020303g Timber Construction Flashcards
What gives heavy timber fire endurance?
The large wood members burn slowly at approx. 0.6 mm per minute. When the wood burns, it forms a self-insulating layer of char. The undamaged inner wood below the chat keeps its strength.
Timber is noticeably distorted by high temperatures. T or F
F. It is not noticeably distorted by high temperatures.
What are some techniques used to gain timber framing my fire resistance?
Avoiding concealed spaces under floors and roofs, using approved fastenings, construction details and adhesives.
Define sawn timber.
Sawn timber refers to posts and beams with a minimum thickness of 140 mm
Can columns be joined or must they be of one continuous piece?
Columns can be either continuous or spliced. Spliced columns are fastened by means of dowels, wood splice plates, metal plates or metal detectors plates.
What is the difference between girders and beams?
Girders are horizontal loadbearing members with the difference being that girders carry more load and are larger than beams.
Where are purlins on a timber structure and what is their function?
Purlins are intermediate or secondary elements of a roof or floor structure. They span from beam to beam and carry the decking.
What are some advantages to using laminated floor joists in timber construction?
Less likely to deflect and cause noisy floors. Moisture content is more easily controlled than with solid timber. The joists will have less of a tendency to shrink, twist or crack.
Decking for timber framing is produced in two grades. What are they? Which is of a higher quality?
Select and commercial. Select is of a higher quality.
When both beams and girders are used, how does the delineation of support go?
When both beams and girders are used, columns support the girders, girders support the beams, beams support the joists and the joists support the sheathing or decking.
What is the difference between select and commercial grade decking?
Select is of a higher quality in appearance and is considered a stronger and stiffer material than commercial grade.
What is the purpose of solid wood decking?
Solid wood decking provides stiffness and rigidity to the main supporting structural members and provides a nailing surface for finishes.
Describe mechanically laminated decking?
Mechanically laminated decks consist of square-edged dimension lumber set on edge, wide face to wide face, with the pieces connected by nails or other fasteners.
How is 64 mm (2-1/2”) and 89 mm (3.5”) decking secured in place?
They have 6 mm diameter holes drilled through the edge at 90 degrees to the board face every 760 mm (30”) on centre. Each new deck board is nailed to the previous one with deck spikes through the holes, as well as being fastened down to the supporting member it rests on.
What allowances should he made where decking meets a parapet wall?
Dimensional changes that occur in solid wood decking require that it be kept back 10 to 12 mm from walls and parapets.
Post and beam and timber frame structures are defined as having an on-centre spacing greater than ___ mm.
600 mm
How is post and beam and timber framing able to have greater on centre spacing?
The increase loading on the structural members is absorbed by the increased size of the members.
Post and beam is generally connected through use of hardware, dowels, bolts, metal plates, etc…
T or F
T
Post and beams hardware is typically visible after completion. T or F
T
Timber frame mainly uses old school methods of connection. T or F
T. Dowels, mortise and tenon, dovetails and scarf and lap joints are common.
Describe braced timber frame structures.
Use crossbracing, knee bracing, shear walls to resist lateral displacement.
What is a bent in regards to timber framing?
A structural framework that is designed to carry lateral and vertical loads and is orientated perpendicular to the length of the building.
Describe unbraced frames.
Rely solely on the dimensional ability and design of the solid components and their connections to resist deflection limits.
What factors must be taken into consideration when determining hardware and methods used for timber connections?
The hardware or methods used for connections must support and transfer loads effectively without adversely affecting the connected timbers.
What is the difference between shear plates and split rings?
Shear plates are steel to wood. Split rings are wood to wood.
Shear plates prevent deformation of the timber from forces near the bolt. Like a washer the shear plate distributes the connection forces over a larger area of wood.
Split rings transfer load from one member to another via a ring that is installed in a circular kerf cut into each of the members.
Describe glulam timber.
An engineered wood product manufactured by glueing together lumber laminations with waterproof adhesive.
Glulam timber can be curved and tapered. T or F
T. To create pitched and tapered beams.
Can glulam be cambered?
Yes
How much must the lambstock grades be dried?
7% to 15% moisture content before laminating in order to maximize adhesion and minimizing shrinking in service.
Glue laminated members are randomly end jointed along their lengths using finger joints or scarf joints. T or F
T
Which type of glue is used for interior glulam members?
Casein
Which types of glue are exterior glulam members adhered with?
Phenol, resorcinol or melamine resin.
What are the two classifications for glulam?
Stress grade and appearance grade.
Define stress grade glulam members.
Locating higher quality lamstock in high stress areas of the member.
Where are high-strength laminations located in continuous beams?
Top and bottom to give the greatest strength and stiffness.
