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Aluminum curtain wall design guide manual free download.Curtain Walls
An object brought out into the sun is heated by the sun s near infrared short-wave radiation, raising the object s temperature. The object re-radiates far infrared long-wave radiation based on its emittance a property of the material.
The higher the emittance, the more it re-radiates the sun s heat it has absorbed, reducing its surface temperature. The lower the object s emittance, the less it radiates heat, increasing its surface temperature.
Emissivity is a term used to describe the ability of a surface to reflect infrared radiation. Polished metals are materials with low emissivity low-e surfaces, whereas dark and dull surfaces generally have high emissivity.
Thus, thin layers of tiny metal particles can be applied to glass to create low-e coatings beneficial in reducing outdoor solar heat gain in summer and indoor thermal heat loss in winter. Another method of reducing heat gain other than low-e coatings is by physically blocking solar radiation from reaching the glazing.
Sunshades are effective when used on the outside of the curtain wall. In contrast, little benefit is gained by placing shading devices such as blinds on the inside of the wall to control heat gain because solar radiation is absorbed then re-radiated to the interior space.
Deciduous trees are used in a similar manner to sunshades in residential areas by locating them to shade window openings, where heat gain is the highest in summer; then in winter when their leaves fall off solar heat gain contributes to the heating requirements as passive or free heating from the sun. This increases indoor temperatures and simultaneously increases HVAC cooling loads in summer. In winter, passive heating, intentionally allowing solar radiation through the glazing, can be used to advantage in heating-dominated climates.
Controlling heat gain with glazing is achieved with tinted glass, reflective coatings, and low-e coatings. Tinting of glass is achieved by chemically altering the glass composition by adding metals and metal oxides. Tinted glass absorbs more solar radiation than clear glass but without a low-e coating will heat the inboard lite through infrared radiation, which in turn radiates to the interior space. Tinted glass is usually not a preferred method of reducing solar gains, because high proportions of visible wavelengths are blocked, thus reducing desirable visible light transmittance.
Low-e coatings are better suited for glazing, because they can block the solar infrared wavelengths with less effect on visible transmittance. Reflective or metallic mirror coatings can be applied that reflect most wavelengths of solar radiation, but the main drawback remains insufficient visible light transmittance. The newest technology in metallic coatings is thin layers of metallic particles called low-e coatings.
The level of sophistication of these coatings is such that all wavelengths can be efficiently reflected or absorbed while still allowing visible light transmittance. These are called spectrally selective coatings, or low solar gain coatings.
Nonspectrally selective coatings allow transmittance of visible and infrared solar radiation, providing passive solar heating in heating-dominated climates. Higher-performing curtain wall can reduce the amount of solar heat gain that enters the interior space by the use of tinted and low-e coated glazing and by thermal separation of aluminum framing. Vision openings are the main source of heat gain because of the transparent properties of glazing. Spandrel openings are opaque by definition and therefore are not a significant contributor to solar heat gain.
The measure of a curtain wall s performance against solar heat gain is the solar heat gain coefficient SHGC. SHGC is a unitless ratio between zero and one, with zero indicating no heat gain and one indicating all incident solar radiation contributes to heating the indoor space. A wall s SHGC can be determined by full-scale laboratory testing or by computer simulation.
The overall curtain wall SHGC has two components: glazing and framing. Glazing permits indoor heat gain through direct transmission, absorption and re-radiation, and convection. The portion not transferred to the interior either is reflected back outdoors or absorbed and reradiated outdoors.
Framing is opaque and therefore cannot transmit solar radiation but can contribute to indoor heating through absorption and re-radiation and convection. When determining the overall SHGC, the same area weighting procedure that was used for u-value applies. The difference is that SHGC for cog is identical to eog because of the one-dimensional nature of heat gain across the glazing.
Visible transmittance, solar heat gain, and heat loss u-value are the three primary criteria in the selection of glazing. The glazing makeups shown in Table are commercially available at the time of this publication and were selected to provide comparisons of how optical, solar, and thermal performance of glazing is affected.
All makeups in Table consist of clear 6 mm lites unless indicated with a tint, reflective, or low-e coating, which is always located on the air space side of the lite. All units consist of a The percent difference is based on makeup no. Metric u-values can be converted to imperial by dividing by 5. Tinted glass causes no change to u-value but decreases the SHGC owing to solar infrared absorption with a corresponding reduction in visible transmittance VT as indicated in makeup no.
