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I rapporten undersöks om besparingar kan göras i projekteringsskedet av byggnadsverk. Undersökningen görs genom att sammanställa och analysera utnyttjandegraden av pelare i fyra stålhallar belägna i Örebroregionen. Syftet är att undersöka om besparingar går att göra och i sådant fall hur stora dessa är. Dimensioneringen har primärt genomförts i programmet Ramanalys, där varje pelare i de valda konstruktionerna har analyserats och dimensionerats enskilt. Laster som är beroende av ort, byggnadsutformning, placering med mera, har tagits fram med hjälp av Eurokod och tillhörande nationell bilaga, EKS. Laster på fackverk, installationer, tak- och väggkonstruktion har uppskattats då dessa dimensioneras av leverantörer. Uppskattningarna har gjorts med hjälp av leverantörernas snabbdimensioneringsprogram. Stommarna som har analyserats har varit av typen stålhallar. Optimeringen har begränsats till att gälla dessa stålhallars stompelare. Resultatet av denna undersökning visar att besparingar går att göra. I de fall som detta arbete har undersökt ligger de ekonomiska besparingarna på mellan 10-24%. Denna besparing ligger enbart på materialkostnadsdelen, vilket tydligt skall understrykas. Besparingen är alltså enbart på stålvikten och ingen hänsyn till övriga eventuellt uppkommande kostnader för transport, montering, extra nedlagd konstruktörstid osv. Genom att räkna för en högre utnyttjandegrad av ingående element kan man göra besparingar av material. I detta fall handlar det om stålvikt som kan reduceras genom att välja mer optimerade, dvs. slanka dimensioner. Utnyttjandegraderna i denna jämförelse hamnar då, på vissa element uppemot 98-99%. Slutsatsen av denna studie är att man kan räkna mer optimerat och på så sätt reducera materialvikter och sänka kostnaden där av. / This report investigates if there are savings to be made during the phase of construction planning. The study will be carried out through compiling and analyzing the capacity level of columns in four steel constructions situated in the region around Örebro. The Purpose is to study if there are savings to be made, and if so, how big these savings are. The design has mainly been carried out using the software Ramanalys, where every column in the construction has been analyzed and designed. Loads that are dependent on location, building design, topography etc have been calculated with the help of Eurocode and the associated national annex, EKS. Loads from trusses, installations, roofs and walls have been estimated as these are designed by suppliers. The estimations have been made using the quick-designing programs provided by the suppliers’ websites. The frames that have been analyzed are of the type steel constructions. The optimization has been limited to the columns in the frame of these constructions. The result of this study shows that savings can be made. In the constructions we have studied, the financial savings are between 10-24 %. These savings refer solely to the material cost of the component, which must be clearly emphasized. The savings are thus only on kilograms of steel and no account is taken for other possible incurred costs such as transport, assembly, extra time for the constructor etc. By calculating for a higher degree of utilization of the frame columns, one can save material that otherwise would have to be paid for. In this case steel weight that can be reduced by choosing slimmer and more optimized dimensions. The capacity levels in this comparison is on some elements utilized around 98-99 %. The conclusion of this study is that one can do more optimized designs and thus reduce material weights and lower the cost thereof.

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M.Ing. (Civil Engineering) / The purpose of this investigation was to develop the basic information necessary for formulating creteria for the design of Type 3CR12 steel hot-rolled sections as columns. The mechanical properties needed for structural design are established. Investigations into the behaviour of axially loaded compression members indicated that the overall column buckling of compression members may be predicted with confidence by the tangent modulus approach. Finally simplified design recommendations are made for the design of Type 3CR12 steel hot-rolled columns. The need for future research are identified.

