926 resultados para Glued laminated timber
Resumo:
Active matrix liquid crystal displays (AMLCD) need to be protected in severe environments. This is achieved through a ruggedisation process, where the display is laminated with cover glasses to become a more robust structure. The ruggedisation process can in itself cause stresses in the display and this can lead to delamination failures during the lamination process, during qualification testing or in-service. Controlling the magnitude of stress in a display during the lamination process is of course very important and this depends highly on the materials used. This paper discusses the use of finite element analysis to investigate the use of different materials in the lamination process and how such materials can affect the stress magnitude in the display.
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Cotoneaster pannosus (Rosaceae), an ornamental shrub native to China, is reported for the first time in Tarragona Province (Catalonia, Spain). Data on demography and accompanying species for the new locality are provided, in addition to a chrorological update at nation level.
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A 37-m thick layer of stratified clay encountered during a site investigation at Swann's Bridge, near the sea-coast at Limavady, Northern Ireland, is one of the deepest and thickest layers of this type of material recorded in Ireland. A study of the relevant literature and stratigraphic evidence obtained from the site investigation showed that despite being close to the current shoreline, the clay was deposited in a fresh-water glacial lake formed approximately 13 000 BP. The 37-m layer of clay can be divided into two separate zones. The lower zone was deposited as a series of laminated layers of sand, silt, and clay, whereas the upper zone was deposited as a largely homogeneous mixture. A comprehensive series of tests was carried out on carefully selected samples from the full thickness of the deposit. The results obtained from these tests were complex and confusing, particularly the results of tests done on samples from the lower zone. The results of one-dimensional compression tests, unconsolidated undrained triaxial tests, and consolidated undrained triaxial compression tests showed that despite careful sampling, all of the specimens from the lower zone exhibited behaviour similar to that of reconstituted clays. It was immediately clear that the results needed explanation. This paper studies possible causes of the results from tests carried out on the lower Limavady clay. It suggests a possible mechanism based on anisotropic elasticity, yielding, and destructuring that provides an understanding of the observed behaviour.Key words: clay, laminations, disturbance, yielding, destructuring, reconstituted.
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Palaeoecological methods can provide an environmental context for archaeological sites, enabling the nature of past human activity to be explored from an indirect but alternative perspective. Through a palynological study of a small fen wetland located within the catchment of a multi-period prehistoric complex at Ballynahatty, Co. Down, Northern Ireland, we reconstruct the vegetation history of the area during the early prehistoric period. The pollen record reveals tentative evidence for Mesolithic activity in the area at 6410-6220 cal. BC, with woodland disturbance identified during the Mesolithic-Neolithic transitional period ca. 4430-3890 cal. BC. A more significant impact on the landscape is observed in the Early Neolithic from 3944-3702 cal. BC, with an opening up of the forests and the establishment of a mixed agricultural economy. This activity precedes and continues to be evident during the Mid-Neolithic during which megalithic tombs and related burial sites were constructed at Ballynahatty. Due to chronological uncertainties and a possible hiatus in peat accumulation in the fen, the contemporary environment of the Ballynahatty timber circle complex (constructed and used ca. 3080-2490 cal. BC) and henge (dating to the third millennium cal. BC) cannot certainly be established. Nevertheless, the pollen record suggests that the landscape remained open through to the Bronze Age, implying a long continuity of human activity in the area. These findings support the idea that the Ballynahatty prehistoric complex was the product of a gradual and repeated restructuring of the ritual and ceremonial landscape whose significance continued to be recognised throughout the early prehistoric period.
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Microlaminated sediment cores from the Kalya slope region of Lake Tanganyika provide a near-annually resolved paleoclimate record between similar to 2,840 and 1,420 cal. yr B.P. demonstrating strong linkages between climate variability and lacustrine productivity. Laminae couplets comprise dark, terrigenous-dominated half couplets, interpreted as low density underflows deposited from riverine sources during the rainy season, alternating with light, planktonic diatomaceous ooze, with little terrigenous component, interpreted as windy/dry season deposits. Laminated portions of the studied cores consist of conspicuous dark and light colored bundles of laminae couplets. Light and dark bundles alternate at decadal time scales. Within dark bundles, both light and dark half couplets are significantly thinner than within light bundles, implying slower sediment accumulation rates during both seasons over those intervals.