Tinting is not the most effective method to reduce solar heat gain, because the emissivity of the glass is unchanged. A reflective coating in makeup no. But the tradeoff is a significant reduction in visible transmittance. A slight reduction in u-value is because of the reduction in coating emissivity to from 0. Low-e coatings are effective at reducing u-value while allowing higher visible transmittance levels.
Low-e coatings do not generally change the appearance of glass, making them difficult to detect by visual inspection.
Makeups 5, 6, and 7 are examples of low-e coatings with varying emittances ranging from about 0. Low-e coatings are unique materials, because emissivity varies over the UV, visible, and solar infrared spectrums and can be modified to block certain spectra while transmitting others.
A high solar heat gain coating as in makeups no. Again, u-value decreases with decreasing coating emissivity even when the low-e coating is on the third surface as seen in makeup no. The drop in SHGC results from the low-e coating placement moving to surface 3, allowing more solar radiation to reach the inboard lite to re-radiate to the interior. This is a form of passive heating beneficial in cold climates.
Replacing air with argon in the air space has the effect of reducing convective heat losses due to the lower density of argon gas compared with air. In makeup no. Makeup no. The tradeoff is also the lowest VT of all the combinations listed, which negates the benefit of natural lighting gained from using glazing.
U-value is unchanged from no. Triple glazing allows further gains in u-value through the use of dual low-e coatings and argon gas fill. Makeups no. The decrease in VT is the third highest but is far less than the performance gains from u-value and SHGC nonetheless a tradeoff to consider. The makeups in Table are only one example of each step in glazing performance.
Numerous combinations of units and makeups are available from glazing manufacturers with variations in VT, SHGC, and tint. A spectrally selective low-e coating with given emissivity can have several VT levels with and without tints. Each manufacturer s line of low-e coatings has its own transmittance and reflectance over the three radiation spectra, which affects performance. For project-specific glazing requirements a glazing manufacturer should be consulted to narrow the choice of available products.
Knowing the relationships among u-value, SHGC, and VT will help in the selection of the optimum glazing makeup on the basis of the priorities of the project and help to understand the tradeoffs that accompany the available glazing options. However, air leakage of conditioned interior air is a source of energy loss.
The conditioned air required energy input from the mechanical system to cool or heat it depending on the climate and season. Loss of that conditioned air through cladding leakage requires sooner replacement of that lost conditioned air to maintain desired interior conditions. A leaky curtain wall can be compared to a leaky faucet, the water dripping down the drain a small but constant loss added to the household water bill.
If small openings in curtain wall are present, air leakage flow is driven by pressure differentials across the wall created by the mechanical system, stack effect, and pressure differentials from external wind pressure.
A tight curtain wall prevents energy loss due to air infiltration. An air-tight curtain wall is created by sealing joints between adjacent materials and framing members. Proper detailing of project shop drawings is important. Perfect air tightness is not practically achievable, so an upper limit is specified for mockup performance testing or field testing. Dew point DP temperatures for a range of air temperatures and humidity levels are plotted on a psychrometric chart Fig.
The condensation referred to here is that which appears on interior surfaces of the air or vapor barrier, inside the building, and can lead to indoor performance issues resulting from mold, staining, and corrosion.
Condensation on the exterior of the air or vapor barrier, outside the building, does not affect the indoor environment. Northern, heating-dominated climates increase the importance of condensation in the design of a curtain wall system where outdoor design temperatures can range from 15 C to 30 C. Interior surface temperatures are relatively low because of a conditioned space that is being cooled. Hot and humid outdoor air contacting a cool interior surface can cause condensation.
Under these conditions, interior surfaces temperatures can be below the DP temperature of hot and humid infiltrating outdoor air. Surface temperatures can be determined and condensation assessed by two methods: mockup testing and computer thermal modeling. Mockup testing for condensation is usually one of the tests performed during mockup performance testing. The conditions at which condensation is to be determined are specified at the time the project is tendered. Condensation performance in this case no condensation is to be met at these conditions.
The corresponding dew point temperature from Fig. Thermal modeling of framing members also can be performed to determine surface temperatures that drop below 1. Where condensation occurs, the framing or glazing can be thermally improved to prevent condensation. Center of glass temperatures rarely drop below the DP temperature. Section 5.
