CE2351 SA 2 Lecture Notes

download CE2351 SA 2 Lecture Notes

of 89

Transcript of CE2351 SA 2 Lecture Notes

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    1/89

    UNIT-1

    FLEXIBILITY MATRIX METHODS

    Since twentieth century, ineter!in"te #tructure# "re $ein% wie&y u#e '(r it# ($)i(u#

    !erit#* It !"y $e rec"&&e th"t, in the c"#e (' ineter!in"te #tructure# either the re"cti(n# (r the

    intern"& '(rce# c"nn(t $e eter!ine 'r(! e+u"ti(n# (' #t"tic# "&(ne* In #uch #tructure#, thenu!$er (' re"cti(n# (r the nu!$er (' intern"& '(rce# ecee# the nu!$er (' #t"tic e+ui&i$riu!

    e+u"ti(n#* In "iti(n t( e+ui&i$riu! e+u"ti(n#, c(!"ti$i&ity e+u"ti(n# "re u#e t( e)"&u"te the

    un.n(wn re"cti(n# "n intern"& '(rce# in #t"tic"&&y ineter!in"te #tructure* In the "n"&y#i# ('

    ineter!in"te #tructure it i# nece##"ry t( #"ti#'y the e+ui&i$riu! e+u"ti(n# /i!&yin% th"t the

    #tructure i# in e+ui&i$riu!0 c(!"ti$i&ity e+u"ti(n# /re+uire!ent i' '(r "##urin% the c(ntinuity ('

    the #tructure with(ut "ny $re".#0 "n '(rce i#&"ce!ent e+u"ti(n# /the w"y in which

    i#&"ce!ent "re re&"te t( '(rce#0* e h")e tw( i#tinct !eth( (' "n"&y#i# '(r #t"tic"&&y

    ineter!in"te #tructure eenin% u(n h(w the "$()e e+u"ti(n# "re #"ti#'ie2

    1* F(rce !eth( (' "n"&y#i# /"( .n(wn "# '&ei$i&ity !eth( (' "n"&y#i#, !eth( (' c(n#i#tent

    e'(r!"ti(n, '&ei$i&ity !"tri !eth(0

    3* Di#&"ce!ent !eth( (' "n"&y#i# /"( .n(wn "# #ti''ne## !"tri !eth(0*

    In the '(rce !eth( (' "n"&y#i#, ri!"ry un.n(wn "re '(rce#* In thi# !eth( c(!"ti$i&ity

    e+u"ti(n# "re written '(r i#&"ce!ent "n r(t"ti(n# /which "re c"&cu&"te $y '(rce i#&"ce!ent

    e+u"ti(n#0* S(&)in% the#e e+u"ti(n#, reun"nt '(rce# "re c"&cu&"te* Once the reun"nt '(rce#

    "re c"&cu&"te, the re!"inin% re"cti(n# "re e)"&u"te $y e+u"ti(n# (' e+ui&i$riu!*

    In the i#&"ce!ent !eth( (' "n"&y#i#, the ri!"ry un.n(wn# "re the i#&"ce!ent#* In thi#

    !eth(, 'ir#t '(rce -i#&"ce!ent re&"ti(n# "re c(!ute "n #u$#e+uent&y e+u"ti(n# "re written

    #"ti#'yin% the e+ui&i$riu! c(niti(n# (' the #tructure* A'ter eter!inin% the un.n(wn

    i#&"ce!ent#, the (ther '(rce# "re c"&cu&"te #"ti#'yin% the c(!"ti$i&ity c(niti(n# "n '(rce

    i#&"ce!ent re&"ti(n#* The i#&"ce!ent-$"#e !eth( i# "!en"$&e t( c(!uter r(%r"!!in%

    "n hence the !eth( i# $ein% wie&y u#e in the !(ern "y #tructur"& "n"&y#i#* In %ener"&, the

    !"i!u! e'&ecti(n "n the !"i!u! #tre##e# "re #!"&& "# c(!"re t( #t"tic"&&y eter!in"te

    #tructure* F(r e"!&e, c(n#ier tw( $e"!# (' ientic"& cr(## #ecti(n "n #"n c"rryin%

    uni'(r!&y i#tri$ute &(" "# #h(wn in Fi%* 4*1" "n Fi%* 4*1$*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    2/89

    The &("# "re "( the #"!e in $(th c"#e#* In the 'ir#t c"#e, the $e"! i# 'ie "t $(th en# "n

    thu# i# #t"tic"&&y ineter!in"te* The #i!&y #u(rte $e"! in Fi%* 4*1$ i# " #t"tic"&&y

    eter!in"te #tructure* The !"i!u! $enin% !(!ent in c"#e (' 'ie- 'ie $e"! i# wL2/12

    /which (ccur# "t the #u(rt#0 "# c(!"re t( w&356 /"t the centre0 in c"#e (' #i!&y #u(rte

    $e"!* A( in the re#ent c"#e, the e'&ecti(n in the c"#e (' 'ie- 'ie $e"!

    w&75867EI i# 'i)e ti!e# #!"&&er th"n th"t (' #i!&y #u(rte $e"! 9w&

    75867EI * A(, there i#

    rei#tri$uti(n (' #tre##e# in the c"#e (' reun"nt #tructure* Hence i' (ne !e!$er '"i, #tructure

