Because conventional seismic force resisting systems rely on yielding of key structural members to limit seismic forces, structural damage is expected after a design-level earthquake. Repairing this damage can be very expensive, if it is possible at all. Researchers have been developing a new family of self-centring systems that avoid structural damage. One such system is a controlled rocking steel frame, which is the subject of this thesis. In a controlled rocking steel frame, the columns of a frame are permitted to uplift from the foundation, and the response is controlled by using a combination of post-tensioning and energy dissipation. Although previous studies have confirmed the viability of this system, they have also shown that rocking does not fully limit the peak seismic forces because of higher mode effects. If a structure is designed to account for these effects, it may be uneconomical, but if it is not designed to account for them, it may be unsafe. The purpose of this thesis is to develop recommendations for the design of controlled rocking steel frames, particularly with regard to higher mode effects. A theoretical framework for understanding higher mode effects is developed, and large-scale shake table testing is used to study the behaviour of a controlled rocking steel frame. Two mechanisms are proposed to mitigate the increase in structural forces due to higher mode effects, and these mechanisms are validated by shake table testing. Numerical modelling of controlled rocking steel frames is shown to become more reliable when higher mode mitigation mechanisms are used to limit the seismic response. In the final chapters, the thesis proposes and validates a new methodology for the limit states design of controlled rocking steel frames.

Because conventional seismic force resisting systems rely on yielding of key structural members to limit seismic forces, structural damage is expected after a design-level earthquake. Repairing this damage can be very expensive, if it is possible at all. Researchers have been developing a new family of self-centring systems that avoid structural damage. One such system is a controlled rocking steel frame, which is the subject of this thesis. In a controlled rocking steel frame, the columns of a frame are permitted to uplift from the foundation, and the response is controlled by using a combination of post-tensioning and energy dissipation. Although previous studies have confirmed the viability of this system, they have also shown that rocking does not fully limit the peak seismic forces because of higher mode effects. If a structure is designed to account for these effects, it may be uneconomical, but if it is not designed to account for them, it may be unsafe. The purpose of this thesis is to develop recommendations for the design of controlled rocking steel frames, particularly with regard to higher mode effects. A theoretical framework for understanding higher mode effects is developed, and large-scale shake table testing is used to study the behaviour of a controlled rocking steel frame. Two mechanisms are proposed to mitigate the increase in structural forces due to higher mode effects, and these mechanisms are validated by shake table testing. Numerical modelling of controlled rocking steel frames is shown to become more reliable when higher mode mitigation mechanisms are used to limit the seismic response. In the final chapters, the thesis proposes and validates a new methodology for the limit states design of controlled rocking steel frames.

The trends for analysis and design of steel frames are indicated in this dissertation. The current practice consists of applying the first-order elastic analysis with amplification factors or second-order elastic analysis in combination with the AISC-LRFD interaction equations. Determination of the effective length factors and individual member capacity checks are necessary to select adequate structural member sizes. The direct analysis method is a second-order elastic analysis approach that eliminates the determination of effective length factors from the current AlSC-LRFD method. Unsupported member length is used to calculate the axial strength of a member. Equivalent notional loads and/or modified stiffness are applied together with the external loads to account for the effects of initial out-of-plumbness and inelastic softening. For both AlSC-LRFD and direct analysis methods, a structure is analyzed as a whole, but the axial and flexural strength of each member is examined individually. Inelastic redistribution of internal forces in the structural system cannot be considered. As a result, determined member forces are not correct and more conservative member sizes will be obtained. Moreover, member-based approaches cannot predict structural behaviors such as failure mode and overstength factor. The advanced analysis method considered in this work is a second-order refined plastic hinge analysis in which both effective length factors and individual member capacity checks are not required. In addition, advanced analysis is a structure systembased analysis/design method that can overcome the difficulties of using member-based design approaches. Thus, advanced analysis is a state-of-the-art method for steel structure design. Several numerical examples are provided to show the design details of all three methods. The design requirements corresponding to each analysis approach are illustrated in these examples. The pros and cons of each method are discussed by comparing the design results. Advanced analysis is also a computer-based analysis and design procedure consistent with the features of performance-based design. Applying advanced analysis to performance-based fire resistance and seismic design are proposed. This dissertation shows advanced analysis is efficient in predicting the duration that structures could support load under elevated temperature and capable of determining the performance level of a structure subjected to seismic forces.

