Semipermenent Structures.

© Architen Landrell Associates Limited, Station Road, Chepstow, Monmouthshire, NP16 5PF

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Basic Theories of Tensile Architecture

Membrane structures rely on double curvature to resist imposed loads efficiently.

Imagine a flat piece of fabric. An imposed download of snow can only be resisted by tension in the horizontal fibres – a bit like making the catenery cables on a suspension bridge horizontal and expecting them to still carry the weight of the road deck.

In Fig 1, a classic Hyperbolic Paraboloid, any point on the membrane surface can be restrained by the corner points. The two high points pick up any downloads and the two low points resist the wind uplift.

The flatter the fabric, ie the smaller height difference between the high and low points, the greater the resultant loads will be at the corners.

Inflatable fabric structures are synclastic forms where constant air pressure balloons the fabric into shapes also exhibiting double curvature. Anticlastic forms like the Hyperbolic Paraboloid have opposing curvatures.

Other common anticlastic forms are the cone (Fig 2) and the arch form (Fig 3).

Nearly all tensile canopies are derived from either one or a combination of these three shapes. The surface of the membrane adopts a similar kind of characteristic double curvature.

The creative challenge to designers is to explore the development of striking new forms, which satisfy the structural requirements of the membrane’s surface. Developing new shapes


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of push-up elements, and varying the design of the perimeter connections enables dramatic variation in the appearance of a structure.

Membrane forms can be soft or spiky, rotund or leaf-like. They are frequently a combination of these forms.

Pre-Stress is the tensile forces introduced in the canopy during erection.

The shape of a membrane surface is determined by the ratio of prestress in the two principal directions of curvature. These are established in the computer form generation process. The absolute values of prestress are calculated to be sufficient to keep all parts of the membrane in tension under any load case.

Any imposed live load will be carried by redistributing the stresses within the membrane. If this results in any section going into compression, ie going slack, then creases will appear.

Similarly if the prestress is not high enough a snow load could cause ponding.


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Tensile Fabric Structures and Performance WIND A frequently asked question is if ‘tensiles’ are suitable for windy sites. The answer is yes as long as the canopy is properly engineered. In the computer analysis of the different load cases wind uplift is usually as great as the live snow load. A factor of safety between 4 and 6 is then used to select the fabric weight. The detailing of the fittings and surrounding structure needs to take into account the maximum deflections of the membrane. Boundary details need to accommodate the oscillations that may be generated at the canopy extremities. Our conical canopy in Mauritius (see photo library on web site) is 32m in diameter and is designed for and has regularly experienced 150mph winds. In these extreme circumstances an annual retension/maintenance check is recommended. Designing for heavy snow loads requires more care as you have a greater risk of melt water ponding. The profiles would generally need to be steeper and spans smaller. SUN PVC fabrics incorporate UV stabilisers which protect colour fastness and base cloth slowing the rate of degradation, however in high UV areas lifespan will be reduced. After 20 years the PVC will lose its flexibility and will become more brittle. In areas of high humidity regular cleaning will reduce the risk of mould growth on the surface of the fabric causing permanent staining. For a design life of over 10 years in areas of high UV, pollution or humidity, PTFE/glass becomes a better option. FIRE The fire performance of a membrane depends on the basecloth and the seam details. All membranes will de-tension under high temperatures. The speed of this process depends on the temperature and the pretension in the membrane. PVC/polyester will creep at around 70-80ºC and seams will start peeling apart at around 100º. At 250ºC the PVC membrane will melt back from the heat source creating vent holes for heat and smoke. PVC has fire retardants in the coating so that it self extinguishes when the flame source is removed and therefore would not produce flaming droplets. With PTFE fabric the glass base cloth withstands temperatures up to 1000ºC and the openings are limited to failed seams which would part at approx 270ºC. The net effect in a fire can be quite beneficial as most canopy designs form a smoke reservoir which may well allow sufficient time for escape, and when sufficiently hot self venting will occur through a failed seam. Critical steelwork should be supported so that partial failure of a damaged roof will not cause collapse of the structure. The design should consider smoke generated by the membrane used. PTFE fabric used internally may require sprinkler systems or mechanical extraction to reduce toxic fume production at temperatures over 400ºC. THERMAL INSULATION A single layer of either PVC/polyester or PTFE/glass with a typical weight of around 1200gm/m2 has a U Value of approx 4.5 W/m2K. In this respect it is very similar to glass so that a twin skin with a 200mm air gap will give a U Value of 2.6 W/m2K By suspending a quilt in the air gap you can get down to a U value to meet any building code requirements, but you obviously lose the some of the benefits of translucency CONDENSATION As you would expect in some cold weather conditions condensation is likely to occur with roofs covering a sealed heated space. The design of the roof gradients and edge detailing can minimise any problems. Ventilation can obviously reduce the risk but if more control is


