Thesis (DEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Geotechnical engineering is a relatively young field of engineering and one in which there are still many unanswered questions and gaps in our knowledge. Added to this, the geotechnical materials on each new site on which geotechnical work is undertaken are the unique product of many influences including geology, geomorphology, climate, topography, vegetation and man. There is thus plenty of scope for innovation. This dissertation describes the contributions made to Geotechnical Engineering in South Africa by the Candidate over a period of close on 40 years. It describes the three-step process followed in the majority of these contributions. Step one is the identification of a problem that requires investigation, the application of new techniques or simply the consolidation of existing knowledge. Step 2 is the investigation of the problem and the development of a solution. Step 3 is sharing the outcome of this work with the profession by means of publications, by presentations at seminars and conferences or by incorporation into standards / codes of practice. Part 1 of the dissertation describes the exciting environment in which geotechnical engineers operate. This environment is characterised by openness and cooperation between practitioners of geotechnical engineering, be they geotechnical engineers, engineering geologists, contractors, suppliers or academics. This part also explores the parallels in the roles played by academics and practitioners and how each can contribute to the advancement and dissemination of knowledge. Part 2 describes contributions made in various fields including problem soils (dolomites, expansive clays, uncompacted fills, etc.), lateral support, pile design and construction, health and safety, and cooperation with international organisations. Part 3 describes the Candidate's involvement in the introduction of limit states geotechnical design into South African practice culminating in the drafting of SANS 10160-5 on Basis of Geotechnical Design and Actions. It also describes the Candidate's work with the ISSMGE Technical Committee TC23 dealing with limit states design. Part 4 deals with the Candidate's contribution to other codes and standards and his role on various committees of the Engineering Council of South Africa and the South African Bureau of Standards. The final part of the dissertation provides an overview of the process followed in making such contributions, highlighting the role played by curiosity and a desire to share the knowledge gained with others in the profession. It continues by identifying work that still needs to be done in many of the areas where contributions have been made and concludes with a statement of what the candidate would still like to achieve during the remainder of his career. The Candidate gratefully acknowledges the generous opportunities afforded to him by his colleagues at work and the invaluable guidance and mentorship received from fellow professionals in academia and practice. / AFRIKAANSE OPSOMMING: Geotegniese ingenieurswese is 'n relatiewe jong wetenskap en een met vele kennisgapings en waarin daar nog talle vrae onbeantwoord bly. Daarby is geotegniese materiale uniek tot elke terrein waarop werk aangepak word en die produk van 'n kombinasie van prosesse; insluitend geologie, geomorfologie, klimaats toestande, topografie, plantegroei en menslike aktiwiteite. Daar is dus nog ruim geleentheid vir innoverende bydraes. Hierdie verhandeling beskryf die Kandidaat se bydraes tot Geotegniese Ingenieurswese in Suid-Afrika oor die afgelope 40 jaar. Dit beskryf 'n drie-voudige benadering wat in die meeste van die bydraes gevolg is. Die eerste stap is om die probleem te definieer en te omskryf in terme van die ondersoek wat geloods moet word, asook die noodsaaklikheid vir die ontwikkeling van nuwe tegnologie teenoor die konsolidasie van bestaande inligting. Tydens die tweede stap word die probleem ondersoek en 'n oplossing ontwikkel. Die derde stap is om die resultate te deel met die geotegniese bedryf by wyse van publikasies, voorleggings by konferensies en seminare, en insluiting in praktykkodes en standaarde. Deel 1 beskryf die opwindende werksomstandighede waarbinne geotegniese ingenieurs hul bevind. Dit word geken aan die ope samewerking tussen belanghebbende partye; onder andere ingenieurs, ingenieursgeoloë, kontrakteurs, verskaffers en akademici. Deel 1 beklemtoon ook die parallelle rolle wat vertolk word deur akademici en praktiserende ingenieurs en hoe beide partye bydraes maak tot die ontwikkeling en verspreiding van tegnologie. Deel 2 beskryf die Kandidaat se bydraes tot verskeie navorsingsvelde; waaronder probleemgrondtoestande (dolomiet, swellende kleie, ongekonsolideerde opvullings ens.), laterale ondersteuning, ontwerp en konstruksie van heipale, beroepsveiligheid, en samewerking met internasionale organisasies. Deel 3 beskryf die Kandidaat se betrokkenheid by die bekendstelling van limietstaat geotegniese ontwerp in die Suid-Afrikaanse bedryf wat uitgeloop het op die samestelling van SANS 10160-5 Basis of Geotechnical Design and Actions. Dit beskryf ook die Kandidaat se samewerking met die ISSMGE Technical Committee TC23 wat te make het met limietstaat ontwerp. Deel 4 beskryf die Kandidaat se bydraes tot ander kodes en standaarde en die rolle wat hy vertolk het op verskeie komitees van die Suid-Afrikaanse Raad vir Ingenieurswese asook van die Suid-Afrikaanse Buro van Standaarde. Die laaste deel van die verhandeling bied „n oorsig oor die proses wat gevolg is in bostaande bydraes met die klem op die rol van weetgierigheid en die begeerte om sulke kennis te deel met ander belanghebbendes. Om af te sluit, identifiseer die Kandidaat oorblywende tekortkominge in baie van die vraagstukke waar hy bydraes gelewer het en gee 'n opsomming van wat hy graag nog sal wil bereik tydens die verdere verloop van sy loopbaan. Die Kandidaat gee met dank erkenning aan sy kollegas vir die ruim geleenthede wat hom gebied is en die waardevolle leiding en mentorskap wat hy ontvang het van mede praktiserende ingenieurs en akademici.