The improvement of curtain wall thermal performances and the optimisation of the issues connected with this technology can lead to a sensible reduction of the energy consumption of the building as well as to an increase level of occupant comfort and longer durability of the façade. The aim of this work is to improve the curtain wall technology especially as far as the connection between the glass and the frame is concerned, since it is the part that mainly affects the performances of the whole façade. This project focuses on the different aspects of the thermal performance of curtain wall systems in order to achieve a higher thermal performance, meeting the objectives of lowering energy demand, improving durability and enhancing indoor comfort. In order to develop new high performance curtain wall connections and to test their level of performance compared with the state of the art ones, two methods were deployed: a numerical and an experimental one. FEM analysis was performed with the software THERM (LBNL) analysing the profile of surface temperatures and the U-values of the details. In the FEM analysis, different materials and geometries were studied. The experimental characterisation of the thermal energy performance of the studied design options was performed by means of thermometric measurements in a climatic cell. The purpose of the experimental analysis was the verification of the effective improvement of the performance in the new details and the comparison with the simulation, aiming at the validation of the simulation model.

Utförandet av klimatdeklarationer för nya byggnader är ett nationellt initiativ i Sverige som syftar till att minska den bebyggda miljöns klimatpåverkan. Denna undersökning syftar till att utföra två klimatdeklarationer för ett LSS-boende för att jämföra dess ursprungliga betongstomme med ett alternativ i stål ur ett klimatperspektiv. Stomalternativens påverkan på byggnadsdelars värmegenomgångskoefficienter (U-värde) och beständighet undersöks också för att få en helhetsbild av stålstommens konsekvenser på byggnaden. Den alternativa stommen baseras på en konstruktion från ett komparativt projekt och anpassas för att uppfylla brandskydds- och ljudisoleringskraven för den undersökta byggnaden. I den nya stommen används stålregelväggar, fackverkstakstolar och en reducerad grundkonstruktion.De frågeställningar som besvaras under studien är; vilken av de undersökta stommarna medför minst klimatpåverkan enligt de utförda klimatdeklarationerna, vilken byggnadsdel medför störst klimatpåverkan i varje stomme och hur påverkas byggnadsdelars initiala värmegenomgångskoefficienter samt beständighet vid byte till stålstommen. En klimatdeklaration definieras som ett dokument som redovisar en byggnads klimatpåverkan fördelad på dess bruttoarea (kg CO2eq/m2 BTA) under hela dess livscykel. Dokumentet grundar sig i livscykelanalys-metoden och omfattar Byggnadsskedet (A1-4 inklusive spill i A5) till en början enligt Boverkets rekommendation. De deklarationer som studien baseras på utförs med Byggsektorns miljöberäkningsverktyg med hjälp av generisk klimatdata från verktygets databas. Mängdningen av byggnadens material baseras på en Revit modell och ritningar utgivna av Här! Malmö samt information från produkttillverkare. U-värdena för konstruktionerna beräknas huvudsakligen i Excel enligt metoden beskriven i en byggnadsfysikbok. För att besvara frågorna om beständighet utförs en litteraturstudie baserad på information från materialböcker, varudeklarationer samt “Peer-reviewed” vetenskapliga artiklar hämtade från “Libsearch”. Enligt resultatet från deklarationerna medför betongstommen en total klimatpåverkan på 371,55 kg CO2eq/m2 BTA medan stålstommen medför en påverkan på 193,14 kg CO2eq/m2 BTA vilket motsvarar ett reduktionstal på 48 procent. Från deklarationerna går det också att avläsa att grunden medför störst klimatpåverkan för stålkonstruktionen medan stommen har störst påverkan i betongkonstruktionen. Vid beräkning av värmegenomgångskoefficienten medför bytet till stålstomme en reduktion av värdet för vindsbjälklaget från 0,137 till 0,104 W/m2K medan plattan på mark är i princip oförändrad (0,073 till 0,074 W/m2K). U-värdet för stålregelväggen (0,148 W/m2K) hamnar mellan de beräknade värdena för betongväggen med förbättrad och standard isolering (0,134 respektive 0,198 W/m2K). Enligt resultatet från litteraturstudien kan betong anses vara ett underhållsfritt material med högre beständighet mot brand och fukt än trä och stål som oftast måste behandlas och skyddas.Vid jämförelse med referensvärden från Svenska Miljöinstitutet hamnar endast stålstommen klimatpåverkan under det angivna gränsvärdet för flerbostadshus (216 kg CO2eq/m2 BTA). Betongstommens relativt höga klimatpåverkan anses bero på att stommen används i ett envåningshus. Stålstommen anses vara bättre ur klimatperspektiv men faktorer som kortare underhållsintervall och livslängd innebär att reduktionstalet som beskrivs är förmodligen mindre över hela livscykeln. / The introduction of climate declarations aims at minimizing the building sector's climate impact but earlier studies compare building frames by using declarations from two different buildings. This study focuses on creating two climate declarations in order to compare the concrete frame of a residential building with an alternative steel frame on the same building from a climate perspective. The steel frames’ effect on different building components thermal transmittance (U-value) and on the building’s durability are also analysed. The climate declarations in this study span over the Manufacture and Construction Process stages of the building’s life-cycle and are created with the use of the Construction Sector’s Environmental Calculation Tool and its built-in database. U-values for building components were calculated with Excel and a literature study was used to determine different building materials durability. The results from the climate declarations show that the concrete frame leads to a climate impact of 371,55 kg CO2eq/m2 gross floor area while the steel frame leads to an impact of 193,14 kg CO2eq/m2 gross floor area which corresponds to a reduction of the building's climate impact by 48 percent with the steel frame. The concrete frame accounts for the biggest amount of the building’s total climate impact while the foundation has the highest impact with the steel frame. The results from the U-value calculations show a decrease in the roof’s U-value from 0,137 to 0,104 W/m2K with the steel frame while the foundations U-value remains virtually unchanged (0,073 to 0,074 W/m2K). The comparison of the U-value for steel and concrete outer walls was inconclusive. According to the results from the literary study concrete was proved to be more durable and have better resistance to fire and humidity when compared to wood and steel and was considered to need little to no maintenance during a building’s lifespan.

