No / This paper presents a numerical modelling method to predict the shear behaviour of typical wall-stud cold-formed steel wall panels subjected to in-plane monotonic loads. In the research presented in this paper, different material and mechanical properties for cold-formed steel sheets, self-drilling screwed connectors and wall fixing boundary conditions were considered to explore the influence of sheath sheeting, connectors and fixing boundary conditions on the structural behaviour of selected wall panels. After the FE model being validated against experimental results, a parametric study was conducted and the comparison and analysis highlight the effect of different sheaths, connectors on to the structural shear behaviour of typical wall-stud cold-formed steel wall panels.

Koldioxidutsläppen i världen orsakar stora miljöförstöringar och byggbranschen står för en stor del av utsläppen. Samtidigt som utsläppen behöver minska finns ett behov av att bygga fler idrottshallar i Sverige. Utöver det behöver även kostnaderna hållas så låga som möjligt. Därför syftar denna studie till att klargöra hur stor skillnaden i pris och koldioxidutsläpp är beroende på val av pelare i ett verkligt fall. De pelare som undersökts och jämförts är varmformade konstruktionsrör (VKR), kallformade konstruktionsrör (KKR) och energisnåla kallformade konstruktionsrör (Zero KKR). För att genomföra studien dimensionerades pelare till en idrottshall enligt europeiska standarder, så kallade Eurokoder. Dimensioneringen utgick från stålleverantören Tibnors sortiment. Information om pris och koldioxidutsläpp för de dimensioner som togs fram samlades in från Tibnor och dess återförsäljare. En sammanställning av informationen gjordes i tabeller och diagram för jämförelse. Resultatet visar att det totala priset för pelare till idrottshallen är 20,7% lägre vid val av KKR istället för VKR. Jämförelsen visar även att det går att göra en utsläppsbesparing på 8,7% genom att, genomgående, välja KKR istället för VKR till pelare för den idrottshall som undersökts. Med Zero KKR skulle det vara möjligt att minska koldioxidutsläppen pelarna till idrottshallen orsakar med ytterligare 66,8% och slutsatsen kan dras att användning av Zero KKR alltid skulle bidra till en markant minskning av koldioxidutsläppet. / Carbon dioxide emissions worldwide cause significant environmental damage and the construction industry is responsible for many of these emissions. At the same time that emissions need to be reduced, there is a need to build more sports halls in Sweden. In addition, costs also need to be kept down. Therefore, this study aims to clarify how big the difference in price and carbon dioxide emissions is depending on the choice of columns in a real case. The colums that has been investigated and compared is Hot-Formed Hollow Sections, Cold-Formed Hollow Sections and the energy efficient Zero Cold-Formed Hollow Sections. To do the investigation, columns for a sports hall were dimensioned according to European standards, so-called Eurocodes. Dimensioning was based on the steel supplier Tibnor's range. Data regarding price and carbon dioxide emissions for the dimensions produced were collected from Tibnor and its dealers. A compilation was made in tables and charts for comparison. The result shows that the total price for the columns to the sportshall is 20,7% lower for Cold-Formed Hollow Sections than Hot-Formed Hollow Sections. The comparison also shows that it is possible to save 8.7% on emissons by consistently choosing Cold-Formed Hollow Section instead of Hot-Formed Hollow Sections as pillars for the investigated sports hall. With Zero Cold-Formed Hollow Sections, it would be possible to reduce the carbon dioxide emissions for the columns of the sports hall by a further 66.8% and the conclusion can be drawn that using Zero Cold-Formed Hollow Sections would always contribute to a significant reduction in carbon dioxide emissions.

