Currently, ASHRAE has determined the zone method and modified zone method are appropriate calculation methods for materials with a high difference in conductivity, such as cold-formed steel (CFS) walls. Because there is currently no standard U-Factor calculation method for CFS walls, designers and code officials alike tend to resort to the zone method. However, the zone method is restricted to larger span assemblies because the zone factor coefficient is 2.0. This tends to overestimate the amount of surface area influenced by CFS. The modified zone method is restricted to C-shaped stud, clear wall assemblies with framing factors between 9 and 15%. The objective of the research is to narrow the gap of knowledge by re-examining the modified zone method in order to more accurately determine R-Values and U-Factors for CFS wall assemblies with whole wall framing factor percentages of 22% and above.

Utmattning av stålmaterial är ett fenomen som varit känt i närmare 190 år men trots det är det fortfarande långt ifrån helt utforskat. Utmattningsegenskaper hos grundmaterial och svetsar är idag relativt utforskat, medan områden som utmattningsegenskaper hos kallformade stålprofiler fortfarande mer eller mindre är outforskat. Med utforskningen av utmattningsegenskaper hos kallformade stålprofiler som huvudsyfte delades examensarbetet upp i två delar. En överliggande kranbomsoptimering med huvudmålet att sänka vikten så mycket som möjligt med hjälp av materialbyte till ett mer höghållfast stål och optimal användning av material med avseende på utmattning. Den andra delen av examensarbetet är en framtagning av en provkropp med huvudmålet att kunna testa utmattningsegenskaper för kallformade stålprofiler samt att ge dimensionerande värden till kranbomsoptimeringen. Provstavsframtagningen resulterade i tre versioner av provkroppar som i teorin ska ge utmattningsegenskaper i longitudinell riktning för kallformade stålprofiler. Eftersom provstavarna inte kunde prövas på grund av tidsbrist baserades kranbomsoptimeringen på teoretiska värden. Resultatet av kranbomsoptimeringen var att vikten kunde sänkas från 1027 kg till 435 kg utan att påverka andra beaktade kranegenskaper. / Even though fatigue in steel structures is a phenomenon that was discovered almost 190 years ago it is still far from fully explored. The fatigue properties of base materials and welded materials are currently relatively well known, but the fatigue properties of cold-formed steel profiles are still more or less unknown. With the investigation of fatigue properties of cold-formed steel profiles as the main purpose, this master thesis was divided into two parts. An overhead optimization of a crane with the main goal of reducing weight as much as possible with the help of upgrading materials to higher strength steels and using the materials in an optimal way with respect to fatigue. The second part of the master thesis is the development of a test specimen with the main goal of testing the fatigue properties of cold-formed steel profiles and to provide dimensioning values for the optimization of the crane. The development of test specimen resulted in three versions of specimens which in theory will provide fatigue properties in the longitudinal direction for cold-formed steel profiles. Since the test specimens could not be tested because of shortage of time, the optimization of the crane had to be based on theoretical values. The results of the optimization were that the weight could be lowered from 1027 kg to 435 kg without affecting any other consideration characteristics of the crane.

