Pull-out behaviour of axially loaded basalt fibre reinforced polymer (BFRP) rods bonded parallel to the grain of glulam elements

Synopsis: Bonded-in rod timber joints off er several advantages over conventional types of joint, including high local force transfer, very stiff connections, and improved ?re and aesthetic properties since the connection is completely hidden in the insulating timber members. More recently, the use of ?bre reinforced polymer (FRP) as a connecting rod, alternative to steel rods, in bonded-in rod connections for timber structures has been investigated. However, the investigation into the behaviour of such joints is limited, in particular, connections involving basalt ?bre reinforced polymers (BFRP) bars - which is the primary focus of this research. This paper presents an experimental programme conducted to investigate the behaviour of bonded-in BFRP bars loaded parallel to the grain of glulam members. Tensile pull-out tests were conducted to examine the effect of bonded length and bond stress-slip on the structural capacity of the connection. An analytical design expression for predicting pull-out capacity is proposed and the results have been compared with some established design equations. It was found that pull-out load increased approximately linearly with the bonded length, up to maximum which occurred at a bonded length of 15 times the hole diameter, and did not increase beyond this bonded length. The most signi?cant failure modes were failure at the timber/adhesive interface followed by pullout of the BFRP rod. Increased bonded lengths resulted in higher bond slip values compared to lower equivalent bonded lengths. The proposed design model gave the best predictions of pull-out capacity compared with other existing models.

Granular anchors under vertical loading - axial pull

Granular anchors are a relatively new concept in ground engineering with relatively little known regarding their load–displacement behaviour, failure modes, ultimate pullout capacity and also potential applications. A granular anchor consists of three main components: a base plate; tendon and compacted granular backfill. The tendon is used to transmit the applied load to the base plate which compresses the granular material to form the anchor. A study of the load–displacement response and ultimate pullout capacity of granular anchors constructed in intact lodgement till and made ground deposits is reported in this paper. Parallel tests were also performed on cast insitu concrete anchors which are traditionally used for anchoring purposes. A new method of analysis for the determination of the ultimate pullout capacity of granular anchors is presented and verified experimentally, with the dominant mode of failure controlled by the column length to diameter ratio. Granular anchors with L/D > 7 principally failed on bulging whereas short granular anchors failed on shaft resistance, with the latter mobilising similar pullout capacities as conventional concrete anchors.

Cube, cylinder, core and pull-off strength relationships

This limited experimental investigation examined the relationships between the compressive strengths of cubes, cylinders, cores and the estimated compressive strengths derived from pull-off tests for a relatively low-strength structural-grade concrete (<35 N/mm2). Test specimens were cast and tested at 7, 14, 28, 56 and 84 days. The relationships of the trends of the test results to the trends of results of standard cube specimens and standard cylinder specimens were compared. It was found that the mean strength of each type of specimen tended to increase as a function of the natural logarithm of the specimen age. The mean strength of cylinders of length/diameter ratio 2.0 was found to be slightly greater (by about 7.5%) than the generally accepted value of 80% of the mean cube strength. Core results were corrected using correction factors defined in BS 6089 and the UK national annex to BS EN 12504-1. The mean corrected cube strength of cores taken from cubes was approximately 12% greater than the mean companion cube strength. The mean corrected cylinder strength of cores taken from cubes was approximately 5% greater than the mean companion cylinder strength. The potential cube and cylinder strengths of cores taken from slabs cured under different environmental conditions correlated well with companion cube and cylinder strengths respectively at 28 days. The pull-off test results gave a variable but, on average, slightly conservative estimate of the cube compressive strength of the relatively low-strength structural-grade concrete, using a simple general linear estimated compressive cube strength to tensile strength correlation factor of 10.

Pull-out behaviour of axially loaded Basalt Fibre Reinforced Polymer (BFRP) rods bonded perpendicular to the grain of glulam elements

The behaviour of Basalt Fibre Reinforced Polymer (BFRP) loaded perpendicular to glulam timber elements was investigated. It was found that pull-out load increased approximately linearly with the bonded length up to maximum which occurred at a bonded length of 250 mm (~15 times the hole diameter) and did not increase beyond this bonded length. Failure mode of the samples was mostly shear fracture which was located at the cylindrical zone at the timber/adhesive interface. Increased bonded lengths resulted in corresponding decrease in interfacial bond stress. At 250 mm bonded length, the pull-out capacity of the proposed design model was about 2% lower than that of the tests. The results also showed that the bond stress of the theoretical model (at the ascending and descending branches) of the stress–slip curve was approximately 5–10% of that of the experiment.