Master of Science / Department of Architectural Engineering and Construction Science / Sutton F. Stephens / Cold‐formed steel has become a preferred building material for wall framing in many different types of structures. One of its main uses has been as non‐structural members in curtain wall assemblies of structural steel framed buildings. In an exterior wall application, the main purpose of the curtain wall is to transfer out of plane loads to the steel frame while not supporting any superimposed gravity loads. Therefore, when the curtain wall is in the plane of the structural steel frame, the vertical deflection of the spandrel beam directly above the wall must be known to provide the appropriate deflection gap between the beam and the curtain wall so that gravity loads are not transferred to the wall. Common practice is to size the gap for the deflection from 100% of the live load. In some cases, the deflection gap may be significant, and since this gap must also be provided in the exterior cladding of the wall, it creates a design issue for the architect. This report presents the results of an investigation into the feasibility of reducing the size of the deflection gap when the wall is located directly under the spandrel beam. In this study, analytical models were developed for common design situations of curtain walls constructed of cold‐formed steel studs in structural steel framed buildings. This study investigates two common stud heights combined with different floor live loads. Taking into account that wall studs have some available axial compressive strength, a procedure was developed to determine an appropriate reduction for the gap. Using an iterative process a relationship is made between the axial compressive strength of the stud and the amount of axial load the stud can support to establish a factor which gives the percentage the live load gap for 100% live load can be safely reduced by.

Master of Science / Department of Architectural Engineering and Construction Science / Sutton F. Stephens / Cold-formed steel has become a preferred building material for structural farming in many different types of structures, commonly for repetitive members such as floor joists, roof rafters, roof trusses and wall studs. For wood framed structures with repetitive members, a repetitive member factor increases the allowable bending stress from 1.00 to 1.50 times the reference design value, depending on both the type of material and the type of load. Currently, however, the bending strength of cold-formed steel repetitive members is not permitted to be increased, even though the method of framing is quite similar to that of wood except for the material properties. Typical light-frame wood construction consists of floor, roof, and wall systems, each with repetitive members connected by sheathing. A repetitive system is one of at least three members that are spaced not farther apart than 24-inches. These members must also be joined by a load distributing element adequate to support the design load. The behavior of the individual members, then, is affected by inclusion into this system. Additionally, the connected sheathing increases the bending capacity of bending members due to both composite action and load sharing. Composite action is a result of T-beam-like action between the repetitive member and connected sheathing, but is limited by nail slippage in the connection. Secondly, due to differential deflection between the members, sheathing is also able to distribute loads from weaker, more flexible members to the more rigid and stronger members. This effect is known as load-sharing. The same general principles of repetitive use should apply to cold-formed steel due to its similarity to wood construction. Accordingly, this paper conducts a preliminary study of the effects of both composite action and load-sharing in cold-formed steel assemblies and subsequently recommends using a repetitive member factor for cold-formed steel members.

Master of Science / Department of Architectural Engineering and Construction Science / Kimberly Waggle Kramer / Cold-formed steel framing sheathed with wood structural panels is a common method of construction for wall, roof and floor systems in cold-formed steel structures. Since wood structural panels are attached with screws at relatively close spacing, a certain amount of composite behavior will be present. However, the benefit of composite behavior of this system is currently not being taken advantage of in the design of these structural systems. While composite effects are present, they are not yet being accounted for in design due to a lack of statistical data. To determine the amount of composite action taking place in these systems, the slip modulus between steel and wood is required. The slip modulus reflects the amount of shear force able to be transferred through the screw connection, to either member of the composite system. This thesis presents the results of a study conducted to determine values of the slip modulus for varying thicknesses of cold-formed steel and plywood sheathing. Push tests were conducted and the slip moduli were determined based on ISO 6891 and ASTM D1761. Compared with data from a previous preliminary study performed by others, the values determined from these tests for the slip modulus were deemed reasonable. The determination of the slip modulus will lead to the ability to calculate a composite factor. Determination of a composite factor will allow cold-formed steel wood structural panel construction to become more economical due to the available increase in bending strength.