Conductive heat loss of framing members and surface temperature generally have an inverse relationship: the higher the conductive heat loss, the lower colder the surface temperature. Framing members and eog are the highest heat loss u-value components because of the high conductivity of aluminum framing members.
Conductive heat loss governs these components. As a result, condensation, if any, generally will occur on framing members and eog. The same thermal improvements applied to framing and eog u-values also can be applied to improve condensation resistance.
Wider thermal separation of member inboard and outboard extrusions using nylon thermal breaks reduces conductive heat loss. Substituting a warm edge spacer for an aluminum spacer in the IGU also will reduce convective heat loss at the eog and framing.
Stainless steel spacers are available that are thinner than aluminum and inherently less conductive. Aluminum is nearly 10 times more conductive than stainless steel. The programs are updated regularly along with a glazing database of commercially available glazing called the International Glazing Database IGDB. The IGDB contains more than 1, entries from numerous suppliers. Products range from clear glazing of all thicknesses to tinted lites, reflective coated lites, low-e coated lites, laminated lites, and more.
Optics is useful for comparing transmittance and reflectance among glazing products in the IGDB over the solar and long-wave spectrums. It allows easy evaluation of the spectra transmitted and reflected by the various low-e products available. Existing products also can be modified if not available in the IGDB. For example, most lites in the database are nominally 6 mm thick. If the optical properties of a 10 mm lite were needed but only 6 mm were available, a new lite can be created as a user-defined product and Optics will calculate its optical properties.
Window is set up to take glass and frame thermal properties from lists the user specifies and use them to perform area-weighting calculations for u-value and SHGC making it much faster to work with than a spreadsheet.
Therm is a two-dimensional heat transfer finite element program used to model eog and framing members. It imports IGUs from Window for modeling eog and can import. It has its own library of standard building materials with associated thermal properties, although user-defined materials can be created if not in the library.
GANA glazing manual, 50th anniversary Ed. Topeka, KS. Struabe, J. Building science for building enclosures. NFRC simulation manual. Insulating glass specs and tech.
Brown Waterproofing design of curtain walls is critical to maintaining the safety, comfort, and thermal performance of a building and its occupants. Although rain, especially when driven by wind, provides the greatest challenges to the waterproofing professional, other factors, such as condensation, must be accounted for also.
Gravity, kinetic energy, air pressure differentials, surface tension, and capillary action all work to provide a means for water to enter into buildings. This chapter discusses the natural forces that act on a curtain wall and some of the solutions that various systems use to maintain the watertight integrity of the building.
The curtain wall must incorporate various features such as thermal breaks for the frames, double or triple glazing for the vision area, and an insulated spandrel pan area. Connections and fasteners may also include thermal breaks or thermal separators.
Frame geometry for thermally conductive aluminum frame materials can be altered to minimize the proportion of framing exposed to the outdoors Thermal Breaks Aluminum has a very high thermal conductivity. Many manufacturers incorporate thermal breaks with low conductivity materials, such as PVC, The polyamide between the aluminum frame sections at the perimeter of the glazing panes acts as the thermal break.
The thermal break separates the interior right side aluminum material from the exterior left side aluminum material, effectively breaking the thermal conductivity from inside to outside or vice versa. The glazing units must be retained in the curtain wall in a manner robust enough to withstand wind loads, seismic loads, and thermal expansion.
Consequently, metal pressure bars or pressure plates are fastened to the outside of the mullions to retain the glass. To prevent thermal conductivity, these systems frequently include protective gaskets, which function as thermal breaks.
Because these gaskets are not expected to remain completely watertight for long-term service, a properly designed system will channel the water and vapor that enters the system at the gasket corners. Ideally, moisture will be managed correctly to weep out through the snap cover weep holes or other drainage slots. Pressure Plate Typ. The glass is retained at an interior mullion with the use of an exterior pressure plate and snap cover with weeps drilled per the manufacturer s requirements.
According to the manufacturer s installation instructions, the vertical gasket runs through the joint plug notch at the horizontal location, and all corners of the gaskets are sealed. Many other manufacturers use similar technology Insulation Thermal performance of opaque areas of the curtain wall is a function of insulation and air or vapor barriers.
