framed structures.ppt

7/27/2019 Framed Structures.ppt

1/16

Framed

structuresIntegrantes:

Robert Alzuarde

Annia da Costa

Floralba Sanoja
http://upload.wikimedia.org/wikipedia/commons/c/c2/Post_and_Beam_Barn.JPG


2/16

Concept and a little bit of history

The ultimate purpose of building techniques is to create a stable

structure. Structures are stable when all their parts are in a state ofequilibrium. The forces that have to be controlled in order to

maintain it are tension and compression, they tend to push or pull

bodies in a given direction.

Frames structures are the example of an applied technique that is

supported mainly by a skeleton or frame, this structure is able tostand by itself as a rigid structure without depending on floors or walls

to resist deformation. Materials such as wood, steel, and reinforced

concrete, which are strong in both tension and compression, make the

best members for framing.


3/16

Timber-framed or half-timbered houses were common in medieval Europe.

But later was supplanted by the balloon frame and the platform frame

A modern lightweight wood-frame structure, was invented in Chicago andhelped make possible the rapid settlement of the western United States. The

framed building enjoyed an extensive revival after World War II as the basic

form of American suburban housing. During the 19th century, brick or stone

walls continued to bear loads, though cast-iron framing was sometimes used

supplementary, being embedded in walls or sometimes freestanding. True

skeletal construction on a large scale was first achieved in Chicago by WilliamLe Baron Jenney in the Home Insurance Company Building (188485). This

building featured a frame of both iron and steel. In the 20th century

reinforced concrete emerged as steelsmain competitor.

The French architect Auguste Perretwas the first to give external expression

to a framed building (1903); he exposed as much as possible the reinforced-concrete framework of his buildings and eliminated most nonstructural

elements.


4/16

Types of framing

Balloon Framing:

Balloon framing is a method of wood construction used primarily in

Scandinavia, Canada and the United States. It utilizes long continuous

framing members (studs) that run from sill plate to eave line with

intermediate floor structures nailed to them, with the heights of window sills,

headers and next floor height marked out on the studs with a storey pole.

Balloon framing has been largely replaced by platform framing.The advent of cheap machine-made nails, along with water-powered

sawmills in the early 19th century made balloon framing highly attractive,

because it did not require highly-skilled carpenters

The main difference between platform and balloon framing is at the floor

lines. The balloon wall studs extend from the sill of the first story all the way tothe top plate or end rafter of the second story. The platform-framed wall, on

the other hand, is independent for each floor.


5/16

Disadvantages

The creation of a path for fire to readily

travel from floor to floor. This is mitigated

with the use of fire stops at each floor level.

The lack of a working platform for work on

upper floors.

The requirement for long framing members.

Larger balloon-framed buildings will have

central bearing walls. Therefore, the

cumulative shrinkage in the center of such

a building is considerably more than the

shrinkage at the perimeter where there are

much fewer horizontal members.

Advantages:

Balloon framing provides a more direct load path down to the foundation.

Additionally, balloon framing allows more flexibility for trade workers in

that it is significantly easier to pull wire, piping and ducting without having

to bore through or work around framing members.
http://en.wikipedia.org/wiki/File:Balloon_frame.jpg


6/16

Platform framing:

Is the most common method of light-frame construction for houses and small

apartment buildings in Canada and the United States.

The framed structure sits atop a concrete or treated wood foundation. A sill

plate is anchored. Generally these plates must be pressure treated to keep

from rotting. The bottom of the sill plate is raised a minimum 6 inches

(150 mm) above the finished grade by the foundation. This again is to

prevent the sill-plate from rotting as well as providing a termite barrier.

The floors, walls and roof are typically made torsionally stable with the

installation of a plywood or composite wood skinreferred to as sheathing.Spacing the framing members properly allows them to align with the edges

of standard sheathing.

Where the design calls for a framed floor, the resulting platform is where the

framer will construct and stand that floorswalls (interior and exterior load

bearing walls and space-dividing, non-load bearing partitions). Additionalframed floors and their walls may then be erected to a general maximum of

four in wood framed construction. There will be no framed floor in the case

of a single-level structure with a concrete floor known as a slabon grade.


7/16

Stairs between floors are framed by

installing stepped stringers and then

placing the horizontal treads and

vertical risers.

A framed roof is an assembly of rafters

and wall-ties supported by the top storys

walls.

Floor joists can be engineered lumberconserving resources with increased

rigidity and value. They allow access for

runs of plumbing, HVAC, etc. and some

forms are pre-manufactured.

