary projects. Several housing projects have been unsuccessful due to a misunderstanding of the necessary collaboration and buy-in that are required from all parties concerned. The focus of this study is to identify the required skill sets and responsibilities of the Housing Project Manager in the Housing environment, and in turn, will support the development of the foundation of the civil engineering postgraduate curricula. Civil engineers are educated with a strong focus on technical subjects, but not much attention is paid to many of the less technical aspects as found in housing projects. Furthermore, the multi-disciplinary aspects of large projects do not receive sufficient attention in either the undergraduate or postgraduate curricula. Considering that many civil engineers become actively involved as managers of housing projects, this paper will present an investigation into the requirements of the curricula of a postgraduate qualification for civil engineers towards becoming managers in housing projects. The investigation will include aspects of multi-disciplinary coordination, the less technical aspects of housing development, but will not exclude a comprehension of technical involvement. In order to identify these skill sets and responsibilities several approaches were adopted. The approaches adopted in this dissertation include: (i) a comprehensive literature study regarding the housing environment and the position of the housing project manager, (ii) a review of several housing case studies with project management related problems, (iii) consulting with several housing management professionals from different sectors in the housing industry, and (iv) a review of existing formulations of the role and responsibilities of the housing project manager. The findings from this study provide evidence that civil engineers operating in the housing environment as project managers require additional education, due to the multi-disciplinary nature of housing projects. The main conclusion drawn from this study is that educating civil engineers towards the management of housing projects would contribute significantly to the housing environment through increasing productivity and quality, and can contribute to meet the housing targets of the government. / AFRIKAANSE OPSOMMING: Die ontwikkeling van massa behuising is 'n uitstekende voorbeeld van multidissiplinêre projekte. Verskeie behuisingsprojekte was al onsuksesvol as gevolg van 'n misverstand oor die nodige samewerking en bydraes wat vereis word van alle betrokke partye. Die fokus van hierdie studie is om die vaardighede en verantwoordelikhede van die behuisingsprojekbestuurder in die behuisingsomgewing te identifiseer. Hierdie kennis ondersteun die ontwikkeling van ʼn raamwerk vir ʼn nagraadse kurrikulum in behuisingsbestuur. Siviele ingenieurs is opgelei met 'n sterk fokus op tegniese vaardighede, maar relatief min aandag word geskenk aan minder tegniese aspekte soos gevind word in behuisingsprojekte. Verder, multidissiplinêre bestuursaspekte van groot projekte ontvang nie voldoende aandag in óf die voorgraadse óf nagraadse kurrikula nie. Wetende dat baie siviele ingenieurs aktief betrokke raak as bestuurders van behuisingsprojekte, ondersoek hierdie studie ʼn raamwerk vir ʼn nagraadse kwalifikasie vir siviele ingenieurs as bestuurders van behuisingsprojekte. Die ondersoek sluit in aspekte van die multidissiplinêre koördinasie asook minder tegniese aspekte van behuisingsontwikkeling, maar dit sluit nie 'n begrip van die tegniese betrokkenheid uit nie. Verskeie benaderings is toegepas om die vaardighede en verantwoordelikhede van behuisingsbestuurders te identifiseer. Die benaderings sluit in: (i) 'n omvattende literatuurstudie ten opsigte van behuising en die posisie van die behuisings-projekbestuurder, (ii) 'n oorsig van verskeie behuisings- gevallestudies met projekbestuur verwante probleme, (iii) raadpleging met verskeie professionele rolspelers van verskillende sektore in die behuisingbestuur omgewing, en (iv) 'n hersiening van bestaande beskrywings van die rol en verantwoordelikhede van die behuisings-projekbestuurder. Die bevindinge van hierdie studie verskaf bewyse dat siviele ingenieurs wat in die behuisingsbedryf as projekbestuurders optree, bykomende opleiding benodig as gevolg van die multidissiplinêre aard van projekte. Die belangrikste gevolgtrekking van hierdie studie is dat die opleiding van siviele ingenieurs in die bestuur van behuisingsprojekte ʼn aansienlike bydrae kan lewer tot behuising deur produktiwiteit en kwaliteit te verhoog. Dit kan bydra tot die bereiking van die regering se behuisingsdoelwitte.