Use of composite steel construction with precast hollow core slabs is now popular in the UK,but the present knowledge in shear capacity of the headed shear studs for this type of composite construction is very limited. Currently, all the information is based on the results obtained from experimental push-off tests. A finite element model to simulate the behaviour of headed stud shear connection in composite beam with precast hollow core slabs is described. The model is based on finite element method and takes into account the linear and non-linear behaviour of all the materials. The model has been validated against the test results, for which the accuracy of the model used is demonstrated. Parametric studies showing the effect of the change in transverse gap size, transverse reinforcement diameter and in-situ concrete strength on the shear connection capacity are presented.

Use of composite steel construction with precast hollow core slabs is now popular in the UK, but the present knowledge in shear capacity of the headed shear studs for this type of composite construction is very limited. Currently, all the information is based on the results obtained from experimental push-off tests. A finite element model to simulate the behaviour of headed stud shear connection in composite beam with precast hollow core slabs is described. The model is based on finite element method and takes into account the linear and non-linear behaviour of all the materials. The model has been validated against the test results, for which the accuracy of the model used is demonstrated. Parametric studies showing the effect of the change in transverse gap size, transverse reinforcement diameter and in-situ concrete strength on the shear connection capacity are presented.

This paper is concerned with the behaviour of beam ¿ column connections of steel ¿ concrete composite beams with precast hollow core slabs. Experiments were carried out to investigate the joint rotation characteristics and ultimate moment capacity of these connections. Details of the test specimens, instrumentation, test set-up and test procedures are described. Results obtained for the connection moment capacity, rotation capacity and failure modes are presented. It is found that through proper design and detailing, these simple steel connections display the characteristics of a semi-rigid connection with very little extra cost.

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Conventional fixed base walls are typically characterized by yielding that results in permanent damage, residual drifts and costly losses due to the service shutdown for structural repairs. Controlled rocking masonry walls have been developed as a solution to prevent structural damage when seismic events take place. These systems purposely allow the wall to rock from its foundation and have an uplift at the base, thus replacing the typical yielding at the base of conventional fixed-base walls. Controlled rocking masonry walls have traditionally been controlled by using unbonded post-tensioning strands to provide the self-centering behaviour. Although post-tensioning has shown favourable results, its implementation is difficult in practical applications, and post-tensioning losses due to yielding of the strands at large deformations can reduce their self-centering ability. In order to overcome such issues, an alternative controlled rocking system for masonry walls was developed recently, which is designed to self-center through vertical gravity loads only, instead of the post-tensioning tendons. The rocking response of this alternative system is controlled by using energy dissipation devices, so the system is referred to as Energy Dissipation-Controlled Rocking Masonry Walls (ED-CRMWs). The vertical gravity loads are primarily transferred to the ED-CRMWs from the floor slab at each level. Therefore, the wall-slab interaction should be investigated in order to ensure a fully resilient system. In this regard, the current study identifies and categorizes the potential issues that are expected to occur due to the interaction between the wall rocking mechanism and the floor slab, and then investigates the most common of these issues using a parametric study. The parametric study focuses on the vertical incompatibility of displacements that a hollow- core slab suffers when its supporting walls uplift by different displacements during seismic events. Three different spans, four different cross-sections and two different alternatives of prestress configurations are considered in this study. The models were developed using ABAQUS 6.18 commercial software. The results show the cracking/yielding behaviour of the slabs and their displacement capacities at five different stages. The obtained results are promising for the usage of hollow-core slabs on ED-CRMWs or similar systems that require this interaction, as the range of displacement capacities can accommodate many of the vertical displacement incompatibilities expected in many potential situations. / Thesis / Master of Applied Science (MASc)

No / The chapter describes the ongoing work on modeling the semi-rigid composite beam-column connections of composite beams with precast hollow core slabs. Using the finite element (FE) software ABAQUS, a three-dimensional (3D) model of a composite joint is set up. The technique of simulating bolt force, endplate, concrete elements, reinforcement, and shear connectors, and the interaction between slabs and steel beams is presented in the chapter. Preliminary results on the steel joint and simplify composite joint are also presented in the chapter. FE model for the bare steel joints and the simplified composite joints are presented, and the result of the simplified composite model showed good agreement with the experimental result but with lower joint stiffness. Further work on the full finite element model of composite joints is still going on.