Proper placement of insulation at the curtain wall perimeter reduces energy loss and potential condensation issues. Mineral wool insulation at the perimeter of the building provides thermal performance in addition to fire protection. The International Building Code ICC requires that an approved system such as mineral wool be used to provide a barrier to prevent vertical fire spread in the interior void between the exterior curtain wall and the floor assembly.
As seen in Fig. These materials also minimize the potential for condensation in unconditioned space. Projects for which condensation control is a critical concern, such as high interior humidity buildings, require project-specific finite element analysis thermal modeling using software such as Therm.
Therm is a state-of-the-art, Microsoft Windows based computer program developed at Lawrence Berkeley National Laboratory LBNL for use by building component manufacturers, engineers, educators, students, architects, and others interested in heat transfer. Therm models two-dimensional heat-transfer effects in building components, such as windows, walls, foundations, roofs, doors, appliances, and other areas, where thermal bridges are of concern.
Therm s heat-transfer analysis allows evaluations of the product s energy efficiency and local temperature patterns. These specific details may relate directly to problems with condensation, moisture damage, and structural integrity. The top screen shot shows the model with various building components identified by different shades, and the bottom screen shot shows the resultant temperature gradient as calculated by the program.
This particular screen shot shows that the temperature outside is cold, and it moves toward warm in a distinct pattern. The larger the CRF number the. O Brien states that AAMA intends designers to use the CRF in construction specifications to prescribe a level of condensation resistance for fenestration products. Both the glass area and the frame are tested at various locations to determine the interior and exterior temperatures with a thermocouple device.
If a designer wants to reduce the chances of condensation occurring on the windows in a building, he or she will specify a high CRF. In warmer climates, a designer may specify a lower CRF, as the risk of condensation on windows is reduced and the cost savings associated with buying windows with lower CRFs is more attractive.
Watertight frame corner construction and good glazing pocket drainage, where applicable, are critical to prevent water penetration to the interior or onto insulating glass below.
Vigener and Brown state that water penetration resistance is a function of glazing details, frame construction and drainage details, weather stripping and frame gaskets, interior sealants and perimeter flashings and seals.
These components counteract the five different forces that contribute in whole or in part to water intrusion: gravity, kinetic energy, air pressure difference, surface tension, and capillary action. Wind loading, which is described in depth in Chapter 7 of this primer, creates pressure differentials caused by a variety of factors. Wind loads are calculated into pressures based on wind speed in a geographical region, building height, and other dimensional characteristics. Exposure to water in urban or suburban settings, type of building, and other factors are characteristics that are unique to that particular building.
These pressure differentials can cause windblown rain to exceed the force of gravity and allow water to travel uphill. Thermal expansion of various building materials can affect directly or indirectly the capillary influence and surface tension characteristics of the curtain wall components.
As materials expand and contract at similar or different rates in reaction to temperature changes, the joints can become tighter than anticipated, thereby enhancing capillary action between the components. Similarly, the curtain wall materials generally interact with other building materials via abutment to columns or wall panels and via wall anchorages. Surface tension characteristics of the assembly can change in response to these expansions or contractions resulting in unintended.
Seals, gaskets, and movable joints must be designed into the system to accommodate the differential movement among these elements Design and Detailing of Flashing and Weep Holes Curtain wall design should start with the assumption that external glazing seals, perimeter sealant joints, and curtain wall sills are not water tight.
Each type of system has its own unique method and components to shed or manage moisture. Structural silicone glazed SSG systems may appear to be reliant on sealant only, but in fact they rely on a complete waterproofing system as shown in the following examples.
Unitized systems, which are manufactured in a plant setting and installed in large sections in the field, are self-contained and compartmentalized. Stick-built systems are manufactured in the field and rely on careful integration of adjacent parts and pieces to remain watertight at joints and interfaces. Pressure-equalized systems are designed on the premise of compartmentalization and venting.
Integration of perimeter flashings helps ensure watertight performance of pressure-equalized curtain wall and its connection to adjacent wall elements. The drainage system must be designed to manage condensation and rain in all cases. Drainage features include frames sloped to the exterior, large closely spaced weep or vent holes, and drainage at each horizontal mullion. The moisture infiltration control is provided by drainage cavities in the system behind the structural silicone sealant directing water to weep holes at the stack joint.
