Hey ya. Here's some initial thoughts into my major assignment. some i couldn't incorporate into the assignment, Emma wasn't feeling the best and just was purely exhausted after being unwell that it was all to much. Hope it makes sense and may be of some use to someone.
CONSTRUCTIONS AND STRUCTURES
MAJOR ASSIGNMENT
ARCHITECTS:
The influences of the chosen architect and the influential aspects of their structure:
The requirements of the client, for the Sainsbury Centre of Visual Arts, in this case the client wanted enough space to house their artwork and collection, whilst also providing space for the education of others. This meant that a multifunctional spaced structure was required predominantly uninterrupted. Through a long span structure this was manageable and based his design upon the military and aerospace hangers, a simplistic and functional design that enabled the main focus of the building to be placed on the inside and the exhibition of the Sainsbury’s. He used the Sainsbury’s theory of art collection in his idea basis of the work, being that ‘first and foremost, the piece must make an emotional impact on them,’ hence, the design of the building must firstly make an emotional impact on the occupants before they enter. Once inside, the perception, or emotion felt may change.
An excessive height for the building was included so that the variety of different art pieces could be exhibited. The height also allowed the upper stories to house areas for learning providing the multifunctional use of the building, also allowing for a greater advantage in the cooling system, as the heat raise it remained away from the occupant. The cavity in the wall was always required as it allowed a greater amount of space in the interior of the building, and also placed less restrictions on the placement of the internal walls. By having no restrictions to the arrangement of the interior through the possibility of supporting columns it allowed a greater flowing attribute to be incorporated. The uninterrupted perception of the structure is clearly visible from the interior and the exterior, giving the occupant a great sense of freedom.
The truss system used a 2.5m wide truss allowing services, and rooms to be incorporated into the walls of the structure, freeing the internal space. The trussing system was enclosed using a plastic-coated aluminium-panel system with adjustable louvers which controlled the amount of light emitted into the structure. Through this adjustable window system it allowed the heat emitted into the building to be reduced, hence, reducing the amount of running costs to the building. The adjustable windows allowed the use of natural resources to be used for the cooling of the building, meaning that no air-conditioners are required to maintain the cooler learning environment. Through the walling additional bracing was added to strengthen the structure further.
The truss system used inner and outer skins which created the cavity within the walls which housed the different elements. The skins composed of interchangeable panels with the main ones being;
• Flat panels – glazed, solid or grilled
• Special glazed – corners
• Special solid – corners, once again
Through each panel a different attribute was incorporated which allowed a variation of external appearances avoiding the same pattern throughout the façade. The glass panels were interchangeable between clear and opaque, they were based on a sandwich principle which provided the centre with much acoustic properties.
Materials predominantly used in their architecture:
Materials that were predominantly used in much of Norman Fosters architecture was glass, aluminium and steel. His designs were based on a simplistic and functional manner that served the purpose of the occupants meeting their needs and desired. These materials allow greater variability into their uses. Curved aluminium sheeting covered the corners of the building creating a continuation of the walls and the roof. This resulted in the overall affect that the building was continuous, the simplicity of the design gave the impression that additions could easily be added, however, Foster believed that it would ruin the emotion that the building had already created, hence the opposing addition below the original structure.
Architectural features that should be incorporated into the design:
- 5m x 5m section – the section will incorporate the flooring to the roofing, with the main focus being upon the continuation of the walling to the roofing junction. Tis junction is one continuous surface, enhancing the aesthetic properties of the exterior. However, internally the junction is not based on a curved aspect, but on two 45° angled joints in the truss (mitred corner).
