BEAM What is beam? Beams support mainly vertical loads, and are small in cross-section compared with their span. Engineering diagrams adopt simple conventions to represent beams, supports and loads. This section section deals specifcally specifcally with the engineering design o beams. beams. Although "beam" beam" is a word in common usage or engineering design, it has a very particular defnition. A beam is beam is a structural member which spans horiontally between supports and carries carries loads which act at right angles to the length o the beam. !urthermore, the width and depth o the beam are "small" compared with the span. Typically, Typically, the width width and depth are less than span#$. span#$. Horizontal or inclined structural member spanning a distance between one or more supports, and carrying vertical loads loads across across (transverse to) its longitudinal axis, as a girder, joist, purlin, or rafter. Three basic types types of of beams are (!) "imple span, supported at both ends, (#) $ontinuous, supported supported at more than two points points,, and (%) $antilever, supported at one end with the other end overhanging and free free..
Types of Beams: Beams can be classified into many types based on three main criteria. They are as follows:
1.
Based on geometry: 1.
Straight beam Beam with straight profile
!.
"#r$ed beam Beam with c#r$ed profile
%.
Tapered beam Beam with tapered cross section
&.
!.
Based on the shape of cross section: i.
'(beam Beam with )'* cross section
ii.
T(beam Beam with )T* cross section
iii.
"(beam Beam with )"* cross section
Based on e+#ilibri#m conditions: 1.
Statically determinate beam ,or a statically determinate beam- e+#ilibri#m conditions alone can be #sed to sol$e reactions.
!.
Statically indeterminate beam ,or a statically indeterminate beam- e+#ilibri#m conditions are not eno#gh to sol$e reactions. Additional deflections are needed to sol$e reactions.
%.
Based on the type of s#pport: 1.
Simply s#pported beam
!.
"antile$er beam
%.
$erhanging beam
&.
"ontin#o#s beam
/.
,i0ed beam
"lassification of beams based on the type of s#pport is disc#ssed in detail below:
1. Simply s#pported beam: A simply s#pported beam is a type of beam that has pinned s#pport at one end and roller s#pport at the other end. epending on the load applied- it #ndergoes shearing and bending. 't is the one of the simplest str#ct#ral elements in e0istence.
The following image ill#strates a simply s#pported beam.
Simply S#pported Beam 2SSB3
!. "antile$er beam: A cantile$er beam is fi0ed at one end and free at other end. 't can be seen in the image below.
"antile$er Beam
%. $erhanging beam: A o$erhanging beam is a beam that has one or both end portions e0tending beyond its s#pports. 't may ha$e any n#mber of s#pports. 'f $iewed in a different perspecti$e- it appears as if it is has the feat#res of simply s#pported beam and cantile$er beam.
$erhanging Beam
&. "ontin#o#s beam: A contin#o#s beam has more than two s#pports distrib#ted thro#gho#t its length. 't can be #nderstood well from the image below.
"ontin#o#s Beam
/. ,i0ed beam: As the name s#ggests- fi0ed beam is a type of beam whose both ends are fi0ed.
,i0ed Beam
4ead more: http:55mechteacher.com5beam56i077%B&Blg8t'
Slab A shallow- reinforced(concrete str#ct#ral member that is $ery wide compared with depth. Spanning betwe en beams- girders- or col#mns-slabs are #sed for floors- roofs- and bridge dec9s. 'f they are cast integrally with beams or girders- they may be considered the top flangeof those members and act with them as a T beam. A one(way slab is s#pported on fo#r sides and has a m#ch larger span in one direction than in the other may be ass#med to bes#pported only a long its long sides. 't may be designed as a beam spanning in the short direction. ,or this p#rpose a 1(ft width can bechosen and the depth of slab and reinforcing determin ed for this #nit. Some steel is also placed in the long direction to resist temperat#restresses and distrib#te concentrated loads. The area of the steel generally is at least .!; of the concrete area. A slab s#pported on fo#r sides and with reinforcing steel perpendic#lar to all sides is called a two(way sla b. S#ch slabs generally aredesigned by empirical methods. A two(way slab is di$ided into strips for desig n p#rposes. When a slab is s#pported directly on col#mns- witho#t beams and girders- it is called a flat plate or flat sla b. Altho#gh thic9er and morehea$ily reinforced than slabs in beam(and(girder constr#ction- flat slabs are ad$antageo#s beca#se they offer no obstr#ction to passageof light 2as beam constr#ction does3< sa$ings in story height and in the simpler formwor9 in$ol$ed< less danger of collapse d#e too$erload< and better fir e protection with a sprin9ler system beca#se the spray is not obstr#cted by beams. See "oncrete col#mn-4einforced concrete
Types of slab #. o
T-%haped %labs T-shaped slaps get their name from the T-shape of the footer and block foundation. Often called block slabs as a reference to the foundation using concrete blocks during construction, T-shaped foundations find use in areas where freezing of the ground occurs according to the Concrete Network website. This three-stage process begins with digging footers dug and backfilling with concrete. Stage 2 inoles the building of a block perimeter wall on top of the footers. This inerted T-shape is the e!terior wall of the foundation. "fter wall construction, the interior of the block slab receies dirt and grael to seeral inches below the top of the block wall before adding a concrete slab oer the grael and dirt completes the T-shaped slab.