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required then it would be necessary to incorporate a second skin and possibly additional thermal quilt. Control of the air flow in the air gap is recommended to get the best environmental control. A sealed air gap is best in winter for insulation and a good air flow in the summer will help cooling. The design of roofs especially conic forms can make use of the passive stack effect ventilation with fans or louvres used to enhance the performance if required. ACOUSTICS A single fabric membrane is virtually transparent to low frequency sound due to its low mass. A double skin with an acoustic quilt interlayer will give you the absorption figures required. Reverbation times on the other hand can be very successfully reduced with tensile fabric linings with acoustic quilt behind either wall mounted or hung on drop wires. VANDALISM Unlike glass or brittle panels fabric is highly resistant to impact damage from blunt objects. It is however susceptible to sharp objects. Small cuts can be repaired with glue-on patches. Larger tears may need specialist repair with portable hot air welders. If an invisible repair is reqired then the membrane may need to be removed and a replacement panel inserted in the factory. Graffiti solvents may damage the PVC lacquers so should be avoided. PTFE fabrics are highly resistant to abuse as paints won’t key to the surface. The sensible solution is to design out the problem as much as possible by putting the fabric out of reach and detail the masts accordingly to minimise the risk of climbing. In vulnerable areas a modular canopy with slide out panels may be a sensible precaution to minimise replacement costs. Some structures such as public bus stops in very exposed sites are probably not ideally suited for membranes. Advantages over overhead glass canopies are that thrown objects tend to bounce off a fabric canopy and the Health and Safety issue of falling glass is largely resolved. CLEANING For the smaller structures this is done with long handled brushes and soapy water if necessary from cherry pickers or tower scaffolds. With the larger membranes trained rope access riggers abseil from high level anchorage points or traverse across the membrane with a ‘Latchway’ or similar restraint system using brushes and water filled back packs or pressure washers. Every structure has its own maintenance manual describing fixing points and cleaning procedures. Ideally canopies should be cleaned annually but PTFE/glass fabric would be the preferred option if cleaning is unlikely or impractical. This is because it’s inherent ‘non-stick’ surface resists pollutant adhesion and allows rain to clean off most dirt. Raw PVC is readily adhered to by pollutants so all membranes are treated with dirt resistant lacquers or surface foils. Careful cleaning maintains their life and the optimum appearance of the membrane. WARRANTIES The fabric manufacturer can issue a 5 year up to a 10 year warranty covering the structural strength and integrity of the fabric. The specialist subcontractor can be asked for a collateral design warranty. Architen are introducing an extended warranty of the complete structure in conjunction with a cleaning and maintenance contract. We recommend that some structures have annual inspections to ensure the ongoing integrity of each critical component.


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Detailing of Tensile Membranes LOAD RESOLUTION Canopies fall into two main types, those that transfer tensile loads into adjoining structures and those containing the tensile loads within their own frame. The first type may generate large lateral loads which may result in the need for additional reinforcement in existing structures. Likewise a typical ‘lightweight’ canopy with masts and cable tie backs to ground level will generally need large concrete foundations or screw anchors to resist the tensile loads. As part of the preliminary design process a provisional load analysis derived from a computer model will give typical loads directions and size of the design loads. BOUNDARY DETAIL The boundary of the membrane falls into two categories: Curved/scalloped edge- This generally consists of a cable slid through a pocket on the edge of the membrane. In larger canopies webbing belts are added parallel to the edge to take out the shear loads. An alternative detail used for PTFE canopies is to have an exposed cable connected to the clamped edge of the membrane by series of stainless steel link plates. Straight edge- The membrane would have a bead/kedar edge formed by sealing a flexable pvc rod in a small pocket. This can then be trapped behind an aluminium clamp plate bolted directly onto the structural steel work or slid into an aluminium luff track extrusion. Canopies can be tensioned by hydraulically jacking up the mast with the base being housed in a sand pot or the mast can be extended with a telescopic section. Corners can be pulled out with rigging screws, U bolts or by the shortening the perimeter mast tie back cables. Individual scallops can be tensioned by shortening the edge cable where the swaged studs connect onto the membrane plate. A very common detail is to pull panels into parallel luff tracks and tension by drawing out the corner plate that slides inside the luff track.

ARCHITEN LANDRELL ASSOCIATES LIMITED STATION ROAD, CHEPSTOW, NP16 5PF

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THE DEVELOPMENT OF AN ACOUSTIC AND DUAL COLOURED PTFE MATERIAL FOR TENSILE STRUCTURES PRESENTING AUTHOR W H BROWN COMPANY LANDRELL FABRIC ENGINEERING LTD., UK ABSTRACT: Landrell Fabric Engineering Ltd. were commissioned to design, manufacture and install an acoustic liner and dual coloured PTFE coated glass cloth material for Skyscape, a prestigious auditorium containing two 2,500 seater cinemas, ticket office and refreshment area, situated next to Greenwich’s Millennium Dome in London. A five Layered, 64-ton inner liner was produced, achieving an overall reduction in sound of Rw 32dB, whilst limiting fire propagation to a high standard. The outer roof consists of a specially commissioned, dual coloured, PTFE coated glass cloth, and fabric liners cover the 22-meter (72 feet) high walls of the auditoria. Over eighty-six thousand square feet of material were used in the construction of this 170 feet by 390 feet building. The building was completed in nine months, and is a dramatic centre stage partner to the Millennium Dome in the United Kingdom’s millennium celebrations. INTRODUCTION This paper concerns Landrell’s development of an acoustic liner for a building called Skyscape. This building was built on the Greenwich site in London as part of our Millennium celebrations and is one of the main attractions provided at the renowned Millennium Dome (Photograph 1). The Dome site is peculiar in that the entire site had to be built from so called ecologically friendly or ‘green’ materials. This meant that none of the buildings could use PVC in their construction, to the extent that the designers considered avoiding the use of electrical wire with a PVC coating insulator.