- Details to be shown in posters – the details that should be shown in the posters include;
- Floor to roof section
- 3D model of the walling system – highlighting the junctions and the way the trusses relate with each other
- Detail of the flooring junction
- Detail of the roof to wall junction
- Walling – detailed drawings and annotation of how the window system operates and works, the height of the warehouse, the thickness of the truss and how it functions together
- Roofing – details of the roofing elements, why they incorporate boardwalks, and how the height of the ceiling reduces the overall heat of the warehouse and why that is important
- Flooring – the detail of how the flooring attaches itself to the ground for the 2.5mish truss system
- Window – The different panels available in the window system and how they result in a cooler building that may not require the use of air-conditioning
Steel
- High strength and stiffness compared to reinforced concrete, timber, and brickwork
- Suitable in bending, compression, and tension
- Relatively easy to connect
- Has tendency to corrode
- Easy to erect
- Fabricated for the needs of the structure off-site minimising the chance of any imperfections and irregularities
- Relatively quick erection time
- Protection against fire may be required
- Length limited by the carrying capability of the truck and site access
- Welding on site is avoided because it’s time consuming and the quality is hard to control, therefore generally bolted connections occur
- Steel frames generally connected to concrete footing using holding-down bolt
Uses:
- Skeletal structures
- Tend to be slender in appearance and can be utilised as an architectural affect – as is used with Norman Fosters work
- Formed into sections to minimise the weight of the supporting structure
- Sectional shapes also allow for the connection to be made with ease
- Sectional shapes include
- UB – Universal Beam
- UC – Universal Column
- PFC – Parallel Flange Channel – generally a C shape
- RSA – Rolled Steel Angle – generally an L shape
- SHS – Square Hollow Section
- RHS – Rectangular Hollow Section
- CHS – Circular Hollow Section
Common Applications for Steelwork – architectural and engineering
- High and low rise construction
- Shopping centres
- Large span roof structures
- Lightweight and tensile structures
- Bridges
- Industrial buildings
- Processing plants
- Telecommunication and transmission towers
- Offshore platforms
- Wharfs
Framing Concepts and Connection Types:
Connections Types:
- Rigid Construction – assumes the connections has sufficient rigidity to hold the original angles unchanged
- Semi-Rigid Construction – is where the connections may not have enough rigidity to hold the original angles unchanged, but are assumed to have the capacity to furnish a dependable and known degree of flexural restraint
- Simple Construction – assumes the connections wont develop bending moments, stability provided through triangulation (bracing)
Connection Methods:
Flexible Connection Methods:
- Flexible connection methods include the following;
- Angle Seat
- Bearing Pad
- Flexible End Plate
- Angle Cleat – single or double
- Web Side Plate
- These connections offer low restraint to beam rotation, being close in behaviour to that of an ideal pin
- Most common flexible connection are the flexible end plate, the angle cleat and the web side plate
- Such connections are assumed to;
- Behave as a simple support
- Simple to fabricate
- Simple to erect
- Less costly than the other two connection methods
Rigid Connection Methods
- Rigid connection methods include the following;
- Field welded moment connection – with erection cleat (also use fillet welded web cleats in lieu of beam web welds)
- Stub girder connections – fully shop welded beam stub, spliced on site
- Bolted moment end plate connection
- These connections offer very high restraint to beam rotation, being close in behaviour to fully fixed (or encastre) connections
- The most common rigid connection methods are the stub girder connection, and the bolted moment end plate connection
- Such connection methods are;
- More complex in fabrication
- More difficult to erect where tight tolerance are involved
- More costly of the two connection types
Basic Framing Systems - Mine based on one-way rigid framework???? Or is trusses irrelevant to this system
One-Way Rigid Framework
- Most commonly employed structural sections
- Exhibit bending resistance about the x-axis and inferior bending resistance about the y-axis
- Rigid beam-to-column connection required about the unbraced plane is required – more costly as it is a rigid connection
- Simple, flexible connections can be utilised along the braced plane
- More restriction in planning the floor layout since space must be reserved for supporting elements, however it is rarely a problem since the bracing can be arranged within the thickness of the perimeter of the walls or be tied to a bracing element
- It is generally necessary to construct a rigid system consisting of either wind girders or a diaphragm having great rigidity along it’s own plane
- Possible to distribute the lateral forces to the individual stabilising element
- In the unbraced plane the frame is rigid
- In the braced plane, ‘pinned’ connecting beams are employed in order to provide beam continuity and/or reduce the lateral deflection of the frame in this direction
- Typical applications of one-way rigid framework include;
- Low-rise industrial frames (portal frames)
- Rectangular frames (especially where bracing can be accommodated within the perimeter)
- Industrial structures
- Architectural structures (bracing elements are often used as part of the architecture feature)
Summary of Framing Systems
| Framing System | Advantages | Disadvantages |
| Two-way Rigid Connections | No stabilising elements required for lateral forces in any plane Freedom of layout planning Plastic design methods can be used if desired – economic in material Continuous beam design leads to reduced beam size | Requires the use of rigid connection, which are more costly than simple connections Columns ideally should have near equal stiffness in both direction – hence fabricated box column may be needed Large column movement |