Les éléments séparatifs à base de plaques de plâtre (cloisons, bloc-porte…) sont d’abord destinés à délimiter les espaces à l’intérieur d’une construction. Ils contribuent aux exigences essentielles pesant sur l’ouvrage en termes de sécurité en cas d’incendie, d’isolation thermique et acoustique. La réglementation française stipule que la vérification de la résistance au feu des ces éléments doit être vérifiée par des essais en vraie grandeur menées selon des procédures normalisées et qui sont souvent onéreux pour les industriels. De plus, la limite du four (5 m de hauteur et 7 m de largeur actuellement) pose un problème pour les fabricants quand ils veulent valider des cloisons plus grandes. Par conséquent, la tendance industrielle est de développer une méthode prédictive du comportement au feu des éléments séparatifs. Cette thèse présente une étude dans le cadre du projet de recherche de EFECTIS France, ce qui conduit à l'élaboration d'un modèle numérique capable de prédire le comportement thermo-mécanique des cloisons en plaques de plâtre se composant d’une ossature métallique vissée sur des parements en plaques de plâtre, quand elles sont soumises à une action thermique normalisée de EN 1363-1 sur une face. Dans cette étude, on présente d’abord des programmes d’essais qui permettent d’une part, d’identifier les propriétés thermo-physiques et thermo-mécaniques de plaques de plâtre cartonné, à température ambiante et à haute température, et d’autre part de caractériser la liaison cinématique de la fixation par vissage des parements en plaques de plâtre sur les montants acier de l’ossature interne, à température ambiante. En suite, on présente le développement des modèles thermique et mécanique avec le logiciel CAST3M en utilisant les paramètres mesurés lors des programmes d’essais sur les matériaux et les assemblages. Les modèles développés permettent de prendre en compte : (i) les phénomènes de transfert thermique par conduction, rayonnement et convection au travers d’une cloison - (ii) la chute du parement exposé de la cloison pendant l’essai - (iii) le comportement mécanique de la cloison elle-même, c'est-à-dire le comportement thermo-mécanique de ses éléments constitutifs (plaques de plâtre cartonné et montants métalliques) ainsi que celui des assemblages vissés des plaques de parements sur les montants d’ossature. / The fire resistance of building elements (partition walls, door sets ...) by means of tests according to standard procedures is often expensive for manufacturers. In consequence, Efectis France is conducting a specific research project aiming to develop an efficient and economical tool in order to carry out the preliminary design of new products as well as their optimization and extend the application of experimental results to configurations different from those of the test (change of size, of component, of boundary conditions ...). This thesis presents a study in the scope of above research project, which led to the development of a numerical model capable of predicting the thermo-mechanical behavior of separating elements such as flexible partitions made with internal steel studs and plasterboard facings, when they are subjected to standard thermal action of EN 1363-1 on one side. This study is organized in three steps. The first one is an experimental investigation relative to the characterization of thermo-physical and of thermo-mechanical properties of plasterboards used in above mentioned partition walls. In the second step, a specific numerical model for the analysis of plasterboard partition fire behavior is developed. This model allows treating not only nonlinear heat transfer but also the nonlinear structural behavior of the partitions from thermal stresses taking into account the degradation of rigidities for the punctual screwing of plasterboards on the steel studs. In the third step, the prediction of the numerical model is compared with experimental results in terms of temperature and displacements of the partitions. The comparisons enable to show the validity of the numerical model to predict appropriately the fire behavior of plasterboard partitions.

No Brasil, o emprego de estruturas de aço constituídas por perfis formados a frio tem crescido consideravelmente, em virtude da ampla disponibilidade de laminados planos no mercado (chapas finas), bem como pela busca de soluções estruturais mais competitivas. Nesse cenário, pode-se destacar as estruturas mistas de aço e concreto destinadas aos edifícios habitacionais de pequeno porte, em que os tradicionais perfis laminados são substituídos por perfis formados a frio tanto nas vigas como nos pilares. Embora o sistema de vigas mistas possa ser considerado consolidado no campo dos perfis laminados e soldados, o comportamento estrutural no caso de perfis formados a frio necessita de investigação mais aprofundada, de modo a verificar os modos de ruína e a viabilidade do emprego dos modelos teóricos clássicos. Nesse trabalho foi desenvolvido um estudo teórico e experimental sobre as vigas mistas em perfis formados a frio duplo U enrijecido, focalizando a ligação mista (ligação viga-pilar) e consequentemente a resposta estrutural da região de momento fletor negativo. O programa experimental consistiu da análise de dois protótipos cruciformes para determinar a curva momento-rotação, o momento resistente, a rigidez, a capacidade de rotação e identificar modos de falha. Foi possível constatar maior capacidade de rotação da ligação com cantoneiras de assento e de alma quando comparada a uma ligação totalmente soldada. Comparando com o modelo experimental o método dos componentes avaliou de forma razoável a rigidez em serviço, já o método proposto por Leon et. al. superestimou muito esse parâmetro, a capacidade de rotação foi avaliada de forma satisfatória pelos dois métodos. O momento resistente negativo da viga mista obtido experimentalmente apresentou um valor intermediário entre os valores teóricos obtidos por processo plástico e elástico. / In Brazil, the cold-formed steel structures have been widely used justified by the large availability of steel sheets in the market (thin sheets) and the search for more competitive structural solutions. Thus as steel and concrete composite structures are applied in small constructions the traditional hot-rolled one is replaced by cold-formed members in the beams and columns. Even though the composite beams system is known in the hot-rolled and welded shapes field, the structural behavior of the cold-formed steel still needs more accurate investigation to verify the failure modes and the viability of the classic theoretical models. In this work a theoretical and experimental study about cold-formed steel and concrete composite beams was developed, focusing on the beam-to-column connection and the structural behavior on the region of hogging bending. For the experimental program two cruciform models of beam-column connections were analyzed to obtain the moment-rotation curves, the stiffness, and the rotation capacity. It was possible to verify the largest rotation capacity of the connection with the steel seat and web angle when compared with the totally welded connection. In the case of connection the method of the components estimates well the secant stiffness and the rotation capacity presenting a value closer to the ones obtained experimentally, Leon et al. procedures estimated well the initial stiffness and the rotation capacity, but the value of the secant stiffness is much larger than the experimental one. In the case of composite beam the ultimate strength (Mmax) experimentally obtained presented an intermediate value to the ones obtained by the plastic and elastic method.