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Photograph 1. The Millennium Dome, London; Skyscape is the building along the left hand side of the photograph. SKYSCAPE Skyscape (photograph 2) is two, 2,500 people auditoria, linked by a refreshment area, ticket office and other services in between (figures 1 and 2). This building is the first in a new generation of permanent structures, born out of the quick build, temporary structure industry. It has a span of 170 feet and an overall length of over 390 feet, built up in 50 feet modules. In the future, structures of this length can easily be increased by the inclusion of additional modules, and the width can also be increased up to 230 feet. PTFE coated glass cloth was chosen for the outer roof for its durability. It has a life expectancy of around 25 years. It is also a very lightweight material, and is exceptionally strong. When combined with the correct materials it can withstand all weather conditions well. Outer Roof: What make the building interesting are two novel features. Firstly the materials used on the outer roof had to be coloured silver on the outside and black on the inside. No such material existed when we started on the project, and so we had to find a supplier that could carry out the necessary research and development in to the manufacture of this material. After checking with and receiving samples from major fabric manufacturers, we decided to use a material supplied by Taconic International. The material they developed had a bright silver finish on the outside, with an almost matt black finish on the underside. Of all the samples received, this was by far and away the best finish obtained.


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Photograph 2. The Skyscape building at night. Taconic were very experienced in the manufacture of the PTFE coated glass cloth, but nobody had hitherto successfully managed to product this material with a dual coasting. They overcame this obstacle by using the ‘kiss-coating’ technique. This involves passing the 2m wide fabric panels through a series of rollers under tension. When there is a slight lessening of tension between the rollers, the fabric sags just enough to kiss the surface of a bath containing the pigmented PTFE coating material. Taconic claims that this technique allows a fabric with a different colour on each side to be produced for the first time ever. Inner Liner. The second interesting feature of the building was the sound reduction levels required. To stop both local residents in Greenwich and occupants of the Dome being disturbed, the local council insisted that a reduction in the sound of Rw 30dB was achieved (Rw is approximately equivalent to STC), which is about the same level of reduction as 50mm or 2 inches of solid timber would give. We were asked to produce and inner liner to the roof of the building so that this could be accomplished. This lining had to follow the contoured shape of the external roof and act in sympathy with the external tensile structure. We had to manufacture this from a material that would not contribute at all to the propagation of a fire and the material used had to be something other than PVC.


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We found that there was no suitable product on the market ready to use, so we spent a considerable time looking for the correct materials with which to make this liner. In the end we found a supplier who specialised in the production of noise control solutions and produced sound absorbent parcel shelves and panels for cars, tractors, motorcycles and military vehicles. They also worked on cinemas, but we found that the materials used there were not flexible or strong enough to be suspended over a length of up to 13 meters or 42 feet. Acoustics is a very black art indeed. Sound is a medium not dissimilar to water in the way it can disperse. A gap the size of a keyhole will allow the sound to escape from the building. This of course meant that the sealing around suspension brackets and connection details had to be very thorough, and considered with care. In a typical fabric structure there is a high level of reverberation produced within the building envelop. This means that when you make a loud sound, you can hear it for a number of seconds after the sound has been made. In a live concert where loud noises are produced continually, the reverberation causes the noise level to build up within the auditorium and ruin the performance. To limit this phenomenon, the liner inner layer was designed to reduce the reverberation time within the auditoria: hence sound will ‘die’ at a much faster rate than previously.