Thesis (MScIng)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: SHCC (Strain-Hardening Cement-based Composite) is a type of HPFRCC (High Performance Fibre Reinforced Cement-based Composite) that was designed and engineered to overcome the weaknesses of ordinary concrete. It shows a high ductility as it can resist the full tensile load at a strain of more than 3%. This superior response is achieved with multiple cracking under tensile loading which has a pseudo strain-hardening phenomenon as a result. The purpose of the research project reported in this thesis document was to design and build a new piston-driven extruder for the production of SHCC as well as R/SHCC (reinforced SHCC) elements and to investigate and characterise the structural and mechanical behaviour of extrusion moulded SHCC. A new piston-driven extruder, specifically for academic purposes, was designed based on the principles of fluid flow mechanics. Although fluid flow is not an ideal model to represent the flow of viscous material through an extruder, it was deemed sufficient for this specific study. A new extruder with the capacity to extrude SHCC and R/SHCC was built. Provision was made that this extruder can be fitted with extruder dies and transition zones of varying shapes and sizes. A comparative study between unreinforced as well as reinforced cast SHCC and extruded SHCC as well as a suitable R/C (Reinforced Concrete) was conducted. Three-point bending tests, representative of the envisioned structural application, were performed on specimens of each of the composites. The unreinforced cast SHCC and especially the unreinforced extruded SHCC have a comparative level of performance to the cast R/C. These specimens displayed a similar cracking pattern of multiple cracks, although less pronounced in the extruded SHCC. The extruded SHCC has superior first cracking and ultimate strength in comparison to cast SHCC, but with accompanying lower ductility. The reinforced SHCC specimens failed in a combination of flexure and shear. The extruded R/SHCC specimens formed multiple diagonal cracks before failure, while the cast R/SHCC specimens formed only a few diagonal cracks, before delaminating along the reinforcement. The higher shear capacity and thus the ability to form multiple diagonal cracks of the extruded R/SHCC can be ascribed to the better fibre orientation of the specimens in the longitudinal direction, while the cast specimens have a random orientation of fibres. R/SHCC and especially extruded R/SHCC could be a far superior structural material to R/C. Mechanical characterisation of extruded SHCC was done with the use of uni-axial tensile and compressive tests. The results of these tests were compared with the results of uni-axial tensile tests previously performed on cast SHCC as well as uni-axial compressive tests that were performed on cast SHCC in this research study. The extruded SHCC displayed superior tensile performance in terms of first cracking and ultimate strength in comparison to cast SHCC, but with accompanying lower ductility. In terms of compressive performance the extruded SHCC has a higher ultimate strength, but with a lower ductility than cast SHCC. The extruded SHCC also has a much higher E-modulus than cast SHCC. This can partly be attributed to the difference between the water/binder ratios of the cast and extruded SHCC, but can mainly be ascribed to the lower porosity as a result of high extrusion forces involved in the manufacturing of extruded SHCC. A simple bending model for SHCC has also been introduced. This model is based on the mechanical characteristics of SHCC. The model somewhat underestimates the resistance moment of the extruded and cast SHCC, but this underestimation is more pronounced in the case of the cast SHCC. Various reasons for the underestimation is discussed, but it is postulated that the main reason for the difference in experimentally determined and the calculated resistance moment of the cast SHCC is the possible variation in ingredient properties and specimen preparation and testing, since the characterisation of the cast SHCC was done over a long period of time and by different researchers. The bending model is however deemed sufficient for the design purposes of SHCC. / AFRIKAANSE OPSOMMING: SHCC (“Strain-Hardening Cement-based Composite”) is ‘n tipe HPFRCC (“High Performance Fibre Reinforced Cement-based Composite”) wat ontwerp is om die swakhede van gewone beton te oorkom. Hierdie materiaal het ‘n hoë duktiliteit en kan die volle trekkrag weerstaan met ‘n vervorming van meer as 3%. Hierdie uitstaande gedrag word gekenmerk deur meerdere krake wat vorm gedurende ‘n trek belasting wat vervormingsverharding tot gevolg het. Die doel van die navorsingsprojek wat weergegee word in hierdie tesis dokument was om ‘n nuwe suier-aangedrewe ekstrueerder vir die produksie van SHCC sowel as R/SHCC (bewapende SHCC) te ontwerp en te bou en om die strukturele en meganiese gedrag van ge-ekstrueerde SHCC te ondersoek en te karakteriseer. ‘n Nuwe suier-aangedrewe ekstrueerder, spesifiek for akademiese doeleindes, is ontwerp gebaseer op die beginsels van vloeistof vloeimeganika. Alhoewel vloeistof vloeimeganika nie ‘n ideale model is vir die voorstelling van die vloei van ‘n viskose materiaal deur ‘n ekstrueerder nie, word dit beskou as aanvaarbaar vir die doeleindes van hierdie spesifieke studie. ‘n Nuwe ekstrueerder met die kapasiteit om SHCC en R/SHCC te ekstrueer is gebou. Voorsiening is ook gemaak dat ekstrueerder vorms (“dies”) en oorgangsones van verskillende vorms en groottes aan die ekstrueerder geheg kan word. ‘n Vergelykende studie tussen onbewapende sowel as bewapende gegote en ge-ekstrueerde SHCC, sowel as ‘n gepasde R/C (“Reinforced Concrete”) is uitgevoer. Drie-punt buigtoetse, verteenwoordigend van die voorgestelde strukturele toepassings vir SHCC, is uitgevoer op proefstukke van elk van die bogenoemde materiale. Die meganiese gedrag van die onbewapende gegote SHCC en spesifiek die onbewapende geekstrueerde SHCC is vergelykbaar met die meganiese gedrag van gegote R/C. Hierdie proefstukke het ooreenstemmende kraakpatrone van veelvuldige krake getoon, alhoewel dit minder prominent was in die geval van ge-ekstrueerde SHCC. Die ge-ekstrueerde SHCC het hoër eerste kraak- en maksimum sterktes in vergelyking met gegote SHCC, maar met gepaardgaande laer duktiliteit. Die bewapende SHCC proefstukke het in ‘n kombinasie van buig en skuif gefaal. Die geekstrueerde R/SHCC proefstukke het meerdere diagonale krake gevorm voor faling, terwyl die gegote R/SHCC proefstukke slegs ‘n paar diagonale krake gevorm het, voordat dit langs die bewapening gedelamineer het. Die hoër skuifkapasiteit van ge-ekstrueerde SHCC en dus die vermoë om meerdere diagonale krake te vorm, kan toegeskryf word aan