lintels and arches 2 (1).pptx

7/24/2019 lintels and arches 2 (1).pptx

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Arches and Lintels

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Lintels and Arches

Lintels and arches are structural members

designed to support the load above

openings.

Transmit superimposed loads to walls

adjacent to the openings.


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Lintels

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Introduction

A lintel is defned as a horizontal structuralmember which is placed across the opening.

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lassifcation o! Lintels

Lintels are classifed according to thematerials o! their construction"

#1$ Timber lintels

#%$ &tone lintels

#3$ 'ric( lintels

#4$ )ein!orced 'ric( lintels

#*$ &teel lintels

#+$ )ein!orced cement concrete lintels

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Timber lintels Locall, available

)elativel, costl,- structurall, wea( andvulnerable to fre.

asil, deca,- i! not properl, ta(en care.

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&tone Lintels

/sed - where stonesare easil, available.

onsists o! a simplestone slab o! greaterthic(ness.

0igher cost

annot with standtensile loads.

&T2 LITL


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&tone Lintels


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'ric( Lintels

0ard- well burnt -

frst class bric(sare used.

&uitable !or small

span.

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)ein!orced 'ric( Lintels

6or large spans andheav, loads

The, are rein!orced with

mild steel bars. 7er, common due to

durabilit,- strength andfre resisting properties.

8oints are flled withcement concrete.

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)ein!orced 'ric( Lintels

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&teel Lintels :rovided at large

opening and where thesuper;imposed loadsare heav,.

)olled steel joists or Isections are used .

ither used singl, or in

combination o! two orthree units.

8oint with bolts.

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)2LL< &TL 82I&T


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)ein!orced ement oncreteLintel

ommon in use.

The, ma, be pre;cast.

6or smaller span- the

pre;cast concrete

lintels are used.


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Arches

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A)0& The structure

constructed o!wedge shaped bloc(o! stones or bric(s

-jointed togetherwith mortar andprovided across the

opening to carr, theweight o! thestructure above the

opening. 1*


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'asic concept; Arch action An arch is a pure compression member.

It can span a large area b, resolving !orces intocompressive stresses and- in turn eliminating tensilestresses. This is sometimes re!erred to as archaction.

As the !orces in the arch are carried to the ground-the arch will push outward at the base- called thrust.

As the rise- or height o! the arch decreases- theoutward thrust increases.

In order to maintain arch action and prevent thearch !rom collapsing- the thrust needs to berestrained- either with internal ties- or e=ternalbracing- such as abutments.

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L>T& 26 A)0& 1


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T0IAL T)>&

The various technical terms used in arches areas !ollows";

1?Abutment";This is the end support o! an arches.

%?:ier";This is support an intermediate o! an arch.

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3?Intrados";This is the inner curve or sur!ace o!an arch.

4?=trados";This is the outer curve or sur!ace o!the arches.

*?7oussoirs";The voussoirs or arch stones arethe wedge shaped units !orming the arch.

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+?& i i t Th i i t


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+?&pringing stone";The springing stone orspringer is the frst voussoir at springing levelon either side o! the arches.

?&pringing line";This is an imaginar, line joiningthe two springing points.

?rown";This is the highest point o! e=trados orit is the highest part o! an arches.

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5?@e,stone";This is the highest central wedgeshaped bloc( o! an arch.

19?&(ew bac(";This the sur!ace o! the abutmenton which the arch rests.

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11?&pan";This is the clear horizontal distancebetween the two supports.

1%?)ise";this is the vertical distance between

highest point on the intrados and the springingline.

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14?0aunch o! an arch";This is the portion o! arch

situated centrall, between the (e, and s(ew

bac(s.

1*?&pandril";This is the curved triangular

enclosed b, the e=trados o! the arch- ahorizontal line !rom the crown o! the arch and

perpendicular line !rom the springing o! the

outer curves.

1+? &ot"; It is the inner sur!ace o! an arch

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6ailure o! an Arch

ver, element o! arch remains in compression. An arches !ail due to";

1?rushing o! the masonr,.

%?&liding o! voussoirs.3?)otation o! some joints about an edge.

4?/neven settlement o! an abutment or pier.

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1. rushing o! the masonr,

I! the compressive stress e=ceeds the sa!e

crushing strength o! the masonr, unit and

mortar - the arch will !ail in crushing.

The material should be o! adeBuate

strength and size o! voussoirs and should

be properl, designed to bear the thrust

transmitted through them.

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%. &liding o! 7oussoirs

To sa!eguard against sliding o! voussoirs past each

other due to transverse shear -the voussoirs o!

greater height should be provided.

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3. )otation o! some joint about an edge )otation can be prevented -i! the line o! resistance is

(ept within intrados and e=trados. Also- the line o!

thrust should be made to cross the joint awa, !rom

the edge to prevent the crushing o! that edge.