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For this layer we required a material that would fold without creasing, be easy to work with, readily available, cheap, non-PVC and still conform to the highest flame retardency specification. Spun polyesters were tried but found to be of poor resistance to burning. Another material, called ‘Melatech’, was looked at, but we found that it would break up when folded. We also investigated using mineral wool glass cloth, but found that it was possibly carcinogenic, not to mention expensive. We eventually decided to use ‘Rockwool’, or Glass wool. This is the same type of material that one would find in house insulation. Despite the very unfriendly nature of this material to the skin we felt that this was the best option, as it satisfied all of our requirements as discussed earlier. For the surface finish of this inner layer we needed a matt black finish for which we used a material called E Glass. This is a silicone coated woven glass fabric. This was supplied as a standard finish and suited our needs perfectly. The only problem was that is was glass fabric, and because it only had a small amount of surface coating, was very brittle. Great care had therefore to be taken with the construction, design, and material handling during installation. Another problem with this glass fabric facing relates to the differential of stretch characteristics. When put together with the base polymeric fabric under load, the base fabric will stretch two or three times more than the glass. This gives a significant risk of failure of the glass cloth. We how ever over came this problem by the introduction of quilting. Because the Rock wool compressed during sewing, it effectively caused extra glass to be sewn in to the structure, giving sufficient extra length to compensate for the difference in stretch. This theory was tested by putting a one metre wide section under tension and stretching it with a hydraulic ram until we reached a load of 1.5tons. This was far in excess of the expected load, and well within the capability of the fabric. The main sound-insulating element of the liner is the central layer, a floppy barrier with high damping and low stiffness properties. The heavier this element of the liner is, the greater the overall sound insulating quality of the liner. But because the liner needs to be suspended within the structure, the material needs to be as light as possible. We needed to achieve the optimum performance for a specified maximum mass. Several variants came close to being suitable for this central layer, he most promising being lead based. It was found that lead sheeting had the great advantage of being sewable, and we could have used mechanical fixings such as staples or rivets to hold it together. But unfortunately lead has a ‘memory’, and we feared that once it was folded and stacked it would not hang properly, giving creases, and thereafter a poor finish inside this prestigious structure. Sand was a potentially cheap alternative for the central layer, but would have required a very difficult type of construction. High frequency welding and sand is a bad combination: not only will it cause arcing out of the welding machine when in contact with the welding process but it is also a very messy and labour intensive material. Had we used sand, it would have required a construction form based on rows of tubes filled with sand and sewn together side by side. This could have left gaps between the tubes that would have allowed sound to escape. After further research we identified a material known as ‘Polymeric Mass Layer’@ this is made from waster materials and chalk, and has a rubbery type of construction with some resistance to tearing. It also had sufficient tensile strength to work in this environment. We were initially concerned about the material’s high degree of elasticity; however, tests proved that it was able to hold its own weight over the length we required, and with an adequate safety margin. A suitable material had been found: polymeric mass layer would not crack; it folded without memory, had good resistance to burning, and was not made from PVC.


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Finally, the outer layer of the liner helps control the resonance of the void between the inner and outer layers of the structure. This helps the overall effectiveness of the liner by reducing the build up of noise outside the liner in a similar way to the inner layer of the liner reducing the build up of noise within the structure. With this newly designed, layered fabric construction, we had five layers of fabric to join together and to manufacture into a reasonably tensile structure (figure 3)

Construction. The construction was twofold; we used a laminating process to glue the mineral wool to the mass layer and to the tissue; the whole was then sewn into a quilted finish giving the appearance of a giant ‘puffa jacket’. FTL Happold, based in New York, carried out the patterning, we supplied the fabric and designed the supporting steelwork, and our supplier carried out the manufacture of the quilted layer. They used a team of 30 people, set up in a temporary production line and manufactured the 64 tonnes of fabric in approximately 8 weeks. The Noise Control Centre performed testing of the liner on 29 March 1999 in accordance with current British Standards (BS EN ISO 717-1:1997). The test panel was erected in an aperture of approximately 9 square metres between two reverberant chambers, which were constructed to suppress the transmission of sound by flanking paths. As the test specimen was smaller than the test aperture, the specimen was installed within purpose built a highly insulating infill partition (figure 4). Both chambers were irregularly shaped and contained several reflecting diffuser panels to improve the diffusion of the sound fields. A steady sound source with a continuous spectrum in the frequency bands of interest was used to drive an Omni directional loud speaker, located sequentially in two positions in the source chamber. Sound level measurements were made simultaneously in both chambers at one-third octave intervals from 100Hz to 5000Hz. Measurements were made with a microphone attached to a rotating microphone boom to obtain a good average of the sound pressure levels in each chamber. Measurements were also made of the noise level in the receiving chamber in the absence of the noise source in order that corrections for background noise could be made.


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The weighted Sound Reduction Index (Rw) in decibels (dB) is then calculated by comparing the sixteen values of Sound Reduction Index from 100Hz to 3150Hz with a defined reference curve, which is incremented until the requirements of BS EN ISO 717 are met. We set out to achieve a sound reduction of Rw 30dB, and after initial testing we discovered that this was accomplished (chart 1). A full-scale test on a 9m panel was performed at a later date, and that performance was measured at Rw 32dB. It is likely that the installed performance is even better than this. The design therefore was a success. To make sure that the panels would fit, we used the same patterning process for the liner as the external roof. A computer model was set up by FTL, from which wind and snow loadings were calculated, and patterns were then generated to suit the fabric width. These patterns were sent to us in the UK in digital form, and we then laser cut the shapes from stiff PVC to be used as templates. Because of the multi layered nature of the liner, and as a result of the physical width of the fabric we were now dealing with, the only tool we could find to cut these panels was a jig saw. This crude method did however work, and the panels were passed to the sewing machines for finishing.