die longitudinale orientasie van vesels van die proefstukke, terwyl gegote proefstukke se vesels meer lukraak georienteerd is. R/SHCC en spesifiek ge-ekstrueerde R/SHCC kan‘n superieure strukturele materiaal in vergelyking met R/C wees. Die meganiese karakterisering van ge-ekstrueerde SHCC is gedoen met die gebruik van direkte trek- en druktoetse. The resultate van die hierdie toetse is vergelyk met die resultate van direkte trektoetse uit ‘n vorige studie op gegote SHCC,, sowel as met die uitslae van direkte druktoetse wat op gegote SHCC in hierdie navorsingstudie gedoen is. Die ge-ekstrueerde SHCC het superieure trekgedrag in terme van eerste kraak en maksimum sterktes in vergelyking met gegote SHCC getoon, maar met gepaardgaande laer duktiliteit. In terme van drukgedrag het die ge-ekstrueerde SHCC ‘n hoër maksimum druksterkte, maar met ‘n laer duktiliteit in vergelyking met die gegote SHCC. Die ge-ekstrueerde SHCC het ook ‘n veel hoër Emodulus as gegote SHCC. Dit is gedeeltelik as gevolg van die verskil in die water/binder verhouding van die gegote en ge-ekstrueerde SHCC, maar kan grootliks toegeskryf word aan die laer porositeit van ge-ekstrueerde SHCC as gevolg van die hoë ekstrusie kragte. ‘n Eenvoudige buigmodel vir SHCC word ook voorgestel. Hierdie model is geabseer op die meganiese gedrag van SHCC. Die model onderskat die weerstandsmoment van ge-ekstrueerde SHCC sowel as gegote SHCC, maar hierdie onderskatting is meer prominent in die geval van gegote SHCC. Verskeie redes vir hierdie onderskatting word genoem, maar dit word beweer dat in die geval van gegote SHCC dit grootliks as gevolg van moontlike variasies in die materiaal eienskappe en proefstukke se voorbereiding en toetsing is, aangesien die karakterisering van die gegote SHCC oor ‘n lang tydperk en deur verskillende navorsers gedoen is. Die buigmodel word nogtans as voldoende beskou vir die ontwerpdoeleinde van SHCC.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2007. / Research on cranes and crane support structures has been completed at Stellenbosch University’s Structural Division. In order to link the research already completed with that which is practically relevant, an industry related expert survey was proposed. Consequently, the research title is “Best Practice of Crane Support Structures Design – An Expert Survey”. The primary objective of the study is to complete research, which can be used at a later stage to compile a “best practice” guideline for support structures design. The expert survey allows practical experience and opinion to be gathered from experts. The primary drawback being the uncertainty involved in such opinionated research material. For this reason an attempt is made in the thesis to apply a scientific approach, in order to attain rationally defendable results. The survey was conducted using interviews with experienced crane support structure designers and crane manufacturers in South Africa. The experts were then rated according to their answers to seeded questions, the number of colleague recommendations they each received and the years of experience each expert has. The expert opinion was subsequently combined using the expert ratings as weights. To further improve the scientific rationale behind the results, several of the topics mentioned by the experts were verified using related literature - thereby validating the use of the combined expert opinion for this research. The results obtained from the survey and verification process are regarded as useful to the objectives of the study. Information concerning pre-design specifications, loads and actions, structural analysis, design, design details and fatigue was compiled. The direct results are tabulated in an appendix and commentary, based on the expert opinions, is provided. A failure investigation was also completed with less success than initially intended. This was due, in part, to confidentiality issues and a lack of failure information easily accessible to the experts. For this reason the results of the failure investigation focuses more on various failure mechanisms. The success of the survey indicates that expert opinion is a useful tool for research. Furthermore, the minor differences in expert opinion, when compared to information obtained from crane support structure literature, indicates that the expertise in the South African crane support structure design is at an international standard.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2007. / In structural engineering practice the actions imposed by overhead travelling cranes onto the supporting structure are defined as static forces amplified by dynamic coefficients and applied as pseudo-static forces without taking the interaction between crane and supporting structure into account. To investigate the validity of this approach, the forces generated at the wheels of an experimental crane are measured, as the crane traverses on the supporting structure. The interaction at the wheels of the crane is also visually recorded. These wheel load results will also be used by other researchers, to calibrate a numerical model of the experimental system. A full-scale 5 ton electric overhead travelling crane (EOTC) running on top of rails and a supporting structure, was designed and erected for research purposes. The crane has a span of 8.3 m and wheel spacing of 4 m, which can be modified. The supporting structure consists of three simply supported mono-symmetric plate girders on each side, with a total length of 13.8 m. This is supported by columns with a height of about 3.5 m. This paper describes the calibration of this system for measurement purposes. A data acquisition system was implemented to capture forces, strains, deflections and accelerations at various points on the crane and the supporting structure as well as to measure the velocity of the crane. The forces at the crane wheels are measured through strain gauges on the end carriage load measuring system. The calibrated facility is used to investigate the behaviour of the crane and the supporting structure under regular and exceptional wheel loads, which are classified as follows: - Regular wheel loads occur during normal payload hoisting and lowering, longitudinal crane travel with payload and lateral crab travel with payload. - Exceptional wheel loads occur during eccentric payload hoisting (payload outside normal operational area), impact forces on end-stops, maximum hoisting of the payload, failure of a longitudinal drive mechanism of the crane, misalignment of the supporting structure and skewing of the crane. The maximum values of these experimentally determined wheel loads and the dynamic response of the system is used to help describe the behaviour of the electric overhead travelling crane and its supporting structure.

