types of frame based on its material
TRANSCRIPT
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CHAPTER II
Types of Frame Based on Its MaterialA. Bamboo frame
In general, part of the building which can be build from bamboo is cheaper
than other material building for the same purpose. The bamboo itself can be found
easily in Indonesia. Some buildings using bamboo as a material component of the
building can be seen in the pictures below.
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a. The advantages of bamboo as frame of building:1. Bamboo has a high strength; the tensile strength can be compare
with steel. However this highly strength has not been used well
because usually stalks of bamboo structure are connected withrope or wedge that have a low strength.
2. The shape of bamboo is pipe, so that the humadity is high.Because of that the bamboo is goog enough for carry the
bending moment. The characteristic of bamboo has a high
durability against the wind and earth-quake.
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b. The disadvantages of bamboo as frame of building1. Bamboo can be burnt easily, however there is a way to keep
the bamboo resist to the fire, but the cost is too expensive.
2. The strength of connection on bamboo generally is veryweak because the connecting process frequently is done
conventionally using hammer, peg, and rope. On the
conventional connecting process, the fiber which is parallel
with low friction causes bamboo broken by nail or peg.
Connecting with rope depends on the workers skill.
Connection strength is based on friction between rope and
bamboo or one to another bamboo.
Thus, conventional connecting will lower the strength of
bamboo then its strength cant be used optimally. While the
rope is loose because of changing caused by temperature,
the friction will be decreased then the construction may
collapse. Therefore connections on bamboo which use rope
must be checked periodically and the ropes must always be
setted in order to not loose.
The application of bamboo
- Roof trussRoof truss structure made of bamboo is traditionally used to consist of ridge,
rafters and beams gording using a connection from rope fiber or wedge with low
strength. To widen the roof will require an additional pile in the middle. Many
research and development has been done, even the truss of bamboo which
strengthened with steel plate and fill the connection with the mortar (cement and
sand) are able to resist the load of 4 tons. Below are examples of bamboo truss
with span 12 m along with examples of truss that connections reinforced with
fillers.
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Figure 1.1 bamboo truss
Figure 1.2 bamboo connections with fillers (Morisco & Marjono (1996))
B.Steel frameCold-formed steel (CFS) is lightweight, easy to handle, cost
effective, and a high quality alternative to traditional residential framing
materials. CFS offers the builder a strong, dimensionally stable, easy-to-work framing system whose use can be traced back to 1850.
a. The advantages of steel frame1. Consistent Material Quality2. Non-Combustible Material3. Dimensionally Stable in any Climate
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4. Insect Resistance and steel will not Rot5. High strength, so can reduce the dimension and its own weight
of the structure. it is quite beneficial for high rise building, the
long structure of bridge, or other building which build on the
bad soil condition.
6. High durability.7. The elasticity, based on Hooke law that steel has a high tension
because of its elasticity.
8. High ductility, because the steel which receive high tensile willhad high strain before the collapse.
9. Easily to connect with other member of each element usingweld or bolt.
10. The implementation process of construction is faster thanother material.
b. The disadvantages of steel frameEven though steel frame has a lot of advantage, but its also has
some disadvantage, especially in terms of maintenance, such as steel
structure which directly contact with air or water, periodically should
be painted. The protection against the fire hazard also important,
because the strength of steel material will be weaken drastically as the
effect of the temperature rise highly, the others weakness is buckling
problem which is a function of the slimness of a section
Environmentally Sensitive
All steel products are recyclable! The overall recycling rate for steel
products in the US is 60%. Insteel building products,the minimum recycled
content is 25%. This recycling is accomplished with no degradation in product
quality or loss of properties. A contributing factor in the steel industrys ability to
achieve significant recycling is that magnetic separation is the easiest and most
economical method of removing steel from the solid waste stream. The amount of
energy needed to produce a ton of steel has been reduced by 34% since 1972.
Steel Framing Components
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The steel component known as the structural C is the predominant shape for
framing floors, walls, and roofs. The primary difference from one use to another is
the thickness of the steel and the depth of the member.
Floors Builders commonly opt for steel floor joists ranging in depth from 6- to
12-inches and steel thickness from 0.034- to 0.101-inches. Instead of using
overlapped joists at a center support, a single length of steel joist is commonly
used to span continuously.
Walls There are two basic types of studs:
Structural C studs for interior and exterior load-bearing walls that range in
depth from 2 to 8 to accommodate the necessary insulation thickness and
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ranging in thickness from 0.034- to 0.071-inches depending on the anticipated
load.