Envolto ao já conhecido comportamento de cantoneiras esbeltas de abas iguais, questões aparentemente contraditórias tem sido reportadas em estudos experimentais de diversos autores, entre elas a ocorrência de modos de instabilidade em desacordo com aqueles obtidos via análise de estabilidade elástica, e forças axiais resistentes muito diferentes dos resultados teóricos (em geral, conservadoramente). Nestas condições, este trabalho procura analisar a fundo o comportamento das cantoneiras esbeltas de abas iguais, de modo a contribuir com o entendimento dos fenômenos que dificultam a interpretação dos resultados experimentais, dentre os quais, o afastamento longitudinal entre a rótula e a extremidade das barras (no caso de barras com extremidades rotuladas), e o sentido da imperfeição global de flexão em torno do eixo de menor inércia, o qual mostrou-se um fator chave na determinação do comportamento das cantoneiras, especialmente para comprimentos próximos da transição entre os dois modos globais de instabilidade elástica. Para esta faixa de comprimentos, diferentes níveis de interação entre os dois modos globais podem ser obtidos. Ademais, estudos experimentais realizados por diversos autores, aqui complementados por uma série de ensaios realizados em cantoneiras com extremidades engastadas, formam um vasto banco de resultados, que é utilizado para (além de comparações nos estudos teóricos) avaliar diversos procedimentos de previsão teórica sugeridos por diferentes autores, ou advindos de interpretações a partir do procedimento normativo, à luz do comportamento teórico estudado na primeira etapa do trabalho. Assim, destes procedimentos, apenas um baseado no Método da Resistência Direta, e dois baseados no Método das Larguras Efetivas demonstraram bons resultados, sendo que todos eles, desconsiderando o modo de flexo-torção como um modo global de instabilidade. Ao fim, comenta-se da necessidade de se expandir alguns estudos específicos, pois ao adotar-se um procedimento baseado somente no modo global de flexão, apesar de se mostrar estatisticamente mais eficiente, verifica-se a possível ocorrência de resultados demasiadamente contra a segurança. / On the well known behavior of equal-leg angle columns, some questions apparently paradoxical have been reported in experimental results from several authors, including the occurrence of different instability modes from the expected by the elastic stability analysis, and maximum axial compressive load expressly different (generally conservative) from theoretical previsions. Therefore, the aim of this work is to improve the knowledge about the equal-leg angle columns behavior, contributing to the understanding of the features that complicate the interpretation of experimental results, among which, the longitudinal distance between the end sections and the center of hinges (pin-ended columns), and also the direction of the minor-axis flexural initial imperfection, which proved to play a key role in the post-critical column behavior, specially for column lengths near of the transition between global buckling modes (major-axis flexural-torsional and minor-axis flexural modes). On this range of lengths, different modal interaction amplitudes can be obtained, only with the direction of the minor-axis flexural initial imperfection (i.e., the amplitude of this imperfection plays a negligible influence on the column behavior). Furthermore, putting together a fairly large column ultimate strength data bank comprising experimental test results performed by several authors, collected from the available literature, and new experimental results on fixed-ended angle columns performed in this work, important comparisons with theoretical studies can be showed as well as evaluation of several ultimate strength theoretical prevision procedures, either those suggested by another authors as those arising from interpretations of normative procedures in the light of theoretical behavior verified in the first stage of labor. In conclusion, only one procedure based on Direct Strength Method and two procedures based on Effective Width Method exhibited accurate results, all of which neglecting the flexural-torsional mode as a global mode. Thus, it is important to mention that some additional studies are needed, because if adopted a procedure based only in the minor-axis flexural mode, despite being statistically advantageous, it is verified the possibility to occurs quite unconservative results.