Terças de aço formadas a frio são muito utilizadas em sistemas de cobertura e fechamento. Para conferir continuidade entre tramos adjacentes e possibilitar um melhor aproveitamento de material, são empregadas ligações parafusadas por transpasse e com luva. O comportamento estrutural dessas ligações é muito dependente da sua configuração geométrica e do nível de carregamento. Com base em uma série de nove experimentos e análises teóricas, o comportamento estrutural dessas ligações foi investigado no tocante aos esforços resistentes e à rigidez. Observou-se que o modo de falha tem sempre uma componente distorcional significativa e uma resistência menor que a prevista pela metodologia atual de projeto. No caso do momento fletor resistente, a distribuição de tensões de flexão oblíqua é a que melhor se aproxima do comportamento real das terças, sendo possível a partir de uma análise de estabilidade elástica considerando tal comportamento, e, baseado no método da resistência direta e na curva de dimensionamento do modo distorcional, obter uma previsão segura do momento fletor resistente. Além disso, a rigidez da ligação, com relação aos deslocamentos verticais é bastante dependente do tipo de ligação, sendo que as terças com ligações por luva são mais deformáveis que terças sem ligações. Por outro lado, terças com ligações por transpasse são menos deformáveis que terças fisicamente contínuas. As parcelas de rigidez da ligação são apresentadas, e a componente de deformação do furo é a mais significativa. Uma expressão para deduzir a rigidez rotacional da ligação é apresentada, juntamente com um modelo de barras para modelagem da ligação. Os resultados teóricos se ajustam muito bem aos experimentais. Conclui-se em linhas gerais, que as ligações por transpasse podem ser consideradas plenamente satisfatórias do ponto de vista de comportamento estrutural, sendo que terças com essas ligações são mais resistentes e rígidas que terças com continuidade física. O mesmo não ocorre nas terças com ligações por luva, porém, dada a limitação no número de ensaios, tais ligações carecem mais estudos. / Cold-formed steel purlins are widely used in roofs and wall systems. The continuity of long runs of cold-formed steel purlins is guaranteed by sleeve and overlap bolted connections, which allows a better load distribution and material savings. The structural behavior of these connections is highly dependent on their geometric configuration and load level. The strength and stiffness of these connections were determined through a series of nine experiments, numerical and analytical analysis. Results have shown that distortional buckling has a major contribution on the stability analysis of the cold-formed steel purlin. To safely determine the flexural strength of the purlin, one must consider unrestrained bending stress distribution and distortional buckling. The connection type influences the rigidity of the purlin thus the vertical displacement. Purlins with overlapped connections are stiffer than physically continuous ones, although purlins with sleeved connections are not. The bearing deformation at the connection region is responsible for a reduction in the system stiffness. To account for the change in stiffness and determine the vertical displacement, an expression for the bearing stiffness and a beam model are proposed. The results of this model show good agreement with experimental data. The general conclusion of this research is: overlapped bolted connections enhance the structural response of the purlins when compared to physically continuous ones. The same does not hold true for purlins with sleeved connections.