Drywall studs for non-load-bearing partitions that range in depth from 1- to 6-
inches and metal thichness ranging from 0.01- to 0.034-inches. The thermal
efficiency of the steel-framed exterior walls may be increased by installing
insulation board on the exterior of the wall.
Roofs The broad range of available sizes and thicknesses allow steel framing to
be used in virtually any roof system. Steel trusses can be built on-site or off-site in
truss fabrication plants.
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Framing Methods
There are three basic residential steel framing methods: stick-built,
panelized, and pre-engineered.
Stick-built - Replace wood members with steel members (one-for-one
replacement). As shown below, the steel-framed non-load-bearing wall appears
very similar to that of a comparable wood-framed wall.
Panelized - Factory-assembled panels delivered to site and connected together.
The panelized approach represents an efficient approach for repetitive building
designs and, as a result, is a popular approach in hotel/motel construction and
other multi-unit applications.
Engineered - Location and placement of framing members is engineered to take
advantage of steels properties. Spacing of framing members may increase to as
much as 8-feet with horizontal stabilizers.
Barriersto Steel Framing
Five key barriers to the expansion of residential steel framing have been
identified.
Cost of Construction
Distribution Infrastructure
Standardized Product
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Consumer Preference
Thermal Performance
Reinforced Concrete Frame
In this modern area, concrete is the one mostly be used. The concrete
itself obtained by mixing cement, fine agregate (sand), coarse agregate and water.
Due the chemical reaction between the cement and water, concrete set into
atrificial stone and as the result, the mixture will binds the constituents together as
a pasteor matrix. Fresh concrete can be molded into any shape, after hardening
period an curing in 28 days, the concrete will take its optimum strength. But
concrete has a weakness through tensile strength, so that the steel bars is provide
to overcome this weakness by plant the steel bars in concrete to form a composite
material called reinforced concrete.
The strength achived will depend on this factor, such as :
a. Type of cement used.b. Type and size of agregates.c. Water.d. Use of admixtures.e. Water/Cement ratio.f. Grade strength.
Reinforced concrete (RC) frames consist of horizontal elements (beams)
and vertical elements (columns) connected by rigid joints. These structures are
cast monolithically that is, beams and columns are cast in a single operation in
order to act in unison. RC frames provide resistance to both gravity and lateral
loads through bending in beams and columns (Figure 2). There are several
subtypes of RC frame construction:
onductile RC frames with/without infill walls
onductile RC frames with reinforced infill walls
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Ductile RC frames with/without
infill walls
Figure 2: A plan of a typical RC
frame building in Ahmedabad,India; note the portion that
collapsed in the 2001 Bhuj
earthquake (WHE Report 19, India)
Figure 4: Features
of nonductile RC
frame construction
in Taiwan (WHE
Report 61)
SEISMIC PERFORMANCE
Some earthquakes around the word have revealed the following patterns
of damages and failures in RC frame construction:
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Shear failure and concrete crushing failure in concrete columns. These are the
most undesirable nonductile modes of failure (Figure 5). This behavior can lead to
the loss of gravity load-bearing capacity in the columns and potentially a total
building collapse.
Figure 5: Shear failure of a reinforced concrete column in the 2001 Bhuj
earthquake (WHE Report 19, India)
Partial ductile design and detailing. Systems that exhibit some (limited) yielding
behavior can eventually form dangerous collapse mechanisms as a result of
stiffness or strength degradation at sections without ductile detailing.
Conceptual design deficiencies. This includes such deficiencies as incomplete
load path and architectural planning deficiencies such as vertical and/or horizontal
irregularities. Architectural features play an important role in the performance of
RC frame buildings.
Inappropriate column/beam relative strengths. This can lead to failure of
individual members and connections when the weak column-strong beam
mechanism develops.
Inadequate detailing of reinforcement.
Soft-story effects. In many applications, architectural considerations result in a
taller first story, which causes a soft-story formation due to drastic change in the
stiffness between adjacent stories (Figure 6). The presence of a soft story results
in a localized excessive drift that causes heavy damage or collapse of the story
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during a severe earthquake (Figure 7). Another typical case of soft story arises
when the first floor is left open (that is, no infills) to serve a commercial function
(stores) or as a parking garage (very common in Turkey, India, and Cyprus), while
upper floors are infilled with unreinforced masonry walls. A relatively rare case
results when the strength of the two adjacent stories is significantly different
(weak story) leading to localized deformations similar to the soft-story
mechanism.