    (e# n(t c(&&"#e #uen&y* The re!"inin% !e!$er# c"rry the &("* The eter!in"te #tructur"&

    #y#te! c(&&"#e# i' (ne !e!$er '"i* H(we)er, there "re i#")"nt"%e# in u#in% ineter!in"te

    #tructure#* Due t( #u(rt #ett&e!ent, there wi&& $e "iti(n"& #tre##e# in the c"#e (' reun"nt

    #tructure# where "# eter!in"te #tructure# "re n(t "''ecte $y #u(rt #ett&e!ent*

    The "n"&y#i# (' ineter!in"te #tructure i''er# !"in&y in tw( "#ect# "# c(!"re t( eter!in"te

    #tructure*

    "0 T( e)"&u"te #tre##e# in ineter!in"te #tructure#, ""rt 'r(! #ecti(n"& r(ertie# /"re" (' cr(## #ecti(n"n !(!ent (' inerti"0, e&"#tic r(ertie# "re "( re+uire*

    $0 Stre##e# "re e)e&(e in ineter!in"te #tructure ue t( #u(rt #ett&e!ent#, te!er"ture ch"n%e "n

    '"$ric"ti(n err(r# etc*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    3/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    4/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    5/89

    UNIT-3 >&"#tic An"&y#i#

    1. Introduction

    1.1 Background

    U t( n(w we h")e c(ncentr"te (n the e&"#tic "n"&y#i# (' #tructure#* In the#e "n"&y#e# we u#e

    #uer(#iti(n ('ten, .n(win% th"t '(r " &ine"r&y e&"#tic #tructure it w"# )"&i* H(we)er, "n e&"#tic

    "n"&y#i# (e# n(t %i)e in'(r!"ti(n "$(ut the &("# th"t wi&& "ctu"&&y c(&&"#e " #tructure* An

    ineter!in"te #tructure !"y #u#t"in &("# %re"ter th"n the &(" th"t 'ir#t c"u#e# " yie& t( (ccur "t

    "ny (int in the #tructure* In '"ct, " #tructure wi&& #t"n "# &(n% "# it i# "$&e t( 'in reun"ncie#

    t( yie&* It i# (n&y when " #tructure h"# eh"u#te "&& (' it# reun"ncie# wi&& etr" &(" c"u#e# it

    t( '"i&* >&"#tic "n"&y#i# i# the !eth( thr(u%h which the "ctu"& '"i&ure &(" (' " #tructure i#

    c"&cu&"te, "n "# wi&& $e #een, thi# '"i&ure &(" c"n $e #i%ni'ic"nt&y %re"ter th"n the e&"#tic &("

    c""city*

    T( #u!!"ri?e thi#, >r('* Se"n e =(urcy /U=D0 u#e t( #"y2

    a structure only collapses when it has exhausted all means of standing*

    Be'(re "n"&y?in% c(!&ete #tructure#, we re)iew !"teri"& "n cr(## #ecti(n $eh")i(ur

    $ey(n the e&"#tic &i!it*

    Basis of Plastic Design

    2.1 Material Behaviour

    A uni"i"& ten#i&e #tre## (n " ucti&e !"teri"& #uch "# !i& #tee& tyic"&&y r()ie# the

    '(&&(win% %r"h (' #tre## )er#u# #tr"in2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    6/89

    A# c"n $e #een, the !"teri"& c"n #u#t"in #tr"in# '"r in ece## (' the #tr"in "t which yie&

    (ccur# $e'(re '"i&ure* Thi# r(erty (' the !"teri"& i# c"&&e it# ductility*

    Th(u%h c(!&e !(e ( ei#t t( "ccur"te&y re'&ect the "$()e re"& $eh")i(ur (' the

    !"teri"&, the !(#t c(!!(n, "n #i!&e#t, !(e& i# the idealized stress-strain curve* Thi# i#

    the cur)e '(r "n ie"& e&"#tic-&"#tic !"teri"& /which (e#n@t ei#t0, "n the %r"h i#2

    A# c"n $e #een, (nce the yie& h"# $een re"che it i# t".en th"t "n ine'inite "!(unt (' #tr"in c"n

    (ccur* Since #( !uch (#t-yie& #tr"in i# !(e&e, the "ctu"& !"teri"& /(r cr(## #ecti(n0 !u#t "(

    $e c""$&e (' "&&(win% #uch #tr"in#* Th"t i#, it !u#t $e #u''icient&y ucti&e '(r the ie"&i?e

    #tre##-#tr"in cur)e t( $e )"&i* Net we c(n#ier the $eh")i(ur (' " cr(## #ecti(n (' "n ie"&

    e&"#tic-&"#tic !"teri"& #u$:ect t( $enin%* In (in% #(, we #ee. the re&"ti(n#hi $etween "&ie

    !(!ent "n the r(t"ti(n /(r !(re "ccur"te&y, the cur)"ture0 (' " cr(## #ecti(n*

    Cross Section Behaviour

    Moment-Rotation Characteristics of General Cross Section

    e c(n#ier "n "r$itr"ry cr(##-#ecti(n with " )ertic"& &"ne (' #y!!etry, which i# "( the &"ne