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As James Scott’s Seeing Like a State attests, forests played a central role in the rise of the modern state, specifically as test spaces for evolving methods of managing state resources at a distance, and as the location for grand state schemes. Together, such ambitions necessitated both the elimination of local understandings of forest management – to be replaced by centrally controlled scientific precision – and a narrowing of state vision. Forests thus began to be conflated with trees (and their timber) alone. All other aspects of the forest, both human and non-human, were ignored. Through the lens of the 18th and early 19th century New Forest in southern England, this paper examines the impact of government attempts to shift the focus of state forests from being remnant medieval hunting spaces to spaces of income generation through the creation of vast sylvicultural plantations. This state scheme not only reworked the relationship between the metropole and the provinces – something effected through systematic surveys and novel bureaucratic procedures – but also dramatically impacted upon the biophysical and cultural geographies of the forest. By equating forest space with trees alone, the British state failed to legislate for the actions of both local commoners and non-human others in resisting their schemes. Indeed, subsequent oppositions proved not only the tenacity of commoners in protecting their livelihoods but also the destructive power of non-human actants, specifically rabbits and mice. The paper concludes that grand state schemes necessarily fail due to their own internal illogic: the narrowing of state vision creates blind spots in which human and non-human lives assert their own visions.
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Published contemporary dinoflagellate distributional data from the NE Pacific margin and estuarine environments (n = 136) were re-analyzed using Canonical Correspondence Analysis (CCA) and partial Canonical Correspondence Analysis (pCCA). These analyses illustrated the dominant controls of winter temperature and productivity on the distribution of dinoflagellate cysts in this region. Dinoflagellate cyst-based predictive models for winter temperature and productivity were developed from the contemporary distributional data using the modern analogue technique and applied to subfossil data from two mid to late Holocene (~5500 calendar years before present–present) cores; TUL99B03 and TUL99B11, collected from Effingham Inlet, a 15 km long anoxic fjord located on the southwest coast of Vancouver Island that directly opens to the Pacific Ocean through Barkley Sound. Sedimentation within these basins largely comprises annually deposited laminated couplets, each made up of a winter deposited terrigenous layer and spring to fall deposited diatomaceous layer. The Effingham Inlet dinoflagellate cyst record provides evidence of a mid-Holocene gradual decline in winter SST, ending with the initiation of neoglacial advances in the region by ~3500 cal BP. A reconstructed Late Holocene increase in winter SST was initiated by a weakening of the California Current, which would have resulted in a warmer central gyre and more El Niño-like conditions.
Resumo:
Abstract: A vibrant inner city parish needed space for meetings, language classes, children’s play and other support accommodation as well as a clearer link between the interior of the listed church and the space outside.
The project builds itself about the entrance to the church. The form is manipulated such that the intervention recedes from those entering the church, drawing them into the plan before becoming readable as an addition. The resultant poché between this entrance sequence and the fabric of the church is hollowed out to provide the required accommodation. These rooms are insulated and lined in cork to allow for their use separate to the main body of the church. With budget at a premium the construction methodology was developed from an analysis of traditional Irish boat building techniques, which allowed the use of the solid timber to act as the primary structure with no additional material support.
Constructed in solid walnut the intervention reads with the existing brick interior and yet is clearly identifiable as a contemporary addition.
Aims / Objectives Questions
1 To accommodate new space inside an existing protected structure.
2 To form a new threshold between interior and exterior.
3 To develop an affordable means of construction that would be durable and rapid to erect.
4 To make a contemporary addition in sympathy with the qualities of the existing protect structure, in line with best conservation practice and research.
5 Traditional forms of construction as a model for contemporary technologies.
Resumo:
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.
Resumo:
This project involves the construction of a dwelling in the outskirts of Dublin City. Situated in a disused quarry, the house act as an inhabited bridge, spanning between natural and man made outcrops, service structures and a shared entrance staircase. The houses language derives from the structure necessary to achieve these spans.
The section internally is modeled to present a variety of scales of spaces. More intimate living spaces and bedrooms occur in a lower, north-facing wing. Taller living spaces address the south.
Incorporating rainwater harvesting, wood-gasifying boilers, on site wind powered electrical generation, solar thermal panels and very high levels of insulation the houses are close to energy neutral. The fact that the house is constructed in massive timber construction means that 250 tonnes of carbon are sequestered in its construction. The design includes a 25yar replanting strategy to replace the existing coniferous-forested surrounds with native species in a coppiced planting strategy to allow ongoing fuel for the house, and cash crops to be sold on.
Located in an area of outstanding natural beauty the planning and design of the house involved research into patterns of rural development, the relationship between man made interventions and the natural landscape and the technology of the vernacular. This latter research forms part of the themes being explored under the Kevin Kieran Arts Council / OPW Bursary
Aims / Objectives Questions
1 To design and construct a low energy place to dwell.
2 To investigate the relationship between man-made interventions and new construction in an area of outstanding natural beauty.
3 To derive a language of construction that is contemporary in nature but refers to precedents embedded in the vernacular.