Abstract This thesis has been made within the European Industrial Doctorate (EID) project called Mathematics and Materials Science for Steel Production and Manufacturing, abbreviated as MIMESIS, which has five partners: EFD Induction in Norway; SSAB, Outokumpu, and the University of Oulu in Finland; and Weierstrass Institute for Applied Analysis and Stochastics (WIAS) in Germany. The main aim of this work was to develop a steel composition and processing route suitable for making a slurry transportation pipeline with the aid of induction hardening, and to characterize the phase transformations and microstructures involved in the various stages of the processing route. A novel steel chemistry was designed based on metallurgical principles assisted by computational thermodynamics and kinetics. The designed composition is a medium-carbon, low-alloy steel microalloyed with niobium, in wt.% 0.40 C, 0.20 Si, 0.25 Mn, 0.50 Mo, 0.90 Cr, and 0.012 Nb. This was subsequently cast, thermomechanically rolled on a laboratory rolling mill to two bainitic microstructures, and finally subjected to the thermal cycles predicted to be encountered with the internal induction hardening of a typical pipe geometry. The phase transformations and microstructures found at various stages of the simulated production process have been characterized and algorithms developed to enable the optimization of microstructure and hardness through the pipe wall thickness. / Tiivistelmä Tämä väitöskirja on tehty osana Euroopan teollisuustohtori (European Industrial Doctorate, EID) -ohjelmaa projektissa eli Matematiikka ja materiaalitiede teräksen valmistuksessa ja käytössä (Mathematics and Materials Science for Steel Production and Manufacturing, MIMESIS). Ohjelmassa on viisi partneria: EFD Induction Norjasta; SSAB, Outokumpu ja Oulun yliopisto Suomesta; ja Weierstrass Institute for Applied Analysis and Stochastics (WIAS) Saksasta. Työn päätavoitteina oli kehittää teräksen koostumusta ja prosessointireittiä, jotka soveltuvat lietteen kuljetusputken valmistukseen induktiokarkaisun avulla, sekä karakterisoida prosessin eri vaiheiden aikana tapahtuvat faasimuutokset ja mikrorakenteet. Uusi teräskoostumus suunniteltiin metallurgisten periaatteiden pohjalta hyödyntämällä laskennallista termodynamiikkaa ja kinetiikkaa. Suunniteltu teräs on niobilla mikroseostettu, matalaseosteinen ja keskihiilinen, eli painoprosentteina 0,40 C, 0,20 Si, 0,25 Mn, 0,50 Mo, 0,90 Cr ja 0,012 Nb. Teräs valettiin, valssattiin ja jäähdytettiin termomekaanisesti laboratoriovalssaimella kahdeksi bainiittiseksi mikrorakenteeksi ja lopulta altistettiin lämpösykleille, joiden ennustettiin olevan tyypillisiä sisäisesti induktiokarkaistulle teräsputkelle. Simuloidun tuotantoprosessin eri vaiheissa havaitut faasimuutokset ja mikrorakenteet on karakterisoitu. Sen lisäksi on kehitetty algoritmit, jotka mahdollistavat mikrorakenteen ja kovuuden optimoinnin putken seinämän paksuuden läpi.

no / The behaviour of circular concrete-filled steel tubes (CFT) with various concrete strengths under axial load is presented. The effects of steel tube thickness, the bond strength between the concrete and the steel tube, and the confinement of concrete are examined. Measured column strengths are compared with the values predicted by Eurocode 4, Australian Standards and American Codes. 15 specimens were tested with 30, 60 and 100 N/mm2 concrete strength, with a D/t ratio from 22.9 to 30.5. All the columns were 114 mm in diameter and 300 mm in length. The effect due to concrete shrinkage is critical for high-strength concrete and negligible for normal strength concrete. All three codes predicted lower values than that measured during the experiments. Eurocode 4 gives the best estimation for both CFT with normal and high-strength concrete.

Developing a rational method of design has long been the goal of structural engineering. For steel structures, through the development of plastic design and electronic computation, this now seems possible. Several methods have been proposed within the last five years, and one method has been programmed for the digital computer. Five methods are here discussed and compared and the method of Heyman and Prager is investigated in detail. The assumptions and restrictions of the Heyman-Prager method, along with the computer program developed by Kalker, are investigated and discussed. The author attempts to evaluate the usefulness of, and place the Heyman-Prager method in a proper perspective in the overall planning, design, analysis phases of the total structural evolution. It is concluded that a more efficient computer program could be developed to facilitate the structural solution and some methods by which this might be accomplished are suggested. A comprehensive bibliography is provided which traces the development of practical minimum weight, plastic design from its inception up to the present time. / Master of Science