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The amount and complexity of software applications for the building industry is increasing constantly. It has been a long term goal of the software industry to support integration of the various models and applications. This is a difficult task due to the complexity of the models and the diversity of the fields that they model. As a result, only large software houses have the ability to provide integrated solutions on the basis of a common information model. Such a model can more easily be established since the different software is developed within the same group. Other software suppliers usually have to revert to importing and exporting of data to establish some form of integration. Even large software houses still sometimes make use of this technique between their different packages. In order to obtain a fully integrated solution, clients have to acquire complex and expensive software, even if only a small percentage of the functionality of this software is actually required. A different approach to integration is proposed here, based on providing an integration framework that links different existing software models. The framework must be customisable for each individual's unique requirements as well as for the software already used by the individual. In order for the framework to be customisable, it must either encompass the information requirements of all existing software models from the outset, or be flexible and adaptable for each user. Developing an encompassing software model is difficult and expensive and thus the latter approach is followed here. The result is a model that is less general than BIM-style models, but more focussed and less complex. The elements of this flexible model do not have predetermined properties, but properties can instead be added and removed at runtime. Furthermore, derived properties are not stored as values, but rather as methods by which their values are obtained. These can also be added, removed and modified at runtime. These two concepts allow the structure and the functionality of the model to be changed at runtime. An added advantage is that a knowledgeable user can do this himself. Changes to the models can easily be incorporated in the integration framework, so their future development is not limited. This has the advantage that the information content of the various applications does not have to be pre-determined. It is acknowledged that a specific solution is required for each integration model; however the user still has full control to expand his model to the complexity of BIM-type models. Furthermore, if new software models are developed to incorporate the proposed structures, even more seamless and flexible integration will be possible. The proposed framework is demonstrated by linking a CAD application to a cost-estimation application for buildings. A prototype implementation demonstrates full integration by synchronising selection between the different applications. / AFRIKAANSE OPSOMMING: Die hoeveelheid en kompleksiteit van sagteware programme vir die bou industrie is konstant aan die vermeerder. Dit was nog altyd 'n lang termyn doelwit van die sagteware industrie om integrasie van die verskeie modelle en programme te ondersteun. Hierdie is 'n moeilike taak as gevolg van die kompleksiteit van die modelle, en die diversiteit van die velde wat hierdie programme modelleer. Die gevolg is dat net groot sagteware huise die vermoë het om geïntegreerde oplossings te bied op die basis van 'n gemeenskaplike inligting model. So 'n tipe model kan makliker bymekaargestel word siende dat al die verskillende sagteware binne dieselfde groep ontwikkel word. Ander sagteware verskaffers moet gewoonlik gebruik maak van sogenaamde uitvoer/invoer tegnieke om 'n mate van integrasie te verkry. Selfs groot sagteware huise maak ook gebruik van hierdie tegnieke tussen hulle verskeie pakkette, in plaas van om die programme direk met mekaar te koppel. Om 'n vol geïntegreerde oplossing te verkry, moet kliënte komplekse en duur sagteware aanskaf, selfs al word net 'n klein gedeelte van die funksionaliteit van hierdie sagteware gebruik. 'n Verskillende benadering word hier gevolg, gebaseer op 'n integrasie raamwerk wat verskillende bestaande sagteware modelle met mekaar koppel. Die raamwerk moet aanpasbaar wees vir elke individu se unieke opset. Vir die raamwerk om aanpasbaar te wees, moet dit óf alle bou industrie inligting inkorporeer van die staanspoor af, óf dit moet buigbaar en aanpasbaar wees vir elke gebruiker. Om 'n model te ontwikkel wat alle bestaande inligting inkorporeer van die staanspoor af is moeilik en duur, dus word die tweede benadering gevolg. Die eindresultaat is 'n model wat minder omvattend is as BIM-tipe modelle, maar eerder gefokus en minder kompleks. Die elemente van hierdie buigbare model het nie voorafbepaalde eienskappe nie, eienskappe kan bygevoeg en weggevat word terwyl die program hardloop. Verder word afgeleide eienskappe nie gestoor as waardes nie, maar eerder as metodes wat gebruik word om hulle waardes mee af te lei. Hierdie konsepte laat toe dat die struktuur en funksionaliteit van die model verander kan word terwyl die program hardloop. 'n Verdere voordeel is dat 'n kundige verbruiker die veranderinge self kan doen. Veranderinge in die modelle kan maklik ingesluit word in die integrasie model, so toekomstige ontwikkeling word nie beperk nie. Dit beteken dat die inhoud van die modelle nie vooraf bepaal hoef te word nie. Al het die raamwerk 'n gespesialiseerde oplossing vir elke gebruiker tot gevolg, het die gebruiker nogtans volle beheer om sy model uit te brei tot die omvattendheid van BIM-tipe modelle. Indien nuwe sagteware modelle ontwikkel word met die integrasie raamwerk in gedagte, kan nog gladder en buigbare integrasie moontlik wees. In hierdie tesis word 'n tekenprogram met 'n kosteberaming program gekoppel om die voorgestelde raamwerk te demonstreer. 'n Prototipe implementering demonstreer volle integrasie deur seleksie binne die programme te sinchroniseer.

