There is increasing demand, from both engineers and their clients, for structures that can be rapidly returned to occupancy following an earthquake, while also maintaining or reducing initial costs. One possible way towards this goal is to ensure that seismic damage occurs only within elements that can be removed and replaced following a damaging earthquake. For concentrically braced frames that use hollow structural sections, the current design practice requires field welding of the brace to the gusset in a way that causes the brace to buckle out-of-plane. In the event of a damaging earthquake, the out-of-plane brace buckling may damage both the gusset plate and also any adjacent exterior cladding. The plate cannot be easily replaced, resulting in expensive and time-consuming repairs, and the damaged cladding could endanger the lives of people evacuating the building and of other pedestrians. Through multiple design iterations, a new steel concentrically braced frame connection type was developed that can be bolted into place and that confines damage to replaceable components. The proposed connection is expected to result in reduced erection costs and be easier to repair following a major earthquake. Moreover, the new connection causes buckling to occur in-plane, preventing dangerous damage to the cladding. Large scale experimental testing on two variations of the new connection was performed. The cyclic, uniaxial testing of a brace with the new connection demonstrated the connection’s ability to behave in a desirable manner, with tensile yielding, brace buckling and connection rotation occurring during the expected drift levels associated with earthquake loading. A nonlinear finite element model of a brace with the new connection was developed and discussed. The finite element model was able to replicate the results of the experiment and will allow for further research and development of the new connection. The new connection shows promise as a replaceable connection for the seismic design of concentrically braced frames. / Thesis / Master of Applied Science (MASc) / Earthquakes can cause major, devastating damage to city structures. The cost of repairs and the time needed to make those repairs can be crippling, to the point where it is easier to tear down the structures than properly repair them. Designers and engineers need improved ways to design these structures to be more easily repaired, without driving up the initial cost of the structure. This research developed, tested and modelled a new, replaceable connection for earthquake resistant braces. The new connection is easier to install, easier to replace and provides added safety when compared to traditional designs.

Cold-formed steel purlin systems are widely used in modem building construction, for supporting the roof and floor structures. The rotational behaviour of beam-to-beam bolted connections, which are used between the sections, significantly affects the performance of purlin systems and is hard to predict. The behaviour models currently available for the connections only offer linear or multilinear predictions with low levels of accuracy. The aim of the research presented in this thesis is to develop and propose a nonlinear, more accurate behaviour model for the sleeved modified Z bolted connections, by means of experimental and numerical analysis. Finite element models are presented for the single-bolt, single-lap connection, sleeved modified Z connections in the simply supported arrangement, and a six-span purlin system. Based on the numerical results that have been validated by the experiments, a nonlinear behaviour model is proposed for the sleeved modified Z connections. In the model, the behaviour of the connections is divided into four stages, based on the dominant mechanism that provides the resistance to the rotation. Different formulas are used in different stages to determine the behaviour of the connection, boundary conditions, and magnitudes of bolt forces. The new model reflects well the true behaviour of the connections, and provides a good understanding of what happens inside the connections. The model reveals the failure pattern of the connections and enables optimization in the design of purl in systems, for improving efficiency in material usage.