Atualmente, os perfis de chapa dobrada têm encontrado intensa aplicação como elementos estruturais nas construções em aço e como consequência, estão sujeitos aos mais diversos tipos de carregamentos. Este trabalho apresenta os aspectos gerais do dimensionamento de perfis de chapa dobrada submetidos à flexão enquanto utilizados como vigas propriamente dito e, também, enquanto utilizados como terças. Analisam-se seções tipo U, tipo U enrijecido e tipo Z enrijecido. Os ensaios em perfis fletidos foram realizados sobre 3 diferentes condições de carregamento, com dois vãos distintos, em um total de sessenta e quatro perfis ensaiados. Para os perfis conectados às telhas de aço, os ensaios foram realizados em uma \"caixa de sucção\" desenvolvida especificamente para este projeto. Os perfis foram conectados às telhas pela mesa por meio de parafusos auto-brocantes, sendo realizados quinze ensaios. Os resultados dos ensaios são comparados com os resultados teóricos, resultados normatizados e resultados de alguns procedimentos aproximados. / Nowadays, the cold-formed steel members have intense application as structural elements in constructions and, in consequence, they are subjected to several types of loads. This work presents the general aspects of the study of cold-formed steel members subjected to flexion used as beams and, also, as purlins. Sections of type U, type C and type Z are analysed. The tests in beams were carried out under three different conditions of loads, with two distinct spans, in total of sixty four tests. For the purlins connected to roof system, the tests were in a \"suction box\", developed especially for this project. The purlins were connected to the roof system by the flange by using self-drilling screws, being carried out fifteen tests. The results of those tests are compared with the theoretical results, design specification provisions and results of some approximated procedures.

No Brasil, o emprego de estruturas de aço constituídas por perfis formados a frio tem crescido consideravelmente, em virtude da ampla disponibilidade de laminados planos no mercado (chapas finas), bem como pela busca de soluções estruturais mais competitivas. Nesse cenário, pode-se destacar as estruturas mistas de aço e concreto destinadas aos edifícios habitacionais de pequeno porte, em que os tradicionais perfis laminados são substituídos por perfis formados a frio tanto nas vigas como nos pilares. Embora o sistema de vigas mistas possa ser considerado consolidado no campo dos perfis laminados e soldados, o comportamento estrutural no caso de perfis formados a frio necessita de investigação mais aprofundada, de modo a verificar os modos de ruína e a viabilidade do emprego dos modelos teóricos clássicos. Nesse trabalho foi desenvolvido um estudo teórico e experimental sobre as vigas mistas em perfis formados a frio duplo U enrijecido, focalizando a ligação mista (ligação viga-pilar) e consequentemente a resposta estrutural da região de momento fletor negativo. O programa experimental consistiu da análise de dois protótipos cruciformes para determinar a curva momento-rotação, o momento resistente, a rigidez, a capacidade de rotação e identificar modos de falha. Foi possível constatar maior capacidade de rotação da ligação com cantoneiras de assento e de alma quando comparada a uma ligação totalmente soldada. Comparando com o modelo experimental o método dos componentes avaliou de forma razoável a rigidez em serviço, já o método proposto por Leon et. al. superestimou muito esse parâmetro, a capacidade de rotação foi avaliada de forma satisfatória pelos dois métodos. O momento resistente negativo da viga mista obtido experimentalmente apresentou um valor intermediário entre os valores teóricos obtidos por processo plástico e elástico. / In Brazil, the cold-formed steel structures have been widely used justified by the large availability of steel sheets in the market (thin sheets) and the search for more competitive structural solutions. Thus as steel and concrete composite structures are applied in small constructions the traditional hot-rolled one is replaced by cold-formed members in the beams and columns. Even though the composite beams system is known in the hot-rolled and welded shapes field, the structural behavior of the cold-formed steel still needs more accurate investigation to verify the failure modes and the viability of the classic theoretical models. In this work a theoretical and experimental study about cold-formed steel and concrete composite beams was developed, focusing on the beam-to-column connection and the structural behavior on the region of hogging bending. For the experimental program two cruciform models of beam-column connections were analyzed to obtain the moment-rotation curves, the stiffness, and the rotation capacity. It was possible to verify the largest rotation capacity of the connection with the steel seat and web angle when compared with the totally welded connection. In the case of connection the method of the components estimates well the secant stiffness and the rotation capacity presenting a value closer to the ones obtained experimentally, Leon et al. procedures estimated well the initial stiffness and the rotation capacity, but the value of the secant stiffness is much larger than the experimental one. In the case of composite beam the ultimate strength (Mmax) experimentally obtained presented an intermediate value to the ones obtained by the plastic and elastic method.