Water flows down the drainage cavity in front of the air seal and will weep at the sill in a manner such as is seen in Fig Fig. The perimeter of the frame is sealed and weep holes are drilled into the sill of the perimeter anchors at specified intervals.
The perimeter sealant is a critical component and should be coordinated between the manufacturer of the curtain wall system and the sealant manufacturer. Any substrate adhesion issues at adjoining construction must be coordinated as well. In some instances, primer may be needed to ensure a proper seal. PER systems block the forces that can drive water across a barrier. The air pressure differential is the predominant force that drives a considerable amount of rainwater into the wall assembly according to Rousseau, Poirier, and Brown of the Canadian National Research Council.
According to Rousseau et al. In its basic form, the outer cladding screen blocks most but not all of the water; the pressure-equalization chamber consists of airtight selfcontained compartments, and the open joints or air vents allow air pressure to vent, equalize, and eventually drain any moisture at the sills that may enter the system. The concept is common with many unitized systems manufacturers.
Wet glazing and pocket sills that collect water that penetrates the glazing should be sloped to drain toward the exterior of the system. The unitized system is sealed to the end dam to prevent migration of moisture from one component to the next. This installation is shown in the isometric view of Fig In the System by Kawneer, the specifications state, Water Drainage: Each lite of glass shall be compartmentalized using joint plugs and silicone sealant to divert water to the horizontal weep locations.
Weep holes shall be located in the horizontal pressure plates and covers to divert water to the exterior of the building. As stated in the installation manual, the air and water performance of the Reliance curtain wall system is directly related to the completeness and integrity of the installation process both the seal installed at the shear blocks and the glazing gasket installed at.
All pressure plates must also be installed properly. The installation of zone plugs shown in Figs and are designed to divert water from the verticals onto the horizontals where it is wept out of the system to the exterior at the horizontal pressure plate. These figures also show the installation of mullion end caps, which are designed to maintain continuity at the perimeter seal and extend the perimeter sealant line out at the mullion to simplify the installation.
They may vary in design or installation technique, but. The designer must understand the manufacturer s details and moisture strategies to make certain that unintended circumstances, such as blocking weep holes or cutting flashing short for interior finishes, is avoided at all times. A pressure-equalized rain screen system will simplify the designer s job by allowing nature to do much of the work to combat the forces to which the curtain wall will be subjected.
The air seals, air barriers, and venting must be carefully inspected, but the long-term performance of the system will be well worth the initial attention to detail. Force sealant into all races on face of mullion. Voluntary specifications for aluminum, vinyl PVC and wood windows and glass doors. Birkeland, O. Garden, G. Rain penetration and its control.
International building code, chapter 7, section Kawneer, an Alcoa company. Series curtain wall architectural detail manual, 4, Norcross, GA. O Brien, S. Finding a better measure of fenestration performance: An analysis of the AAMA condensation resistance formula. RCI Interface, 5, Oldcastle. Vigener, N. Whole building design guide Curtain walls. Clift and Noah Bonnheim A curtain wall is usually the first building component loaded by wind.
The curtain wall engineer intuitively knows that wind effects on a structure will probably control the system s structural design, but the process of quantifying appropriate design criteria is not obvious.
This process involves bluff body aerodynamic analysis, rigorous consultation with and adherence to established code sources, careful selection of material composition and geometry, consideration of manufacturing and installation limitations, and other considerations. The process requires accurately tracing a wind load from its initial interaction with the outer curtain wall panel surface to its perimeter supports, onto its framing members, and finally to the building s primary structure.
Attention to detail is paramount. The curtain wall industry requires material quantity optimization on a scale far greater than the structural steel or concrete industries. Most structural engineers trained in steel and concrete construction round off to the nearest inch, but the expense of aluminum alloy materials and the intricate fit of detail assemblies in the curtain wall industry require accuracies to more than one thousandth of an inch.
Successful curtain wall design for wind loads requires the ability to model three-dimensional objects as they are acted on by a load and forecast how that load is distributed and resisted in a structure. Modeling techniques include free body diagrams and finite element analysis using computer software, among others.
This analysis requires a conceptual understanding of the design components and hierarchical structure of curtain walls.