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4. /neven settlement o! an abutment orpier

/neven settlement o! abutment -which causes

secondar, stresses in arch.

0ence- the abutment which has ultimatel, to bear all

the load trans!erred to the arch - should be strong

enough.

Also- the arch should be s,mmetrical - so thatuneBual settlements o! the two abutment is

minimised.

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lassifcation o! Arches

An arch ma, be classifed according totheir"

1?>aterial o! construction and wor(manship

%?&hape o! curve !ormed b, their sot or

intrados

3?umber o! centers.

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LA&&I6IATI2 'A&< 2 >AT)IAL AA&0I:

BRICK ARCHES

*Rough brick arches

*Axed brick arches*Gauged brick archesSTONE ARCHES

*Rubbe arches

*Ashar archesCONCRETE ARCHES

*!recas" co#cre"e bock arches

*$o#oi"hic co#cre"e arches 39


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')I@ A)0&

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)2/D0 ')I@ A)0&

These arches are built withordinar, bric(s- which are

not in wedge shape .

>ade up o! rectangular

bric( that are not cut into

wedge shape. urvature

are obtained b, mortar.

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AE< ')I@ A)0&

'ric(s are cut to wedge;

shape.

8oints o! arches are o!

uni!orm thic(ness.

ot dress fnel, so it

does not give muchattractive appearance.

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DA/D< ')I@ A)0& Accuratel, prepared to wedge shape.

&peciall, shaped bric(s (nown as F)/'')

')I@&G are used .

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&T2 A)0&

3*

)/''L A)0&


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)/''L A)0& >ade o! rubble stones- which are hammer

dressed- roughl, to the shape and size o!voussoirs o! the arch and f=ed in cementmortar.

These arches are used !or small span upto 1 m.

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A&0LA) A)0& &tones are cut to proper

shape o! voussoirs and

are !ull, dressed-

properl, joint with

cement or lime.

The voussoirs made o!

!ull thic(ness o! the

arch.

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2)T A)0&

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:)A&T 2)T 'L2@


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:)A&T 2)T 'L2@A)0&

/sed !or smallopenings inbuilding.

The voussoirs- in

the !orm o! cementconcrete bloc(sare prepared inspecial moulds .

Denerall, - theconcrete bloc(sare used without

rein!orcement.35

>22LIT0I 2)T


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>22LIT0I 2)TA)0&

onstructed !romcast;in;situconcrete -either plainor rein!orced -depending upon thespan and magnitudeo! loading.

Huit suitable !or largerspan 3.9 m?.

The curing is done %to 4 wee(s.

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l if i di


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lassifcation according toshape

6lat arch

&egmental arch

&emi;circular arch)elieving arch


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6LAT A)0

Acts li(e a lintel-when it providedover the opening .

8oints radiated tocenter.

/sed onl, !or lightloads onl,.

&pan up to 1.*9 m.

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6LAT A)0

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&D>TAL A)0

&egmental in shapeand provided over theopenings.

8oints radiate !rom acenter o! arch- whichlies below thespringing line.

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4*


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&>I;I)/LA) A)0 The shape o! the curve given to the arch

sot is semi;circular.

The center o! the arch lies on the springingline.

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&>I I)/LA) A)0


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&>I;I)/LA) A)0

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)LI7ID A)0


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)LI7ID A)0

Chen wooden lintel

is provided over the

wider opening- a

bric( relieving arch is

constructed above

the lintel.

)elieving the load o!

masonr, over lintel.

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02)& &02 A)0 0as a shape o! a horse shoe- incorporating

more than a semi circle

:rovided mainl, !rom architecturalconsiderations

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*1

: i t d A h


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:ointed Arch

Also (nown as Dothic arch

onsists o! two arcs o! circles meeting atthe ape=

Triangle !ormed ma, be eBuilateral or

isosceles

*%


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*3

LA&&I6IATI2 'A&< 2


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LA&&I6IATI2 'A&< 2/>') 26 T)&

O#e ce#"red arch.

T%o ce#"red arch. Three ce#"red arch.

&our ce#"red arch.

&i'e ce#"red arch.*4


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2 T)< A)0

&egmental- semi circular- Jat arches come under this categor,.

:er!ectl, circular arch (nown as bulls e,e arch provided !or

circular window.

**


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*+

TC2 T)< A)0


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TC2 T)< A)0

:ointed- semi;elliptical arches comeunder this categor,.

*

T0) T)< A)0


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T0) T)< A)0

lliptical arches

come under this

categor,.

21-2% and 23

are the center.

*

21

2%23

62/) T)< A)0


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62/) T)< A)0

It has !our centers.

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6I7 T)< A)0

This t,pe o! arch -having fve centreMs-gives good semi;elliptical shape.

lintels and arches 2 (1).pptx

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