A utilização de perfis formados a frio na construção metálica no Brasil vem crescendo de forma significativa. Dentro deste mesmo contexto, atenções especiais estão sendo direcionadas às ligações utilizadas neste tipo de perfil, pelo fato de as chapas que as constituem resultarem cada vez mais esbeltas em função da significativa redução na sua espessura (elevada relação largura/espessura). Por esta razão, as ligações em perfis formados a frio têm sido estudadas por pesquisadores, tanto no contexto mundial como no Brasil. Neste sentido, o presente trabalho tem por objetivo realizar estudos relacionados às ligações parafusadas em perfis formados a frio, com vistas a avaliar a resistência e o comportamento destas ligações por meio de modelagem numérica, simulando o comportamento estrutural com a utilização do código de cálculo ANSYS v.6.0, elaborado com base nos Métodos dos Elementos Finitos (MEF). No sentido de avaliar a eficiência e a confiabilidade dos modelos elaborados, os resultados numéricos obtidos foram comparados com resultados experimentais obtidos em ensaios, bem como, comparados com resultados numéricos obtidos utilizando-se outros padrões de modelagem. / The use of cold-formed steel members in the steel building in Brazil comes growing of significant form. Inside of the same context, special attentions are being directed to the connections used in the cold-formed steel members, or the fact of the sheets used to this kind of steel members result each time more thin. For this reason the connections in cold-formed steel members have been studied for researchers, as much in the worldwide context as in Brazil. The objective of this work is studies the bolted connections in cold-formed steel member to evaluate the resistance and the behavior of these connections by means of numerical modeling, simulating the structural behavior with the use of the code of calculation ANSYS v.6.0, elaborated based on Finite Element Methods. With the objective to evaluate the efficiency and the trustworthiness of the elaborated model, the numerical results where compare with experimental results gotten in assays, as well as, compared with numerical results gotten using other standards of modeling.

O emprego de parafusos auto-atarraxantes em ligações metálicas, nos últimos anos, têm aumentado de forma significativa, principalmente como dispositivo de ligação entre componentes leves da construção metálica, como por exemplo, nas ligações entre telhas metálicas e terças. Tais ligações apresentam modos de falha diferentes dos observados para as ligações parafusadas convencionais, em função do tipo de parafuso e das reduzidas espessuras dos elementos conectados, definidos como \"pull-out\" e \"pull-over\". No Brasil, a carência de estudos específicos nesse tema foi uma das razões da omissão da recente norma brasileira de dimensionamento de estruturas de aço constituídas por perfis formados a frio - NBR 14762:2001, quanto a procedimentos específicos para o projeto de ligações com parafusos auto-atarraxantes. Nesse trabalho foi desenvolvido um estudo abrangente sobre as ligações metálicas com parafusos auto-atarraxantes, com ênfase na ligação telha-terça, onde são apresentados os procedimentos e as recomendações das principais normas estrangeiras, bem como os ensaios padronizados para caracterização dos parafusos e avaliação do comportamento estrutural e resistência de ligações. São apresentados também os resultados de uma investigação experimental, com base no ensaio padrão do AISI (1996) (American Iron and Steel Institute), em 27 corpos-de-prova com variação no diâmetro do parafuso e espessura dos componentes da ligação (terça e telha), com o objetivo principal de avaliar as expressões das AISI (2001b e 1996) para dimensionamento. Como conclusão, são relatadas as dificuldades associadas ao ensaio padrão, que apesar de sua concepção simples, conduz à elevada variabilidade nos resultados, indicando a necessidade da adoção de ensaios mais representativos e confiáveis. / The use of screws in steel connections has increased significantly in recent years, mainly as connecting devices between light-gage components in steel construction, as, for example, in joints between metal roofing and purlins. These connections exhibit different failure modes from those displayed by conventional bolted connections, due to the type of fastener and the reduced thicknesses of the connected elements, defined as pull-out and pull-over. In Brazil, the lack of specific studies of this theme was one of the reasons for the omission of specific procedures for the design of screw connections from the new edition of the brazilian code for cold-formed steel members - NBR 14762:2001. The work reported here involved a comprehensive study of steel connections using screws, with emphasis on the sheating-purlin connection. A presentation is made of the procedures and recommendations of the main foreign codes, as well as of standardized tests for characterizing screws and evaluating the structural behavior and strength of connections. Also presented are the results of an experimental investigation based on the standard test of the AISI (1996) (American Iron and Steel Institute) applied to 27 test specimens with varying screw diameters and connector component thicknesses (purlin and sheeting), whose main purpose was to evaluate the AISI\'s design equations (2001b e 1996). To conclude, a report is made of the difficulties associated with the standard test, which, despite its simple conception, leads to considerably variable results, indicating the need for the adoption of more representative and reliable tests.