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Lateral-torsional buckling (LTB) is an important failure mode that needs to be taken into account during the design of steel beams. The fundamental equation for determining the elastic critical moment of a beam was derived with the assumption that the beam is subjected to a uniform bending moment distribution. Loads on steel structures generate a great variety of bending moment distributions. The effect of the bending moment distribution is taken into account by a parameter known as the equivalent moment factor. The procedure outlined in the South African National Standard for limit-states design of hot-rolled steel work, SANS 10162-1:2011, for determining the equivalent moment factor was originally developed for a bending moment that is uniformly or linearly distributed, however it is currently used for all bending moment distributions. A Finite Element (FE) model was developed in this investigation for determining the equivalent moment factor. The numerical model included residual stresses and initial geometric imperfections commonly found in hot-rolled steel beams. To validate the assumptions made during the development of the FE model an in-depth experimental investigation was conducted on simply supported beams. Three different load configurations were considered in the experimental study in order to simulate various bending moment distributions. A comparison of the equivalent moment factor between the numerical results and the results obtained from various steel specifications, including SANS 10162-1:2011, was carried out in an attempt to quantify the positive and negative attributes of the various methods employed by steel design specifications. The experimental investigation concluded that the FE model is able to successfully represent a simply supported beam with realistic characteristics that include residual stresses and imperfections. The comparative study illustrated that for a bending moment distribution with a constant moment gradient, SANS 10162-1:2011 provides excellent results. However, for the other distributions considered in this investigation highly conservative results were obtained for the equivalent moment factor. The relevance of these findings were made clear by considering three design cases found in steel structures. The resistance moment of the beams in each of these cases was calculated according to each of the steel specifications. It was found that the use of a highly conservative procedure for determining the equivalent moment factor can lead to the uneconomical design of a structure. / AFRIKAANSE OPSOMMING: Laterale-torsie knik is ’n belangrike falings modus wat in ag geneem moet word tydens die ontwerp van staal balke. Die fundamentele vergelyking vir die bepaling van die elastiese kritieke moment van ’n balk is afgelei met die aanname dat die balk onderworpe is aan ’n eenvormige buigmoment verdeling. Belastings op staalstrukture genereer ’n groot verskeidenheid van buigmoment verdelings. Die effek van hierdie buigmoment verdelings word in ag geneem deur ’n parameter wat bekend staan as die ekwivalente moment faktor. Die prosedure uiteengesit in die Suid-Afrikaanse Nasionale Standaard vir die ontwerp van warm-gewalste staalwerk, SANS 10162-1:2011, vir die bepaling van hierdie faktor is oorspronklik ontwikkel vir ’n buigmoment wat uniform of linieêr verdeel is oor die lengte van die balk, maar dit word tans gebruik vir alle buigmoment verdelings. ’n Eindige Element (FE) model is ontwikkel in hierdie ondersoek vir die bepaling van die ekwivalente moment faktor. Die numeriese model sluit die residuele spannings en aanvanklike geometriese imperfeksies wat in die algemeen teenwoordig is in warm-gewalste profiele in. Die aannames wat gemaak is tydens die ontwikkeling van die FE model is bevestig met ’n in diepte eksperimentele ondersoek oor die gedrag van eenvoudig opgelegde balke. Drie verskillende las konfigurasies is oorweeg in die eksperimentele studie om verskeie buigmoment verspreidings na te boots. ’n Vergelyking van die ekwivalente moment faktor tussen die numeriese resultate en die resultate verkry van verskeie staal spesifikasies, insluitend SANS 10162-1:2011, is uitgevoer in ’n poging om die positiewe en negatiewe eienskappe van die verskillende metodes wat gebruik word in verskillende staal ontwerp spesifikasies, te kwantifiseer. Die eksperimentele ondersoek het tot die gevolgtrekking gelei dat die FE model in staat is om ’n eenvoudige opgelegte balk te verteenwoordig, met realistiese eienskappe wat residuele spannings en imperfekies insluit. Die vergelykende studie toon dat SANS 10162-1:2011 uitstekende resultate bied vir ’n buigmoment verdeling met ’n konstante moment gradiënt. Dit was egter gevind dat vir ander verdelings wat in hierdie ondersoek oorweeg is, SANS 10162-1:2011 hoogs konserwatiewe resultate bied. Die toepaslikheid van hierdie bevindinge is duidelik gemaak deur drie ontwerp gevalle wat algemeen in staalstrukture gevind word te bestudeer. Die weerstandsmoment is in elk van die gevalle bereken volgens elke staal spesifikasies. Daar is gevind dat die gebruik van ’n hoogs konserwatiewe prosedure vir die bepaling van die ekwivalente moment faktor kan lei tot die ontwerp van ’n onekonomiese struktuur.