Indexaa

Structural Diagrams:Framing

(Non-concrete/ non-metal)

Structural Diagrams:Framing

(Non-concrete/ non-metal)

Jeff Graybill

&

Johanna Mikitka

Jeff Graybill

&

Johanna Mikitka

AE-390

Professor James E. Mitchell

October 20, 2004

Referenced Materials

Navigate the System: 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

System Description

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.

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.

All definitions taken from The Penguin Dictionary of Architecture and Landscape Architecture.

What about the loads?!

Transmission of LoadsLOADS

TRIBUTARY AREABEAMS

GIRDERS

BEAMSBEAMS

GIRDERSGIRDERS

COLUMNS

COLUMNS

COLUMNS

FOUNDATION SYSTEM

What loads must be considered in building design?

What types of foundations systems are available?

THEY MADE IT! THE LOADS HAVE REACHED THE GROUND!

Loads to Consider

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

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

Contents of Table from Hibbeler - based on Minimum Design Loads for Buildings and Other Structures, ASCE 7-98.

Foundation Systems

Graphic: http://www.slcc.edu/tech/techsp/arch/courses/ARCH1210/Photos/Fndtyp.jpg

http://www.slcc.edu/tech/techsp/arch/courses/ARCH1210/Photos/Fndtyp.jpg



Terms of the System1. 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.

1

32

4

567

Graphic from Ching.All definitions taken from The Penguin Dictionary of

Architecture and Landscape Architecture.

In terms of the Class

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.

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 Ease/speed of construction Simplicity & Durability of structure Modular benefits

Camp/Park facilities Aesthetically pleasing/appropriate for location Ease/speed of construction

Click here for some outstanding examples of the use of exposed timber framing systems!

Graphic: http://www.iaw.on.ca/~blkcreek/

http://www.jointefforttimberframing.com/

http://www.jointefforttimberframing.com/

Limitations 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.

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

http://www.tpub.com/engbas/6-1.htm

Shear-Plate Connector

Shear plates are typical for wood-steel connections.

Pairs of sheer plates can be used to form wood-wood connections.

http://www.tpub.com/content/engineering/14070/css/14070_27.htm

Spike Grid Connector

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.


Toothed-ring Joints

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


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?

Nominal Depth vs. Span

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’.

Depth vs. SpanLaminated 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.

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.

S-P-F Design Values (psi)

Grade Size

Bending

Fb

Tension parallel to grain

Ft

Shear parallel to grain

Fv

Compression perpendicular

to grain

Fc perp

Compression parallel to

grain

Fc

Modulus of Elsasticity

E

2x4 1875 1050 16102x6 1625 910 15402x8 1500 840 1470

2x10 1375 770 14002x12 1250 700 14002x4 1310 675 13202x6 1135 585 12652x8 1050 540 1205

2x10 960 495 11502x12 875 450 11502x4 750 375 7452x6 650 325 7152x8 600 300 680

2x10 550 275 6502x12 500 250 650

Design values are in pounds per square inch (psi)

135*Select

Structural425 1500000

S-P-FNo. 1

& No. 2

135* 425 1400000

*New Shear Design Values

No. 3 135* 425 1200000

http://www.cwc.ca/products/lumber/visually_graded/us_values.php

Douglas Fir- LarchDesign Values (psi)

Grade Size

Bending

Fb


Ft


Fv


to grain

Fc perp


grain

Fc


E

2x4 2025 1235 21852x6 1755 1070 20902x8 1620 990 19952x10 1485 905 19002x12 1350 825 19002x4 1275 750 16102x6 1105 650 15402x8 1020 600 14702x10 935 550 14002x12 850 500 14002x4 710 450 9452x6 615 390 9052x8 570 360 8652x10 520 330 8252x12 475 300 825

No. 1 &

No. 21600000


No. 3 1400000


180*Select


Douglas Fir-

Larch (North)

180*

180*

625

625

Grade Size

Bending

Fb


Ft


Fv


to grain

Fc perp


grain

Fc


E

2x4 2025 1235 21852x6 1755 1070 20902x8 1620 990 1995

2x10 1485 905 19002x12 1350 825 19002x4 1275 750 16102x6 1105 650 15402x8 1020 600 1470

2x10 935 550 14002x12 850 500 14002x4 710 450 9452x6 615 390 9052x8 570 360 865

2x10 520 330 8252x12 475 300 825

No. 1 &

No. 21600000


No. 3 1400000


180*Select


Douglas Fir-

Larch (North)

180*

180*

625

625


Hem-Fir Design Values (psi)

Grade Size

Bending

Fb


Ft


Fv


to grain

Fc perp


grain

Fc


E



145*Select


Hem- Fir

(North)370

370


No. 1 &

No. 21600000

No. 3 1400000

145*

145*


Northern SpeciesDesign Values (psi)

Grade Size

Bending

Fb


Ft


Fv


to grain

Fc perp


grain

Fc


E


1600000

No. 3 1400000

110*

110*



110*Select


Northern Species

350

350

No. 1 &

No. 2

Grade Size

Bending

Fb


Ft


Fv


to grain

Fc perp


grain

Fc


E


1600000

No. 3 1400000

110*

110*



110*Select


Northern Species

350

350

No. 1 &

No. 2


Wood Densities for Design LoadsWood 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.

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

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.

Typical uses and applications

Commercial: Walkway Canopies Shade Structures Metal Roofing

Residential: Lattice Pool Enclosures Sunrooms Carports

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.

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.

www.colonialcolumns.com

Other specific uses 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.

www.roofdomes.com

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

www.specialized.com

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

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.

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


Indexaa

Documents

horizontal members

hibbelerlive loads

considerdead loads

building design

minimum design loads

main horizontal timber

timberframed buildings

vertical members columns