%lab-on-&round %labs o
Slab-on-ground slabs, called monolithic slabs due to their single-pour design, uses thick outer footings and filled with rebar reinforcement to form the slab. #oles dug for the footer and filled with rebar comprise the thick sides of the slab, and forms make a barrier for the pouring of the concrete. The slab is poured with one pour from the foundation holes to the top of the slab forms.
!rost-'rotected %labs o
" frost-protected slab is a monolithic slab that uses the heating within the structure to protect the slab foundation from freezing temperatures. $ol%st%rene insulation placed along the perimeter of the slab retains heat from the structure to preent the ground temperature of the ground around the footings from freezing.
'ost-Tensioned %lab o
$ost-tensioned slabs emplo% the same materials as other concrete slabs, but with the addition of high-strength plastic coated steel cables. $ost-tensioning of a slab occurs b% placing the cables throughout the slab before pouring and, after the slab has hardened, tension applied to the cables compresses the slab to increase the oerall strength of the slab. "ccording to &rian "llred's article in (esidential Concrete magazine, the strength of concrete is in compression.
4ead more : http:55www.ehow.com5abo#t=//%%///=types(concrete(slab(designs.html
(olumn A column is essentially a vertical member designed to transmit a compressive load. Being a compression member, it is reasonable to suppose that a column would ail by crushing o the material when the load reached a high enough value, but or most columns ailure occurs at a lower load than the crushing strength . This is because most columns are relatively slender, they are long in relation to their lateral dimensions. )t is generally seen that when a slender member is loaded in compression, as or e*ample when a slender garden cane is leaned on rather heavily, it will bow sideways or buc+le, and i the load is then increased urther the cane will eventually ail in bending. ), on the other hand, a stoc+y column is used, one with a low length to breadth ratio, then a crushing mode o ailure is more li+ely than a buc+ling mode. !or e*ample, i a bloc+ o timber $ mm * $ mm * #$$ mm high were loaded in compression, one could not imagine it ailing by buc+ling. Thus the normal compression elements, length and lateral dimension play a part in determining the mode o ailure that will result. Also, or a given section, there will be a critical length o the compression member below which it will be crushed and above which it will buc+le.The shape o a column is also very important. !or e*ample, a sheet o cardboard has practically no strength as a column, but i bent to orm an angle section or other shapes as shown below, it is capable o supporting a load.
There are several dierent column types. ierent column types support dierent editors, dierent fltering options, and so on. Every data column type has the ollowing Boolean properties/ Exportable - etermines whether the column should be included into the e*ported fle or not. Display - etermines whether the column is displayed in browser mode. 0hen Display is False, the column is rendered in the browser but all the cells are styled with "display: none", so that they are not visible to the user. Display does not aect whether the column editor is visible in an edit orm, but i the table view uses an in-place editor, the column editor does not appear. Visible - etermines whether the column is rendered in browser mode. 0hen Visible is False, the column is not even rendered in the •
•
•
browser. Visible does not aect whether the column editor is visible in an edit orm, but i the table view uses an in-place editor, the column editor does not appear.
!oundation %hallow !oundation %ystem %pread oundation 1at2at oundation eep oundation system 'ile 'ile wall (aissons iaphgram • •
• • • •
%hallow oundation A shallow oundation is type o oundation which transer buidings load to the soil.%hallow oundations include spread ooting oundations,rat oundations +nown as mat-slab oundations,slab on grade oundations,strip oundations,buoyancy oundation,pad oundations,rubble trench and earth bag oundation. %hallow oundation are ta+en to be those where the depth below fnished ground level is less than 3m and include strip oundations,pad and rat oundation.%hallow oundation are those oundations that have a depth o embedment to width ratio o appro*imately less than our. Advantages shallow oundations. (ost is aordable (onstruction procedure is simple 1aterial is mostly concrete 4abour does not need e*pertise. • • • •
isadvantaged shallow oundations %ettlement 4imit o capacity soil structure )rregular ground surace !oundaion sub5ected to pullout,torsion and moment. • • • •
eep oundation eep oundations is those ounding too deeply below te fnished ground surace or their base bearing capacity to be aected by surace conditions,this is usually at depths 63 m below fnished ground level.eep oundations can be used to transer
the loading to the deeper,more competent at depth i unsuitable soil are present near the surace. Advantages eep !oundations •
http/www.scribd.comdoc7389:3;%hallow-!oundation-and-eep-!oundation<