Short-column effects. The short- or captive-column failure occurs due to partial
restraining of the columns that are, in turn, subjected to high shear stresses and
fail in shear if unable to resist these stresses.
Figure 6: Soft-story mechanism
(WHE Report 61, Taiwan)
Figure 7: Building collapse due
to soft-story mechanism in the
2003 Boumerdes earthquake
(WHE Report 103, Algeria)
In several instances, seismic performance of RC frame buildings has been
quite poor, even when subjected to earthquakes below the design level prescribed
by code. One of the underlying reasons is the absence of an effective mechanism
for code enforcement in some countries. This deficiency in governmental
oversight is linked to several related factors, such as the lack of technical control
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Figure 8: Jacketing of RC frame members (WHE Report 11, Colombia)
Figure 9: Illustration of seismic strengthening with addition of RC infill walls
(WHE Report 62, Taiwan)
An alternative procedure which has been recently developed for RC frames with
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unreinforced masonry infill walls proposes the use of carbon-fiber, reinforced
polymers (CFRP) applied on existing unreinforced masonry infill walls (Figure
10) to increase the overall lateral load capacity. Although its cost is higher, this
method is easy to apply and much faster when compared to the installation of new
concrete infill walls.
Figure 10: Strengthening of brickinfilled RC frame
with CFRP
C. Timber FrameyProtection of Materials
Lumber, panel products and millwork (windows, doors and trim) should
be protected from the weather when delivered at the building site. Preparation of
a construction schedule will assure that lumber and millwork are delivered as
needed. Follow these simple rules:
1) Support framing lumber, plywood and panel products at least six inchesabove ground and protect them below and above with a waterproof cover
such as plastic film. Finish lumber and flooring, particularly, are to be
protected from ground or concrete slab moisture and kept under cover
preferably indoors until installation.
2) Store door and window assemblies, siding and exterior trim inside. Wherethis is not practical, these materials are to be elevated from the ground and
protected above and below with a weatherproof cover. Millwork items are
often pre-treated with a water repellent preservative as received. Whether
treated or not, such materials are to be stored under cover.
3) Untreated exterior millwork should receive a water-repellent preservativetreatment before installation. Store interior doors, trim, flooring and
cabinetwork in the building. Where wet plaster is used it must be
permitted to dry before interior woodwork, cabinetry and flooring are
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installed.
Types of frame construction from timber
1. PLATFORM FRAMEIn platform-frame construction, first floor joists are completely
coveres with sub-flooring to form a platform upon which exterior walls
and interior partitions are erected. This is type of construction is
commonly used in home building. Platform construction is easy to erect.
Its provides a work surface at each floor level and is readily adapted to
various methods of prefabrication. In platform systems it is common
practice to assemble wall framing on the floor and tilt the entire unit into
place.
Platform frame
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2. BALLON FRAMEIn balloon-frame construction, exterior wall studs continue through the
first and second stories. First floor joists andexterior wall studs both bear on
the anchored sill. Second-floor joists bear on a minimum 1x4-inch ribbon
strip, which has been let-in to the inside edges of exterior wall studs.
In two-story buildings with brick or stone veneer exteriors, balloon
framing reduces variations in settlement of framing and the masonry veneer.
Where exterior walls are of solid masonry, balloon framing of interior bearing
partitions also reduces distortions in door and closet openings in crosswalls.
The requirement for longer studs, and the difficulty in accommodating current
erection practices and firestopping, has reduced the popularity of this system.
Ballon Frame
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3. FASTENINGNails, used alone or in combination with metal framing anchors and
construction adhesives, are the most common method of fastening 1- and 2-
inch framing lumber and sheathing panels. Ring or spiral shank nails provide
higher load-carrying capacities than common nails of the same diameter, and
are particularly useful where greater withdrawal resistance is required. Nailed
joints provide best performance where the load acts at right angles to the nails.
Nailed joints with the load applied parallel to the nail (in withdrawal) should be
avoided wherever possible, since joints are weakest when nailed in this
manner.
Where tilt-up wall framing is not practical, or where stronger stud-to-plate
attachment is required (as in the use of rigid foam sheathing), toe-nailing is the
most practical method of framing studs and plates. In toe-nailing, nails are
driven at a 30-degree angle (approximately) to the stud. Studs can be pre-
drilled to simplify this operation and prevent excessive splitting.