    (' &("in%* e c(n#ier the cr(## #ecti(n #u$:ect t( "n incre"#in% $enin% !(!ent, "n "##e##

    the #tre##e# "t e"ch #t"%e*

    =r(## #ecti(n "n Stre##e#

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    7/89

    M(!ent-R(t"ti(n =ur)e

    Stage 1 Elastic Behaiour

    The "&ie !(!ent c"u#e# #tre##e# ()er the cr(##-#ecti(n th"t "re "&& &e## th"n the yie& #tre## ('

    the !"teri"&*

    Stage ! "ield Moment

    The "&ie !(!ent i# :u#t #u''icient th"t the yie& #tre## (' the !"teri"& i# re"che "t the

    (uter!(#t 'i$re/#0 (' the cr(##-#ecti(n* A&& (ther #tre##e# in the cr(## #ecti(n "re &e## th"n the

    yie& #tre##* Thi# i# &i!it (' "&ic"$i&ity (' "n e&"#tic "n"&y#i# "n (' e&"#tic e#i%n* Since "&&

    'i$re# "re e&"#tic, the r"ti( (' the eth (' the e&"#tic t( &"#tic re%i(n#,

    Stage # Elasto-Plastic Bending

    The !(!ent "&ie t( the cr(## #ecti(n h"# $een incre"#e $ey(n the yie& !(!ent* Since $y

    the ie"&i?e #tre##-#tr"in cur)e the !"teri"& c"nn(t #u#t"in " #tre## %re"ter th"n yie& #tre##, the

    'i$re# "t the yie& #tre## h")e r(%re##e inw"r# t(w"r# the centre (' the $e"!* Thu# ()er the

    cr(## #ecti(n there i# "n e&"#tic c(re "n " &"#tic re%i(n* The r"ti( (' the eth (' the e&"#tic c(re

    t( the &"#tic re%i(n i# * Since etr" !(!ent i# $ein% "&ie "n n( #tre## i# $i%%er th"n the yie&

    #tre##, etr" r(t"ti(n (' the #ecti(n (ccur#2 the !(!ent-r(t"ti(n cur)e &(##e# it# &ine"rity "n

    cur)e#, %i)in% !(re r(t"ti(n er unit !(!ent /i*e* &((#e# #ti''ne##0*

    Stage $ Plastic Bending

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    8/89

    The "&ie !(!ent t( the cr(## #ecti(n i# #uch th"t "&& 'i$re# in the cr(## #ecti(n "re "t yie&

    #tre##* Thi# i# ter!e the >&"#tic M(!ent =""city (' the #ecti(n #ince there "re n( 'i$re# "t "n

    e&"#tic #tre##, A( n(te th"t the 'u&& &"#tic !(!ent re+uire# "n in'inite #tr"in "t the neutr"& "i#

    "n #( i# hy#ic"&&y i!(##i$&e t( "chie)e* H(we)er, it i# c&(#e&y "r(i!"te in r"ctice* Any

    "tte!t "t incre"#in% the !(!ent "t thi# (int #i!&y re#u&t# in !(re r(t"ti(n, (nce the cr(##-#ecti(n h"# #u''icient ucti&ity* There'(re in #tee& !e!$er# the cr(## #ecti(n c&"##i'ic"ti(n !u#t

    $e &"#tic "n in c(ncrete !e!$er# the #ecti(n !u#t $e uner-rein'(rce*

    Stage % Strain &ardening

    Due t( #tr"in h"renin% (' the !"teri"&, " #!"&& "!(unt (' etr" !(!ent c"n $e #u#t"ine*

    The "$()e !(!ent-r(t"ti(n cur)e rere#ent# the $eh")i(ur (' " cr(## #ecti(n (' " re%u&"r e&"#tic-

    &"#tic !"teri"&* H(we)er, it i# u#u"&&y 'urther #i!&i'ie "# '(&&(w#2

    ith thi# ie"&i?e !(!ent-r(t"ti(n cur)e, the cr(## #ecti(n &ine"r&y #u#t"in# !(!ent u t( the

    &"#tic !(!ent c""city (' the #ecti(n "n then yie in r(t"ti(n "n ineter!in"te "!(unt*

    A%"in, t( u#e thi# ie"&i?"ti(n, the "ctu"& #ecti(n !u#t $e c""$&e (' #u#t"inin% &"r%e r(t"ti(n#

    th"t i# it !u#t $e ucti&e*

    Plastic &ingeN(te th"t (nce the &"#tic !(!ent c""city i# re"che, the #ecti(n c"n r(t"te 'ree&y th"t i#, it

    $eh")e# &i.e " hin%e, ecet with !(!ent (' M "t the hin%e* Thi# i# ter!e "plastic hinge, "n

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    9/89

    i# the $"#i# '(r &"#tic "n"&y#i#* At the &"#tic hin%e #tre##e# re!"in c(n#t"nt, $ut #tr"in# "n

    hence r(t"ti(n# c"n incre"#e*

    'nal(sis of Rectangular Cross Section

    Since we n(w .n(w th"t " cr(## #ecti(n c"n #u#t"in !(re &(" th"n :u#t the yie& !(!ent, we "re

    intere#te in h(w !uch !(re* In (ther w(r# we w"nt t( 'in the yie& !(!ent "n &"#tic