No description available.

As evoluções tecnológicas juntamente com o surgimento de novas necessidades dos usuários resultaram em diversos novos tipos de métodos construtivos. O conceito de industrialização das edificações vem evoluindo com velocidade, e estes novos sistemas construtivos surgiram como alternativa aos sistemas tradicionais buscando entre outros, melhor desempenho térmico, energético, lumínico, acústico e de sustentabilidade. Diante desta crescente demanda por inovação, a ABNT (Associação Brasileira de Normas Técnicas) passou a estudar um conjunto de normas para estabelecer critérios de desempenho ao validar os novos sistemas construtivos de edificações habitacionais. Isto se concretizou com a publicação da Norma de Desempenho (ABNT NBR 15575/2013), que estipula parâmetros para desempenho dessas construções e métodos detalhados de acordo com o desempenho desejado. Simultaneamente, as simulações computacionais evoluíram, permitindo menor custo de experimentação, são capazes de antecipar resultados antes somente possíveis após testes físicos com protótipos e também a encontrar alternativas de soluções também quanto à eficiência energética e ao conforto dos usuários. Entre alguns programas existentes para simulação de desempenho térmico, está o EnergyPlus, o qual foi utilizado para este estudo, tendo como principal objetivo avaliar o desempenho térmico de painéis de light steel frame pré-fabricados utilizados na fachada e nas vedações internas de um sistema construtivo modular composto por estrutura metálica, e piso e a laje de concreto. Para o desenvolvimento do estudo, foi utilizado como modelo base uma residência térrea, configurada por ambientes independentes, que virão a compor uma residência inteira onde serão inseridos os painéis de light steel frame pré-fabricados. As 16 tipologias de painéis foram estudadas em três diferentes cidades do Brasil, sendo elas situadas nas regiões Nordeste, Sudeste e Sul e em dias típicos de verão e inverno, utilizando os recursos de simulação computacional (EnergyPlus) possibilitando a análise comparativa de desempenho térmico de cada tipologia ao serem submetidos a diferentes temperaturas e regime de insolação. A maioria das tipologias de painéis apresentam resultados favoráveis apenas para a cidade de Fortaleza, e desfavoráveis para as cidades de São Paulo e Curitiba, onde somente a última tipologia de painel atendeu os requisitos mínimos de desempenho para todas as cidades. Este estudo não contempla dados experimentais ou ensaios físicos. / Technological developments coupled with the emergence of new user needs resulted in several types of new construction methods. The concept of building industrialization has been evolving with speed, and these new construction systems have emerged as an alternative to traditional systems. These alternative systems seek better thermal performance, energy efficiency, light performance, acoustic and sustainability, among other things. Faced with this growing demand for innovation, ABNT (Brazilian Technical Standards Association) went on to study a set of rules to establish performance criteria to validate the new construction systems of residential buildings. These criteria were established with the publication of Performance Standard (NBR 15575/2013), which provides detailed parameters for performance of these buildings and provides methods according to the desired performance. At the same time, computer simulations have evolved, allowing lower cost of experimentation. These simulations are able to anticipate results which were previously only possible after physical tests of prototypes and also are able to find alternative solutions for energy efficiency and comfort of users. Among some existing programs for simulating thermal performance is the EnergyPlus, which was used for this study, with the primary objective of evaluating the thermal performance of prefabricated light steel frame panels. These panels were used in the facade and the internal seals of a building system composed of modular steel structure and floor and the concrete slab. To develop the study, a one-story residence was used as a base model, set by independent environments, composed entirely of the prefabricated light steel frame panels. The 16 panel types were studied in three different cities in Brazil, located in the Northeast, Southeast and South, and on a typical day of summer and winter. Using the computer simulation resources (EnergyPlus) enabled comparative analysis of thermal performance of each type when subjected to different temperatures and insolation regime. Most panel types have favorable results only in the city of Fortaleza, and unfavorable in the cities of São Paulo and Curitiba, whereas only the last panel type met the minimum performance requirements for all cities. This study does not include experimental data or physical tests.

