Glencoe: Section 63 Flashcards
Construction process of post and beam structure
starts with foundation
entire structural frame is assembled next including roof
the frame is self bracing, rigid enough without sheathing
frame is covered using structural insulated panels.
continues with standard sequence construction of doors, windows, mechanical, and interior finish
Disadvantage of timber framing
high wood working skill is required, some joints are complex
Most desireable aspects of modern timber frame is
the structure, typically exposed on the inside of the house as in an exposed frame. Structural as well as decorative
Structural insulated panels (SIPs) (foam-core panels)
consists of 3 1/2” thick expanded polystrene (EPS) foam insulation between sheets of exterior plywood or OSB.
Panels size of SIPs
4’x8’ to 8’x28’.
How are SIPs fanstened together
2x4 or 2x6 splines.
Spline
a thin strip of wood used to reinforce a joint.
Depending on how they are designed, SIPs may be
structural or non structural. In a timber frame house they are not structural because the frame is carrying all the loads
Pro of SIP panel wall
speeds up construction process and forms the interior wall and exterior sheathing at the same time.
Con of SIP panel wall
Difficult to run wire through
Manufactured housing
Houses built completed or partially on assembly lines.
Shear wall
a wall designed to resist lateral (sideways) forces.
One way to create shear wall
using specific nail spacing to attach sheathing is one way to create a shear wall.
It is crucial to provide shear strength at
corner of house
The top shear wall must be fastened to the
second-floor framing.
The bottom of the shear wall must be fastened to the
sill plate which is bolted to foundation.
Hurricane straps
used to reinforce connection between roof and wall framing.
Hold-down anchors
steel brackets that prevent wall from toppling. Installed at each corner of house. Attached to foundation with anchor bolts and framing with lag screws.
Load:
type of force that creates stresses on structure,
Design valueL
number assigned to how well a particular wood sresists stress.
Extreme fiber stress in bending
When a load is applied to a joist, header or beam, it bends. This produces tension sresses in the wood farthest from the load and compression stresses closest to the load
Tension Parallel to Grain
when the ends of a piece of wood are pulled in opposite directions, tension along the grain results. This might occur in a floor joist attached to two walls that are bowing outward.
Horizontal Shear
Shear stresses occur where two portions of the wood are trying to slide past each other in opposite directions. A deep heavily loaded beam might experience shear stresses near the center line of the wood.
Compression Perpendicular to the Grain
This occurs when the wood rests on supports, An example would be a joist (D in types of stresses) Any load on the wood tends to crush wood fibers at bearing points. This problem can be reduced by increasing the bearing area.
Compression Parallel to the Grain
This occurs when loads are supported on the ends of the wood. This is typical of studs, posts, and columns. The resulting stresses affect the wood fibers uniformly along the full length of the wood.
Modulus of Elasticity
This is the ratio showing the amount that wood will bend in proportion to its load. The actual amount of bending is called deflection. An example would be how “Springy” a floor is when walked on.
Span table
lists the maximum spacing allowed between different sizes of joists or rafters.
On Center
type of spacing which refers to the distance from the center line of one of the structural members to the center line of the closest member.
How can a carpenter find the right spacing for a specific specie and grade of wood
use span tables
Loads on a structure are divided into two types
live loads and dead loads
Dead load
total weight of the building including structural frame and anything permanently attached.
Live load
non permanently attached objects such as furniture and people.