    !(!ent, "n we ( #( '(r " rect"n%u&"r #ecti(n* T".in% the #tre## i"%r"!# 'r(! th(#e (' the

    !(!ent-r(t"ti(n cur)e e"!ine re)i(u#&y, we h")e2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    10/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    11/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    12/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    13/89

    Sha)e *actor

    Thu# the r"ti( (' e&"#tic t( &"#tic !(!ent c""city i#2

    Thi# r"ti( i# ter!e theshape factor,f, "n i# " r(erty (' " cr(## #ecti(n "&(ne* F(r "rect"n%u&"r cr(##-#ecti(n, we h")e2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    14/89

    An #( " rect"n%u&"r #ecti(n c"n #u#t"in 9C !(re !(!ent th"n the yie& !(!ent,

    $e'(re " &"#tic hin%e i# '(r!e* There'(re the #h"e '"ct(r i# " %(( !e"#ure (' the e''iciency

    (' " cr(## #ecti(n in $enin%* Sh"e '"ct(r# '(r #(!e (ther cr(## #ecti(n# "re

    Methods of Plastic 'nal(sis

    3.1 IntroductionThere "re three !"in "r("che# '(r er'(r!in% " &"#tic "n"&y#i#2

    +he Incremental Method

    Thi# i# r($"$&y the !(#t ($)i(u# "r("ch2 the &("# (n the #tructure "re incre!ente unti& the

    'ir#t &"#tic hin%e '(r!#* Thi# c(ntinue# unti& #u''icient hin%e# h")e '(r!e t( c(&&"#e the

    #tructure* Thi# i# " &"$(ur-inten#i)e, $rute-'(rce@, "r("ch, $ut (ne th"t i# !(#t re"i&y #uite

    '(r c(!uter i!&e!ent"ti(n*

    +he E,uilirium or Statical/ Method

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    15/89

    In thi# !eth(, 'ree "n re"ct"nt $enin% !(!ent i"%r"!# "re r"wn* The#e i"%r"!# "re

    ()er&"i t( ienti'y the &i.e&y &(c"ti(n# (' &"#tic hin%e#* Thi# !eth( there'(re #"ti#'ie# the

    e+ui&i$riu! criteri(n 'ir#t &e")in% the tw( re!"inin% criteri(n t( eri)e there 'r(!*

    +he 0inematic or Mechanism/ Method

    In thi# !eth(, " c(&&"#e !ech"ni#! i# 'ir#t (#tu&"te* irtu"& w(r. e+u"ti(n# "re then written'(r thi# c(&&"#e #t"te, "&&(win% the c"&cu&"ti(n# (' the c(&&"#e $enin% !(!ent i"%r"!* Thi#

    !eth( #"ti#'ie# the !ech"ni#! c(niti(n 'ir#t, &e")in% the re!"inin% tw( criteri" t( $e eri)e

    there 'r(!*

    e wi&& c(ncentr"te !"in&y (n the ine!"tic Meth(, $ut intr(uce n(w the Incre!ent"&

    Meth( t( i&&u#tr"te the !"in c(ncet#*

    Incremental Analysis

    Illustratie Eam)le Pro))ed Cantileer

    e n(w "##e## the $eh")i(ur (' " #i!&e #t"tic"&&y ineter!in"te #tructure uner

    incre"#in% &("* e c(n#ier " r(e c"nti&e)er with !i-#"n (int &("2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    16/89

    Since the e". !(!ent# "re &e## th"n the yie& !(!ent#, we .n(w th"t yie& #tre## h"# n(t $een

    re"che "t "ny (int in the $e"!* A(, the !"i!u! !(!ent (ccur# "t A"n #( thi# (int wi&&

    'ir#t re"ch the yie& !(!ent*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    17/89

    Equilirium Method

    Introduction

    T( er'(r! thi# "n"&y#i# we %ener"&&y '(&&(w the '(&&(win% #te#2

    1* Fin " ri!"ry #tructure $y re!()in% reun"nt unti& the #tructure i# #t"tic"&&y eter!in"teG

    3* Dr"w the ri!"ry /(r 'ree0 $enin% !(!ent i"%r"!G

    8* Dr"w the re"ct"nt BMD '(r e"ch reun"nt, "# "&ie t( the ri!"ry #tructureG

    7* =(n#truct " c(!(#ite BMD $y c(!$in% the ri!"ry "n re"ct"nt BMD#G

    9* Deter!ine the e+ui&i$riu! e+u"ti(n# 'r(! the c(!(#ite BMDG

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    18/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    19/89

    F(r Ste 4, we #(&)e thi# e+u"ti(n '(r the c(&&"#e &("2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    20/89

    !inematic Method "sing #irtual $ork

    Introduction

    >r($"$&y the e"#ie#t w"y t( c"rry (ut " &"#tic "n"&y#i# i# thr(u%h the ine!"tic Meth( u#in%

    )irtu"& w(r.* T( ( thi# we "&&(w the re#u!e #h"e "t c(&&"#e t( $e the c(!"ti$&e

    i#&"ce!ent #et, "n the etern"& &("in% "n intern"& $enin% !(!ent# t( $e the e+ui&i$riu!