Thesis (MEng) -- Stellenbosch University, 2004. / ENGLISH ABSTRACT: East London is situated on the south-eastern, Indian Ocean, coast o f South Africa. The sediment transport regime at East London is quite unlike the regimes at other ports in South Africa. A major ocean current (the Agulhas) flows exceptionally close to the coastline in this area, thus significantly affecting nearshore sediment movements. The proximity o f a strong ocean current opposed to the net longshore drift (wave driven transport) creates an anomalous sediment transport regime in comparison with that found at most coastlines throughout the world. Furthermore, the Port o f East London (Figures 1.1 and 1.2) is the only major river harbour in South Africa, which all results in a very intricate pattern o f sediment movement in the area, making it o f particular interest. The aims o f this thesis are to study the littoral sediment transports at East London, achieve a holistic understanding o f this complex sediment transport regime and to quantify the various transport rates as far as possible. The study area includes the coastal zone between the Goda and Nahoon Rivers (Figure 1.3) with the main focus on the Hood Point to Orient Beach area (Figure 1.4). The offshore marine environmental conditions are also considered as they have a strong influence on nearshore currents, waves and sediment transport patterns. The prerequisite to understanding the sediment transport processes is a thorough investigation o f the relevant coastal processes. Thus, an in-depth study is undertaken o f the physical environmental data/information, nearshore processes and coastal dynamics that determine or topography changes, the wave regime, the Agulhas Current, the nearshore current regime, the continental shelf sediment dynamics, sediment characteristics, seabed features, the Buffalo River, the tides, the wind regime, and coastal morphodynamics. The specific contribution of each aspect of the environmental data/information to the qualitative understanding of the overall sediment transport regime is determined, and the various modes of sediment transport in different areas are quantified. All o f this information is then synthesised into an expose' o f the sediment transport regime at East London, as briefly described in the conclusions (Section 5 and Table XI) and illustrated in Figure 4.30: There is a net longshore transport (wave driven) of about 250 000 m3 to 300 000 m3 per year on average from the Foreshore area towards the head of the main breakwater, with the total transport into the main sand trap and entrance channel areas from the south-west estimated at 275 000 m3/year. In the offshore zone, large amounts of sediment are transported downcoast by means of the strong Agulhas Current, which also has a significant influence on nearshore currents and sediment transport in the harbour entrance area. About 75 000 m3/year of sand is transported into the “Bar” area (the seaward part of the entrance channel) from the north-east with downcoast flowing nearshore currents, which is the predominant current direction. The riverine input into the harbour has been estimated at less than 10 000 m3/year of sand. In this thesis, therefore, the sediment transport regime (and sediment transport balance) is derived fo r East London, providing for the first time a holistic understanding o f the complex sediment transport regime. It is recommended that more field data should be collected on specific aspects of this study and that the longer term effects of major weather systems should be investigated further. The numerical wave modelling should be extended and the integration of field measurements and numerical modelling to predict sediment transport and resultant bottom changes should be assessed in detail. Ultimately, the information contained in this thesis should feed into a wider regional investigation, with the aim of drawing up a sediment budget for the entire “regional macro sedimentary cell” of which the present study area forms a part. / AFRIKAANSE OPSOMMING: sedimentvervoer-regime by Oos-Londen is anders as die by ander hawens in Suid-Afrika. ‘n Hoof oseaan-stroom (die Agulhas) vloei besonder naby aan die kus in die gebied en het gevolglik ‘n beduidende impak op sedimentvervoer-patrone in die nabystrandse gebied. Die direkte teenwoordigheid van ‘n sterk diepwater stroom wat teen die netto (golfgedrewe) langsstrandse vervoer inwerk, veroorsaak ‘n ongewone sedimentvervoer-regime in vergelyking met wat algemeen wereldwyd gevind word. Daarbenewens is die Oos-Londenhawe (Figure 1.1 en 1.2) die enigste groot rivier-hawe in Suid-Afrika. A1 die ongewone toestande lei tot ‘n ingewikkelde patroon van sedimentvervoer in die gebied. Die doel van hierdie tesis is om die sedimentvervoerregime by Oos-Londen te bestudeer, ‘n holistiese begrip van die ingewikkelde sedimentvervoerregime te verkry, en om die verskillende komponente van die sedimentvervoer regime so ver as moontlik te kM’antifiseer. Die studiegebied sluit die kusstrook tussen die Goda- en Nahoonriviere in (Figuur 1.3). Daar word egter op die Hoodpunt tot Orientstrand-gebied gefokus (Figuur 1.4). Die diepwater, mariene omgewingstoestande word ook beskou, aangesien hul ook ‘n groot impak op die nabystrandse strome, golwe en sedimentvervoer-patrone het. ‘n Deeglike ondersoek van die toepaslike kusprosesse is ‘n voorvereiste om ‘n goeie begrip van die sedimentvervoer-prosesse op te bou. Gevolglik is ‘n diepgaande ondersoek gedoen na die fisiese omgewingsdata en -inligting, nabystrandse prosesse en kusdinamika wat die sedimentvervoer-regime bepaal of bei'nvloed. Dit het ondersoeke ingesluit na: onderhoudsbaggervolumes, bodemtopografie veranderinge, die golfklimaat, die Agulhasstroom, die nabystrandse stroom-regime, die sedimentdinamika op die kontinentale plaat, sediment eienskappe, die windklimaat, die geaardheid van bodemvorme, die Buffelsrivier, getyaksie, en kus-morfologie. Daar is bepaal wat elke aspek van die omgewingsdata/inligting bydra tot ‘n kwalitatiewe begrip van die algehele sedimentvervoer-regime. Verder is die verskillende komponente van die sedimentvervoer in verskeie gebiede gekwantifiseer. Al hierdie inligting is toe versoen in ‘n beskrywing van die sedimentvervoer-regime by Oos-Londen, soos wat in die gevolgtrekkings (Deel 5 en Tabel XI) gegee word en in Figuur 4.30 geillustreer word: Daar is ‘n gemiddelde netto golfgedrewe langsstrandse vervoer van ongeveer 250 000 m3 tot 300 000 m3 per jaar vanaf die strandgebied suid van die hawe na die punt van die hoof-golfbreker. Die totale beraamde vervoer vanaf die suidweste na die hoofsandvangput en ingangskanaal-gebied is 275 000 m3 per jaar. In die diepsee word groot hoeveelhede sediment langs die kus af vervoer deur die sterk Agulhasstroom, wat ook ‘n beduidende impak het op nabystrandse strome en sedimentvervoer in die haweingangsgebied. Omtrent 75 000 m3 sand word per jaar na die “Bar”-gebied vervoer vanaf die noord-ooste deur nabystrandse strome wat langs die kus af vloei. Dit is ook die oorwegende nabystrandse stroomrigting (uitgesluit die brandersone). Sawafafsetting in die hawegebied afkomstig van die Buffelsrivier word op minder as 10 000 m3 per jaar geskat. Die sedimentvervoer-regime (en sediment-balans) by Oos-Londen word dus afgelei, en vir die eerste keer saamgesnoer in ‘n bree insig van die komplekse sedimentvervoer-regime. Daar word aanbeveel dat meer velddata verkry moet word oor sekere aspekte van hierdie studie en dat die langtermyn-impakte van groot weerstelsels verder ondersoek word. Die wiskundige golf-modellering moet uitgebrei word en die gesamentlike benutting van veldmetings met wiskundige modellering om sedimentvervoere en gevolglike bodemveranderinge te voorspel, moet deeglik ondersoek word. Uiteindelik behoort die inligting vervat in hierdie tesis in te voer in breer streeks-ondersoeke, met die oog daarop om ‘n sediment-begroting vir die “Ooskaapse makro-sedimentvervoer-regime” op te stel.