Pull-out forces in shear connectors in composite beams with large web openings

Composite beams with large web openings are often used, and their design is controlled by Vierendeel bending at the four corners of each opening, which is assisted by local composite action with the floor slab. Development of this Vierendeel bending resistance may be limited by pull-out failure of the shear connectors. In this paper, a non-linear elasto-plastic finite element model of a composite beam with web openings was used to investigate this mode of pull-out failure. A test was performed on a typical composite slab in which the shear connectors were subject to pure tension and the failure load was 67 kN, which is approximately 70% of the longitudinal shear resistance. The results of the finite element model are compared against those obtained using the established design theory, that does not limit the vertical pull-out resistance of the shear connectors. It is shown that the local bending resistance due to composite action should be reduced when limited by pull-out of the shear connectors. A parametric study investigated the effect of openings of 600 to 1200 mm length. A simple model is developed to establish the Vierendeel bending resistance, when limited by pull-out of the shear connectors.

Pull-out behaviour of steel grid soil reinforcement embedded in silty sand

This paper investigates the pull-out behaviour (particularly the bearing resistance) of a steel grid reinforcement embedded in silty sand using laboratory tests and numerical analyses. It is demonstrated that the various common analytical equations for calculating the bearing component of pull-out resistance give a wide range of calculated values, up to about 200% disparity. The disparity will increase further if the issue of whether to use the peak or critical state friction angle is brought in. Furthermore, these equations suggest that the bearing resistance factor, N, is only a function of soil friction angle which is not consistent with some design guidelines. In this investigation, a series of large scale laboratory pull-out tests under different test pressures were conducted. The test results unambiguously confirmed that the N factor is a function of test pressure. A modified equation for calculating N is also proposed. To have more in-depth understanding of the pull-out behaviour, the tests were modelled numerically. The input parameters for the numerical analysis were obtained from laboratory triaxial tests. The analysis results were compared with the experimental results. Good agreement between experimental and numerical results was achieved if the strain-softening behaviour from peak strength to critical state condition was captured by the soil model used. © 2013 Elsevier Ltd.

Promoting healthy dietary behaviour through personalised nutrition: technology push or technology pull?

The notion of educating the public through generic healthy eating messages has pervaded dietary health promotion efforts over the years and continues to do so through various media, despite little evidence for any enduring impact upon eating behaviour. There is growing evidence, however, that tailored interventions such as those that could be delivered online can be effective in bringing about healthy dietary behaviour change. The present paper brings together evidence from qualitative and quantitative studies that have considered the public perspective of genomics, nutrigenomics and personalised nutrition, including those conducted as part of the EU-funded Food4Me project. Such studies have consistently indicated that although the public hold positive views about nutrigenomics and personalised nutrition, they have reservations about the service providers' ability to ensure the secure handling of health data. Technological innovation has driven the concept of personalised nutrition forward and now a further technological leap is required to ensure the privacy of online service delivery systems and to protect data gathered in the process of designing personalised nutrition therapies.

Implementação da filosofia pull na produção na empresa Schnellecke

Trabalho Final de mestrado para obtenção do grau de Mestre em Engenharia Mecânica perfil Manutenção e Produção

Controlo e monitorização de um sistema de Auto-Pull

Esta dissertação descreve o estudo do controlo e da monitorização de um sistema de autopull, bem como o estudo da implementação de um destes sistemasnuma área de negócio. Inicialmente, de modo a percecionar as melhores opções a tomar para a realização deste projeto foram estudadas duas redes de comunicação locais, redes Ethernet e redes CAN, tendo-se optado pelas redes Ethernet, sendo as razões que determinaram esta escolha explanadas no desenvolvimento do relatório. Após ter sido selecionada a rede que foi utilizada, foram estudados os requisitos do sistema e procuradas no mercado soluções que os satisfaçam. Para a comunicação em tempo real foram utilizadas Web Sockets e para a utilização destas,foi necessário um servidor de Web Sockets, tendo a escolha recaídosobre onodejs. Posteriormente, foi elaborada uma interface gráfica que permitiu a criação de um sistema inteligente que auxilia os clientes do espaço a efetuarem pedidos bem como a chamarem os funcionários, não necessitando de passar os longos tempos de espera que normalmenteestão associados a estes espaços. Posto isto, foi realizado um website que deverá apresentar o espaço, os próximos eventos a realizar e outras informações importantes. Este sistema torna-se uma mais-valia para a divulgação da tecnologia implementada e para a divulgação dos espaços que eventualmente venham a adotar um sistema análogo. De seguida foi efetuado um plano de negócios, simulando um espaço físico que eventualmente implementasse esta tecnologia. Para tal, foi estudada a envolvente externa e interna em que este negócio estaria inserido, as políticas de marketing que deveriam ser seguidas e ainda um plano financeiro que descrevesse o investimento, as vendas esperadas e todos os restantes componentes económicos do projeto. Por último foram tecidas as principais conclusões inerentes ao projeto desenvolvido e analisadas as possibilidades de melhorias futuras.