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Structural Diagrams: Framing (Non-concrete/ non-metal)

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Presentation on theme: "Structural Diagrams: Framing (Non-concrete/ non-metal)"— Presentation transcript:

1 Structural Diagrams: Framing (Non-concrete/ non-metal)
Referenced Materials Jeff Graybill & Johanna Mikitka AE-390 Professor James E. Mitchell October 20, 2004

2 Navigate the System: Back System Description Transmission of Loads
Loads to Consider Detail for Dead Loads Foundation Systems Terms of the System The System According to the class & Comments Typical Uses Limitations Materials and Construction Issues Numeric Parameters Alternatives to Timber Construction Typical Uses and Applications Aluminum Structural Framing Aluminum / Fiberglass Columns Other Potential Alternative Building Materials Advantages to Non- metal/concrete Structures Generalizations Back

3 System Description Back
A Framed Building is a structure whose weight is carried by the framework instead of by load-bearing walls. The term includes modern metal and reinforced concrete structures as well as timber-framed buildings. There are several techniques for wood framed constructions: Balloon Framing- A skeleton of light machine-cut uprights or studs is attached to the joints or horizontal members by nails to form a cage or crate, with clapboard covering also nailed so that the whole is held together by nails. The studs run from sill to roof plate, spaced about 16 inches apart. Post and Beam- An ancient and, structurally, the simplest type of construction: vertical members (columns, posts, piers, or walls) support horizontal members (beams or lintels). Platform Framing- see Balloon Framing (Platform framing differs from balloon framing in that the vertical members run from platform to platform rather than from sill to roof plate.) Half-timbering- A method of construction in which walls are built of interlocking vertical and horizontal timbers. The spaces are filled with non-structural walling of wattle and daub, lath and plaster, etc. What about the loads?! Back All definitions taken from The Penguin Dictionary of Architecture and Landscape Architecture.

4 Transmission of Loads Back
TRIBUTARY AREA BEAMS BEAMS BEAMS GIRDERS GIRDERS GIRDERS COLUMNS COLUMNS COLUMNS FOUNDATION SYSTEM THEY MADE IT! THE LOADS HAVE REACHED THE GROUND! What loads must be considered in building design? What types of foundations systems are available? Back

5 Loads to Consider Back Dead Loads:
“Dead loads consist of the weights of the various structural members and the weights of any objects that are permanently attached to the structure.” (Hibbeler) Live Loads: Building Loads Wind Loads Snow Loads Earthquake Loads Other Loads: Blast Loads Variance in temperatures Uneven settling of soil Back

6 Dead Load - Design Loads
Plywood 36 lb/ft3 Wood, Douglas Fir 34 lb/ft3 Wood, Southern Pine 37 lb/ft3 Wood, Spruce 29 lb/ft3 Wood studs 2x4, unplastered 4 psf Wood studs 2x4, plastered one side 12 psf Wood studs 2x4, plastered two sides 20 psf Back Contents of Table from Hibbeler - based on Minimum Design Loads for Buildings and Other Structures, ASCE 7-98.

7 Foundation Systems Back
Graphic:

8 Terms of the System Back 5 7 6 4 3 2 1
1. Posts - In timber-framed buildings the main vertical timbers of the walls. 2. Girder - A box girder is of hollow rectangular or other closed cross-section with transverse plates or other diaphragm members at intervals for strengthening. 3. Principal Beam - In the body of a building a main horizontal timber supporting floor or ceiling joists. 4. Joist - Horizontal parallel timbers laid between the walls or the beams of a building to carry the floorboards. 5. King Post - A vertical timber standing centrally on a tie- or a collar-beam and rising to the apex of the roof where it supports the ridge. 6. Rafter - Inclined lateral timbers sloping from wall-top to apex and supporting the roof covering. 7. Ridge Beam - A horizontal, longitudinal timber at the apex of a roof supporting the ends of the rafters. 5 7 6 4 3 2 1 Back All definitions taken from The Penguin Dictionary of Architecture and Landscape Architecture. Graphic from Ching.