Method of loadingnails
Sizes off common wire nails
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4.ROOF AND CEILING FRAMINGRoof construction must be of adequate strength to withstand anticipated
snow and wind loads. Framing members must be securely fastened to each
other, to sheathing and to exterior walls to enable the roof system to serve as a
structural unit.
roof framing gable overhang and flat roof framming
Valley Rafter Roof Framing
Hip Rafter Roof Framing
Roof Framing at Eave
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Shed Dormer Roof Framing Gable Dormer Framing
Roof Trusses
Roof framing may be fabricated as light trusses and installed as complete
units. Such framing is designed according to accepted engineering practice. The
truss members are joined together by fasteners such as nails, nails and glue, bolts,
metal plates or other framing devices.
Use of roof trusses eliminates the need for interior bearing partitions and
frequently results in more rapid installation of roof and ceiling framing. Roof
trusses are generally spaced 24 inches on center. Where roof trusses are used,
gable ends are usually framed in the conventional manner using a common rafter
to which gable end studs are nailed. Eave overhangs are framed by extending the
top chords of the trusses beyond the wall.
Where hip and valley construction is required, modified trusses or
conventional framing are used to meet the condition.
Ceiling-Floor-PartitionSeparation
In some localities truss uplift may be a problem. This problem is
characterized by the separation of the floor or ceiling from an interior partition. A
widely used technique to minimize truss uplift separation is to allow the gypsum
board ceiling to float or rest on the partition and remain unattached to the truss
on either side of the partition. In cases where trusses are perpendicular to
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partitions, the gypsum board ceiling remains unattached at least 18 inches from
the ceiling/ wall intersection.
FlatRoofs
Flat roofs should be avoided if possible because they are difficult to
ventilate and insulate adequately and present weather proofing problems. Flat roof
joists are securely nailed to exterior wall plates and to each other where they join
over interior partitions.
RoofSheathing
Wood structural panels or 1-inch board lumber provides a solid base for
roof coverings. Structural panels are manufactured in various thicknesses and are
usually 4x8' in surface dimension. Recommended spans, spacing between panel
edges and thickness are stamped on the panel face. Structural panels are installed
with the long dimension perpendicular to rafters and with the panel continuous
over two or more spans.
Spaced Sheathing
Where wood shingles or shakes are to be applied as the finished roof, solid
sheathing is used or nominal 1x4 lumber is nailed perpendicular to rafters and
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trusses with each board spaced a distance from the next board equal to the weather
exposure of the shingles or shakes. (5 inches is common exposure for shingles.
Shakes may be exposed 7 to 13 inches depending on their length.) Because shakes
are not smooth surfaced, an 18-inch wide underlay of asphalt felt is used between
each course. Where wind driven snow is encountered, solid sheathing and Type
15 asphalt felt are used under wood shakes.
Ventilation ofAttic Spaces
Ventilation of all attic spaces is required to eliminate moisture
condensation on roof framing in cold weather and to permit heat to escape in
warm weather.
For gable roofs, a screened, louvered opening is used which provides a net
open area of 1/150 of the area of the ceiling below. Where a -inch wide screened
slot is also provided in the eave soffits, or where a vapor retarder having one perm
or less permeability is installed on the warm side of the ceiling, the total
ventilating area may be reduced to 1/300 of the ceiling area. With hip roof
construction, a -inch wide screened slot in the eave soffits, and ventilator at the
ridge to provide 1/450 inlet and 1/900 outlet fractions of the ceiling area below,
assures adequate ventilation. For flat roofs, blocking, bridging and insulation are
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arranged to prevent obstruction of air flow. Such roofs are ventilated at eave
soffits to provide net open area equal to 1/250 of the area of the ceiling below. A
vapor retarder of one perm or less permeability is applied under the ceiling finish
below flat roofs.
Advantages
The use of timber framing in buildings offers various aesthetic and
structural benefits, as the timber frame lends itself to open plan designs and allows for
complete enclosure in effective insulation for energy efficiency. In modern construction
timber-frame structure offers many benefits:
y it is rapidly erectedy it lends itself well to prefabrication, modular construction and mass-production.y an "average"-sized timber-frame home can be erected within 2 to 3 days.y the frame can be encased with SIPs for the drying in: that is, ready for windows,
mechanical systems, and roofing.
y it can be tailored to suit customer tastes and creativity such as carvings orincorporation of heirloom structures such as barns etc.
y it can use recycled or otherwise discarded timbers.y
it offers some structural benefits as the timber frame, if properly engineered,lends itself to better seismic survivability. Consequentially, there are lots of old
half-timbered houses which still stand despite the foundation having partially
caved in over the centuries.