This paper describes the finite element modelling of steel beams acting compositely with proprietary precast hollow core slabs. A companion paper (Lam D, Elliott KS, Nethercot DA. Experiments on composite steel beams with precast hollow core floor slabs. Proceedings of the Institution of Civil Engineers: Structures and Buildings 1999; in press [1]) reports results of full scale bending tests and compression slab tests. The finite element package ABAQUS was used to extend the scope of the experimental work, by first demonstrating that a 2-dimensional plane stress analysis is sufficiently accurate, providing that the correct material input data and shear stud characteristics obtained from isolated push-off tests are used. The FE results are within 5% of the experimental results. An extensive parametric study was carried out to investigate the flexural behaviour of composite beams with variations in transverse reinforcement ratio, stud spacing and steel UB section.

no / The recently published report on Rethinking Construction in the UK has highlighted the need to reduce on-site activities as part of its drive for greater efficiency, improved quality and greater certainty in the delivery of construction projects. For multi-storey buildings, the use of precast slabs in the floors - particularly if this can be done without the need for in-situ screeds - drastically reduces the volume of on-site concreting required. Although the use of precast hollow core slabs in steel framed buildings are common, their use in composite design with steel beams is relatively new. By designing the steel beams and precast hollow core slabs compositely, a reduction in beam size and overall floor depth can be achieved, which would lead to an overall reduction in construction cost. This paper summarises the recent developments and on-going research on composite construction with precast hollow core slabs.

As lajes alveolares são elementos eficientes do ponto de vista estrutural, pois os alvéolos permitem significativa redução de peso próprio sem comprometer a resistência e a rigidez. Além disso, é muito comum nesses elementos o uso de protensão, o que permite que estas lajes consigam vencer grandes vãos e se tornem uma solução competitiva. No entanto, para certas combinações de vãos, espessura da laje, ligações e propriedades dos materiais, esse sistema estrutural pode ser suscetível a vibrações excessivas. Há poucos estudos sobre a sensibilidade a vibrações destes elementos cuja aplicação é comum em situações de especial interesse como escritórios, nos quais as vibrações podem causar significativos incômodos aos usuários. Este trabalho visa contribuir para o melhor entendimento sobre a sensibilidade a vibrações de pavimentos com lajes sujeitas à ação dinâmica de atividades humanas. Além disso, pretende-se avaliar o comportamento dinâmico dos pavimentos com lajes alveolares em diferentes situações de interesse: painéis isolados, unidos por chaves de cisalhamento e após a concretagem da capa. Foi realizado um estudo experimental em um pavimento de um edifício comercial em estrutura de concreto pré-moldado nas três situações distintas da construção e foram obtidas as frequências naturais, modos de vibração e amortecimento para cada etapa, bem como uma análise do conforto ao usuário, a partir dos limites previstos em normas nacionais e internacionais. Foi também realizada uma análise numérica, na qual, além da determinação teórica de modos de vibração e frequências naturais, foram determinados os níveis de vibração gerados pelo caminhar de pessoas. As frequências naturais obtidas numericamente apresentaram diferença média de 11% com relação às experimentais. A diferença média dos picos de aceleração numéricos e experimentais foi de 9%. Tais resultados possibilitaram validar o modelo numérico proposto. A análise de conforto do pavimento indicou que a norma brasileira ANBT NBR 6118 (2014) não apresenta prescrições suficientes para se evitar vibrações excessivas em pavimentos com lajes alveolares protendidos. Os resultados permitiram concluir que as chaves de cisalhamento e a capa estrutural foram determinantes para garantir níveis aceitáveis de vibração no pavimento analisado. / Hollow core slabs are very efficient structural members, since their voids allow a significant reduction of self-weight, without jeopardizing the strength and stiffness. Moreover, prestressed concrete is commonly employed in this type of structure, allowing their use in large spans. Consequently, this is a very competitive solution. However, for certain combination of spans, slab thickness, connections and materials properties, this structural system can be susceptible to excessive vibrations. There is a lack of studies on vibration sensitivity of these elements, which are commonly applicable in situations of special interest, as offices, in which vibration can cause significant annoyance to users. This work aims to contribute to a better understanding about vibration sensitivity of hollow core slabs floors. Moreover, we intend to evaluate the dynamic behavior of hollow core slabs in different situations of interest: single panels, panels joined by shear keys and after completion of concrete topping. This analysis involves the determination of natural frequencies, mode shapes, damping ratios and vibrational levels generated by walking. An experimental study was carried out on a floor of a precast concrete structure of a commercial building in three different stages of construction. In this study, the natural frequencies, mode shapes and damping for each step were obtained, as well as an analysis of comfort, based on limits defined by national and international standards. A numerical analysis was also performed in which the vibration modes and natural frequencies were theoretically determined and the vibration levels generated by walking were estimated. The natural frequencies obtained numerically showed an average difference of 11% compared to experimental. The average difference between the numerical and experimental peak acceleration was 9%. These results allowed the validation of the numerical model proposed. The comfort analysis of the floor indicated that the Brazilian standard ANBT NBR 6118 (2014) does not provide sufficient provisions to avoid excessive vibrations in floors with prestressed hollow core slabs. The results showed that the shear keys and the structural topping were crucial to ensure acceptable levels of vibration.