    #et* e c"n then e+u"te etern"& "n intern"& )irtu"& w(r., "n #(&)e '(r the c(&&"#e &(" '"ct(r

    '(r th"t #u(#e !ech"ni#!*

    Re!e!$er2

    E+ui&i$riu! #et2 the intern"& $enin% !(!ent# "t c(&&"#eG

    =(!"ti$&e #et2 the )irtu"& c(&&"#e c(n'i%ur"ti(n /#ee $e&(w0*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    21/89

    N(te th"t in the "ctu"& c(&&"#e c(n'i%ur"ti(n the !e!$er# wi&& h")e e&"#tic e'(r!"ti(n in

    $etween the &"#tic hin%e#* H(we)er, #ince " )irtu"& i#&"ce!ent (e# n(t h")e t( $e re"&, (n&y

    c(!"ti$&e, we wi&& ch((#e t( i%n(re the e&"#tic e'(r!"ti(n# $etween &"#tic hin%e#, "n t".e

    the !e!$er# t( $e #tr"i%ht $etween the!*

    'ctual Colla)se Mechanism

    S( '(r (ur re)i(u# $e"!, we .n(w th"t we re+uire tw( hin%e# '(r c(&&"#e /(ne !(re th"n it#

    e%ree (' reun"ncy0, "n we thin. th"t the hin%e# wi&& (ccur uner the (int# (' e". !(!ent,

    A "nC* There'(re i!(#e " unit )irtu"& i#&"ce!ent "tC "n re&"te the c(rre#(nin% )irtu"&

    r(t"ti(n# (' the hin%e# u#in% ,

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    22/89

    2ther Colla)se Mechanisms

    F(r the c(&&"#e !ech"ni#! &((.e "t re)i(u#&y, it #ee!e ($)i(u# th"t the &"#tic hin%e in the

    #"n #h(u& $e $ene"th the &("* But why U#in% )irtu"& w(r. we c"n e"!ine "ny (##i$&e

    c(&&"#e !ech"ni#!* S( &et@# c(n#ier the '(&&(win% c(&&"#e !ech"ni#! "n #ee why the &"#tic

    hin%e h"# t( $e &(c"te $ene"th the &("*

    Plastic &inge et3eenAand C4

    I!(#in% " unit )irtu"& e'&ecti(n "t, we %et the '(&&(win% c(&&"#e !ech"ni#!2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    23/89

    An #( we #ee th"t the c(&&"#e &(" '"ct(r '(r thi# !ech"ni#! een# (n the (#iti(n (' the

    &"#tic hin%e in the #"n*

    +heorems of Plastic 'nal(sis

    %.1 Criteria

    In >&"#tic An"&y#i# t( ienti'y the c(rrect &(" '"ct(r, there "re three criteri" (' i!(rt"nce2

    1* E,uilirium2 the intern"& $enin% !(!ent# !u#t $e in e+ui&i$riu! with the etern"& &("in%*

    3* Mechanism2 "t c(&&"#e the #tructure, (r " "rt (', c"n e'(r! "# " !ech"ni#!*

    8* "ield2 n( (int in the #tructure c"n h")e " !(!ent %re"ter th"n the &"#tic !(!ent c""city ('

    the #ecti(n it i# "&ie t(*

    B"#e (n the#e criteri", we h")e the '(&&(win% the(re!#*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    24/89

    &he "''er ound ("nsa)e* &heorem

    Thi# c"n $e #t"te "#2

    If a !ending moment diagram is found which satisfies the conditions of e"uili!rium

    and mechanism #!ut not necessarily yield$% then the corresponding load factor is

    either greater than or e"ual to the true load factor at collapse&

    Thi# i# c"&&e the un#"'e the(re! $ec"u#e '(r "n "r$itr"ri&y "##u!e !ech"ni#! the &(" '"ct(r i#

    either e"ct&y ri%ht /when the yie& criteri(n i# !et0 (r i# wr(n% "n i# t(( &"r%e, leading a

    designer to thin' that the frame can carry more load than is actually possi!le*

    The Lower bound (Safe) Theorem

    If a !ending moment diagram is found which satisfies the conditions of e"uili!rium and yield#!ut not necessarily that of mechanism$% then the corresponding load factor is either less than or

    e"ual to the true load factor at collapse&

    Plastic Analysis of Beams

    Example 1 Fixed-Fixed Beam with Point Load

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    25/89

    To start the problem, we examine the usual elastic BMD to seewhere the plastic

    hinges are likely to form:

    e "( nee t( .n(w h(w !"ny hin%e# "re re+uire* Thi# #tructure i# 8 #t"tic"&&y ineter!in"te

    "n #( we !i%ht eect the nu!$er (' &"#tic hin%e# re+uire t( $e 7* H(we)er, #ince (ne (' the

    ineter!in"cie# i# h(ri?(nt"& re#tr"int, re!()in% it w(u& n(t ch"n%e the $enin% $eh")i(ur ('

    the $e"!* Thu# '(r " $enin% c(&&"#e (n&y 3 ineter!in"cie# "&y "n #( it wi&& (n&y t".e 8

    &"#tic hin%e# t( c"u#e c(&&"#e*

    S( &((.in% "t the e&"#tic BMD, we@&& "##u!e " c(&&"#e !ech"ni#! with the 8 &"#tic hin%e# "t

    the e". !(!ent &(c"ti(n#2A,, "n C*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    26/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    27/89