Double Framing is a style of framing usedto reduce heat loss and air infiltration.


8/16

raming in construction elementsWalls

Wall framing in house construction includes the vertical and horizontal

members of exterior walls and interior partitions, both of beating walls and

non-bearing walls. These "stick" members, referred to as studs, wall plates and

lintels, serve as a nailing base for all covering material and support the upper

floor platforms, which provide the lateral strength along a wall. The platforms

may be the boxed structure of a ceiling and roof, or the ceiling and floor joistsof the story above. The technique is variously referred to colloquially in the

building trades as "stick and platform", as the sticks (studs) give the structure

its vertical support, and the box shaped floor sections with joists contained

within length-long post and lintels, supports the weight of whatever is above,

including the next wall up and the roof above the top story. The platform,

also provides the lateral support against wind and holds the stick walls trueand square.


9/16

Corners

A multiple-stud post made up of at least three studs, or the equivalent, is

generally used at exterior corners and intersections to secure a good tie

between adjoining walls and to provide nailing support for the interior finish

and exterior sheathing. Corners and intersections, however, must be framed

with at least two studs.

Interior partitions

Interior partitions supporting floor, ceiling or roof loads are called load bearing

walls; others are called non-load bearing or simply partitions. Interior loadbearing walls are framed in the same way as exterior walls.


10/16

Lintels

Are the horizontal members placed over window, door and other openings to

carry loads to the adjoining studs. Lintels are usually constructed of two pieces

of 2 in. (nominal) (38 mm) lumber separated with spacers to the width of thestuds and nailed together to form a single unit. The preferable spacer material

is rigid insulation. The depth of a lintel is determined by the width of the

opening and vertical loads supported.

Roofs

Are usually built to provide a sloping surface intended to shed rain or snow.Roofs are most often covered with shingles made of asphalt, fiberglass and

small gravel coating, but a wide range of materials are used. Steel panels are

popular roof coverings in some areas, preferred for their durability.


11/16

MaterialsLight-frame materials are most often wood or rectangular steel tubes.

Wood pieces are typically connected with nails or screws; steel pieces are

connected by screws.

Wall panels built of studs are interrupted by sections that provide rough

openings for doors and windows. Openings are typically spanned by a

header or lintel that bears the weight of structure above the opening. Areas

around windows are defined by a sill beneath the window, and cripples,

which are shorter studs that span the area from the bottom plate to the sill

and sometimes from the top of the window to a header, or from a header

to a top plate. Diagonal bracings made of wood or steel provide shear

(horizontal strength) as do panels of sheeting nailed to studs, sills and

headers.


12/16

Wood or steel floor frames usually include a rim joist around

the perimeter of a system of floor joists, and often include

bridging material near the center of a span to prevent lateral

buckling of the spanning members.

Interior wall coverings in light-frame construction typically

include wallboard, lath and plaster or decorative wood

paneling.

Exterior finishes for walls and ceilings often include plywood or

composite sheathing, brick or stone veneers, and various

stucco finishes. In natural building, straw bales, cob and adobe

may be used for both exterior and interior walls.
http://en.wikipedia.org/wiki/File:Light_gage_metal_framing.JPG


13/16

Steel vs concretes framing

Steel framing is in advantage for the far greater strength of thematerial, which provides more rigidity with fewer members. The load-

bearing capacity of steel is adequate for buildings many times higher than

those made of other materials. Because the column and beam are fused

by riveting or welding, stresses are distributed between them, and both

can be longer and lighter than in structures in which they work

independently as post-and-lintel. Since structural steel must be protectedfrom corrosion, the skeleton is either covered by curtain walls or surfaced

in concrete or, more rarely, painted.


14/16

Reinforced concreteframes 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.

Benefits: is cheaper, faster, resistant (theres no need to add any extra

protection), it can be easily molded and is adaptable to late changes


15/16

The greater rigidity and continuity of concrete frames give them more

versatility, but steel is favored for very tall structures for reasons of

economy in construction and space. An example is the system called box

frame construction, in which each unit is composed of two walls bearing aslab (the other two walls enclosing the unit are nonbearing curtain walls);

this type of construction extends the post-and-lintel principle into three

dimensions. Here, again, concrete crosses the barriers that separated

traditional methods of construction.


16/16

Fin
http://upload.wikimedia.org/wikipedia/commons/5/50/Wood-framed_house.jpghttp://upload.wikimedia.org/wikipedia/commons/5/53/Post_and_Beam_Barn_Kitchen.jpg

framed structures.ppt

Documents