Thesis (MScIng)--Stellenbosch University, 2005. / Some digitised pages may appear illegible due to the condition of the original hard copy. / ENGLISH ABSTRACT: Reinforced concrete (RC) frames with unreinforced masonry infill form the structural system of many buildings and this is also true for South Africa. It is common practice to consider the masonry infill as a non-structural component and therefore it does not contribute to the performance of the Re frame buildings under lateral loading such as earthquake loading. This is done by leaving a sufficient gap between the Re frame and the infill. This ensures that there is no contact between the frame and the infill during an earthquake event. However, it has been suggested that masonry infill can play a significant role in the performance of a Re frame building under lateral loading. The first part of the study focuses on the South African situation. The relevance of shear walls in these Re frame buildings as well as the size of the gap (between frame and infill) left in practice, are investigated. This is done by finite element analysis. The second part of the study focuses on the effects that the infill can have on the global performance of the structure when there is full contact between the Re frames and infill. The effect of openings in the infill to the response of the frame is also investigated. Finite element models of single span Re frames with infill is built and analyzed in order to investigate possible damage to the infill, frame infill interaction and to obtain the non linear stiffness of the frame with infill as a whole. This obtained non linear stiffness can be modelled in Diana as a non linear spring that will be used in the development of a simplified analysis method. The simplified method developed consists of a frame and two such non linear springs, placed diagonally, and which have the same force versus displacement behaviour as the original frame with infill. These single span frames can be added together to model a whole frame. In a first step to generalise the simplified method, various geometries of infills are considered, varying span and height, as well as opening percentage, representing windows and doors of varying total area and positioning. However, in this study a single masonry type, namely solid baked clay bricks set in a general mortar, is considered. To generalise the approach further, other masonry types can be considered in the same way. The use of these springs in a simplified model saves computational time and this means that larger structures can be modelled in Diana to investigate response of'Rf' frame buildings with infill. The work reported in this thesis considers only in-plane action. Out-of-plane-action of the masonry infill has been reported in the literature to be considerable, under the condition that it is sufficiently tied to the frame to prevent mere toppling over, causing life risking hazards in earthquake events. This matter should be studied in continuation of the current research to generalise the simple approach to three dimensions. / AFRIKAANSE OPSOMMING: Gewapende betonrame (GBR-e) met ongewapende messelwerk invulpanele (invul) vorm die strukturele ruggraat van vele geboue en dit geld ook vir geboue in Suid-Afrika. Dit is algemene praktyk om die invulpaneel in sulke geboue as 'n nie-strukturele komponent te beskou. Daarvolgens dra dit nie by tot die gedrag van 'n GBR gebou onderhewig aan 'n aarbewing nie. Dit word bereik deur 'n groot genoeg gaping tussen die betonraam en die invul te los. Die gevolg is dat daar geen kontak tussen die betonraam en die invul plaasvind indien daar 'n aardbewing sou voorkom nie. Dit is egter voorgestel dat invul 'n noemenswaardige rol kan speel in die gedrag van 'n GBR gebou onderwerp aan 'n horisontale las. Die eerste deel van die studie fokus op die Suid-Afrikaanse situasie. Die relavansie van skuifmure in GBR geboue asook die grootte van die gaping (tussen die raam en invul) wat in die praktyk gebruik word, word ondersoek. Dit word gedoen met behulp van eindige element analises. Die tweede deel van die studie fokus op die effek wat invul kan hê op die globale gedrag van 'n struktuur wanneer daar volle kontak tussen die GBR en die invul is. Die effek wat die teenwoordigheid van openinge in die invul kan hê op die gedrag van 'n GBR is ook ondersoek. Eindige element modelle van enkelspan GBR met invul is gemodelleer en geanaliseer om die moontlike skade aan die invul, die interaksie tussen die GBR en die invul asook die nie-lineêre styfheid van die raam en invul as 'n geheel, te ondersoek. Hierdie nielineêre styfheid kan in Diana as 'n nie-lineêre veer gemodelleer word en word gebruik in die ontwikkeling van 'n vereenvoudigde metode. Hierdie vereenvoudigde metode wat ontwikkel is, bestaan uit 'n raam en twee sulke nielineêre vere (diagonaal geplaas). Die raam met vere het dieselfde krag teenoor verplasingsgedrag as die van die oorspronklike raam met invul wat dit voorstel. Hierdie rame kan saamgevoeg word om 'n raam uit 'n gebou as 'n geheel te modelleer. Verskeie invul geometrieë word gebruik in die analises in 'n eerste stap om die vereenvoudigde metode te veralgemeen. Die span en hoogte asook opening persentasie van die invul word gevariëer om vensters en deure van veskeie grootte en posisie voor te stel. In die studie, 'n enkel messelwerk tipe, naamlik solied klei bakstene geset in algemene mortar, word gebruik. Ander messelwerk tipes kan gebruik word om die metode verder te veralgemeen. Die gebruik van die vere in die vereenvoudigde metode spaar berekenings tyd en dit beteken dat groter strukture in Diana gemodelleer kan word om die gedrag van GBR geboue met invul te ondersoek. Die werk gedoen in die tesis neem slegs in-vlak aksie in ag. Literatuurstudie dui daarop dat goeie uit-vlak-aksie van messelwerk invul bestaan, mits dit goed geanker is aan die raam om te verseker dat dit nie kan omval en 'n gevaar vir lewens in 'n aardbewing inhou nie. Dit behoort verder bestudeer te vord in die vervolging van die huidige ondersoek om die vereenvoudige metode na drie dimensies te veralgemeen.

