Introduction to Prc II

8/17/2019 Introduction to Prc II

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INTRODUCTION TO PRC II

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CE-401 PLAIN & REINFORCED CONCRETE-II 3+0

• Schedule: Tuesday and Thursday 08:00 am to 9:30 am

• Venue: Co!u"er La#-4

• O#$e%"'e:• To give concept to students about the conventional and advanced

designing approaches for various structural elements.

• Course Con"en"s

•Flat ()a# Flat !late and "a#e Slab: $nal%sis and design of &atplate &at slabs and 'a#e slabs for &e(ure and shear under gravit%loading.

• Slender Co)uns: $nal%sis and design of slender columns sub)ectedto combined &e(ure and a(ial loading *uidelines for design of shear'alls+an over vie'.

• ,esign of ,i-erent T%pes of Founda"ons: $nal%sis and design ofeccentric strap strip and mat footings piles and pile caps uo%antFootings.

• ("ars: $nal%sis and ,esign of Various T%pes of Stairs and Staircases.

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Pre-s"ressn* • !rinciples ,esign !hilosoph%: !rinciples of pre+

stressing properties of high strength materialsmportance of high strength concrete and steel used inpre+stressing ehavioral aspects of pre+stressed beamsand comparison 'ith reinforced concrete beams post+tensioning and pre+tensioning techni2ues !roles of

post+tensioned tendons bonded and non+bondedtendons comparison and hard+'are re2uirements.

• !re+stress 4osses: !re+stress losses immediate andtime dependent losses lump sum and detailed

estimation of pre+stress loss.

• $nal%sis and ,esign: Simpl% supported pre+stressedbeams for &e(ure and shear.

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oo,s Re%oended

• N)son $.5. ,ar'in ,. and ,olan6.". ,esign of 6oncrete StructuresFourteenth Edition

• %Cora% 7.6. and elson 7.. ,esignof einforced 6oncrete Sixth Edition

• N)son $.5. ,esign of !re+stressed

concrete 7ohn "ile% and Sons.• .re*or 7.*.;. einforced 6oncrete

,esign !rentice 5all


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/ee,)y Course Ds"r#u"on/ee

,To!%s "o #e %o'ered Coen"s

01

=vervie' one+'a% slab. $nal%sis and design of

&at plate for &e(ure and shear under gravit%loading.

0

$nal%sis and design of &at slab for &e(ure and

shear under gravit% loading =vervie' of

'a#e slab.

$ssignment: 01

03ntroduction to columns overvie' of short

columns. ntroduction to slender columns.?ui@: 01

04 $nal%sis and design of slender columns.

$ssignment: 01

A,,B

$ssignment: 0/0 =vervie' of various t%pes of staircases.

02=vervie' of shear 'all design isolated footing

and rectangular footing.

$ssignment: 0/

A,,B

$ssignment: 030 ,esign of combined footing. ?ui@: 0/0 $nal%sis and design of strip and strap footings. C


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10$nal%sis and design of eccentric mat footings

and buo%ant footings.

$ssignment:03

A,,B

$ssignment: 0<11 =vervie' of piles and pile caps. ?ui@: 03

1

!rinciples of pre+stressing !roperties of highstrength materials mportance of high strength

concrete and steel used in pre+stressing

behavioral aspects of pre+stressed beams and

comparison 'ith reinforced concrete beams.

$ssignment:0<

A,,B

13

!ost tensioning and pre+tensioning techni2uesproles of post tensioned tendons bonded and

non+bonded tendons comparison and

hard'are re2uirements.

?ui@: 0<

$ssignment: 0C

14

!re+stress losses immediate and time

dependent losses lump sum and detailed

estimation of pre+stress force simpl%

supported pre+stressed beams for &e(ure and

shear.