    We need to check that this is the correct solution using theUniueness Theorem:

    An #( the "&ie &(" i# in e+ui&i$riu! with the 'ree BMD (' the c(&&"#e BMD*

    (& )echanism*

    Fr(! the r((#e c(&&"#e !ech"ni#! it i# ""rent th"t the $e"! i# " !ech"ni#!*

    +& ,ield*

    Fr(! the c(&&"#e BMD it c"n $e #een th"t n(where i# eceee* > M

    Thu# the #(&uti(n !eet# the three c(niti(n# "n #(, $y the Uni+uene## The(re!, i# the c(rrect

    #(&uti(n*

    Example 2 Propped Cantilever with Two Point Loads

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    28/89

    F(r the '(&&(win% $e"!, '(r " &(" '"ct(r (' 3*, 'in the re+uire &"#tic !(!ent

    c""city2

    !llowing for the load factor, we need to design the beam for thefollowing loads:

    "nce again we try to picture possible failure mechanisms# $ince

    maximum moments occur underneath point loads, there are two

    real possibilities:

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    29/89

    Mech"ni#!-1

    Mech"ni#!-3

    Therefore, we analyse both and apply the Upperbound Theorem to%nd the

    design plastic moment capacity#

    Mechanism 1: Plastic Hinge at C:

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    30/89

    Mechanism 2: Plastic Hinge at :

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    31/89

    & E"uili!rium*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    32/89

    U#in% the BMD "t c(&&"#e, we@&& chec. th"t the hei%ht (' the 'ree BMD i# th"t ('

    the e+ui)"&ent #i!&y-#u(rte $e"!* Fir#t&y the c(&&"#e BMD 'r(! Mech"ni#!

    1 i#2

    &ence, the total heights of the free BMD are:

    'hecking these using a simply(supported beam analysis:

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    33/89

    Thu#, u#in% "r(ri"te 'ree $(y i"%r"!# ('AC"n.2

    An #( the "&ie &(" i# in e+ui&i$riu! with the 'ree BMD (' the c(&&"#e BMD*

    (& )echanism*

    Fr(! the r((#e c(&&"#e !ech"ni#! it i# ""rent th"t the $e"! i# " !ech"ni#!* A(, #ince

    it i# " r(e c"nti&e)er "n thu# (ne e%ree ineter!in"te, we re+uire tw( &"#tic hin%e# '(r

    c(&&"#e, "n the#e we h")e*

    +& ,ield*

    Fr(! the c(&&"#e BMD it c"n $e #een th"t n(where i# the e#i%n eceee* 177

    .N! Thu# $y the Uni+uene## The(re! we h")e the c(rrect #(&uti(n*

    L"#t&y, we@&& e"!ine why the Mech"ni#! 3 c(&&"#e i# n(t the c(rrect #(&uti(n* Since the )irtu"&

    w(r. !eth( r()ie# "n uer$(un, then, $y the Uni+uene## The(re!, it !u#t n(t $e the

    c(rrect #(&uti(n $ec"u#e it !u#t )i(&"te the yie& c(niti(n*

    U#in% the c(&&"#e Mech"ni#! 3 t( eter!ine re"cti(n#, we c"n r"w the '(&&(win% BMD '(r

    c(&&"#e Mech"ni#! 32

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    34/89

    )rom this it is apparent that Mechanism * is not the uniue solution, and so

    the design plastic moment capacity must be + k-m as implied pre.iously

    from the Upperbound Theorem#

    Basic Collapse Mechanisms

    In 'r"!e#, the $"#ic !ech"ni#!# (' c(&&"#e "re2

    Beam-type collapse

    Sway Collapse

    Combination Collapse

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    35/89

    Combination of Mechanisms

    One (' the !(#t (wer'u& t(( in &"#tic "n"&y#i# i# =(!$in"ti(n (' Mech"ni#!#* Thi# "&&(w# u#

    t( w(r. (ut the )irtu"& w(r. e+u"ti(n# '(r the $e"! "n #w"y c(&&"#e# #e"r"te&y "n then

    c(!$ine the! t( 'in the c(&&"#e &(" '"ct(r '(r " c(!$in"ti(n c(&&"#e !ech"ni#!*

    =(!$in"ti(n (' !ech"ni#!# i# $"#e (n the ie" th"t there "re (n&y " cert"in nu!$er ('

    ineenent e+ui&i$riu! e+u"ti(n# '(r " #tructure* Any 'urther e+u"ti(n# "re ($t"ine 'r(! "

    c(!$in"ti(n (' the#e ineenent e+u"ti(n#* Since e+ui&i$riu! e+u"ti(n# c"n $e ($t"ine u#in%

    )irtu"& w(r. "&ie t( " (##i$&e c(&&"#e !ech"ni#!, it '(&&(w# th"t there "re ineenent

    c(&&"#e !ech"ni#!#, "n (ther c(&&"#e !ech"ni#!# th"t !"y $e ($t"ine '(r! " c(!$in"ti(n