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008. / The South African code for the design loading of building structures, namely SABS 0160 (1989), was revised with the requirements for seismic design prescribed in SANS 10160: Part 4: Seismic actions and general requirements for buildings. SANS 10160: Part 4 incorporates the seismic design provisions of several seismic codes of practice, however, the influence of the value prescribed for the behaviour factor has not been established with regard to South African conditions. The behaviour factor is used by most seismic design codes to account for the energy dissipating effects of plastification in structural systems when subjected to earthquake ground motion, to reduce the elastically determined forces to be designed for. However, a considerable difference is observed in the values of the behaviour factor prescribed for the design of reinforced concrete walls between the leading international seismic codes. The aim of this study is to assess the value of the behaviour factor prescribed in SANS 10160: Part 4 for reinforced concrete structural walls under the influence of South African seismic conditions and code requirements. A method of quantifying the value of the behaviour factor was developed and implemented in the study by Ceccotti (2008). This method entails estimation of the maximum analytical behaviour factor as the ratio of seismic intensity at failure of the structure to the seismic intensity prescribed by the design code. Such a method is adopted for this study where the lateral force resisting systems of six-, eight- and tenstorey buildings are investigated with nonlinear static analysis to quantify the maximum computationally-determined value of the behaviour factor. Firstly, it is observed that it is possible to quantify the value of the behaviour factor through the use of a computational study. The nonlinear static method of analysis is shown to provide reliable results in the estimation of the behaviour factor for a sixstorey building, however, does not perform well for taller buildings. Further investigation with the use of dynamic time-history analysis is proposed to evaluate the influence of the factors identified in this study. The behaviour of structural walls, designed for reduced forces with the prescribed behaviour factor of 5.0, exhibits high yield strengths and resists the design seismic action entirely elastically. This high strength is found to be due to the reliability/redundancy factor prescribed by SANS 10160: Part 4 and because of the high values of structural overstrength. Similar studies observed high values of structural overstrength for buildings designed for low seismic intensity, which were shown to result from the fact that the resistance required to gravity loading became more critical than the seismic loads in the design of the structural system. This study identifies several factors that influence the value of the behaviour factor, such as the number of walls in the lateral force resisting system; the number of storeys of the buildings; available displacement ductility of the structural system; and the ground type designed for.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This study set out to determine the debonding of externally applied Carbon Fibre Reinforced Polymer (CFRP) plates from RC structures under cyclic loading. Triplet shear tests and finite element (FE) analyses were done on the epoxy to determine the bond stress between the CFRP plate and a reinforced concrete specimen. From these tests and analyses the average shear strength of the bond between the epoxy and concrete substrate was determined and the shear strength of the epoxy specified by the supplier could be confirmed. A case study of a statically loaded beam was performed to verify the bond strength. Finally a reinforced concrete (RC) T-section was designed and pre-cracked to simulate a damaged beam in practice. These sections were then externally reinforced by bonding CFRP plates onto the face of the web. The sections were subjected to static and cyclic loading at different force amplitudes. Along with the experimental tests, FE models were developed and analysed which had the same geometrical and material properties as the experimental specimens. Due to time constraint