9 In terms of the Class Back
Class Definition of a System -"A series of individual components interacting in order to ensure that a design functions as desired.” In wood framing, the individual components are the different types of timbers explained in Terms of the System. Subsystems of wood framing include the following: Foundation - needed to support the structure Walls - often fabricated and installed as single components Roof - many roof options are available (due to complexity of these systems, no detail has been provided). Roof constructions include crown-post, king-post, truss, gable, hammerbeam, hipped, gambrel, mansard, helm, etc. Joint systems - there are many techniques for connecting the timber members. Some techniques include mortice and tenon joints, steel plate connections, bolts, nails, screws, etc. The desired function for a wood frame is to adequately meet the spatial and aesthetic needs as well as be structurally adequate to handle all potential loads. Back

10 Typical Uses for Wood Framing
Residential Construction This is the most common use Timber can be used to create many aesthetically pleasing irregular shapes Economic/convenient source of building materials Durable for residential use Ease/speed of construction Small Commercial Buildings Many small commercial buildings are similar to residential construction Modular quality is advantageous Barns Simplicity & Durability of structure Modular benefits Camp/Park facilities Aesthetically pleasing/appropriate for location Graphic: Click here for some outstanding examples of the use of exposed timber framing systems! Back

11 Limitations Back Natural Size limitations
Because the timbers come from trees, sizes are naturally limited by the trees available. The natural strength to resist loading of the timbers limits the span. Does not accommodate large open spaces The framing concept does not allow for large open spaces as the posts are a necessary aspect of the frame. Beam spans range from 8’ to 32’. Wood is organic matter and is therefore subject to decomposition over a period of time. Wood may absorb/lose water content causing warping and deformation in the system over time. Wood is subject to infestations of destructive insects such as termites, carpenter ants, etc. Back

12 Materials and Construction Issues
Typical Strong Woods: Douglas Fir Larch Southern Pine Oak Many types of wood & uses Connections: Metal Connectors Shear Plate Connections Spike Grid Connections Toothed-ring Joints Bolts, screws, nails, etc. Wood on Wood Connections Mortice and Tenon Lap Joint Spline Fabrication On-Site Fabrication Allows for irregular shape construction Off-Site Fabrication Allows for high-speed construction as members only need to be pieced together Beneficial for modular installation Back

13 Shear-Plate Connector
Shear plates are typical for wood-steel connections. Pairs of sheer plates can be used to form wood-wood connections. Back

14 Spike Grid Connector Back
Spike Grid connectors are embedded into the wood members before they are bolted together to provide a source of friction to prevent shearing of the bolts. Back

15 Toothed-ring Joints Back
Toothed-ring Joints are used similarly to the spike grid installation. Back

16 Numeric Parameters Nominal Depth of Beam vs. Span (Solid)
Depth of Beam vs. Span (Laminated) Design Values: Bending, Tension, Shear, Compression, and Modulus of Elasticity How much does it weigh? Back

17 Nominal Depth vs. Span Back
This chart shows span ranges based on the nominal depth of the wood beam selected. Nominal depths are slightly larger than actual depths. Note that with a 24” beam depth maximum span is only 32’. Back

18 Depth vs. Span Laminated Beams
This chart shows span ranges based on the depth of the laminated wood beam selected. Laminated beams can span greater distances that their solid wood counterparts. This is in part because their size is not restricted by nature. Note that Span is in feet and depth is in inches. Back

19 Design Values - Allowable Loadings
S-P-F Design Values (psi) Douglas Fir- Larch Design Values (psi) Hem-Fir (North) Design Values (psi) Northern Species Design Values (psi) These tables will help you to decide what size and what type of wood is necessary based on loading factors such as bending, tension, shear, and compression. Design loadings are given for specified types and grades of timbers. Loadings are presented in pounds per square inch. Back

20 S-P-F Design Values (psi)
Back

21 Douglas Fir- Larch Design Values (psi)
Back

22 Hem-Fir Design Values (psi)
Back

23 Northern Species Design Values (psi)
Back

24 Wood Densities for Design Loads
One of the primary components of the Dead Load calculation is the weights of the structural members. The densities allow the engineer to calculate the weight added by the timber members. Plywood 36 lb/ft3 5.7 kN/m3 Douglas Fir 34 lb/ft3 5.3 kN/m3 Southern Pine 37 lb/ft3 5.8 kN/m3 Spruce 29 lb/ft3 4.5 kN/m3 Back