The catastrophic damage to the infrastructure due to the most recent major earthquakes around the world demonstrated the seismic vulnerability of many existing reinforced concrete buildings. Accordingly, this thesis is focused on a proposed seismic retrofitting system (PSRS) configured to upgrade the performance of seismically vulnerable reinforced concrete buildings. The proposed system is composed of a rigid steel frame with chevron braces and a conventional energy dissipating shear link. The retrofitting system is installed within the bays of a reinforced concrete building frame. A retrofitting design procedure using the proposed seismic retrofitting system is also developed as part of this study. The developed design methodology is based on performance-based design procedure. The retrofitting design procedure is configured to provide a uniform dissipation of earthquake input energy along the height of the reinforced concrete building. The PSRS and a conventional retrofitting system using squat infill shear panels are applied to an existing school and an office building. Nonlinear time history analyses of the buildings in the original and retrofitted conditions are conducted to assess the efficiency of the PSRS. The analyses results revealed that the PSRS can efficiently alleviate the detrimental effects of earthquakes on the buildings. The building retrofitted with PSRS has a more stable lateral force-deformation behavior with enhanced energy dissipation capability than that of the one retrofitted with squat infill shear panels. For small intensity ground motions, the maximum inter-story drift of the building retrofitted with the PSRS is comparable to that of the one retrofitted with squat infill shear panels. But for moderate to high intensity ground motions, the maximum inter-story drift of the building retrofitted with the PSRS is considerably smaller than that of the one retrofitted with squat infill shear panels.

This thesis examines the seismic internal retrofitting of existing deficient reinforced concrete (RC) structures by using structural steel members. Both experimental and numerical studies were performed. The strengthening methods utilized with the scope of this work are chevron braces, internal steel frames (ISFs), X-braces and column with shear plate. For this purpose, thirteen strengthened and two as built reference one bay one story portal frame specimens having 1/3 scales were tested under constant gravity load and increasing cyclic lateral displacement excursions. In addition, two &frac12 / scaled three bay-two story frame specimens strengthened with chevron brace and ISF were tested by employing continuous pseudo dynamic testing methods. The test results indicated that the cyclic performance of the Xbrace and column with shear plate assemblage technique were unsatisfactory. On the other hand, both chevron brace and ISF had acceptable cyclic performance and these two techniques were found to be candidate solutions for seismic retrofitting of deficient RC structures. The numerical simulations by conducting nonlinear static and dynamic analysis were used to estimate performance limits of the RC frame and steel members. Suggested strengthening approaches, chevron brace and ISF, were also employed to an existing five story case study RC building to demonstrate the performance efficiency. Finally, design approaches by using existing strengthening guidelines in Turkish Earthquake Code and ASCE/SEI 41 (2007) documents were suggested.