Concrete technology has been in changeful evolution since the Roman Empire time. It is remarkable that the technological progress became of higher magnitude from the second part of the XX Century. Advances in the development of new cements, the appearance of the fibers as a reinforcement for structural applications, and specially the grand progress in the field of the water reducing admixtures enabled the emergence of several types of special concretes. One of the lasts is the Ultra High Performance Fiber Reinforced Concrete (UHPFRC), which incorporates advances of the Self-Compacting Concrete (SCC), Fiber-Reinforced Concrete (FRC) and Ultra High Strength Concrete (UHSC) technology. This exclusive material requires a detailed analysis of the components compatibility and a high control of the materials and processes. Mainly patented products have been used for the few structural elements carried out so far today, but the costs makes doubtful the development of many other potential applications. In accordance with the previously explained, a simplification of the UHPFRC components and processes is needed. This becomes the first main goal of this Ph.D. thesis, which emphasizes in the use of local available components and simpler mixing processes. Moreover, the singular properties of this material, between ordinary concrete and steel, allow not only the realization of slenderer structures, but also the viability of new concepts unthinkable with ordinary concrete. In this field is focused the second part of the Ph.D. thesis, which develops a bolted connection system between UHPFRC elements. This research summarizes, first of all, the subfamilies belonging to the HPC-UHPC materials. Afterwards, it is provided a detailed comparison between the dosage and properties of more than a hundred of mixtures proposed by several authors in the last ten years of technology. This becomes a useful tool to recognize correlations between dosages and properties and validate or no preconceived ideas about this material. Based on this state of art analysis was performed the later development of mixtures, on Chapter 4, which analized the effect of use of simpler components and processes on the UHPFRC. The main idea was use local components available in the Spanish market, identifying the combinations that provide the best rheological and mechanical properties. Steam curing use was avoided since a process simplification is intended. Diferent dosages were developed to be adapted to various levels of performance, and always trying to be as economical as possible. The concretes designed were selfcompacting and mainly combined two fiber types (hybrid), as the flexural performance was of greater relevance. The compressive strength obtained varied in the range between 100 and 170 MPa (cube L=100 mm), and the flexural strength between 15 and 45 MPa (prism 100 x 100 x 500 mm). Some of the components introduced are very rarely used in UHPFRC, as limestone coarse aggregate or FC3R, a white active residue from the petrol industry. As a result of the research, some simple and practical tips are provided for designers of UHPFRC dosage. At the end of this chapter, five dosages are characterized as examples of useful concretes for different requirement applications. In a second part, the idea of a bolted joint connection between UHPFRC elements was proposed. The connection system would be especially useful for struts and ties elements, as truss structures. The possible UHPFRC failure modes were introduced and two different types of tests were designed and performed to evaluate the joint capacity. The geometry of the UHPFRC elements was modified in order to correlate it with the failure mode and maximum load reached. Also a linear finite element analysis was performed to analyze the UHPFRC elements connection. This supported the results of the experimental tests to deduce formulations that predict the maximum load for each failure mode. Finally, a real size truss structure was assembled with bolted joints and tested to verify the good structural behavior of these connections. To conclude, some applications designed and developed at the Universitat Politècnica de València with the methods and knowledge acquired on UHPFRC are abstracted. In many of them the material was mixed and poured in a traditional precast concrete company, providing adequate rheological and mechanical results. This showed the viability of simpler UHPFRC technology enabling some of the first applications in Spain with this material. / Camacho Torregrosa, EE. (2013). Dosage optimization and bolted connections for UHPFRC ties [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34790 / TESIS

Este trabalho realiza estudo teórico e experimental de ligações parafusadas em chapas finas onduladas, com aço de alta resistência, submetidas a esforços de tração em situação de cisalhamento simples. A aplicação deste tipo de ligação ocorre em paredes de silos cilíndricos metálicos. Também foi avaliada a utilização de montagem com chapas duplas, utilizadas na prática para aumentar a espessura total da parede, devido a demanda por silos cada vez maiores. O programa experimental compreendeu 137 ensaios, nos quais foram variados parâmetros de interesse com aplicações práticas, resultando em dois modos de falha distintos, ruptura da chapa na seção líquida e esmagamento do aço na parede do furo. Foram propostas novas equações para o cálculo da resistência deste tipo de ligação. Os resultados experimentais obtidos mostraram que em ligações com falha por ruptura na seção líquida, reduzir a área líquida à uma área efetiva por meio de um coeficiente redutor resulta em valores conservadores para a resistência deste tipo de ligação. As ligações com chapas duplas apresentaram resistência elevada, superior à condição de chapa simples. / This work presents a theoretical and experimental study of bolted connections with thin, corrugated, high strength steel sheets, subjected to tension in simple shear condition. This type of connection is applicable in walls of cylindrical steel silos. It also was evaluated the case of double sheet assemblage, that is used in practice to increase the total wall thickness, due to the demand for bigger silos. The experimental program comprised 137 tests, in which it were varied chosen parameters of practical interest, providing failure by net section tension rupture and bearing of the sheet. New equations were proposed for the strength calculation of this type of connection. The experimental results indicated that in connections subject net section rupture, to reduce the net section area to an effective area through a reduction coefficient returns conservative values of resistance for this type of connection. The connections with double sheet exhibited high values of resistance, which resulted bigger than for simple sheet cases.