Esta pesquisa teve como principal objetivo analisar o comportamento de lajes alveolares protendidas de uso corrente no Brasil (pequenas espessuras e alta protensão) quanto ao cisalhamento em região fissurada por ação do momento fletor, para diferentes situações: sem e com capa e com preenchimento parcial de alvéolos. Foi desenvolvido um estudo teórico com o emprego de equacionamentos analíticos disponíveis na literatura técnica, envolvendo as recomendações da norma brasileira NBR 6118:2003 (Projeto de Estruturas de Concreto), do ACI-318:2008 (Building code requirements for structural concrete) e da EN 1992-1-1 (2004) (Eurocode 2- Projeto de estruturas de betão Parte 1-1: Regras gerais e regras para edifícios). Foram feitas comparações com resultados experimentais obtidos a partir de inúmeros ensaios de lajes alveolares protendidas. As unidades ensaiadas nesta pesquisa foram disponibilizadas por quatro empresas brasileiras de intensa atividade no mercado, sendo analisadas as capacidades resistentes de diferentes tipos. Assim, foram realizados 96 ensaios, 31 para a determinação da capacidade resistente à flexão e 65, ao cisalhamento, sendo selecionados modelos de lajes com grande emprego no mercado brasileiro. A partir desses ensaios, foi possível entender melhor o comportamento das lajes alveolares protendidas produzidas no Brasil. Com as diversas análises, considerando os ensaios experimentais e um vasto estudo teórico quanto ao dimensionamento dessas lajes, verificou-se a adequabilidade de equações de diferentes normas. Assim, foi possível identificar o equacionamento que melhor representa o comportamento das peças produzidas no Brasil, considerando inclusive peculiaridades de comportamento, que apresentam diferenças constratantes com relação a unidades produzidas em outros países. A partir desses estudos, produziu-se um amplo memorial de cálculo, considerando as diversas tipologias de lajes estudadas, com o objetivo de contribuir de modo didático com os engenheiros de estrururas. Logo, com esta pesquisa, foi possível não somente melhorar o entendimento do comportamento de tais lajes alveolares, como também fornecer subsídios para a avaliação desses elementos, considerando as características específicas das lajes produzidas no Brasil e, assim, contribuir para a padronização do dimensionamento junto à norma brasileira NBR 14861 (Laje pré-fabricada - Painel alveolar de concreto protendido). / This work had as major objective to analyze the behavior of Brazilian prestressed hollow core slabs - small thickness and high level of prestressing - considering shear in a cracked region due to bending moment, for different design situations: without concrete topping, with concrete topping and with filling the voids. A theoretical study was developed with the use of analytical equations available in the technical literature, involving the recommendations of the Brazilian code NBR 6118:2003 (Design of concrete structures), ACI-318: 2008 (Building code requirements for structural concrete) and EN 1992-1-1 (2004) (Eurocode 2: Design of concrete structures - Part 1-1: General rules and rules for buildings), comparing experimental results from many prestressed hollow core slabs tests. The slabs tested in this study were provided by four different Brazilian companies with intense activity in the market, and the resistant capacity of different typologies was analyzed. Thus 96 tests were made, 31 to determine the bending capacity and 64 for the determination of shear strength, and were selected slab models from the Brazilian market that are highly employed. From these tests, it was possible a better understanding of the prestressed hollow core slabs behavior produced in Brazil. With several analysis considering the experimental tests and an ample theoretical study about the design of these slabs, the adequacy of different codes equations were verified. Thus, it was possible to identify the equations that best represent the behavior of elements produced in Brazil, also considering the behaviour peculiarities of these slabs that have contrasting differences, if compared with units produced in other countries. From these studies it was produced a large design manual, considering the various types of studied slabs, aiming to contribute in a didactic way to the structural engineers. So, with this research, it was possible not only to improve comprehension of the behavior of such prestressed hollow core slabs, as well as provide information for evaluation of these elements, considering the specific characteristics of the slabs fabricated in Brazil and thus to contribute with the standardization of the design in the Brazilian code NBR 14861 (Prefabricated slab - Prestressed concrete hollow core panel).