Cold-Formed Steel (CFS) is a material used in the fabrication of structural and non-structural elements for the construction of commercial and residential buildings. CFS exhibits several advantages over other construction materials such as wood, concrete and hot-rolled steel (structural steel). The outstanding advantages of CFS are its lower overall cost and non-combustibility. The steel industry has promoted CFS in recent decades, causing a notable increase in the usage of CFS in building construction. Yet, structural steel elements are still more highly preferred, due to the complex analysis and design procedures associated with CFS members. In addition, the seismic performance of CFS buildings and their elements is not well known. The primary objective of this study is to develop a method for the seismic assessment of the lateral-load resistant shear wall panel elements of CFS buildings. The Performance-Based Design (PBD) philosophy is adopted as the basis for conducting the seismic assessment of low- and mid-rise CFS buildings, having from one to seven storeys. Seismic standards have been developed to guide the design of buildings such that they do not collapse when subjected to specified design earthquakes. PBD provides the designer with options to choose the performance objectives to be satisfied by a building to achieve a satisfactory design. A performance objective involves the combination of an earthquake (i.e., seismic hazard) and a performance level (i.e., limit state) expected for the structure. The building capacity related to each performance level is compared with the demand imposed by the earthquake. If the earthquake demand is less than the building capacity, the structure is appropriately designed. The seismic performance of a CFS building is obtained using pushover analysis, a nonlinear method of seismic analysis. This study proposes a Simplified Finite Element Analysis (SFEA) method to carry out the nonlinear structural analysis. In this study, lateral drifts associated with four performance levels are employed as acceptance criteria for the PBD assessment of CFS buildings. The lateral drifts are determined from experimental data. In CFS buildings, one of the primary load-resistant elements is Shear Wall Panel (SWP). The SWP is constructed with vertically spaced and aligned C-shape CFS studs. The ends of the studs are screwed to the top and bottom tracks, and structural sheathing is installed on one or both sides of the wall. For the analysis of CFS buildings, Conventional Finite Element Analysis (CFEA) is typically adopted. However, CFEA is time consuming because of the large number of shell and frame elements required to model the SWP sheathing and studs. The SFEA proposed in this study consists of modeling each SWP in the building with an equivalent shell element of the same dimensions; that is, a complete SWP is modeled by a 16-node shell element. Thus, significantly fewer elements are required to model a building for SFEA compared to that required for CFEA, saving both time and resources. A model for the stiffness degradation of a SWP is developed as a function of the lateral strength of the SWP. The model characterizes the nonlinear behaviour of SWP under lateral loading, such that a realistic response of the building is achieved by the pushover analysis. The lateral strength of a SWP must be known before its seismic performance can be assessed. In current practice, the lateral strength of a SWP is primarily determined by experimental tests due to the lack of applicable analytical methods. In this investigation, an analytical method is developed for determining the ultimate lateral strength of SWP, and associated lateral displacement. The method takes into account the various factors that affect the behaviour and the strength of SWP, such as material properties, geometrical dimensions, and construction details. To illustrate the effectiveness and practical application of the proposed methodology for carrying out the PBD assessment of CFS buildings, several examples are presented. The responses predicted by the SFEA are compared with responses determined experimentally for isolated SWP. In addition, two building models are analyzed by SFEA, and the results are compared with those found by SAP2000 (2006). Lastly, the PBD assessment of two buildings is conducted using SFEA and pushover analysis accounting for the nonlinear behaviour of the SWP, to demonstrate the practicality of the proposed technology.