4 To develop a low-carbon form of construction that allows the construction of the house to act to sequester carbon
5 To make a contemporary addition in sympathy with the qualities of the existing site
Resumo:
THE MACHINIST LANDSCAPE: AN ENTROPIC GRID OF VARIANCE
‘By drawing a diagram, a ground plan of a house, a street plan to the location of a site, or a topographic map, one draws a “logical two dimensional picture”. A “logical picture” differs from a natural or realistic picture in that it rarely looks like the thing it stands for.’
A Provisional Theory of Non-Sites, Robert Smithson (1968)
Between design and ground there are variances, deviations and gaps. These exist as physical interstices between what is conceptualised and what is realised; and they reveal moments in the design process that resist the reconciliation of people and their environment (McHarg 1963). The Machinist Landscape interrogates the significance of these variances through the contrasting processes of coppice and photovoltaic energy. It builds on the potential of these gaps, and in doing so proposes that these spaces of variance can reveal the complexity of relationships between consumption and remediation, design and nature.
Fresh Kills Park, and in particular the draft master plan (2006), offers a framework to explore this artificial construct. Central to the Machinist Landscape is the analysis of the landfill gas collection system, planned on a notional 200ft grid. Variations are revealed between this diagrammatic grid measure and that which has been constructed on the site. These variances between the abstract and the real offer the Machinist Landscape a powerful space of enquiry. Are these gaps a result of unexpected conditions below ground, topographic nuances or natural phenomena? Does this space of difference, between what is planned and what is constructed, have the potential to redefine the dynamic processes and relations with the land?
The Machinist Landscape is structured through this space of variance with an ‘entropic grid’, the under-storey of which hosts a carefully managed system of short-rotation coppice (SRC). The coppice, a medieval practice related to energy, product, and space, operates on theoretical and programmatic levels. It is planted along a structure of linear bunds, stabilized through coppice pole retaining structures and enriched with nutrients from coppice produced bio-char. Above the coppice is built an upper-storey of photovoltaic (PV); its structures fabricated from the coppiced timber and the PV produced with graphene from coppice charcoal processes.
Resumo:
In this paper, the reliability and thus the suitability of optical fibre strain sensors for surface strain measurement in concrete structures was investigated. Two different configurations of optical strain sensors were used each having different mountings making them suitable for different uses in various structures. Due to the very limited time available to install the sensors and take result, commercially packaged sensors were used. In the tests carried out each sensor was mounted onto a concrete beam which was then subjected to a range of known and calibrated loadings. The performance of the optical strain sensors thus evaluated was compared with the results of conventional techniques. This comparison allows for selecting the best performing combination of sensor/mounting, i.e. long-gauge sensor with mounts bolted to threaded rods glued into the concrete for use in future work in a field test where a limited time window was available for installation, testing and post-test demounting. © 2012 Elsevier B.V.
Resumo:
A vibrant inner city parish needed space for meetings, language classes, children’s play and other support accommodation as well as a clearer link between the interior of the listed church and the space outside.
The project builds itself about the entrance to the church. The form is manipulated such that the intervention recedes from those entering the church, drawing them into the plan before becoming readable as an addition. The resultant poché between this entrance sequence and the fabric of the church is hollowed out to provide the required accommodation. These rooms are insulated and lined in cork to allow for their use separate to the main body of the church. With budget at a premium the construction methodology was developed from an analysis of traditional Irish boat building techniques, which allowed the use of the solid timber to act as the primary structure with no additional material support.
Constructed in solid walnut the intervention reads with the existing brick interior and yet is clearly identifiable as a contemporary addition.
Aims / Objectives Questions
1 To accommodate new space inside an existing protected structure.
2 To form a new threshold between interior and exterior.
3 To develop an affordable means of construction that would be durable and rapid to erect.
4 To make a contemporary addition in sympathy with the qualities of the existing protect structure, in line with best conservation practice and research.
5 Traditional forms of construction as a model for contemporary technologies.
Principal Investigator: Clancy Moore Architects –Colm Moore
Co-investigator(s): Andrew Clancy, Mathew O’Malley
Funding partner/ Client: Select Vestry of St George and St Thomas
Finance. €35’000
Date (start – finished) Start June 2008 – Completed December 2008
Resumo:
Delamination and matrix cracking are routine damage mechanisms, observed by post-mortem analysis of laminated structures containing geometrical features such as notches or bolts. Current finite element tools cannot explicitly model an intralaminar matrix microcrack, except if the location of the damage is specified a priori. In this work, a meshless technique, the Element-Free Galerkin (EFG) method, is utilized for the first time to simulate delamination (interlaminar) and intralaminar matrix microcracking in composite laminates.