These continuous and usually stout structural elements provide ideal locations for anchorage of a wall system. Hence the curtain wall is organized as vertical elements hanging over the side of each perimeter and spanning continuously from floor to floor.
The curtain wall framing system, its connection assemblies, and its anchorage to the primary building structure are where the curtain wall engineer really focuses effort Hierarchy for Structural Design and the Load Path The first element loaded in a curtain wall is a large area of glazing or other panel surfaces that bluntly resists oncoming wind pressure.
These panels then transfer their load to stiffeners or perimeter supports. The perimeter supports either directly or indirectly dump load to linear continuous framing members. These framing members often are arranged in an orthogonal grid pattern of beam-column mullions that span from floor to floor and transfer accumulated loads to the primary building structure.
These last supports are designed as embedded anchors with direct welding or bolting to steel and concrete components Fig. Fig Basic curtain wall structure; wind load flows from the panel surface to perimeter supports, onto framing members vertical mullions and horizontal beams , and finally onto the building s primary structure. Generally, a rectangular panel or glass unit is assumed to be continuously supported around its edges by these horizontals and verticals. The priority of using vertical mullions as the primary framing members is valid in stick-built or unitized designs.
The curtain wall engineer needs to communicate the final reaction values and locations exerted by the curtain wall on the primary building structure to the building s structural engineer. This coordination will confirm the building s capacity to receive and resist curtain wall loads properly. If wall openings are present during a wind event, alternate load paths may occur. Interior pressures can develop that may or may not act in concert with exterior pressures.
This scenario should be considered in projects that have, for example, operable windows and doors, vestibules, and large mechanical ventilation areas Design of Glass Thickness Architectural flat glass is a proprietary product that enjoys a very high profile, often as the most significant visual feature of a building.
Sizing of glass thickness will involve engineering parameters and issues related to aesthetics and manufacturing. To size glass thickness properly, the basic influences are values of span and load.
Shading temperature effects also may affect design for stress capacity. Heat treatment of flat glass during the manufacturing process has a significant effect on strength by prestressing its surface.
Industry standard requirements have been established that define stress limits for three glass types: annealed, heat strengthened, and fully tempered. The controlling influence with respect to load is usually wind pressure; however, some projects require blast loading or debris impact conditions.
Typically, the glass manufacturer will provide review and analysis of applications on a specific project and render its approval. Architects will write performance specifications that may have deflection limits or other items that influence design of glass lites. Stiffness design of glass panels is somewhat subjective. Limiting the magnitude of center of glass deflection should include considerations of occupant comfort, interference with adjacent materials, potential for accumulated movement, or loss of bite.
Distortion from heat treatment of glass may be minimized by selection of thicker panels to improve flatness. Lateral pressures are assumed to be uniformly distributed over the entire surface area of the glass panel.
In lieu of a traditional glazing pocket design, SSG can accomplish a flush profile of glass-to-glass surfaces without any exposed metal.
When all four edges of a typical glass lite are adhered with structural silicone, the only component holding the unit against wind load is the rubber adhesive. Because no mechanical restraints sit around the edges of the glass, structural engineering experience must merge with hyper-elastic rubber theory to achieve integrity.
Fig Plan view of a structural silicone glazing design. The small but continuous bead of structural sealant offers considerable shear and tension values that directly transfer in-plane edge shear forces. This characteristic of SSG is particularly helpful in designing corner conditions in curtain walls. To control loss of glass bite due to in-plane force vectors at corners, one may estimate resistance by dividing the load over the perimeter length of SSG and comparing to allowable strength.
The critical issue with SSG is accomplishing a secure bond between substrates of glass and aluminum. The wide selection of glass coatings and metal finishes available makes sealant compatibility testing a challenge. Proprietary silicone products have been developed by a few manufacturers. Early designers used patch fittings, which are small rectangular metal clamps at discrete points around the glass perimeter in lieu of continuous glazing channels or pockets.
Eventually, these patches were supplanted by drilling holes completely through the glass thickness and installing tee-headed bolts or button discs to restrain the panel. Today, some manufacturers use countersunk holes in the glass so that no metal fixture is visible on the outside surface, just the bolt hole itself Fig.
Dimensions required for countersunk profile will influence selection of glass thickness. Fig Plan view of a countersunk hole design.
