Transcript Timber Portal Frame Construction

Timber Portal Frame Construction
Andrew Kemp
500238299
The Timber Portal Frame
• a planar frame where the lateral and bending
forces are transferred by moment resisting
connections (knee joint) from the portal rafters
to the columns.
• Timber portal frames are cost effective, easy
accommodation of services such as lighting,
plumbing and can be erected quickly and
efficiently.
• The overall appearance is aesthetically
pleasing.
• Timber portal frames are particularly suitable
for use in high visual impact applications.
• No problem with supply of timber.
• Timber has a fair fire rating
Timber Portal Construction Mind Map
Timber Portal
Construction
Design
Architect
Plans
Client
Manufacture
Engineer
Timber Portal
Subcontractor
(off-site)
Timber Portal
Subcontractor
Engineer Drawings
Timber Supplier
Timber Mill
Builders
(on-site construction)
Timber Supplier
Construction
Steel Fabricator
Crane operators
Steel Supplier
Laborers
Builders
Architect/Engineer
Design Of Timber Portal Frames
• Designed by architects in conjunction
with an engineer
• Engineer my also seek advice from
timber supplier
• Timber portal frames can be built using
several different types of sawn timbers
Glulam, LVL and plywood box beams,
ESL, OSB
Designing Timber Portal Frame
• Mainly used in
commercial or
industrial
structures.
• Depending on knee
joint and member
size timber portals
can handle large
spans up to and
above 50m.
• Timber can be
formed into any
shape desired
creating flexibility
for the architect.
Designing Timber Portal Frame
• For large span timber
portals steel hinges
can be used for
efficient erection and
added strength
• The use of steel
gussets can also be
used to add strength to
knee joints
• Nailing is a very
important and set out
part of design of
structure.
• Poor nailing can result
in failure in structure.
Designing Timber Portal Frame
• Timber portal frames are
also able to support large
weights on the members
which allows extra
attachments needed by
the clients such as cranes,
machinery etc to be
designed in.
• There is a number of
different external
claddings that can be
applied to a timber portal
frame some of the popular
options are corrugated
steel sheet, brick veneer
skin and pre cast tilt up
concrete panels.
Ref:jjham
Timber Portal Model
Plywood gusset
Timber Box Beam
Mild steel shoe
Steel Bolts
Concrete Pad Footing
Timber Portal Model
Timber Portal Model
Timber Portal Model
Timber Portal Model
Manufactured Timber Portal Members
• LVL (Laminated Veneer Lumber),
has a high strength on a linear
axis, can be manufactured in large
depths and long lengths.
• Glulam (Glued Laminated Timber)
–a versatile members made of
small pieces of timber glued
together, that can be fabricated in
large depths, widths, lengths, and
formed into a number of shapes,
including curves.
• Plywood is often selected to act
with other timbers to create a
member which shear stresses
must be carried. Such as the web
of a built up box beam section in
which shear forces will be
transmitted. It can be used as
feature paneling or for floors in
which it carries out-of-plane
loads.
Manufactured Timber Portal Members
• ESL (Engineered Strand Lumber),
a versatile product made from
clumps of wood fiber arranged in
a mainly linear pattern and held
together in a glue.
• OSB (Oriented Strand Board),
a panel product manufactured
from thin wafers of wood held in
a glue. The wafers are oriented
during manufacture so that the
grain is mainly parallel to the
length of the board.
• Box Beam similar to a small stud
wall which is covered with
plywood, basically you build the
stud to the size beam needed
then it is boxed in with plywood
the longer the span the deeper
the beam and the more studs.
Manufacture Of Timber Portal Frame
•
•
•
•
•
In the past large sections of timber were used to span large
distances
Timbers of this are now to hard and expensive to obtain
Timber portal members are made up of several structural elements
to form one single timber structural member.
These are manufactured to provide a single timber member that
will span long distances which a solid timber form could not.
All timber portal members are manufactured under strict Australian
Product Standard.
Manufacture Of Timber Portal Frame
• Timber portal members can be
manufactured out of several
timber stress grades depending
on length of span.
• For large spanning timber
portals high stress grade
timbers like F17 would be used.
• Large spanning beams can be
made into sections for easy
transportation and allows
sections to be lifted into place
instead of the use of cranes.
• Members can also be tapered
which is much more economical
and will reduce the weight of
member, this method will not
weaken the member it will
reduce stress on the apex.
Ref: jjham
Manufacture of Timber Portal Frame
• Timber members can
be built on or prefabricated off site
depending on the type
of timber.
• Pre fabrication will
allow slab to be
poured while frame
being built off site,
time saving
• On site building will
mean frame can be
assembled on the
ground and then
raised into place using
cranes, saving cost of
safety issues
Ref: jjham
Construction and Erection
• After construction of footings and of members ether onsite or off-site erection of frame will begin.
• Depending on the size of the frame cranes my have to
be bought in to lift the structure into place.
• Slab can be poured when footing are being poured or
after frame has been risen.
Ref:jjham
Construction and Erection
• Once frame has been
raised portal columns
are fixed into mild steel
shoe which have be
bolted to the footing.
• Mild steel shoe prevents
the timber from sitting
on the concrete which
would allow seeping of
water into the timber
causing rotting.
• Also creating a solid
connection between the
timber and the concrete
footing.
Construction and Erection
• After the portal is
attached to footings
and is free standing
gusset plates can be
nailed to the knee
joint.
• Gusset plates, often
steel or plywood,
fixed by nails, bolts
or other means to
connect timber
members in a truss
or other frame
structure. Gusset
plates may be
applied to one or
both sides of a joint
Basic Timber Portal Frame Plan and Section
Ref: P.J.Yttrup and Associates Pty Ltd / www.timber.org.au
Timber Portal : Belmont Timber Shed
Timber LVL
rafters
Housed in
timber
purlins
External
wiring for
lighting
Clear
fiberglass
sheet
(added
light)
Plywood
Gusset at
knee joint
and apex
Corrugated
steel sheet
cladding
Steel Cross Bracing
Timber Portal : Belmont Timber Shed
•
•
•
Timber portal knee joint
Built in brick skin
Safety mesh under sarking
Timber Portal : Belmont Timber Shed
1
2
•1- timber portal column connected to footing with mild
steel bracket, bolted into footing.
•2-Timber portal supports large roller door attached with
steel bracket and bolts.
Timber Portal Frame Construction
•
Hope this has given an in depth insight into the processes involved in the
construction of timber portal frames, from the design stage to the finished frame.
Andrew Kemp - 500238299