    (' the ineenent c(&&"#e !ech"ni#!#*

    Simple Portal Frame

    /n this example we will consider a basic prismatic 0so all membersha.e the same

    plastic moment capacity1 rectangular portal frame with pinnedfeet:

    e wi&& c(n#ier thi# %ener"& c"#e #( th"t we c"n in'er the r(ertie# "n $eh")i(ur (' "&& #uch

    'r"!e#* e wi&& c(n#ier e"ch (' the (##i$&e !ech"ni#!# (ut&ine "$()e*

    Beam colla)se4

    The (##i$&e $e"! c(&&"#e &((.# "# '(&&(w#2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    36/89

    S3a( Colla)se

    The )irtu"& e'&ecti(n '(r the #w"y c(&&"#e i#2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    37/89

    Comined Colla)se

    The )irtu"& e'&ecti(n '(r thi# '(r! (' c(&&"#e i#2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    38/89

    Colla)se Mode

    Since we (n@t .n(w the re&"ti)e )"&ue# (' / "n 0, we c"nn(t eter!ine the

    c(rrect c(&&"#e !(e* H(we)er, we c"n ienti'y the#e c(&&"#e !(e# i' we &(t

    the three &(" '"ct(r e+u"ti(n# eri)e "$()e (n the '(&&(win% inter"cti(n ch"rt2

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    39/89

    -otice that each mechanism de%nes a boundary and that it isonly the region inside all of these boundaries that is safe# -ow, for

    a gi.en ration of Vto H, we will be able to determine the critical

    collapse mechanism# -ote also that the beam collapse

    mechanism is only critical for this frame at point Pon the chart 2

    this point is also included in the 'ombined mechanism#

    The bending moment diagrams corresponding to each of themechanisms are approximately:

    eam 1way Com!ined

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    40/89

    !n interesting phenomenon is obser.ed at point Qon the chart,

    where the $way and 'ombined mechanisms gi.e the same result#

    3ooking at the bending moment diagrams, we can see that this

    occurs as the moment at the top of the left column becomes

    eual to the mid(span moment of the beam:

    !mportant Problem"

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    41/89

    56I+-#

    S+I**6ESS M'+RI7 ME+&2DS

    The %i)en ineter!in"te #tructure i# 'ir#t !"e .ine!"tic"&&y eter!in"te $y intr(ucin%c(n#tr"int# "t the n(e#* The re+uire nu!$er (' c(n#tr"int# i# e+u"& t( e%ree# (' 'ree(! "t then(e# th"t i# .ine!"tic ineter!in"cy 4.* The .ine!"tic"&&y eter!in"te #tructure c(!ri#e# (''ie ene !e!$er#, hence, "&& n("& i#&"ce!ent# "re ?er(* The#e re#u&t# in #tre## re#u&t"nti#c(ntinuitie# "t the#e n(e# uner the "cti(n (' "&ie &("# (r in (ther w(r# the c&"!e:(int# "re n(t in e+ui&i$riu!* In (rer t( re#t(re the e+ui&i$riu! (' #tre## re#u&t"nt# "t the n(e#the n(e# "re i!"rte #uit"$&e un.n(wn i#&"ce!ent#* The nu!$er (' #i!u&t"ne(u# e+u"ti(n#rere#entin% :(int e+ui&i$riu! (' '(rce# i# e+u"& t( .ine!"tic ineter!in"cy 4.* S(&uti(n ('the#e e+u"ti(n# %i)e# un.n(wn n("& i#&"ce!ent#* U#in% #ti''ne## r(ertie# (' !e!$er# the!e!$er en '(rce# "re c(!ute "n hence the intern"& '(rce# thr(u%h(ut the #tructure* Sincen("& i#&"ce!ent# "re un.n(wn#, the !eth( i# "( c"&&e i#&"ce!ent !eth(* Sincee+ui&i$riu! c(niti(n# "re "&ie "t the :(int# the !eth( i# "( c"&&e e+ui&i$riu! !eth(*Since #ti''ne## r(ertie# (' !e!$er# "re u#e the !eth( i# "( c"&&e #ti''ne## !eth(*

    Intr(ucti(n

    A&& .n(wn !eth(# (' #tructur"& "n"&y#i# "re c&"##i'ie int( tw( i#tinct %r(u#2-

    /i0 '(rce !eth( (' "n"&y#i# "n

    /ii0 i#&"ce!ent !eth( (' "n"&y#i#*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    42/89

    In !(u&e 8, the '(rce !eth( (' "n"&y#i# (r the !eth( (' c(n#i#tent e'(r!"ti(n i# i#cu##e* An

    intr(ucti(n t( the i#&"ce!ent !eth( (' "n"&y#i# i# %i)en in !(u&e 8, where in #&(e-e'&ecti(n

    !eth( "n !(!ent- i#tri$uti(n !eth( "re i#cu##e* In thi# !(u&e the irect #ti''ne## !eth( i#

    i#cu##e* In the i#&"ce!ent !eth( (' "n"&y#i# the e+ui&i$riu! e+u"ti(n# "re written $y

    ere##in% the un.n(wn :(int i#&"ce!ent# in ter!# (' &("# $y u#in% &("-i#&"ce!ent re&"ti(n#*

    The un.n(wn :(int i#&"ce!ent# /the e%ree# (' 'ree(! (' the #tructure0 "re c"&cu&"te $y #(&)in%

    e+ui&i$riu! e+u"ti(n#* The #&(e-e'&ecti(n "n !(!ent-i#tri$uti(n !eth(# were eten#i)e&y u#e

