FRAMES (mainly steel) Flashcards
What is a Framed Structure?
A framed structure (in any material) is one that is made stable by a skeleton that is able to stand by itself as a rigid structure without depending on floors or walls to resist deformation.
How is a Framed Structure classified?
Structures can be classified in a number of ways: solid, framed structure, shell, membrane, composite, trusses, cables and arches, surface structure etc.
What constitutes a frame structure?
- A skeleton structure.
- Loadbearing and enclosure/division functions are separated.
- External envelope responsible only for environmental control / aesthetics.
- Columns with spanning beams that enclose a volume.
- Building frame – columns and horizontal beams.
- Shed frame – columns and roof trusses.
- Portal (or rigid) frame – columns and horizontal or pitched beams with rigid connections.
What building types incorporate the frame structure?
- Residential – house, apartment block.
- Commercial – office.
- Industrial – warehouse, factory, hangar.
- Hospital.
- Retail – shopping mall.
- Leisure – theatre, stadium.
What are the typical forms used to construct frame structures?
- Structural form
- Cellular – cross walls, box construction
- Open plan – beam & column.
What are the advantages of a Frame Structure?
- Saving in floor space – slimmer walls - loadbearing walls become impractical with increasing height,
as strength greatly depends on the thickness of the wall - increasing height increases thickness at lower levels. - Flexible plan – absence of loadbearing walls aids internal space planning.
- Reduction in dead weight – external and internal walls use for enclosure and division only.
- Suits multi storey construction - Greater spans permissible - Allows open plan spaces with few
interruptions> - Standardisation – of columns, beams, fixings and other components.
- Prefabrication– offsite quality advantages.
- Speed of construction – much faster than loadbearing walls.
What are the requirements of building a framed structure?
- Use of appropriate materials.
- Understanding behaviour under load.
- Appropriate forms of main members.
- Bracing members.
- Rigid joints (material saving).
What are the Fire Resistance requirements of a framed structure?
- Structural integrity maintained in the event of a fire.
- Permits full evacuation.
- Allows control and extinction of fire.
- Protects structure and adjacent buildings.
What material properties are ideal for framed structures?
- Ideally strong, stiff and light.
- Stronger the material the less is required to resist a given force.
- Stiffer the material less deformation under load.
- Strength to weight ratio (more strength for lowest weight).
- Depth to span ratio (greatest span for least depth).
- Dead to live load ratio.
- A crucial factor in frame design is the structure’s ability to withstand wind
loadings: - Rigid joints
- Bracing
- Shear walls
- Shear cores.
What are the principal factors constantly influencing a choice of frame material?
- Technical constraints.
- Availability of labour and materials.
- Cost.
- Speed of constructing the frame (hence building).
- Standardised structural members.
- Size and nature of the site (access).
- Fire resistance (Building use).
What are the most common materials found in a frame structure?
- Timber Occasionally used
- Iron
- Cast – brittle Hardly ever used today?
- Wrought – malleable
- Steel Used extensively in UK
- Concrete 2nd most popular framing material:
- In situ reinforced
- Precast
- Pre-stressed (pre and post tensioned).
What is the typical steel frame load out?
- Regular and closely spaced grid.
- Deeper, lighter sections more efficient.
- 1/15 to 1/20 depth/span ratio is economical.
- Typical deflection limit 1/360 of span.
- Simplest form is Universal beams
and stanchions. - Frame Erection sequence.
What are the different types of steel framed structure?
Braced frames.
Exposed frame.
Trusses and Lattice girders.
Portal frame.
Space frames.
What are the basic elements of a steel frame?
- Frame layout.
- Beams.
- Girders & trusses.
- Columns / Stanchions.
- Connections.
- Bracing.
- Composite construction.
- Welded construction.
- Cold formed steel sections.
- Hot rolled mild steel sections.
- Shapes – universal beams, tubes, channels, angles.
- Standard and non-standard sections.
- Built up sections – castellated beams.
What is a girder?
Girders are large horizontal beams that act as the primary support for a building, to which all other smaller beams are connected, forming the structure’s “skeleton.”
That’s the easiest way to picture the difference: girders are oversized beams. In fact, all girders are beams, but not all beams are girders.
What is a beam?
Beams can be used to form the ‘skeleton’ frame of a building or other built asset, typically consisting of vertical columns and horizontal beams which are riveted, bolted or welded together in a rectilinear grid.
What is a stanchion?
Stanchions are vertical posts or bars, usually used as part of a support structure.
What is a composite construction?
In the context of structural engineering, composition constructions occur when two materials are combined together to act as a single unit.
What is cold-formed steel?
Cold-formed steel (CFS) is the common term for steel products shaped by cold-working processes carried out near room temperature.
What is Hot rolled steel in construction?
Hot rolled steel is steel that has undergone the rolling process at a temperature above its recrystallization temperature (usually 1700° F or greater).
Compared to unprocessed steel, the processed material exhibits greater formability and workability, making it easier to work with in subsequent processing operations.
What are the different forms of girders and trusses?
- Plate girders:
- Plates welded into webs
- 15m to 36m spans
- Deep trusses:
- economic where space is available
- often full storey height
- Space frames:
- usually applied to roofs
- 3 dimensional frame of light,
stiff members