Liner Installation. The surface area of material used was 86,000ft2 and the total weight of the lining worked out at 64 tonnes. Due to the sheer bulk of the liner, ten 40ft flat bed trucks were required to carry it to the site, and because of the size of each complete roof section and the weight of the fabric, each of the 16 roof panels were broken down in to 52 pieces: the smallest being approximately 3ft x 21 ft and the largest 46ft x 3 ft. Each piece had been designed to hang from metal brackets on the roof truss and then fixed along the valley using a


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series of metal plates. Each panel was joined together using a high grip Velcro, which was so strong that two men struggle to pull a two-inch strip apart. This meant that we had to be careful during installation not to get a false fitting position. The Velcro also had the advantage of producing an excellent acoustic seal, stopping the leakage of high frequency sound. We assembled the panels together in batches of four, and hoisted them up to the roof on a scissor lift to hang them. It was a simple process but very heavy work. They were installed using two teams of riggers working 12 hour shifts for almost 6 weeks. Internal Walling. The walling had to look the same as the roof, but the building already had metal clad exterior walling which achieved a noise reduction of Rw 27dB. This meant that our quilting was needed to improve the acoustic performance only by a further Rw 3dB. We used a double-sided glass cloth cover over the mineral wool filler and quilted the whole together. Everything was then suspended from the roof and tensioned down to the floor using tubes and ratchets. Installation of the liner took approximately 8 weeks. External Roof Installation. The installation of the outer roof used two teams working around the clock on site and took 12 weeks. As we had manufactured a double skin structure, live loads were now being transferred from the outer fabric membrane to the inner membrane through air pressure and vacuum. Inserting large vents at each end of the structure relieved this. Nonetheless, the acoustic liner had to be strong enough to cope with a proportion of this transferred load, and tests were carried out on the fabric to ensure this was possible. Work on the whole building on site took approximately 9 months including fitting out with a bar and ticket office as well as the two cinemas. Finished Product. Acoustic consultant to the New Millennium Experience Company (NMEC), Jim Griffiths of the Symonds Group described the acoustics of the building as ‘Absolutely Stonking’, which we took to mean that the design was a success! We have received lots of interest on this kind of structure since Skyscape’s construction, and are looking forward to the opportunity of creating more of them around the world in the future. Acknowledgements: The Noise Control Centre, UK Edwin Shirley Staging (ESS) Ltd AIRO (Acoustical Investigation & Research Organisations Ltd) Report No. L/2658 ‘Sealed with a kiss’, ‘staying power’, New Civil Engineer (NCE) Plus, February 2000 ‘Acoustics,’ Microsoft ®Encarta ® Online Encyclopaedia 2000 British Standards Online

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ARCHITEN LANDRELL LTD © 2001

AN ENERGY EFFICIENT FABRIC STRUCTURE

THE CHATHAM MARITIME FOOD COURT=================

PRESENTER: LANCE ROWELL C.E.O ARCHITEN LANDRELL, UNITED KINGDOM

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INTRODUCTION

In response to increasingly stringent rules governing the energy conservation performance of buildings, Architen Landrell has developed a tensile roof system that is capable of meeting the very high thermal values of an insulated conventional roof, while retaining the virtues of sculptural form and a clear structural span. The company has developed a sandwich system and the technology to pattern and join panels that provides an extremely versatile approach to insulating membrane roofs. This system received its debut at the historic naval shipyard in Chatham, United Kingdom. The original shipyard buildings have been restored to create a retail mall, which is augmented by a new food court building that features a 200 ft long arch supporting a tensile fabric roof. The development of the system has created a significant stir in the UK construction world because it has the potential to dramatically expand the number of applications for tensile membrane roofs. People have grown accustomed to tensile fabric being used for stadia and unheated venues, but now the opportunity exists to employ a high performance membrane system as the external envelope for virtually any building. =============================

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HISTORY

The Chatham Outlet Mall has been created in a restored historical landmark building which was originally constructed at Woolwich Dockyard, London, in 1847. It was dismantled and re-erected at its present location in the Naval dockyard at Chatham in about 1876. It comprises a clear central nave with lower aisles running along the North South elevations (fig. 1). The building is historically important as an early example of the use of cast and wrought iron, most of which can still be viewed in the shopping area. The building was the forerunner to some of the greatest clear span buildings of the nineteenth century. After completing the Boiler Shop at Chatham, the contractor went on to build Sir Joseph Paxton’s Crystal Palace for the Great Exhibition ogf1851 as well as Waterloo and Paddington Stations in London. ==========

Fig. 1 Fig. 2 To add a tensile membrane to such a sensitive site may seem a brave move but in fact is was determined by the historically significant building it adjoins. The Boiler Shop is one of the earliest examples of a large scale iron framed building in the UK and the local planning authority was adamant that any extension would stand comparison with the innovative engineering of its nineteenth century neighbour. During the initial design process the food court, with its large tensile membrane roof, offered a double curvature that it markedly different to the angular lines of the Boiler Shop’s iron structure. The planning authority was particularly impressed with the incorporation of a 200ft steel arch from which the fabric is draped, echoing the large spans of the neighbouring Victorian structure. The curvature of the new roof addressed the need for a landmark building that reflected the history of the docks and the sail-like form reminds visitors of the buildings seafaring past. The membrane roof Is 70ft high and supported by the steel arch which transfers the compressive loads to the ground by way of two concrete buttresses (fig. 2). The roof membrane is fixed to a steel perimeter structure supported by seven steel columns which carry the tensile loads to the foundations.