Thesis (MScEng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Experiments conducted on afforested catchments in South Africa have shown that alien trees can cause substantial reductions in catchment runoff (Scott et ai, 2000). In recognition of the impact which alien trees can have on the country's water resources, commercial afforestation was declared a stream flow reduction activity (SFRA) in terms of the National Water Act (NW A) (No. 36 of 1998), and the Department of Water affairs and forestry launched the Working for Water Programme (WfW) in 1995 with the recovery of water resources lost to Invasive alien plants (lAPs) as one of the Programme's objectives. These initiatives have intensified the need to quantify SFR; for example, for licensing purposes to satisfy the requirements of the NWA and for predicting the effects of lAP clearing by WfW projects. Of interest to water resources practitioners, is the impact of SFR on mean annual runoff (MAR), on low flows and on water resource system, or reservoir, yield. In South Africa two basic methods of streamflow reduction (SFR) estimation have been developed for commercial afforestation and lAPs. These are • free-standing empirical relationships in the form of the CSIR SFR CUNes, used in conjunction with the monthly, calibration-based, Pitman model. • component modules in the physically-based, land-use sensitive ACRU rainfall-runoff catchment model, run at a daily time step with relatively fine subcatchment delineation. There has been a strong need for an evaluative comparison of the impacts of SFR estimated via these two methods. This study aimed to meet this need by using both methods to estimate SFR for a number of commercial afforestation and lAP scenarios in three study systems, the Berg, Sabie and Mhlatuze, representing different bioclimatic conditions in South Africa, and running the SFR sequences from the two estimation methods through the Water Resources Yield Model to determine the impact of the SFR on yield. The analysis differentiated between upland and riparian SFR, and between SFR produced by different tree classes. Study conclusions included the following points: • Both the ACRU and SHELL models are capable of achieving a reasonable average seasonal correspondence of high and low flows with the observed averages, though the actual averages produced by the two models can differ substantially. In general, ACRU simulates less SFR than SHELL, and gains in SFR after afforestation or invasion by lAPs may be simulated by ACRU during dry periods. The selection of crop factors for different plant species has a strong influence on the relative water use of the species modelled in ACRU. • The impacts on yield of SFR due to lAPS and afforestation tends to be greater than the impact on MAR, and impacts tend to be more severe for small subcatchments than for the total catchment. A simulated reduction in MAR can result in a simulated increase in yield of a given assurance, if the portion of the flow sequence occurring during the critical period is dominated by streamflow gains, and vice versa. Research recommendations centred on improving the availability of reliable field measurements of parameters and processes required tor the effective modelling of SFR. Based on the results of the study, guidelines were formulated for SFR modelling, focussing on the choice of SFR estimation method and the treatment of various parameters and considerations which influence the outcomes of SFR modelling. / AFRIKAANSE OPSOMMING: Eksperimente wat in bebosde opvanggebiede in Suid-Afrika uitgevoer is, het getoon dat uitheemse bome aansienlike verminderings in opvanggebied-afloop kan veroorsaak (Scott et al,2000). Ter erkenning van die impak wat uitheemse bome op die land se waterbronne kan he, is kornrnersiele bebossing verklaar as 'n stroomvloei-verminderingsaktiwiteit (SVVA) in terme van die Nasionale Waterwet (NWW) (Nr. 36 van 1998). Die Departement van Waterwese en Bosbou het ook die Werk-vir-Water Program (WvW) in 1995 geloods met, as een van die doelwitte, die herwinning van waterbronne wat deur uitheemse indringerplante (UIPe) opgebruik word. Hierdie inisiatiewe het die behoefte om SVV te kan kwantifiseer verskerp; by voorbeeld; for liksensiermqsdoeleindes om die vereistes van die NWW te bevredig, of om die impakte van UIP-opruiming in WvW-projekte te voorspel. Van besondere belang vir waterbron-praktisyns is die impak van SVV op gemiddelde jaarliks afloop (GJA), op lae vloeie en op die lewering van waterbronne, of -stelsels. In Suid-Afrika is twee basiese metodes vir SVV-raming ontwikkel vir komrnersiele bebossing en UIPe, soos volg: • losstaande empiriese verbande in die vorm van die WNNR se SVV-krommes, wat gebruik word saam met die maandelikse, kalibrasie-gebaseerde, Pitman-model wat in die SHELL-sagteware-omgewing ingebou is. • Modules wat komponente vorm in die fisies-gebasserde, grondgebruik-gevoelige ACRU reenval-atloop opvanggebiedmodel, wat op 'n daaglikse tydstap loop, met relatiewe fyn subopvanggebied-indelings. Daar bestaan al lank 'n sterk behoefte aan 'n takserende vergelyking van die impakte van SVV so os geraam via hierdie twee metodes. Hierdie navorsing het beoog om hierdie behoefte te bevredig deur beide metodes in 'n aantal kornrnersiele bebossings- en UIPscenario's in drie stelsels, die