a FE mesh objectivity study was not done, but the chosen element size is believed to be sufficiently small to replicate the experimental tests objectively. The FE analyses and the experimental tests yielded results that were close to each other on both the global scale and in terms of localised behaviour, thus it was decided that the computational approach could be used for the final design of a model of the debonding of CFRP plates bonded onto RC beams under cyclic loading because the data can be analysed more easily and a large variation of tests can be done. For the T-section 3 tests were conducted; a pull-off (static) test where the bonded CFRP plate was pulled from a specimen to get the ultimate failure envelope of the test specimens. The static test was followed by cyclic tests with force amplitude of 85% and 65% of the ultimate pull-off strength. Different measurements were taken to get the global and local displacement behaviour of the section. The global displacement was measured by means of a linear variable displacement transducer (LVDT, displacement meter) clamped onto the CFRP plate that pushed on the top of the concrete and the local displacement was measured with the help of the Aramis system. The displacement was then compared to the same displacements of nodes and elements in the FE models. The result was a confirmation that the results from the FE models were sufficient to design a model for cyclic debonding of CFRP plates from RC structures. From the FE models the relative displacement between the CFRP plate and concrete was obtained in the vicinity of a crack. This relative displacement was then normalised by the respective stress range of the different tests, from which the normalised relative displacement was plotted against the number of cycles to get an equation limiting the number of cycles for a specific stress range. From the results, it appears that for cyclic load levels up to 65% of the peak static resistance, a threshold number of load cycles are required for delamination initiation. Subsequently, a near constant delamination rate is reached. The delamination rate is significantly lower for lower cyclic load levels. Finally, an unstable delamination stage is reached at a level of about 65 μm for all the analyses, after which CFRP pull-off is imminent. Service life design of CFRP reinforcement of RC beams should take into consideration the delamination initiation threshold, the subsequent delamination rate and finally the initiation of unstable delamination. / AFRIKAANSE OPSOMMING: Die projek is uitgevoer om die delaminasie van ekstern aangewende Koolstof Vesel Versterkte Polimeer (KVVP) stroke op gewapende beton strukture te bepaal onder sikliese belasting. Triplet skuif toetse is gedoen op die gebruikte epoksie om die verband-sterkte te bepaaltussen die KVVP stroke en die beton proefstuk. Die skuif toetse is ook met behulp van die eindige element (EE) metode geanaliseer. Die resultaat van die toetse en analises het gewys dat die verband sterkte tussen die KVVP stroke en beton gelyk is aan die skuif sterkte van die epoksie wat verskaf is. `n Gevalle studie van `n monotonies belaste balk is gedoen om die verband-sterkte te verifieër. `n Gewapende beton T-snit is ontwerp en voor-af gekraak om `n beskadigde balk in die praktyk voor te stel. Die beskadigde proefstukke is vervolgens ekstern versterk met KVVP stroke wat aan die web van die T-snit vas geplak is. Die versterkte T-snitte is getoets onder statiese en sikliese belasting. Die sikliese toetse is ook onder verskillende spanningsamplitudes getoets. Om die eksperimentele toetse te verifieër is EE modelle gebou en geanaliseer wat dieselfde geometriese en materiaal eienskappe as die eksperimentele proefstukke gehad het, maar as gevolg van `n tydsbeperking is `n sensitiwiteit studie oor die element grootte nie gedoen nie. Die element grootte is klein genoeg gekies en word beskou as voldoende om die gedrag objektief te simuleer. Die EE analises en eksperimentele resultate was na genoeg aan mekaar op beide globale en lokale vlak. Dus is `n analitiese benadering tot die toetse vervolgens gebruik vir die ontwerp van `n model vir delaminasie van KVVP stroke van gewapende beton strukture onder sikliese belasting. Die EE metode stel die analis in staat om `n verskeidenheid van toetse relatief vinnig uit te voer en om die data van die toetse vinniger te interpreteer as deur fisiese eksperimentele toetse. Drie eksperimente is uitgevoer op die T-snitte, `n aftrek-toets (staties) waar die KVVP strook van `n proefstuk afgetrek is om die falingsomhullende diagram te kry en dan ook twee sikliese toetse teen 85% en 65% van die krag amplitude van die falingskrag. Verplasingsmeters is gebruik om die globale verplasing te kry, deur dit vas te klamp op die KVVP strook en dan die verplasing te meet relatief tot die bokant van die beton. Die lokale veplasing is met behulp van die Aramis sisteem verkry. Die eksperimentele verplasings is dan vergelyk met verplasings van