In lieu of an orthogonal grid of aluminum framing, designers use spider fittings on space frames, tension structures, and cable networks to emphasize the creative freedom of support styles. However, ASTM E does not address point-supported glass boundary conditions, so finite element analyses via computer programs with large deflection capabilities are needed e. Fracture mechanics will control failure behavior, so while advanced finite element analyses are possible, concentrated stress around the hole at a point support may require empirical data to verify capacity Structural Glass Structural glass is a largely uncodified area of building design and construction.
It is a non- load bearing element, supporting only its weight, no other vertical loads. The advantage that alluminium offers is that of being able to be easily extruded into nearly any shape required for design.
Professionals involved in design, fabrication and construction of such systems receive their training on the job and learn the fundamentals through experience of working on different projects. The processes involved in the manufacture of curtain wall systems are: fabrication, assembly, glazing and installation. All these are made on the aluminium extrusion framing members.
In order to make the frame water and air tight, joints of the frame need to be covered with sealant, the insulation is attached to spandrel openings. There are different infill types; the most common one is an insulated glass unit.
Other infills are aluminium, stainless steel or granite panel. The area between aluminium framing members occupied by an infill is called a vision or spandrel. Weather made using a stick system where components are assembled on site or unitized panels using prefabricated, large scale units , building envelopes must be watertight, i. If the model performs as expected, it passes; otherwise, remediation measures are required, and the system must be modified so that it can pass a retest Fig.
Temperature fluctuations critically affect wall details, all building materials expand and contract to some extent with temperature changes, but the amount of movement is greater in aluminium than that in most other building materials. Images from above Fig. Stick built curtain wall is fabricated in the shop and shipped in pieces to the construction site where it is assembled and glazed. Most of the wall production takes place onsite.
Being assembled and glazed outdoors in full exposure to the weather is the most important drawback of stick-built wall systems. Because it is difficult to obtain a good adhesion of the sealants to the joint surfaces they are sealing in variable weather conditions. Unitized curtain wall systems benefits form indoor assembly and glazing, improving its durability. The time required to close in a building is greatly reduced compared with stick-built systems, because most of the production is done in the shop.
Installation involves placing preassembled and pre-glazed frames on a building. Typical curtain wall is made up of transparent vision glass and opaque spandrel-glass infills supported by a metal framework of aluminium extrusions.
Other common infills are: stainless steel panels, painted aluminium panels, granite, limestone, marble, combination between glass and metal panel called a shadow box , vents and louvres. A typical spandrel infill consist of insulation adhered to a galvanized steel sheet backpan or foil back insulation , premanufactured insulation adhered to aluminium foil, inboard of a single insulating glass unit IGU.
Glass requires contact with soft materials called glazing gaskets such as high durometer rigid rubber or silicone to prevent breakage. Low durometer soft gaskets are used at split vertical and horizontal members to form seals against air and water. The vertical extrusions are called mullions or verticals and support the infill and horizontals. The bottom horizontal member in the vision opening is called the sill. Two methods are used to retain glazing: capped systems and structural silicone glazed systems.
There are variations of capped systems where all four sides can be captured, called four-sided systems, but any combination is possible. Structural silicone glazed systems SSG SSG use structural silicone sealants that adhere the glazing to the frame gluing the glazing. The visual difference between the two methods is clear, first one appears to have a picture frame of painted aluminium around the glazing and the second method has an uncluttered appearance, giving the impression of a wall of continuous glass.
Curtain Wall - Custom system of clear and translucent glass louvers suspended on extruded aluminium framing members, in front of a load-bearing reinforced-concrete wall with punched windows Fig.
These louvers are mounted on vertical rails of anodized extruded aluminium that are suspended from the concrete wall on aluminium brackets at each floor level. The glass is factory-glazed along each edge with a structural silicone sealant that adheres it to a minimal frame of extruded aluminium. These units are then mounted onto Y-shaped aluminium mullions, spanning vertically from floor to floor, that bend and twist.
Near the centre of the facade, a portion of the wall peels away from the building mass to form a canopy, sheltering the street entrance and revealing the construction method of the curtain wall Fig. Portions of the undulating wall project outward by as much as 1. With such variation in orientation, the glass surfaces simultaneously transmit and reflect sunlight through and across the facade. The double-pane insulating glass includes a high-performance low-E coating on the second surface for improved thermal performance as well as a silkscreened pattern of white ceramic frit dots for solar shading covering 40 percent of the surface.