25 Alternatives to timber construction
Although not used as widely as timber, concrete, and steel construction materials, lightweight and durable materials are being used for the more decorative structural elements. These materials include aluminum, structural foam, plastics, and fiberglass. Back

26 Typical uses and applications
Commercial: Walkway Canopies Shade Structures Metal Roofing Residential: Lattice Pool Enclosures Sunrooms Carports Back

27 Aluminum Structural Framing
Aluminum framing has advantages in high insulating value, diffuse-light transmitting swimming pool enclosures. Typical ferro-vitreous buildings utilize 2 3/4" structural roof panel systems providing good insulating values, energy performance, human comfort and condensation control. The panels are incorporated into an aluminum box beam sub-structure resulting in an enclosure that is designed to meet or exceed all local snow and wind load requirements - from Canadian snowstorms to Caribbean hurricanes. Aluminum Structural Framing comes factory pre-finished, uses a hollow box-beam design allowing easy wire and conduit concealment, typically will use internal gussets, traditional truss designs, and can be used in a variety of roof styles. Back

28 Aluminum/Fiberglass Columns
The columns are designed for all types of decorative and load bearing installations and are architecturally correct in their proportions and projections. Fiber-glass columns require very little maintenance, are durable and are ideal for indoor or outdoor applications. All components are non-porous, waterproof, and impervious to insect infestation. The fiberglass columns are classified as NFPA Class A and UBC Class 1, with a smoke density rating below 450 according to ASTM E84-01 testing criteria. Structural fiberglass columns are load bearing and will typically have some sort of warranty. They can vary in diameters from 5 to 36 inches with a load-bearing capacity from 16,000 to 31,000 lbs., and can be found in lengths ranging from 8 to 30 feet. Extruded Aluminum sections have high resistance to torsional stress and compression. Aluminum’s properties give the columns excellent load bearing strength and durability. Since Aluminum is also light weight it aids in the ease of installation. Aluminum and Fiberglass also have a longer usable lifetime than wooden members. Back

29 Other specific uses Back
Aluminum is used in architectural skylights which are held using space frames due to its lightweight and strong material properties. Aluminum is also used in prefabricated dome structures typically used on religious or institutional buildings. Alternative materials are also now used in pedestrian bridges and serve as low maintenance crossways for traffic ranging from horses and pedestrians to golf carts. These bridges are environmentally friendly and meet state and federal codes. These materials are used on a smaller scale presently but show potential use on large scale bridges in the future. These alternative construction materials are typically used in the decorative elements of buildings, but are being accepted as load bearing materials due to their weight, strength, cost effective manufacturing, and modular abilities. Roofs can utilize aluminum not only in framing but can replace shingles and traditional roofing products. And, many insurance companies in select states are now offering discounts on homes with metal roofs as an incentive. Back

30 Other Potential Alternative Building Materials
Plastics: Bottles/containers Automotive Furniture, etc. Epoxy Resin members: Bicycle/automotive parts Other sports equipment Structural Foam: Pool walls Automotive parts Computer housings Furniture Industrial Containers Back

31 Advantages to Non-metal and Concrete Structures
Great design flexibility Modular, pre-fabricated, ease of manufacturing High strength to weight ratio Electrical/thermal insulating properties Potentially longer lifespan Cost effective Ease of installation Comparably Aesthetic to other traditional materials Back

32 Generalization: Wood framing is ideal for residential construction and some commercial construction. One of the best aspects to wood framing is the modular concept. This allows you to expand with great ease. For further exploration, one could investigate the combination of the systems presented by the class in this project. More advanced structures may need to use more than one structural concept act as a system and perform the desired functions. Back

33 References: Allen, E., Iano, J. The Architect’s Studio Companion - Rules of Thumb for Preliminary Design. 3rd ed. New York: John Wiley & Sons. 2002 Ching, Francis. A Visual Dictionary of Architecture. New York, New York: John Wiley & Sons, Inc. 1997 Fleming, J., Honour, H., & Pevsner, N. The Penguin Dictionary of Architecture and Landscape Architecture. 5th ed. New York: Penguin. 1999 Back


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