?ui@: 0C

1 ,esign of !re Stressed eams$ssignment:

0CA,,B E


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Le""er .rades and Nuer%a) 7a)ue

• Le""er .rade Nuer%a) 7a)ue

$


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Course .radn* (ys"e

.rades 8)) #e de"erned on "he#ass o9

• C $ssignments 10H

• C ?ui@@es 10H

•

;id+term test /0H• Term !ro)ect 1:

• Ind Semester I(am


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Ru)es 9or C)ass

• Start 'ith Tala'atDtranslation

• T$D*rader:

s (dd;ue

• =Jce 5ours: / 11-30 "o 13-00

• $ll material shall be available in advance on the 'ebsiteDthrough *roup ;ail ce/011K'ecu'.edu.pL

•

Students are e(pected to come prepared for the class• Solving of home assignment in class 'ill contribute

to'ards the studentMs grading of the course

• ,isclaimer D Seating !lan9

mailto:[email protected]:[email protected]


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F)a" P)a"e


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T=PE( OF (LA(

• *en broad &at plate usuall% hori@ontal 'ith topand bottom surfaces parallel or nearl% so

• ;a% be supported b%: – 6 beams masonr% or 6 'alls structural steel

cols directl% b% columns or continuousl% b% the gr

• Support conditions: – T'o opposite sides

– eams on all four sides

– ntermediate beams

– ,irectl% b% columns

– ,irectl% b% columns 'ith thicL ended region nearcolumns

– ibbed construction

– =n ground continuousl% 11


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INTRODUCTION

n general slabs are classied as being one+'a%

or t'o+'a%. Slabs that primaril% de&ect in onedirection are referred to as one-way slabs.Simple-span, one-way slabs have previousl%been discussedN 'hile the design of continuous

slabs so that the slabs can de&ect in t'odirections referred to as two-way slabs 'ill bediscussed in detail.,epending on load conditions and otherre2uirements slabs ma% be strengthened b% theaddition of beams bet'een the columns b%

thicLening the slabs around the columns Adrop panels), and by faring the columns under theslabs Acolumn capitals). These situations will beshown and discussed in the lecture.

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T=PE( OF (LA(

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T=PE( OF (LA(

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T=PE( OF (LA(

Flat plates are solid concrete slabs o uniorm depthsthat transer loads directl% to the supporting columns'ithout the aid of beams or capitals or drop panels.Flat plates can be constructed 2uicLl% due to theirsimple form'orL and reinforcing bar arrangements.

The% need the smallest overall stor% heights toprovide specied headroom re2uirements and the%give the most &e(ibilit% in the arrangement ofcolumns and partitions. The% also provide littleobstruction to light and have high re resistance

because there are fe' sharp corners 'here spallingof the concrete might occur. Flat plates are probabl%the most commonl% used slab s%stem toda% formultistor% reinforced concrete hotels motelsapartment houses hospitals and dormitories.

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T=PE( OF (LA(

Flat plates present a possible problem in transferringthe shear at the perimeter of the columns. n other'ords there is a danger that the columns ma% punchthrough the slabs. $s a result it is fre2uentl%

necessar% to increase column si@es or slabthicLnesses or to use shear heads. Shear headsconsist o steel or channel shapes placed in the slabo!er the columns. $lthough such procedures ma%seem e(pensive it is noted that the simple form'orL

re2uired for &at plates 'ill usuall% result in sucheconomical construction that the e(tra costs re2uiredfor shear heads are more than canceled. For heav%industrial loads or long spans ho'ever some othert%pe of &oor s%stem ma% be re2uired.

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T=PE( OF (LA(

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T=PE( OF (LA(

Flat slabs include two-way reinorced concrete slabs with

capitals, drop panels or both. These slabs are ver%satisfactor% for heav% loads and long spans. $lthough theform'orL is more e(pensive than for &at plates &at slabs'ill re2uire less concrete and reinforcing than 'ould bere2uired for &at plates 'ith the same loads and spans.

The% are particularl% economical for 'arehouses parLingand industrial buildings and similar structures 'heree(posed drop panels or capitals are acceptable.

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T=PE( OF (LA(

n Figure above a two-way slab with beams is shown. Thistype o foor system is obviousl% used 'here its cost isless than the cost of &at plates or &at slabs. n other'ords 'hen the loads or spans or both become 2uitelarge the slab thicLness and column si@es re2uired for &at

plates or &at slabs are of such magnitude that it is moreeconomical to use t'o+'a% slabs 'ith beams despite the19


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T=PE( OF (LA(

$nother t%pe of &oor s%stem is the wa"e slab, anexample o which is shown in the ne(t slide. The &ooris constructed b% arranging s2uare berglass ormetal pans 'ith tapered sides 'ith spaces bet'eenthem as sho'n. "hen the concrete is placed over

and bet'een the pans the 'a#e shape is obtained. The intervals or gaps bet'een the pans form thebeam 'ebs. These 'ebs are rather deep and providelarge moment arms for the reinforcing bars. "ith'a#e slabs the 'eight of the concrete is greatl%

reduced 'ithout signicantl% changing the momentresistance of the &oor s%stem. $s in &at plates shearcan be a problem near columns. 6onse2uentl%'a#e &oors are usuall% made solid in those areas toincrease shear resistance.