The first level is the public free zone, followed by two levels of temporary and permanent gallery space. The brushed-finish stainless steel sculptural elements have a field-applied light catalyst titanium coating that causes water to bead up on the surface, keeping it dry, and makes the material self-cleaning so that pollutants do not damage the metal and cause corrosion.
The overhead glass panels have a white ceramic frit pattern to reduce solar glare. Where a stainless steel stalk passes through the glass enclosure, it is fitted with a synthetic rubber bellows and a gasket for weather-tightness. Just below the bellows is an electrified stainless steel coil-woven sleeve that mitigates thermal bridging in cold weather, preventing condensation from forming inside the building.
Main Entrance Model showing the structure of sculptural form Fig. Steel pipe roof structure 3. Insulated safety glass 8. Aluminium gutter 9. Thermal break Silicone joint sealant Weep Pre-molded rubber seal High strength nut Fig.
Steel pipe roof structure 2. Stainless steel gusset plate 3. Insulated safety glass 4. Condensation drainage valve 5. Silicon glazing seal 6. Insulated safety glass 7. Aluminium mullion 8. Aluminium gutter Aluminium closure panel Steel base plate Primary stainless steel closure plate 2. Secondary stainless steel closure plate 3. Primary water stop 4. Secondary water stop 5. Insulated safety glass 6. Low voltage electrical wire 7. The curtain wall design contributes to the reading of the building as lighter and less solid, thanks to the glass corners on each floor where the tower is recessed.
The glass used throughout the tower is a sealed, double pane unit with a high-performance coating on the number 2 surface that achieves a shading coefficient of 0. The glass has a reflective quality to it, and the color is slightly green, which unifies the entire curtain wall surface vision glass and spandrel glass panels Fig. Double glazing unit, vision glass area 2. Local aluminium angle cleat in transoms to fix corner mullion 3.
Painted aluminium extrusion 4. Back of mullion 5. The architects worked collaboratively with the graphic designer Jaap Drupsteen and the glass manufacturer Saint- Gobain to develop a method of transferring the selected film stills onto glass by CNC- milling them onto a wood panel, which was then used as a mold onto which the glass, along with colored ceramic paste, were placed and then heated.
The inner wall varies from clear insulating glass to a solid, opaque wall. At the office wing, the inner wall alternates between steel-framed insulating glass windows and precast- concrete wall panels faced with insulation and fiber-cement sheeting. Building section Partial elevation Fig. Perimeter sealants, properly designed and installed, have a typical service life of 10 to 15 years.
Removal and replacement of perimeter sealants require meticulous surface preparation and proper detailing. Aluminum frames are generally painted or anodized. Care must be taken when cleaning areas around anodized material as some cleaning agents will destroy the finish.
Factory applied fluoropolymer thermoset coatings have good resistance to environmental degradation and require only periodic cleaning. Stainless steel curtain walls require no coatings, and modern, embossed, as opposed to abrasively finished, surfaces maintain their original appearance indefinitely without cleaning or other maintenance.
Some specially textured matte stainless steel surface finishes are hydrophobic and resist airborne and rainborne pollutants. Static Calculation Cw. Splice Connection Design by Aij. Glass Panel. Glass Calculation. CHS Splice. Paseo Curtain Wall Strutural Calculation. TCC11 Element Design. Curtain wall design. Building Design Assigment Glass Facade. Connection Design Moment.
Basic structural analysis. Aluminium Mullion Analysiss. Design Properties for Crane Runway Beams. Design Calculation-glass Balustrade. Railing Sample Calc WGlass. Kec Metro Reactions. Sheeting Weights. Chequered Plates Calculation. Scia Engineer - Load Generators en 2. Idea CrossSection - Results. Design of Monorail Systems. Deepak Steel Pipes Etc. Purlin Girt Reinforcement. Fixed base plate example. Quikjoint - Results. Quikjoint - Eaves haunch calculations. Post World War 2 Architecture.
Vastu Sastra. Changing language of tribal community-bhillas. New urbanism, tourism and urban regeneration in western Lisbon. World Trade Center. Soal Uts b. Sika Solutions for Watertight Basement Structure.
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