die ooreenstemmende nodes en elemente in die EE modelle. Deur die vergelyking van die resultate is dit bevestig dat die eindige element modelle voldoende is om die model vir sikliese delaminasie van KVVP stroke van gewapende beton strukture te gebruik vir die ontwerp. Uit die EE modelle is die relatiewe verplasing tussen die KVVP strook en die beton gekry in die omgewing van `n kraak. Die relatiewe verplasing is genormaliseer deur elkeen se spanningsamplitude. Die genormaliseerde relatiewe verplasing is dan teenoor die aantal siklusse geteken waarvan `n vergelyking vir die maksimum verplasing afgelei is om die aantal siklusse vir `n gegewe spanning amplitude te beperk. Uit die resultate blyk dit dat vir sikliese laste tot en met 65% van die piek statiese weerstand `n aantal siklusse moontlik is voordat delaminasie begin waarna `n konstante delaminasie tempo bereik word. Die delaminasie tempo is stadiger vir sikliese laste teen `n laer belastings amplitude. Laastens word `n onstabiele delaminasie fase bereik by `n vlak van ongeveer 65 μm, na die oorgang delamineer die KVVP strook binne enkele siklusse. Die beginpunt van delaminasie, die delaminasie tempo en laastens die begin van onstabiele delaminasie moet in gedagte gehou word by die ontwerp diens leeftyd van KVVP versterkte gewapende beton balke.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: There is a general lack of published research on sewage pump station problems and the removal of solids in South African sanitary sewers. Research was undertaken to investigate the problems at sewage pump stations by means of site visits, interviews, literature reviews and laboratory experiments. An in-depth literature study is presented on sewage pump stations, pump station problems and solids in sewers. The problems at sewage pump stations were categorised into identifiable groups with possible generalised solutions. The site visits and literature review indicated a specific lack of knowledge regarding screening baskets used to remove solids at sewage pumping stations. This led to the experimental testing of a screening basket on full scale in a controlled environment to develop an efficiency index for screening baskets. The efficiency index was determined using fuzzy logic methodology with predetermined solids load, basket height above the sump level and solids retention time. The fuzzy logic proved that the basket is best operated halfway submerged, after one hour retention time and with degradable solids in the system. The literature compiled and problems identified in this study were used as the backbone for the development of a conceptual Decision Support Tool (DST) for sewage pump stations. The DST is aimed at requiring limited inputs and providing maximum knowledge output and is presented as a software tool in MS Excel format. The functionality was added by applying visual basic applications in MS Excel user forms. The idea of developing a DST is to assist designers, sewage service providers and operators with understanding the various components and for problem identification pertaining to sewage pump stations in the future. The DST is relatively self-explanatory with a user friendly visual interface that is easy to operate. This study sets the scene for further research into efficiency indices pertaining to different components of sewage pump stations and their application in comprehensive sewage pump decision support tools. / AFRIKAANSE OPSOMMING: Daar is 'n algemene gebrek aan gepubliseerde navorsing oor probleme met rioolpompstasies en die verwydering van ongewenste voorwerpe in Suid-Afrikaanse sanitêre rioolsisteme. Navorsing is gedoen om die probleme by rioolpompstasies te ondersoek deur middel van terreinbesoeke, onderhoude, literatuurstudie en eksperimente in „n laboratorium. 'n Omvattende literatuurstudie is op rioolpompstasies, probleme by pompstasies en ongewenste voorwerpe in rioolnetwerke gedoen. Die probleme by rioolpompstasies is verdeel in identifiseerbare groepe met moontlike oplossings. Die terreinbesoeke en literatuuroorsig het 'n spesifieke gebrek aan kennis met betrekking tot skermmandjies, wat gebruik word om ongewenste voorwerpe by rioolpompstasies te verwyder, aangedui. Dit het gelei tot die eksperimentele toetsing van 'n skermmandjie deur die volskaalse opstelling in 'n beheerde omgewing om 'n doeltreffendheidsindeks vir skermmandjies in die praktyk te ontwikkel. Die doeltreffendheidsindeks is bepaal deur gebruik te maak van “fuzzy logic” metodologie met voorafbepaalde insette naamlik, die mandjie se hoogte bo die watervlak, soort ongewenste voorwerpe en die tyd wat die voorwerpe aan water blootgestel is. Die “fuzzy logic” bewys dat die mandjie die beste werking toon, halfpad onder die water, na „n een uur van blootstelling aan water en met degradeerbare voorwerpe in die stelsel. Die literatuur wat saamgestel is en probleme wat in hierdie studie geïdentifiseer is, is gebruik as die inhoud vir die konseptuele “Decision Support Program” (DST) vir