Berg, Sabie en Mhlatuze, te gebruik. Sodoende word drie verskillende bio-klimaatstreke gedek. Die maandelikse SVV-tydreekse van die twee ramingsmetodes was toe ingevoer in 'n waterbronstelselmodel (WRYM) om die impak van die SVV op die lewering te bepaal. Die ontledings het tussen oewer- en nie-oewer-SVV, asook tussen SVV wat deur verskillende boom-klasse veroorsaak is, onderskei. Die gevolgtrekkings uit die studie het die volgende punte ingesluit: • Seide die ACRU- en SHELL-modelle is in staat om 'n redelike ooreenkoms in seisoenale hoe en lae vloeie met waargenome gemiddeldes te verskaf, alhoewel die eintlike gemiddeldes wat deur die twee modelle gelewer word, aansienlik kan verskil. • Oor die algemeen simuleer ACRU laer SVV as SHELL en klein toenames in vloeie na bebossing of indringing deur UIPe kan soms tydens droe tydperke deur ACRU gesimuleer word. Die keuse van gewasfaktore vir verskillende planttipes het 'n groot invloed op die relatiewe waterverbruik van die planttipes wat in ACRU gemodelleer word. • Die impakte op lewering van SVV te wyte aan beide UIPe en bebossing neig om groter te wees as die impak op GJA, en die impakte neig om meer ernstig te wees vir klein subopvanggebiede as vir die totale opvanggebied. 'n Gesimuleerde vermindering in GJA kan soms saamval met 'n gesimuleerde toename in lewering teen 'n spesifieke betroubaarheid, as die gedeelte van die tydreeks wat gedurende die kritieke tydperk voorkom, heelwat UIP-gebaseerde stroomvloei-toenames bevat en vice versa. Navorsingsaanbevelings fokus op die verbetering van die beskikbaarheid van betroubare veldwaarnemings van parameters en prosesse wat vereis word vir betroubare modellering van SVV. Riglyne vir SVV-modellering is geformuleer, gebaseer op die resultate van hierdie navorsing, met 'n fokus op die keuse van SVV-ramingsmetode, die behandeling van verskeie parameters en oorwegings wat die uitslag van SVV-modellering sou kon bemvloed.

Thesis (MScEng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The lack of a simple rational mechanical model for the shear resistance behaviour of structural concrete members results in the use of simplified empirical methods in codified shear design methods with a limited range of applicability. This may lead on the one hand to insufficient reliability for members on the boundary of the range of applicability and on the other hand to over-conservative designs. Comparison of the provision for shear resistance design of the South African code of practice for the design of concrete structures SANS 10100: 2003 with other related codes shows differences in the design variables taken into account and procedures specified to calculate shear resistance. The thesis describes a systematic evaluation of the reliability performance of the shear performance of reinforced concrete sections subjected to shear only, and in combination with flexural moments, designed with SANS 10100: 2003. Both sections with and without provision for shear reinforcement are considered. A representative range of parametric conditions are considered in the evaluation. Punching shear is not considered in the present review. Shear design as specified by SANS 10100 is compared to the provisions of the closely related British code for the structural use of concrete BS 8110, Eurocode 2 for the design of concrete structures EN 1992 and the American bridge design code AASHTO LRFD. The reliability performance of the shear design method for beams of SANS is considered in terms of a probabilistic shear resistance model, uncertainties in the basic variables such as material properties, geometry and modelling uncertainty. Modelling uncertainty is determined by comparing predicted values with published experimental results. Keywords: structural concrete; shear resistance; shear design; reliability; design codes; code companson / AFRIKAANSE OPSOMMING: Die tekortkoming van eenvoudige rasionele modelle vir skuif gedrag van strukturele gewapende beton lei tot die gebruik van vereenvoudigde empiriese metodes in gekodifiseerde skuif ontwerp met 'n beperkte omvang van gebruik. Dit mag lei tot onvoeldoende betroubaarheid vir ontwerp situasies, maar ook tot oorkonserwatiewe ontwerpe. Vergelyking van voorsienings vir skuifweerstand ontwerp in die SANS beton kode, SANS 10100: 2003 en ander verwante kodes toon verskille in ontwerp veranderings en metodes aan vir die berekening van skuifweerstand. Hierdie tesis beskryf die stelselmatige bepaling van betroubaarheids prestasie van die skuifgedrag van gewapende beton snitte ontwerp volgens SANS. Beide snitte met en sonder skuifbewapening word behandel. 'n Verteenwoordigende bestek van skuif ontwerp parameters word in ag geneem in die beoordeling van die betroubaarheid. Pons skuifword nie hier in ag geneem nie. Skuif ontwerp soos voorgeskryf deur SANS 10100 word verlyk met die ontwerp methodes van die Britse beten kode, BS 8110, die Europese beton kode, Euronorm Eurocode 2 en die Amerikaanse brug kode AASHTO LRFD. Die betroubaarheids prestasie van die skuif ontwerp metode vir SANS word bepaal deur middel van 'n probablistiese skuif ontwerp model. Modelonsekerheid is vir die doeleindes bepaal deur vergelyking met gepubliseerde eksperimentele resultate. Sleutelwoorde: strukturele beton; skuifweerstand; skuif ontwerp; betroubaarheid; ontwerp kodes; kode vergelyking.