Cold-Formed Steel (CFS) is a material used in the fabrication of structural and non-structural elements for the construction of commercial and residential buildings. CFS exhibits several advantages over other construction materials such as wood, concrete and hot-rolled steel (structural steel). The outstanding advantages of CFS are its lower overall cost and non-combustibility. The steel industry has promoted CFS in recent decades, causing a notable increase in the usage of CFS in building construction. Yet, structural steel elements are still more highly preferred, due to the complex analysis and design procedures associated with CFS members. In addition, the seismic performance of CFS buildings and their elements is not well known. The primary objective of this study is to develop a method for the seismic assessment of the lateral-load resistant shear wall panel elements of CFS buildings. The Performance-Based Design (PBD) philosophy is adopted as the basis for conducting the seismic assessment of low- and mid-rise CFS buildings, having from one to seven storeys. Seismic standards have been developed to guide the design of buildings such that they do not collapse when subjected to specified design earthquakes. PBD provides the designer with options to choose the performance objectives to be satisfied by a building to achieve a satisfactory design. A performance objective involves the combination of an earthquake (i.e., seismic hazard) and a performance level (i.e., limit state) expected for the structure. The building capacity related to each performance level is compared with the demand imposed by the earthquake. If the earthquake demand is less than the building capacity, the structure is appropriately designed. The seismic performance of a CFS building is obtained using pushover analysis, a nonlinear method of seismic analysis. This study proposes a Simplified Finite Element Analysis (SFEA) method to carry out the nonlinear structural analysis. In this study, lateral drifts associated with four performance levels are employed as acceptance criteria for the PBD assessment of CFS buildings. The lateral drifts are determined from experimental data. In CFS buildings, one of the primary load-resistant elements is Shear Wall Panel (SWP). The SWP is constructed with vertically spaced and aligned C-shape CFS studs. The ends of the studs are screwed to the top and bottom tracks, and structural sheathing is installed on one or both sides of the wall. For the analysis of CFS buildings, Conventional Finite Element Analysis (CFEA) is typically adopted. However, CFEA is time consuming because of the large number of shell and frame elements required to model the SWP sheathing and studs. The SFEA proposed in this study consists of modeling each SWP in the building with an equivalent shell element of the same dimensions; that is, a complete SWP is modeled by a 16-node shell element. Thus, significantly fewer elements are required to model a building for SFEA compared to that required for CFEA, saving both time and resources. A model for the stiffness degradation of a SWP is developed as a function of the lateral strength of the SWP. The model characterizes the nonlinear behaviour of SWP under lateral loading, such that a realistic response of the building is achieved by the pushover analysis. The lateral strength of a SWP must be known before its seismic performance can be assessed. In current practice, the lateral strength of a SWP is primarily determined by experimental tests due to the lack of applicable analytical methods. In this investigation, an analytical method is developed for determining the ultimate lateral strength of SWP, and associated lateral displacement. The method takes into account the various factors that affect the behaviour and the strength of SWP, such as material properties, geometrical dimensions, and construction details. To illustrate the effectiveness and practical application of the proposed methodology for carrying out the PBD assessment of CFS buildings, several examples are presented. The responses predicted by the SFEA are compared with responses determined experimentally for isolated SWP. In addition, two building models are analyzed by SFEA, and the results are compared with those found by SAP2000 (2006). Lastly, the PBD assessment of two buildings is conducted using SFEA and pushover analysis accounting for the nonlinear behaviour of the SWP, to demonstrate the practicality of the proposed technology.

Lapped joints of cold-formed steel (CFS) Z-shaped purlins are extensively used in metal building roof systems. The research that has been carried out so far for these lapped connections is primarily focused on connections with round holes. However, the lapped connections with vertical slotted holes are extensively used in current construction practice to simplify the erection of continuous Z-shaped roof purlins. There is no design guideline or recommendation available for CFS Z-purlin lapped connections with vertical slotted holes. Presented in this paper are the results of an experimental study and analysis of the structural behaviour of lapped CFS Z-shaped purlin connections with vertical slotted holes. 42 flexural tests were performed on lapped CFS Z-shaped purlins with vertical slotted connections with different lap lengths, purlin depths, thicknesses and spans. The flexural strength and deflection of each specimen were measured. The characteristics of moment resistance and flexure stiffness of the lapped purlins were computed. The test results show that the lapped purlins with vertical slotted holes may be more flexible than the lapped purlins with round holes or continuous purlins without lapped joint. Thus, the slotted connections may need greater lap lengths to achieve full stiffness of continuous purlins. The results also indicate that the characteristics of moment resistance and flexural stiffness in the slotted connections are dependent on the ratio of lap length to purlin depth, the ratio of lap length to purlin thickness, the ratio of purlin depth to purlin thickness, and the ratio of lap length to span. Based on the results, design recommendations for evaluating the moment resistance and flexural stiffness of lapped slotted connections were proposed.