rioolpompstasies. Die DST het ten doel om met beperkte insette die maksimum kennis te verskaf en word aangebied as 'n sagteware instrument in MS Excel formaat. Die funksionaliteit is bygevoeg deur die toepassing van die “visual basic applications” in MS Excel gebruikersvorms. Die doel van die ontwikkeling van 'n DST is om ontwerpers, riooldiensverskaffers en operateurs te help om die verskillende funksies en probleem-identifikasie met betrekking tot rioolpompstasies te begryp. Die DST is relatief selfverduidelikend met 'n gebruikers vriendelike visuele koppelvlak wat maklik is om te bedryf. Hierdie studie bied die basis vir verdere ondersoek na die doeltreffendheidsindekse met betrekking tot die verskillende komponente van rioolpompstasies en die toepassing daarvan in omvattende rioolpomp “DSTs”.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Research in concrete has advanced to such an extent that it is now possible to add steel fibres to concrete in order to improve its durability and ductility. This led to a research group in Europe, FIB, who has provided guidelines to designing Steel Fibre Reinforced Concrete (SFRC) structures. They have found that it is possible for SFRC beams in flexure to be in static equilibrium. However, the time-dependent behaviour of SFRC has not been researched fully and it requires further investigation. When looking at a concrete beam in flexure there are two main stress zones, the compression zone and the tension zone, of which the tensile zone will be of great interest. This study will report on the investigation of the tensile time-dependent behaviour of SFRC in order to determine how it differs from conventional concrete. The concrete has been designed specifically to exhibit strain-softening behaviour so that the material properties of SFRC could be investigated fully. Factors such as shrinkage and tensile creep of SFRC were of the greatest importance and an experimental test setup was designed in order to test the tensile creep of concrete in a simple and effective manner. Comparisons were be made between the tensile creep behaviour of conventional concrete and SFRC where emphasis was placed on the difference between SFRC specimens before and after cracking occurred in order to determine the influence of steel fibre pull-out. The addition of steel fibres significantly reduced the shrinkage and tensile creep of concrete when un-cracked. It was however found that the displacement of fibre pull-out completely overshadowed the tensile creep displacements of SFRC. It was necessary to investigate what effect this would have on the deflection of SFRC beams in flexure once cracked. Viscoelastic behaviour using Maxwell chains were used to model the behaviour of the tensile creep as found during the tests and the parameters of these models were used for further analyses. Finite Element Analyses were done on SFRC beams in flexure in order simulate creep behaviour of up to 30 years in order to determine the difference in deflections at mid-span between un-cracked and pre-cracked beams. The analyses done showed that the deflections of the pre-cracked SFRC beams surpassed the requirements of the Serviceability Limit States, which should be taken into account when designing SFRC beams. / AFRIKAANSE OPSOMMING: Die navorsing in beton het gevorder tot so ‘n mate dat dit nou al moontlik is om staal vesels by die beton te voeg sodat dit beton se duursaamheid en duktiliteit te verbeter. Dit het gelei tot ‘n groep in Europa, FIB, wat dit moontlik gemaak het om Staal Vesel Beton (SVB) strukture te ontwerp. Hulle het gevind dat dit moontlik is vir SVB balke om in statiese ewewig te wees tydens buiging. Die tyd afhanklike gedrag van SVB is egter nog nie deeglik ondersoek nie en benodig dus verdure ondersoek. Wanneer ‘n balk in buiging aanskou word kan twee hoof spanningzones identifiseer word, ‘n druk zone en ‘n trek zone, waarvan die trek zone van die grootste belang is. Hierdie studie gaan verslag lewer oor die ondersoek van tyd-afhanklike trekgedrag van SVB om te bepaal hoe dit verskil van konvensionele beton. Die beton was spesifiek ontwerp om vervormingsversagtende gedrag te wat maak dat die materiaal eienskappe van SVB ten volle ondersoek kan word. Faktore soos krimp en die trekkruip van SVB was van die grootste belang en ‘n eksperimentele toets opstelling was ontwerp om die trekkruip van beton op ‘n eenvoudige en effektiewe manier te toets. Daar was vergelykings getref tussen die trekkruip gedrag van konvensionele beton en SVP en groot klem was geplaas op die verskil tussen SVB monsters voor en na die monsters gekraak het om te bepaal wat die invloed was van staalvesels wat uittrek. Die byvoeging van staalvesels het beduidend die kruip en trekkruip van beton verminder. Daar was alhoewel gevind dat die verplasing van die uittrek van staalvesels heeltemal die trekkruip verplasings van SVB oorskadu het. Dit was nodig om te sien watse effek dit op die verplasing van SVB balke in buiging sal hê. Viskoelastiese gedrag deur Maxwell kettings was gebruik om die gedrag van trekkruip, soos gevind deur die toetse, te modelleer en die parameters van hierdie modelle was verder gebruik vir analises. Eindige Element Analises was gedoen op SVB balke in buiging om die trekkruip gedrag tot op 30 jaar te simuleer op die verskil tussen die defleksies by midspan tussen ongekraakte en vooraf gekraakte balke te vind. Die analises het gewys dat die defleksies van die vooraf gekraakte balke nie voldoen het aan die vereistes van die Diensbaarheid limiete nie, wat in ag geneem moet word wanneer SVB balke ontwerp word.