| One-way Rigid/One-way Braced Connections | Simple connections used in braced planes – reduces cost Can use I-columns – usually rolled sections Can use plastic design methods and continuous beam design in plane of rigid connections – saving in material | Rigid connection used in unbraced planes –increasing cost Some restriction on planning layout – stabilising elements required in one plane |
| Two-way Braced Connections | Simple connections possible – reducing cost Usually uses I-columns Beams assumed simply supported for design; columns designed for axial load only at small eccentricity | Restriction on planning layout because of requirement for provision stabilising elements Little interaction between elements Heavier beam sizes |
Stabilising elements:
A construction element whose function is to provide a means of stabilising the framework in wither one or two planes may be divided into the following categories;
- Triangulated steel bracing panels using the X, K, or diamond pattern of diagonal members
- Vertical Vierendeel cantilevers in steel
- Triangulated steel core
- Reinforced concrete or masonry shear walls
- Reinforced concrete or masonary cores of shear tubes
- Brick in-fill panels and walls
- Light metal cladding used on the stressed skin principle
Floor Systems:
Composite Structural framing:
In composite structural framing the term composite steel beam refers to a flooring system comprising of a steel beam acting with a concrete slab on it’s top flange connected to form an integral units
Advantage of this system is that the concrete slab not only spans between and distributes the loads to the main beams but also forms part of the beams themselves
Cladding Design Principles:
External Walls:
Functional requirements:
- Main purpose of an external wall is to separate the interior from the exteriors
- Allows the interior environment to be modified to make living a great deal more comfortable
- Makes a building wind and weatherproof, must regulate the transmission of heat, light, air and the pollutants of air – sound, water vapour, fire, smoke and dust
Durability:
- One of the most fundamental requirements of an external wall
- Depends on the environmental conditions of the building
- Must control the factors that can affect its own integrity and long-term performance – the intermittent rain-soaking, solar radiation and vapour migration are of great importance as they can result in a large range of problems
Forms of Construction:
- One way of categorising external walls is according to the means of which they resist rain penetration.
- The three categories are;
- Mass Walls
- Penetration is controlled by utilising the moisture storage capacity – water is stored until the rain stops and then it is evaporated
- Generally constructed from masonry
- Can develop micro-cracks in response to loading, ageing and thermal and moisture movements
- Performance improved by the introduction of a discontinuity of air-space – eg. the cavity – provides a space for the water to drain out of the material
- Fully-Sealed Walls
- Constructed from relatively impervious materials such as metal and glass which are designed to drain off all the rain-water
- Aim to provide permanently weather tight seals across all joints in the exposed outer face of construction
- Rain and wind barriers are one – the film of water which flows across the wall is immediately influenced by wind pressures
- Since the joints are required to resist wind and air, they must resist the combined effects of heavy wetting and wind induced air-pressure differentials
- Requires maintenance due to the joints leaking or whistling due to the deterioration of the joining material
- Single-stage joints show major weakness in this area as thermal movement, large amounts of water draining off adjoining surfaces accumulate and may penetrate directly to the interior
- Demand high standard of installation, rely on sealant, gaskets or perishable fittings, require inspection, maintenance and replacements programmes throughout their lives
- Long-term life-span can be increased through the introduction of an airspace immediately behind the sealed out face
- Single-stage joints are subjected to the combined effects of heavy wetting and wind-induced air-pressure differentials but, in the event of a primary seal failure, the cavity provides a space which can be drained to the exterior
- Usually incorporate a secondary defence system complete with internal drainage mechanism
- Rainscreen or Protected Walls
- The outer leaf or ‘rainscreen’ provides the major barrier to rain penetration and the inner leaf of the wall, which forms the air barrier, is kept relatively dry
- If the air barrier and the joint seals on the inner side of the cavity are not allowed to become wet, they cannot leak to the interior
- First, there is the drained and back-ventilated rainscreen which involved draining off most of the rainwater at the outermost surface of the wall and providing for cavity drainage and evaporation of the remainder
- Second, there is the pressure-equalised rainscreen. The aim is to eliminate penetration through the rainscreen not by tightly sealing joints, but by leaving some or all of them open to the passage of air, but not water
- Common to both options is the provision of an airspace immediately behind the outer leaf which can be drained or ventilated
- The major advantages from the two-stage approach to weather resistance include;
- The cladding assembly doesn’t rely on gaskets or sealants which require periodic inspection and maintenance
- Problems of tolerance and fit and cyclic thermal movements in the cladding assembly are less critical than fully sealed
- The inner leaf which forms the air barrier is protected from the effects of heavy wetting – minor imperfections in the air barrier become less critical
- The outer leaf acts as a solar screen so that thermal expansion and contraction of the inner structural element is reduced
- Joint seals on the inner face of the cavity are protected from the potentially deleterious effects of the UV radiation