;an% slabs are continuousl% sp on the gr as for /0


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T=PE( OF (LA(

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• einforced concrete slabs being discussed

are usuall% designed for loads assumed tobe uniforml% distributed over the entireslab panel bounded b% beams orsupporting columns centerlines. ;inor

concentrated loads can be accommodatedthrough t'o+'a% action of thereinforcement. 5eav% concentrated loadsgenerall% re2uire supporting beams.

• The one 'a% and t'o structural action canbe visuali@ed as sho'n in ne(t t'o slides.

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ONE-/A= (LA ACTION

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T/O-/A= (LA ACTION

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E>A7IOR OF T/O-/A= ED.E-(UPPORTED (LA

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CORNER REINFORCEENT

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TEPERATURE AND (>RIN?A.EREINFORCEENT

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ANAL=(I( OF T/O-/A=(LA(

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ANAL=(I( OF T/O-/A= (LA( T'o+'a% slabs bend under load into dish+shaped surfaces

so there is bending in both principal directions. $s a resultthe% must be reinforced in both directions b% la%ers ofbars that are perpendicular to each other. $ theoreticalelastic anal%sis for such slabs is a ver% comple( problemdue to their highl% indeterminate nature. umericaltechni2ues such as nite di-erence and nite elementsare re2uired but such methods are not reall% practical forroutine design.$ctuall% the fact that a great deal of stress redistributioncan occur in such slabs at high loads maLes itunnecessar% to maLe designs based on theoreticalanal%ses. Therefore the design of t'o+'a% slabs is

generall% based on empirical moment coeJcients 'hichthough the% might not accuratel% predict stress variationsresult in slabs 'ith satisfactor% overall safet% factors. nother 'ords if too much reinforcing is placed in one partof a slab and too little some'here else the resulting slabbehavior 'ill probabl% still be satisfactor%. The totalamount o reinorcement in a slab seems more important3/


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ANAL=(I( OF T/O-/A= (LA( Oou should clearl% understand that ne(t three lectures are

devoted to t'o+'a% slab design based on appro(imatemethods of anal%sis there is no intent to prevent fromusing more e(act methods. Oou ma% design slabs on thebasis of numerical solutions %ield+line anal%sis or othertheoretical methods provided that it can be clearl%demonstrated that the% have met all the necessar% safet%and service abilit% criteria re2uired b% the $6 6ode.$lthough it has been the practice of designers for man%%ears to use appro(imate anal%ses for design and to useaverage moments rather than ma(imum ones t'o+'a%slabs so designed have proved to be ver% satisfactor%

under service loads. Furthermore the% have been provedto have appreciable overload capacit%.

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DE(I.N OF T/O-/A=(LA( T>E ACI CODE

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DE(I.N OF T/O-/A= (LA( = T>EACI CODE The $6 6ode A13.C.1.1B species t'o

appro(imate methods for designing t'o+'a%slabs for gravit% loads. These are the e2uivalentframe method and the direct design method.

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E;u'a)en" Frae e"hod

n this method a portion of a structure is taLenout b% itself as sho'n in the ne(t gure. Thesame sti-ness values are used for thee2uivalent frame method as used for the directdesign method. This method is ver% satisfactor%

for frames 'ith unusual dimensions or loadings.


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DE(I.N OF T/O-/A= (LA( = T>EACI CODE

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DE(I.N OF T/O-/A= (LA( ACI 31-0

The 6ode A13.EB provides a procedure 'ith 'hich aset of moment coeJcients can be determined. Themethod in e-ect involves a single+c%cle momentdistribution anal%sis of the structure based on AaB the

estimated &e(ural sti-nessPs of the slabs beams Aifan%B and columns and AbB the torsional sti-nessPs ofthe slabs and beams Aif an%B transverse to thedirection in 'hich &e(ural moments are beingdetermined. These t%pes of moment coeJcients

have been used satisfactoril% for man% %ears for slabdesign. The% do not ho'ever give ver% satisfactor%results for slabs 'ith uns%mmetrical dimensions andloading patterns.

re%" Des*n e"hod

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Introduction to Prc II