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PROJECT

Recent changes in the laws governing new construction in the United Kingdom have made the incorporation of large tensile fabric elements a considerable challenge for designers. Being such a lightweight material, fabric’s inherent limits of thermal performance severely restrict the applications to which it may be put. The strategy adopted in previous years of compensating for poor thermal performance in some areas with a super insulated construction elsewhere has now been made more difficult to implement. Limits in this ‘trade off’ process mean that the architects wishing to use tensile construction face the prospect of confining its use to areas that are essentially protected external areas or keeping the areas to a minimum. Although various methods of measuring building performance may be used, including quantifying Carbon emissions and whole-life impact, the need to insulate buildings to a much higher standard has become unavoidable. The nEw thermal insulation regulations require a U Value of 0.25W/m2 C (SI Units) or 0.044BTU/hr/ft2 , F for roof construction, which would typically be achieved using six inch think fiberglass quilting. The construction detail must also reduce “cold bridge” penetrations and show a measurable reduction in unwanted air leakage which reinforces the established practice in roofing construction of creating a continuous air and vapour barrier above the thermal insulation layer. Architen Landrell (i) was approached by the architect (ii) to design and supply a tensile membrane roof within a tight budget whilst achieving the new thermal insulation requirement. The company had previously researched lightweight tensile acoustic insulation for fabric structures and had developed a system that was installed in a 1000,000 sq ft demountable theatre at the millennium exhibition site in London. This work was the subject of a technical presentation on the development of an acoustic and dual coloured PTFE fabric for tensile structures at the IFAI Expo 2000 (iii). The company used the lessons learned at that time to develop a method of combining high levels of thermal insulation with a curved membrane form. The method requires three membrane layers (Fig. 3/4); an outer membrane identical to a normal tensile roof; an insulated membrane suspended beneath the outer layer; and a lighter weight inner lining giving the underside for the system a smooth appearance.

Fig. 3

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To ensure that the thermal performance of the regulations was met the insulating membrane was made from a sandwich of Isowool (iv) insulation surrounded by aluminium foil and layers of encapsulated air. To provide structural strength the sandwich has a woven synthetic fabric scrim bonded to the insulation that enables the membrane to span distances of up to 100 feet. The biggest challenge for the company was in devising a system of joining the individual strips of insulated membrane, retaining a continuous thermal barrier, carrying pre-stress an d transient loads and forming a long term vapour barrier. Because of the large volume of insulating membrane the shaped membrane had to be assembled on site. The company developed a mechanical interlocking seal design that enabled the individual strips to be shaped and prepared in the factory but delivered to site in a controlled order and assembled in-situ before being hoisted into the roof space as a complete membrane. It was then tensioned and fixed into place using aluminium strips and webbing tensioners.

Fig. 4

The site jointing and the connection of the thermal layer to the steel arch and the building perimeter were designed to form a continuous vapour barrier to condensation, always a potential headache in a thermally insulated roof space. Condensation forms on the inner surface of the outer membrane and drips down onto the outer surface of the thermal insulation. Channels at the roof’s perimeter collect the drips and allow water to safely drain away to the outside. With currently available insulation materials an insulated membrane roof has one drawback; it is opaque. To let in natural light, a continuous roof light was incorporated into the steel arch that forms the spine of the building (Fig. 5). The loss of translucency of the membrane roof inside the food court area is more than balanced by the glazed arch which illuminates the space with natural light and emphasizes the volumetric space. The inner liner is used as a surface on which to project moving images; emphasizing the relaxed environment of the food court and counterbalancing the busy retail buzz of the shopping area. Fig. 5

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The Chatham Food Court tensile roof provides an extremely significant development in thermally insulated membrane roofs, in that it satisfies stringent thermal performance requirements while providing a visually arresting building within a tight budget. By overcoming the thermal limitations usually associated with fabric, it becomes viable as a building material in areas previously ‘off-limits’ to membrane construction. The widely acknowledged benefits of fabric can now be introduced into considerably more building types where lightweight construction has intrinsic advantages. Fabric has now come of age. Acknowledgements:

(i) Architen Landrell Ltd – design, manufacture and installation of tensile roof and steelwork

(ii) John Muir – Kemp Muir Weallands, Architects, London

(iii) www.isowool.com – Membrane/Insulation

(iv) IFAI Expo 2000, Textile Technology Forum

(v) CMJ3 – Building Developer

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For linear viscoelastic response at low stresses the Master Curve is a representation of creep compliance as a factor of time.The effects of temperature and higher stresses may be accommodated by shifts in the time scale of the master curve.Current compliance at any time comprises an elastic portion D0, independent of time and temperature, and a transient component ∆D(ψ) where ψ is the reduced time that incorporated the effects of temperature and stress :The transient component may be expressed as a series of exponentials in the reduced time :

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0 20 40 60 80 100 120 140 160 180

Time (mins)

Stra

in

e1 (MD Strain)

e2 (TD Strain)

e1* (MD Strain relative to t=60mins)

e2* (TD Strain relative to t=60mins)

ec1 (MD Strain - Cylinder Model)

ec2 (TD Strain - Cylinder Model)