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Water-retaining structures are commonly used in South Africa for the storage of potable water and waste water. However, a South African code pertaining to the design of concrete water-retaining structures do not currently exist and therefore use is made of the British Standard BS 8007 (1987). For the design of concrete water-retaining structures in South Africa, only the hydrostatic loads are considered while forces due to seismic activity are often neglected even though seismic excitations of moderate magnitude occur within some regions of the country. Hence, the primary aim of this study was to determine whether seismic activity, as it occurs in South Africa, has a significant influence on water-retaining structures and whether it should be considered as a critical load case. In order to assess the influence of seismic activity on the design of water-retaining structures the internal forces in the wall and the required area of reinforcement were compared. Comparisons were made between the seismic analyses and static analyses for both the ultimate and serviceability limit states. In order to obtain the internal forces in the wall use was made of an appropriate Finite element model. Three Finite element models were investigated in this study and the accuracy of each model was assessed based on the fundamental frequency, base shear force and overturning moment. These values were compared to the values obtained with the numerical method presented by Veletsos (1997) which was verified with Eurocode 8: Part 4 (2006). The results obtained indicated that seismic excitations of moderate magnitude do have a significant influence on the reinforcement required in concrete water-retaining structures. For both the ultimate limit state and serviceability limit state the required reinforcement increased significantly when seismic loads were considered in the design. As in the case for static design of water-retaining structures, the serviceability limit state also dominated the design of these structures under seismic loading. / AFRIKAANSE OPSOMMING: Beton waterhoudende strukture in Suid-Afrika word op ‘n gereelde basis gebruik vir die stoor van drink- sowel as afvalwater. ‘n Suid-Afrikaanse kode vir die ontwerp van hierdie strukture bestaan egter nie en dus word die Britse kode BS 8007 (1987) hiervoor gebruik. Vir ontwerp doeleindes word soms slegs die hidrostatiese kragte beskou terwyl kragte as gevolg van seismiese aktiwiteite nie noodwendig in berekening gebring word nie. Seismiese aktiwiteite van gematigde grootte kom egter wel voor in sekere dele van Suid-Afrika. Die hoofdoel van hierdie studie was dus om die invloed van seismiese aktiwiteite, soos voorgeskryf vir Suid-Afrikaanse toestande, op beton waterhoudende strukture te evalueer asook om te bepaal of dit ‘n kritiese lasgevalle sal wees. Vir hierdie doel is die interne kragte asook die area staal bewapening vir elk van die statiese en dinamiese lasgevalle vergelyk. Vergelykings is getref tussen die dinamiese en statiese resultate vir beide die swigtoestand en die diensbaarheidstoestand. Vir die bepaling van die interne kragte is gebruik gemaak van eindige element modelle. Tydens hierdie studie was drie eindige element modelle ondersoek en die akkuraatheid van elk geëvalueer op grond van die fundamentele frekwensie, die fondasie skuifkrag en die omkeermoment. Hierdie waardes was ondermeer bereken met twee numeriese metodes soos uiteengesit in Veletsos (1997) en Eurocode 8: Part 4 (2006). Die resultate dui daarop dat die invloed van seismiese aktiwiteite op beton waterhoudende strukture in Suid-Afrika nie weglaatbaar klein is nie en wel in berekening gebring behoort te word tydens die ontwerp. Die interne kragte vir beide die swigtoestand en diensbaarheidstoestand is aansienlik hoër vir die seismiese lasgeval as vir die statiese geval. Die diensbaarheidstoestand het deurentyd die ontwerp van beton waterhoudende strukture vir seismiese toestande oorheers.