Disadvantage
y poor prevention of capillary movement of water within any exposedtimber, leading to afore-described creep, or rot
y timber ends, joints and corners poorly protected through coatings, shape orposition
y non-bevelled vertical beams (posts and clapboards) allow water absorptionand retention through capillary action.
y Noise from footsteps in adjacent rooms above, below, and on the samefloor in such buildings can be quite audible. This is often resolved with
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built-up floor systems involving clever sound-isolation and absorption
techniques, and at the same time providing passage space for plumbing,
wiring and even heating and cooling equipment.
y Other fungi that are non-destructive to the wood, but are harmful tohumans such as black mold. These fungi may also thrive on many
"modern" building materials.
y Wood burns more readily than some other materials, making timber-framebuildings somewhat more susceptible to fire damage.
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tension or compression. Consequently, all material in any given element
is utilized to its full extent. Furthermore, most space frames are now
constructed with steel or aluminum, which decreases considerably their
self-weight. This is especially important in the case of long span roofs
that led to a number of notable examples of applications.
2. The units of space frames are usually mass produced in the factory so
that they can take full advantage of an industrialized system of
construction. Space frames can be built from simple prefabricated units,
which are often of standard size and shape. Such units can be easily
transported and rapidly assembled on site by semi-skilled labor.
Consequently, space frames can be built at a lower cost.
3. A space frame is usually sufficiently stiff in spite of its lightness. This is
due to its three dimensional character and to the full participation of its
constituent elements. Engineers appreciate the inherent rigidity and
great stiffness of space frames and their exceptional ability to resist
unsymmetrical or heavy concentrated load. Possessing greater rigidity,
the space frames also allow greater flexibility in layout and positioning
of columns.
4. Space frames possess a versatility of shape and form and can utilize a
standard module to generate various flat space grids, latticed shell, or
even free-form shapes. Architects appreciate the visual beauty and the
impressive simplicity of lines in space frames. A trend is very
noticeable in which the structural members are left exposed as a part of
the architectural expression. Desire for openness for both visual impact
as well as the ability to accommodate variable space requirements
always calls for space frames as the most favorable solution.
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Roof framing for a circular dome.
JointingSystems onSpace Frame
The important thing on space frame are jointing systems the member of
space frame, space frame can be build without connecting the member together.
The type of jointing depends on the connecting technique, whether it is wolding,
bolting, or apllying mechanical connectors. The technique itself is affected by
shape of the members.
Threre are the requirements for jointing systems on space frame:
a. The joinst must be stiff and strong.b. The eccentricity at a joint should be kept to a minimum, yet the joint detailing
should provide for the necessary tolerances that may be required during the
construction.
c. Joints of space frames must be designed to allow for easy and effectivemaintenance.
All connectors can be divided into two main categories: the purpose-made
joint and the proprietary joint used in the industrialized system of construction.
The purpose-made joints are usually used for long span structures where the
application of standard proprietary joints is limited. An example of such types of
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joints is the cruciform gusset plate for connecting rolled steel sections as shown
below.
Connecting joint with cruciform gusset plate.
A survey around the world will reveal that there are over 250 different
types of jointing systems suggested or used in practice, and there are some 50
commercial firms trying to specialize in the manufacture of proprietary jointing
systems for space frames. Unfortunately, many of these systems have not proved
attainment of great success mainly because of the complexity of the connecting
method. These table give a comprehensive survey of the jointing systems all over
the world. All the connection techniques can be divided into three main groups:
(1) with a node, (2) without a node, and (3) with prefabricated units.
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B.Skeleton FameThe skeleton frame consist of identical elements fastened to each other to form
a system of parallepiped-shape cells, each cell being bounded by four frame
elements which at least in part common to two contigously juxtaposed cells.
The cells may be freely cantilevered from upright pillars or freely span
distances between pillars which are multiples of the horizontal dimention of
one cell.
Figure 1 is a perspective and partly exploded partial view of a building
including a skeleton frame of the invention.
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Note :
1.
Rectangular frame elements(horizontal beam and column)
2. Floor plates3. The ceiling of the lower
building portions
4. Wall panels5. Wall panels6. The suspended of floor plates7. Web portion8. Flange portions9. Lugs
10.Lugs11.
Bores for connecting the bolts
12. The notches13.Four L-shapes sections14. Terminal integral flanges15. Aperture plates16.17.Reinforcing angles18.Bars19. Pairs of wedges
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CONSTRUCTION TECHNOLOGY
By:
Anita Tri Rahmawaty
110905019Y
Construction Management 2009
STATE POLYTECHNIC OF JAKARTA
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