Com a publicação das normas NBR 14323:1999 Dimensionamento de estruturas de aço de edifícios em situação de incêndio e NBR 14432:2000 Exigências de resistência ao fogo de elementos construtivos de edificações, despertou-se, ainda mais, a preocupação com o dimensionamento das estruturas em caso de incêndio. Quando o aço é exposto a altas temperaturas apresenta reduções na resistência ao escoamento e no módulo de elasticidade. Em função dessas reduções, a NBR 14432:2000 apresenta tempos requeridos de resistência ao fogo, com os quais, pode-se optar pelo dimensionamento da estrutura, apresentado na NBR 14323:1999, ou pelo revestimento térmico. No entanto, essa última norma não permite a utilização do método simplificado de dimensionamento para perfis formados a frio. Quanto aos revestimentos térmicos, o mais utilizado no Brasil é a argamassa projetada, não adequada aos perfis formados a frio. O presente trabalho faz um breve histórico sobre estruturas de aço em situação de incêndio, sobre perfis formados a frio em temperatura ambiente e em situação de incêndio, além de apresentar tipos de revestimentos térmicos e suas aplicações. Finalmente sugere uma possível maneira de dimensionamento por meio da NBR 14762:2001 Dimensionamento de estruturas de aço constituídas por perfis formados a frio com adaptações para situação de incêndio e de proteção desses perfis em situação de incêndio. / The interest in design of steel structures in fire situation carried out in consequence of publication of Brazilians codes ABNT/NBR 14323:1999 named \"Steel structures fire design - Procedure\" and ABNT/NBR 14432:2000 \"Fire-resistance requirements for building construction elements - Procedure\". When the steel is exposed to elevated temperatures (for example, fire situation) reductions in the strength and deformation properties must be considered. In this sense, the code ABNT/NBR 14432:2000 prescribes values of parameter TRRF (Fire strength required time), with are used for design of steel structures using a simplified method prescribed in ABNT/NBR 14323:1999, or specifying fireproofing. However, this last code doesn\'t prescribe a simplified method for cold-formed steel in fire condition, and the fireproofing materials largely used in Brazil are the sprays, which are not appropriate to cold-formed profiles. In this sense, the main goal of the present work is show a brief context about steel structures in fire conditions, in special cold-formed profiles in room temperature and fire situation, and many types of fire protection materials used in steel structures and its applications. Finally, is suggested a design method to cold-formed profiles in fire, adopting the code ABNT/NBR 14762:2001 \"Design of cold-formed steel structures\", in which appropriate adaptations are considered, as well as a protection procedure to this profiles in fire conditions.

Aborda-se os principais aspectos da fundamentação teórica relativos ao dimensionamento de elementos em aço, constituídos por perfis de chapa dobrada, baseados nas prescrições das normas Americana e Canadense. A fundamentação teórica destina-se a justificar os procedimentos referentes ao dimensionamento de perfis de aço conformados a frio, em particular os elementos comprimidos e fletidos, além dos aspectos da flambagem local destes perfis. Aborda-se também uma análise dos métodos de projeto das estruturas metálicas formadas por estes perfis, apresentando-se algumas disposições e alguns aspectos interessantes e essenciais no desenvolvimento de um edifício industrial leve. Tendo em vista a grande utilização dos perfis conformados a frios em terças, desenvolveu-se uma sistemática de cálculo fornecendo os valores dos momentos admissíveis que poderão ser aplicados para um pré-dimensionamento. / An analysis of the theoretical basis for the design of cold-formed steel structural members, according to the American and Canadian Standards, is made. The theoretical background is used to justify the procedure to obtain the required geometry of the cold-formed steel structural members particularly the compression and flexural members, also to explain some aspects of the local buckling. Furthermore, an analysis of the design method of steel structures with these profiles is made. Some interesting and essential aspects are presented in what concerns to the development of a light industrial building. Having in mind the intensive use of cold-formed members in purlin structures, a procedure for systematic calculation was developed to determine the allowable bending moment values that can be used on a preliminary design.