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008. / In recent years, concern about the water quality in the Berg River received a fair degree of attention, particularly with the imminent construction of the Berg Water Project (BWP). Particular concerns have been expressed about the water quality with respect to total dissolved salts (TDS) at Misverstand Dam. In previous studies (Fourie and Görgens, 1977) it was identified that the saline water was mostly generated in the lower portion of the Berg River Catchment (Matjies, Moorreesburg and Sandspruit Rivers) and that the abstraction of acceptable quality water higher up in the Berg River could possibly result in salinity problems at Misverstand Dam. Contrary to expectation, these studies also showed that for the most saline catchments, a winter peak in TDS concentrations also existed. To help address these concerns, a Water Research Commission (WRC) project was initiated in 2003 in which the newly-developed salinity module of the daily Agricultural Catchment Research Unit (ACRU) agrohydrological model, known as ACRUSalinity, would be configured for the Berg River Catchment. This model had previously been configured and calibrated for the Mkhomazi Catchment (Teweldebrhan, 2003) which exhibited relatively low streamflow TDS concentrations (100 mg/l) and it was deemed necessary to ascertain whether comparable TDS values could be simulated in the Berg River Catchment, where TDS concentration could rise to well above 1 000 mg/l in certain tributaries. In this project, ACRUSalinity was configured for the Berg River Catchment on a distributed basis, aiming to capture the spatial distribution of rainfall and geophysical characteristics which inherently exist in a catchment as expansive as the Berg. Initial application of the "Beta version" of ACRUSalinity to the Berg River Catchment revealed that it failed to produce simulated TDS values which were representative of the observed data. It became evident that the model required both additional salinity-related functions and modifications of existing functions. After the implementation of these algorithm changes the correspondence of simulated and observed TDS concentrations improved markedly. Verification of the ACRUSalinity simulated flows and calibration of the salinity-related parameters was based on the values of predefined objective functions. Reasonably representative flows could be obtained provided that the catchment discretisation and driver rainfall selection process were adequate. Salinity related parameters were determined purely on an iterative basis, although a priori estimation of these parameters was possible. Preliminary interdependency tests of these parameters revealed that the final calibrated set of salinity-related parameters was probably not unique and that some a priori decision making would be required when selecting the most realistic set of parameters. Quantification of the potential effect of the Berg River Dam on the TDS concentrations at Misverstand Dam was achieved as follows: the ACRUSalinity model was verified for flow and calibrated for TDS at available and reliable flow gauging stations. This was then followed by a long-term simulation run which yielded daily TDS time series for comparison, on an exceedance basis, with the observed record. Since the concern about the possible deterioration of water quality at Misverstand Dam was only a winter concern (May to September), comparisons were only drawn over this period. The flow-routing option in ACRUSalinity was not activated and a 1:1 daily comparison of flows and TDS concentrations, based on values of the objective function, was thus not possible. Results from this study showed that even with a daily model, the exceedance percentages of the TDS concentrations after the construction of the Berg River Dam were comparable with the exceedance percentages obtained from the original monthly modelling study (DWAF, 1993). In this study, however, it was possible to capture the increasing TDS concentration which was evident over winter months in the observed data record for the Matjies River and Sandspruit River catchments. The testing of the model’s effectiveness in the evaluation of engineering options was accomplished as follows: several options for ameliorating the possible deterioration of water quality at Misverstand Dam were defined, based on its practicality and cost of implementation. For example, the Withoogte water treatment works abstracts water from Misverstand Dam for supply to the West Coast region when water quality is acceptable (i.e. a TDS lower than 450 mg/l). It was proposed that to minimise the effect of periods when no abstraction from Misverstand could occur due to unacceptable water quality, a second reservoir at the treatment works should be lined and used to provide bridging storage for water from Misverstand Dam when the water quality was acceptable. The calibrated ACRUSalinity model was then modified to reflect the physical attributes of this engineering scenario of interest to produce sets of flow and TDS time series which could be further analysed to determine assurance of supply, in terms of predetermined TDS concentration thresholds in Misverstand Dam. Using this particular engineering option, the analysis revealed that a 300 mg/l TDS upper-limit at Misverstand was too stringent and that 450 mg/l was probably more realistic.