Este trabalho abordou o estudo de ligação viga de aço e pilar misto preenchido com concreto a partir da aplicação de modelos numérico para representar o comportamento de duas tipologias de ligação: uma ligação parafusada com aderência entre os parafusos passantes e o núcleo de concreto e uma ligação soldada, validadas com base em resultados experimentais existentes. Os resultados obtidos nessa etapa foram considerados satisfatórios, dentro da proposta de modelagem, apesar das simplificações adotadas. Após a validação do modelo numérico foi desenvolvido um estudo paramétrico dos modelos de ligação para entender a influência de alguns parâmetros no comportamento global da estrutura, que foram: resistência à compressão do concreto e espessura do perfil tubular e perfil da viga, com posterior discussão da relação momento-rotação das duas tipologias de ligação estudadas. A mudança do perfil da viga foi o parâmetro que mais influenciou no comportamento global da ligação parafusada; enquanto que, para a ligação soldada, as variações de todos os parâmetros influenciaram no comportamento da ligação, com destaque para a variação do perfil da viga. / This research studied connections typology between steel beams to column filled with concrete from the application of numerical models that reproduce the behavior of two connections: bolted beam-column connection and welded beam-column connection, which were calibrated using existing experimental results. At this stage, the results were considered satisfactory, within the proposed model, despite the adopted simplifications. After the calibration, a parametric study was developed with the aim of verifying the influence of some parameters on the overall behavior of the structure, such as the concrete compression strength, the thickness of the tube wall and the beam properties, with discussions of bending moment-rotation of the studied connections. The beam properties were the parameters that most influenced on the overall behavior of the bolted beam-column connection, while, for the welded connection, all parameters influenced on the overall behavior of the connection, specially the beam properties.

Este trabalho abordou o estudo de ligação viga de aço e pilar misto preenchido com concreto a partir da aplicação de modelos numérico para representar o comportamento de duas tipologias de ligação: uma ligação parafusada com aderência entre os parafusos passantes e o núcleo de concreto e uma ligação soldada, validadas com base em resultados experimentais existentes. Os resultados obtidos nessa etapa foram considerados satisfatórios, dentro da proposta de modelagem, apesar das simplificações adotadas. Após a validação do modelo numérico foi desenvolvido um estudo paramétrico dos modelos de ligação para entender a influência de alguns parâmetros no comportamento global da estrutura, que foram: resistência à compressão do concreto e espessura do perfil tubular e perfil da viga, com posterior discussão da relação momento-rotação das duas tipologias de ligação estudadas. A mudança do perfil da viga foi o parâmetro que mais influenciou no comportamento global da ligação parafusada; enquanto que, para a ligação soldada, as variações de todos os parâmetros influenciaram no comportamento da ligação, com destaque para a variação do perfil da viga. / This research studied connections typology between steel beams to column filled with concrete from the application of numerical models that reproduce the behavior of two connections: bolted beam-column connection and welded beam-column connection, which were calibrated using existing experimental results. At this stage, the results were considered satisfactory, within the proposed model, despite the adopted simplifications. After the calibration, a parametric study was developed with the aim of verifying the influence of some parameters on the overall behavior of the structure, such as the concrete compression strength, the thickness of the tube wall and the beam properties, with discussions of bending moment-rotation of the studied connections. The beam properties were the parameters that most influenced on the overall behavior of the bolted beam-column connection, while, for the welded connection, all parameters influenced on the overall behavior of the connection, specially the beam properties.

Este trabalho realiza estudo teórico e experimental de ligações parafusadas em chapas finas onduladas, com aço de alta resistência, submetidas a esforços de tração em situação de cisalhamento simples. A aplicação deste tipo de ligação ocorre em paredes de silos cilíndricos metálicos. Também foi avaliada a utilização de montagem com chapas duplas, utilizadas na prática para aumentar a espessura total da parede, devido a demanda por silos cada vez maiores. O programa experimental compreendeu 137 ensaios, nos quais foram variados parâmetros de interesse com aplicações práticas, resultando em dois modos de falha distintos, ruptura da chapa na seção líquida e esmagamento do aço na parede do furo. Foram propostas novas equações para o cálculo da resistência deste tipo de ligação. Os resultados experimentais obtidos mostraram que em ligações com falha por ruptura na seção líquida, reduzir a área líquida à uma área efetiva por meio de um coeficiente redutor resulta em valores conservadores para a resistência deste tipo de ligação. As ligações com chapas duplas apresentaram resistência elevada, superior à condição de chapa simples. / This work presents a theoretical and experimental study of bolted connections with thin, corrugated, high strength steel sheets, subjected to tension in simple shear condition. This type of connection is applicable in walls of cylindrical steel silos. It also was evaluated the case of double sheet assemblage, that is used in practice to increase the total wall thickness, due to the demand for bigger silos. The experimental program comprised 137 tests, in which it were varied chosen parameters of practical interest, providing failure by net section tension rupture and bearing of the sheet. New equations were proposed for the strength calculation of this type of connection. The experimental results indicated that in connections subject net section rupture, to reduce the net section area to an effective area through a reduction coefficient returns conservative values of resistance for this type of connection. The connections with double sheet exhibited high values of resistance, which resulted bigger than for simple sheet cases.

The Master’s thesis concerns a design of load bearing multi-storey steel construction of scientific institution in Brno. This thesis contains three different solutions of a draft proposal and for the elected solution is processed technical report, structural analysis, material list and drawings.

No description available.

No description available.