Thesis (M.Eng.)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: This study entailed the investigation and evaluation of a new methodology for measuring high discharges passing through bridges. Pressure differences generated around bridge piers have been measured and related to the discharges. These pressure differences are mainly functions of downstream flow conditions. The pressure differences have been converted into velocities by applying Newton's second law expressed in terms of the laws of conservation of energy; momentum; and of power. The energy principle was re-evaluated following a preVIOUSstudy (Retief, 1999) on a limited number of model pier combinations and flow conditions. Comparison of the energy approach with newly developed theories in terms of the momentum and power laws respectively led to the conclusion that the energy principle gave the best results. The question of applicability of the theory to practical pier/stream width and length ratios as well as its validity under flow conditions commonly found under flood conditions required that additional laboratory tests be done. The energy-based discharge equation was calibrated in terms of newly selected measuring points, different pier width and length ratios, as well as pier rotations for both super and sub-critical downstream conditions. According to the new tests performed at the Hydraulics Laboratory of the University of Stellenbosch on model piers, clear relationships were found between discharges and pressure differences measured against the pier. Calibration curves for practical flow measurement application were derived in terms of principle dimensionless parameters. Application of the energy approach at the prototype level needs further investigation. / AFRIKAANSE OPSOMMING: Hierdie studie het behels die ondersoek en evaluering van 'n nuwe metode om hoë vloeie verby brïïe te meet. Drukverskille wat rondom brug pylers opgewekword is gemeet en omgeskakel na vloeie. Hierdie drukverskille is hoofsaaklik funksies van die stroomaf vloei toestande. Die drukverskille is omgeskakel na vloeisnelhede deur die toepassing van Newton se tweede wet, uitgedruk in terme van die behoud van energie, momentum so wel as drywing. Die energie beginsel is weer geëvalueer sedert 'n vorige studie (Retief, 1999) gedoen is op 'n beperkte aantal model pylerkombinasies en vloeitoestande. Hierdie energie-benadering is met nuwe metodes vergelyk, naamlik die momentum en drywings wette. Die gevolgtrekking is gemaak dat die energie metode die beste resultate gee. Die vraag oor die toepaslikheid van die teorie met praktiese pyler/stroom wydte en lengte verhoudings so wel as die toepaslikheid hiervan onder die vloei toestande wat algemeen onder vloedtoestande voorkom het addisionele laboratoriumtoetse vereis. Die energie gebaseerde vloeivergelyking is gekalibreer in terme van nuut geselekteerde meetpunte, verskillende pyler wydte en lengte verhoudings, asook pyler rotasies vir beide super en sub-kritiese stroomaf toestande. Na aanleiding van die toetse gedoen in die Hidroulika Laboratorium van die Universiteit van Stellenbosch op brugpylers, is duidelike verbande gekry tussen die vloeie en die drukverskille soos gemeet teen die pyler. Kalibrasie-kurwes vir die toepassing van praktiese vloeimeting is ontwikkel in terme van die toepassing van dimensielose parameters. Die toepassing van die energiebenadering op prototipe vlak verg verdere ondersoek.

Thesis (M.Ing.)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Laterites are used extensively in the tropics as road building materials in unbound base, sub-base layers and in surface layers. However, most base course specifications usually require the provision of crushed and graded stone or stabilized base and often exclude the general use of as-dug laterites or other naturally occurring gravels. Various field studies in the past have clearly indicated that many lateritic gravel deposits can be used successfully as base course materials in roads carrying low to medium traffic without incurring additional maintenance costs and with considerable cost savings in pavement construction rehabilitation. Further research is needed for the more precise definition of the relationship between laterite characteristics, traffic loading, environment, and pavement performance. In this study, extensive use was made of static and cyclic triaxial testing to investigate the fundamental behaviour of a lateritic gravel material. The tests produce information for characterizing the shear strength, stress-strain properties and behaviour under repeated loading. The gravel was sourced from stockpile at Malans Transport borrow pit at Maaitjies Kuil near Cape Town. Testing was conducted on the material both as granular material and stabilized with cement and foamed bitumen. Testing was done under various conditions of stress, moisture and compaction. The resilient modulus of the lateritic gravel was found to be affected by moisture and compaction apart from the stress condition. Well known models were used to characterize the stressdependent resilient modulus. A model for prediction of permanent deformation was developed which together with the resilient modulus model were applied to the design of a light pavement structure composed of lateritic gravel base. / AFRIKAANSE OPSOMMING: Lateriete word wydverspreid gebruik in die trope as 'n padbou materiaal. Die materiaal word gebruik in ongebonde kroonlae, stutlae en oppervlaklae. Die meeste spesifikasies vir kroonlae vereis dat gegradeerde gebreekte klip of gestabiliseerde materiaal in die kroonlaag gebruik word. Die spesifikasies maak nie voorsiening vir lateriet en gruis wat natuurlik voorkom nie. Verskeie veldstudies in die verlede het duidelik getoon dat lateritiese materiaal met sukses gebruik kan word in die kroonlae van paaie wat ligte tot medium verkeer dra. Lateriete kan gebruik word sonder addidionele onkoste vir instandhouding en daar is merkbare kostebesparings wanneer plaveisels rehabiliteer word. Die verhouding tussen lateriet eienskappe, verkeerslas, omgewingsinvloede en plaveisel werkverrigting moet beter gedefinieer word deur verdere navorsing. In hierdie studie is omvattend gebruik gemaak van eenmalige en herhaalde belasting drie-assige toetse om die fundamentele gedrag van lateritiese materiaal te definieer. Hierdie toetse se resultate lewer inligting oor die skuifsterkte, spanning-vervorming eienskappe en gedrag onder herhaalde belasting. Die gruis wat gebruik is, is verkry vanaf 'n materiaalopslag by die leengroef van Malans Transport te Maaitjies Kuil naby Kaapstad. Die materiaal is getoets as granulêre materiaal en gestabiliseer met sement en skuim-bitumen. Die toetse is gedoen onder verskillende toestande van spanning, voginhoud en verdigting. Daar is bevind dat die veerkragtigheidmodulus van die lateritiese gruis nie net deur die aangewende spanning beïnvloed word nie, maar ook deur die voginhoud en verdigting van die materiaal. Welbekende modelle is gebruik om die spanningsafhanklike gedrag van die materiaal te karakteriseer. 'n Model is ook ontwikkel om die permanente vervorming van die materiaal te voorspel. Die twee modelle vir die veerkragtigheidsmodulus en permanente vervorming is gebruik om 'n ligte plaveiselstruktuur mee te ontwerp wat 'n lateritiese kroonlaag bevat.