Cylinder Test : Loading Conditions

0.00

2.00

4.00

6.00

8.00

10.00

12.00

0 20 40 60 80 100 120 140 160 180

Time (mins)

Stre

ss (M

Pa)

250

255

260

265

270

275

280

285

290

295

Tem

pera

ture

(K)

S1 (MD Stress)

S2 (TD Stress)

Temperatrure

Cylinder Test : Strain Comparisons

0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2%

0 20 40 60 80 100 120

Time (mins)

e1* (MD Strain : Analysis A)e2* (TD Strain : Analysis A)e1* ( Experiment)e2* ( Experiment)e1' (MD Strain : Analysis B)e2' (TD Strain : Analysis B)

WIMBLEDON TENNIS CENTRE

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Office: 610.882.9030 www.SignatureStructuresHome.com Fax: 610.882.9040

EMERGENCY RELIEF

Signature Structures LLC Provides Shelter!

Along with food and water, shelter is a one of the three basic necessities for survival. Whether you are enclosing people or supplies in times of emergency, Signature is equipped and ready to respond quickly. Industry experience and high quality components separate us from the rest. Our partners span the globe, therefore logistically we can deliver our services worldwide. Designed to withstand the earth’s harshest environments and equipped with nearly any building component, our structures provide the shelter you need now. Turn key packages can be modified to meet any requirement complete with doors, lights, HVAC, flooring, cots, bedding, tables and chairs, etc. In critical emergency situations, you need to be able to rely on a professional team with proven experience. Call today to discuss preventative planning or emergency relief.

APPLICATIONS

• Humanitarian Aid Shelters • Medical Staging Areas • Temporary Housing • Classrooms • Storage & Staging • Equipment Logistic Centers • Supply Chain Hubs • Temporary Manufacturing Facilities • Emergency Services ADVANTAGES

• Comfortable & Well Ventilated • Translucent Membrane Options • Fungal Resistant PVC Membrane • Installs Quickly on Most Surfaces • Re-locatable • Full Engineering Packages • Meets Local Building Codes • Fire Code Compliance with ASTM

E84 and NFPA 701

TM

SCHOOL CANOPIES

Want to create a covered external classroom?

Want to provide children with a covered space for wet playtimes?

Want to provide sun shading for the summer months?

Want a walkway canopy to provide protection between buildings? Want to do all this with a creative but economical solution? Architen Landrell offers a range of pre-designed canopies which are simple but stylish and perfect for the school environment. Our range of structures has been designed with school children in mind. They offer weather protection and solar shading and can be supplied in brightly coloured fabrics. Lighting can also be incorporated to add an aesthetic which other materials cannot. Manufactured using PVC coated polyester, these canopies are quick to install, easy to maintain and an attractive addition to any school playground.

The canopies are mostly designed to be modular allowing linear or L shaped configurations, and are available in a range of shapes and sizes. If necessary, some structures can be supplied in kit form with instructions for contractors or parent teacher groups to install. Some are also available with either solid or mesh roll up sidewalls to give greater sun protection.

Our range of walkway canopies provide protection between one building and another and can be fully enclosed if required. They are available in a selection of sizes to fit your site and are modulated to provide maximum flexibility.

Tensile fabric also allows more complex shapes to be created, so for schools who are looking for an architectural feature, as well as a practical canopy, we can offer our larger standard structures. Drawing on our years of experience of designing complex tensile fabric structures, Architen Landrell have designed and engineered these solutions for

the more adventurous of our school clients! They form excellent play canopies, but also offer outdoor teaching and performance space! These are permanent structures and therefore can be created from either PVC coated polyester or the more durable option, PTFE coated glass cloth. However, not all of our structures are permanent! We also offer demountable structures for schools looking for summer or event canopies.

For more information or for the prices of any of these structures, or to discuss the design of a bespoke canopy please just contact us on: T: (0)1291 638200 F: (0)1291 621991 E: [email protected]

To see a selection of the school projects completed by Architen Landrell come visit our website:

www.architen.com

Southern Terrace Retractable CanopiesClient: Westfield Shopping Towns Year of Completion: 2008 Location:

London, UK

Category:Exterior

Market Sector:Retail

Scope Of Works:DesignEngineeringManufactureProject ManagementInstall

Fabric Type:PTFE - Tenara

Design Style:Awning

Function:Solar shading

A third area of the Westfield site was the venue for yet another Architen Landrell structure inOctober 2008! The Southern Terrace is a row of restaurants, shops and cafes where visitors tothe vast shopping centre can relax and unwind.

When planning the area, the designers were concerned about the solar glare which may affect theview of customers, therefore it was decided that an awning style retractable canopy wasnecessary to provide solar protection. We initially carried out a sun path analysis tocalculate the projection of the sun and the most effective positioning of the shades. From thisinformation, we were able to advise Westfield Shopping Towns of the most appropriate solutionto their solar shading problem.

After a successful design stage, Architen Landrell was awarded the contract to manufacture andinstall 24m of retractable canopy to the exterior of the terrace. Six four metre bays form thebasis for the Southern Terrace installation and provide approximately 500 square metres ofshading for the people sitting below. The awnings were fabricated from Gore Tenara to ensurehigh levels of light would still be transmitted through the canopy. Although mostly fixed, theend section of the canopy contains is fitted with an electric motor which automatically extendsthe canopy projection when the sunlight lowers in the sky.

