Structural Systems Flashcards
What are the typical spanning ranges for wood joists?
Usually 20ft, but can be up to 25ft.
What is the maximum recommended spacing for wood joist bridging?
8ft
What is “plank-and-beam” construction? What is it’s typical spacing?
Large solid wood beams span between girders or bearing walls, with planks or laminated boards between beams.
Typically spaced at 4-8ft and spanning 10-20ft.
What are the typical dimensions and spans for glulams?
3/4” or 1-1/4”
by
3-1/8” …. 5-1/8” …. 6-3/4” …. 8-3/4”
Span 15-60ft
What are the typical dimensions of a engineered wood I-joist? What else can it be called?
1-3/4” -to- 5-1/5” wide
9-1/2” -to- 20” deep
“Manufactured” / “lightweight” “I-shaped joist”
What are the typical dimensions for an LVL?
1-3/4” wide by almost any depth
What are the typical dimensions, spacing, and span of wood trusses?
3-1/2” wide
12” -to- 36” deep
Typically 24” O.C.
Span 24-40ft
What are the typical spans for the various types of wood members?
Solid wood joists —— 20-25ft
Solid wood beams —– 10-20ft
Glulams —————– 15-60ft
Wood truss joists ——- 24-60ft
What are the typical spacing and spans for “beam-and-girder” steel construction?
Span 25-40ft
Beams spaced at 8-10ft
What are the typical dimensions and spans for the different types of “open-web steel truss” construction types?
- *Standard Trusses**
- span up to 60ft
- 8-30” deep
- *Long-Span Trusses**
- span up to 96ft
- 18-72” deep
- *Long-and-Deep Trusses**
- span up to 144ft
- 18-72” deep
What are te typical spacings for the different applications of “open-web steel truss” construction?
Floor joists: 2-4ft
Roof joists: 4-6ft
What is the process of “lift-slab” construction?
Concrete slabs are cast on the ground (usually all at once) around the columns, and are then lifted up to floor height and fixed in to the columns.
What are the typical spans for two types of one-way concrete systems?
Beam-and-girder system ………………. 15-30ft
Concrete joist (“pan joist”) system … 20-30ft
What are the typical spans for the three types of two-way concrete systems?
Flat plate: up to 25ft
Flat slab: up to 30ft
Waffle slab: up to 40ft
What is the process of pre-cast concrete pre-stressing?
Cables are put under tension and then councrete is poured into the form. Once the concerte reaches a certain strength, the cables are released, which transferers their stress into the concrete.
Often results in a “camber” in the members before they are placed and loaded.
What is the “slenderness ratio”?
The ratio of the vertical member’s unsupported height to its width.
It indicated the members ability to resist buckling under compression.
What are the primary structural concerns of attaching a facade wall to a building structural system?
- How it will support itself and/or hang off the primary structural system
- How it will transfer lateral loads into the primary structural system
- How it will handle expansion and differential shifting
What are the typical spans for arches of different materials?
Wood arches: 50-240ft
Concrete arches: 20-320ft
Steel arches: 50-500ft
What are the three hinge types of arches?
Fixed arch
Two-hinged
Three-hinged
What is the typical span of a “space-frame” system?
Up to 350ft
What is the typical span of a “folded-plat” system?
30-100ft (longer for reinforced concrete)
What are the general aspects of “thin-shelled” systems?
- Include domes, barrel vaults, typical paraboloids or hyperbolic paraboloids
- Typically of concrete
- Since (theoretically) the shape prevents any bending/moment forces, the structure can be very thin
- Span from 40-200ft (30-160ft for hyperbolic paraboloids)
What are the primary aspects of “stress-skinned” systems?
- One or two layers of sheathing attached to rows of web members
- Typically of wood, but can be made form steel as well
- Typically span from 12-35ft
What are the three primary types of loads that a building must resist?
“Dead Loads”
Weight of the building itself
External loads
Such as wind, snow, eathquake
“Live Loads”
Loads from building use, such as occupants, furniture, equipment, ETC
What are the primary determining factors in selecting a building structural system?
- Effective resistance to loads
- Material efficiency in resisting the types of loads that are expected*
- Building function
- How the use may make certain systems more advantageous, even if they are not the most efficient*
- Integration with other building systems
- Cost
- Including the cost of labor to construct and cost to fire-rate the structural system*
- Fire resistance
- What fire resistance rating is required by code*
- Schedule
- Delivery time of materials and assembly time by on-site labor*
- Construction complexity
- Does it need specialized labor or equipment to assemble? Does it demand certain construction sequencing or additional planning*
- Aesthetics
- Context
- Does the neighborhood or local context of the building demand or prefer a certain system*