As evoluções tecnológicas juntamente com o surgimento de novas necessidades dos usuários resultaram em diversos novos tipos de métodos construtivos. O conceito de industrialização das edificações vem evoluindo com velocidade, e estes novos sistemas construtivos surgiram como alternativa aos sistemas tradicionais buscando entre outros, melhor desempenho térmico, energético, lumínico, acústico e de sustentabilidade. Diante desta crescente demanda por inovação, a ABNT (Associação Brasileira de Normas Técnicas) passou a estudar um conjunto de normas para estabelecer critérios de desempenho ao validar os novos sistemas construtivos de edificações habitacionais. Isto se concretizou com a publicação da Norma de Desempenho (ABNT NBR 15575/2013), que estipula parâmetros para desempenho dessas construções e métodos detalhados de acordo com o desempenho desejado. Simultaneamente, as simulações computacionais evoluíram, permitindo menor custo de experimentação, são capazes de antecipar resultados antes somente possíveis após testes físicos com protótipos e também a encontrar alternativas de soluções também quanto à eficiência energética e ao conforto dos usuários. Entre alguns programas existentes para simulação de desempenho térmico, está o EnergyPlus, o qual foi utilizado para este estudo, tendo como principal objetivo avaliar o desempenho térmico de painéis de light steel frame pré-fabricados utilizados na fachada e nas vedações internas de um sistema construtivo modular composto por estrutura metálica, e piso e a laje de concreto. Para o desenvolvimento do estudo, foi utilizado como modelo base uma residência térrea, configurada por ambientes independentes, que virão a compor uma residência inteira onde serão inseridos os painéis de light steel frame pré-fabricados. As 16 tipologias de painéis foram estudadas em três diferentes cidades do Brasil, sendo elas situadas nas regiões Nordeste, Sudeste e Sul e em dias típicos de verão e inverno, utilizando os recursos de simulação computacional (EnergyPlus) possibilitando a análise comparativa de desempenho térmico de cada tipologia ao serem submetidos a diferentes temperaturas e regime de insolação. A maioria das tipologias de painéis apresentam resultados favoráveis apenas para a cidade de Fortaleza, e desfavoráveis para as cidades de São Paulo e Curitiba, onde somente a última tipologia de painel atendeu os requisitos mínimos de desempenho para todas as cidades. Este estudo não contempla dados experimentais ou ensaios físicos. / Technological developments coupled with the emergence of new user needs resulted in several types of new construction methods. The concept of building industrialization has been evolving with speed, and these new construction systems have emerged as an alternative to traditional systems. These alternative systems seek better thermal performance, energy efficiency, light performance, acoustic and sustainability, among other things. Faced with this growing demand for innovation, ABNT (Brazilian Technical Standards Association) went on to study a set of rules to establish performance criteria to validate the new construction systems of residential buildings. These criteria were established with the publication of Performance Standard (NBR 15575/2013), which provides detailed parameters for performance of these buildings and provides methods according to the desired performance. At the same time, computer simulations have evolved, allowing lower cost of experimentation. These simulations are able to anticipate results which were previously only possible after physical tests of prototypes and also are able to find alternative solutions for energy efficiency and comfort of users. Among some existing programs for simulating thermal performance is the EnergyPlus, which was used for this study, with the primary objective of evaluating the thermal performance of prefabricated light steel frame panels. These panels were used in the facade and the internal seals of a building system composed of modular steel structure and floor and the concrete slab. To develop the study, a one-story residence was used as a base model, set by independent environments, composed entirely of the prefabricated light steel frame panels. The 16 panel types were studied in three different cities in Brazil, located in the Northeast, Southeast and South, and on a typical day of summer and winter. Using the computer simulation resources (EnergyPlus) enabled comparative analysis of thermal performance of each type when subjected to different temperatures and insolation regime. Most panel types have favorable results only in the city of Fortaleza, and unfavorable in the cities of São Paulo and Curitiba, whereas only the last panel type met the minimum performance requirements for all cities. This study does not include experimental data or physical tests.