Like the other Westfield London projects the timescale in which to complete the project wasvery tight. The cladding to the main faade of the building had to be completed before our workcould start which left us with only two and a half weeks to install the steelwork, fabricpanels and electrical elements. As a result, a massive amount of work had to be completed offsite to ensure that installation was as efficient as possible.

The long, narrow nature of the street meant that access was limited and shared with severalother contractors during the day. Like the other projects, the majority of work was completedat night to avoid the crowded environment.

The Westfield London projects have undoubtedly been a success due to the large amounts ofeffort given by all members of the project team. Wed like to say thank you to all involved and...see http://www.architen.com for more information.

© Architen Landrell Associates www.architen.com

semi permanent installation, hire marquees - marquee hire - uk for corporate anniversaries - parties - product launches - storage - company and business events by Complete Events

Semi-Permanent Installation

Client: Panasonic

Our Brief & the Client's Objectives:

To provide a fully operational kitchen and canteen facility within a semi-permanent structure.

The client was undertaking a major factory expansion programme which included the construction of a new canteen facility. It was of vital importance to them that their staff did not suffer a second rate facility (alternatives might have included portacabins and such like) and so the new temporary facility needed to be as close to a tailor-made permanent building as possible.

With over 600 staff working to a 24hr 364 day a year shift programme, and a ten month construction time scale for the new building reliability, comfort and strict hygiene requirements were of paramount importance. With little time for personal involvement the client's demand was for Complete Events to provide a 'Turn-Key' solution of the highest specification.

Our lead time was very short - the whole project was planned and built within a matter of weeks. This included marquee specification brief & design configuration, liaison with the relevant authorities, technical site visits, build, full commissioning & handover of facilities.

Fully

Serviced Temporary Buildings

The facility included:

Immaculate and durable Exterior: Positioned next to a major trunk road a smart exterior to the structure, consummate to the client's immaculate image and profile, was essential. A taught white canvas roof and double skinned metal clad walls ensured this, as well as providing strength and all-weather durability

Kitchen Facilities: Craned in portable (interlinked) kitchen units, including cooking unit, preparation unit and crock wash unit, with accessible filtration sump for catering waste, foul water waste & fresh water supply facilities, underfloor plumbing etc.

Office Space & Dry Storage: Portable units for these facilities were also craned into the structure so that the caterers had a self-contained working area

Spacious Canteen Area: with seating for 200, full roof linings (conforming to BS5438 and BS586 pt.II Flammability Tests), wall mounted television, emergency lighting, notice board areas and in-built fully ventilated smoking area

Multiple Access: incorporating up & over garage doors for loading deliveries, professionally fitted fire doors to meet relevant Health & Safety regulations, and externally lockable doors

Temperature Control: Heat: A 'return air' system allowing for economical heating of the facility, thermostatically controlled for ease of use

Ventilation/Air Conditioning: Air conditioning units for the Summer months and ventilation facility upon 'return air' system for gentle air movement

Semi-permanent propane gas tanks: Propane Gas was selected as the most appropriate (economical and safe) form of fuel for the facility, supplying heating & ventilation units and internal catering equipment. The pipe work distribution system was installed by a Corgi registered engineer

Non-slip floor covering: professionally laid 2mm vinyl Altro, glued and welded for maximum strength

Wall mounted 30" extractor fans, insectocutors and 30" roof mounted paddle fans within the canteen area, fridge and freezer storage, low level strip lighting and internal swing doors

Spacious Service area, with: - Portable bain-marie food service units - Self-service vending machines - Push bar fire exits - Extinguishers/blankets and emergency exit lights - Wall mounted speaker units for in-built PA system - Self service microwave units - Variety of comfortable furniture - Hand washing facilities

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Electric: All power supplied through single and three phase distribution boards, fully protected by OF shunt remotes, with Amp meter load consumption VDUs. Watertight plugs and connectors were used throughout the facility. Easy access manual mains switch and master trips. All tested to appropriate standards

Maintenance: As well as a turn-key product for the client to walk into, we were requested to supply a scheduled support & maintenance service, which kept the space immaculate and allowed us to eliminate avoidable problems before they occurred

Removal: With an extremely quick removal schedule the client could use the canteen structure until the last moment, and have it removed without disrupting the opening of the new facility. The space was left in an immaculate condition, to be returned to car park use the next day

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Complete Events

Events House, Red Shute Hill, Hermitage, Newbury, Berkshire, RG18 9QL, UK

Tel: +44 (0)1635 202 466 | Fax: +44 (0)1635 202 467 | E-mail: http://www.marqueesolutions.co.uk/contact-us.htm

© Copyright 2006 Complete Events and its licensors - All rights reserved. Complete Events is a Registered Trademark of Hutchott Ltd.

Address

http://www.marqueesolutions.co.uk/contact-us.htm

November 23 - 27

Booth # 3A131 - Hall 3

Semipermenent Structures.

Documents

Transcript of Semipermenent Structures.