    $e'(re the hi%h #ee c(!utin% er"* A'ter the re)(&uti(n in c(!uter inu#try, (n&y irect #ti''ne##

    !eth( i# u#e*

    The i#&"ce!ent !eth( '(&&(w# e##enti"&&y the #"!e #te# '(r $(th #t"tic"&&y eter!in"te "n

    ineter!in"te #tructure#* In i#&"ce!ent 5#ti''ne## !eth( (' "n"&y#i#, (nce the #tructur"& !(e& i#

    e'ine, the un.n(wn# /:(int r(t"ti(n# "n tr"n#&"ti(n#0 "re "ut(!"tic"&&y ch(#en un&i.e the '(rce

    !eth( (' "n"&y#i#* Hence, i#&"ce!ent !eth( (' "n"&y#i# i# re'erre t( c(!uter

    i!&e!ent"ti(n* The !eth( '(&&(w# " r"ther " #et r(ceure* The irect #ti''ne## !eth( i# c&(#e&y

    re&"te t( #&(e-e'&ecti(n e+u"ti(n#*

    The %ener"& !eth( (' "n"&y?in% ineter!in"te #tructure# $y i#&"ce!ent !eth( !"y $e tr"ce t(

    N")ier /1469-168

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    43/89

    Let "n e&"#tic $(y i# "cte $y " '(rce F "n the c(rre#(nin% i#&"ce!ent $e uin the irecti(n

    (' '(rce* In !(u&e 1, we h")e i#cu##e '(rce- i#&"ce!ent re&"ti(n#hi* The '(rce /30 i#

    re&"te t( the i#&"ce!ent /u0 '(r the &ine"r e&"#tic !"teri"& $y the re&"ti(n

    where the c(n#t"nt (' r((rti(n"&ity 'i# e'ine "# the #ti''ne## (' the #tructure "n it h"# unit#

    (' '(rce er unit e&(n%"ti(n* The "$()e e+u"ti(n !"y "( $e written "#

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    44/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    45/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    46/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    47/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    48/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    49/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    50/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    51/89

    WWW#6/D7!8T&/93U$#'"M

    =h"ter-3 O$:ecti)e#

    A'ter re"in% thi# ch"ter the #tuent wi&& $e "$&e t(

    1* Deri)e !e!$er #ti''ne## !"tri (' " tru## !e!$er*

    3* De'ine &(c"& "n %&($"& c(-(rin"te #y#te!*

    8* Tr"n#'(r! i#&"ce!ent# 'r(! &(c"& c(-(rin"te #y#te! t( %&($"& c(-(rin"te #y#te!*

    7* Tr"n#'(r! '(rce# 'r(! &(c"& t( %&($"& c(-(rin"te #y#te!*

    9* Tr"n#'(r! !e!$er #ti''ne## !"tri 'r(! &(c"& t( %&($"& c(-(rin"te #y#te!*

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    52/89

    WWW#6/D7!8T&/93U$#'"M

    >&"ne tru##e# "re !"e u (' #h(rt thin !e!$er# interc(nnecte "t hin%e# t( '(r! tri"n%u&"te

    "ttern#* A hin%e c(nnecti(n c"n (n&y tr"n#!it '(rce# 'r(! (ne !e!$er t( "n(ther !e!$er $ut n(t

    the !(!ent* F(r "n"&y#i# ur(#e, the tru## i# &("e "t the :(int#* Hence, " tru## !e!$er i#

    #u$:ecte t( (n&y "i"& '(rce# "n the '(rce# re!"in c(n#t"nt "&(n% the &en%th (' the !e!$er* The

    '(rce# in the !e!$er "t it# tw( en# !u#t $e (' the #"!e !"%nitue $ut "ct in the ((#ite irecti(n#

    '(r e+ui&i$riu! "# #h(wn in Fi%* 37*1*

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    53/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    54/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    55/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    56/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    57/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    58/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    59/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    60/89

    WWW#6/D7!8T&/93U$#'"M

    56I+-$- C'B8ES '6D S5SPE6SI26 BRIDGES

    In#tructi(n"& O$:ecti)e#2

    A'ter re"in% thi# ch"ter the #tuent wi&& $e "$&e t(

    1* Di''erenti"te $etween ri%i "n e'(r!"$&e #tructure#*

    3* De'ine 'unicu&"r #tructure*

    8* St"te the tye #tre## in " c"$&e*

    7* An"&y#e c"$&e# #u$:ecte t( uni'(r!&y i#tri$ute &("*

    9* An"&y#e c"$&e# #u$:ecte t( c(ncentr"te &("#*

    81*1 Intr(ucti(n

    ="$&e# "n "rche# "re c&(#e&y re&"te t( e"ch (ther "n hence they "re %r(ue in thi# c(ur#e in

    the #"!e !(u&e* F(r &(n% #"n #tructure# /'(r e*%* in c"#e $ri%e#0 en%ineer# c(!!(n&y u#e

    c"$&e (r "rch c(n#tructi(n ue t( their e''iciency* In the 'ir#t &e##(n (' thi# !(u&e, c"$&e#

    #u$:ecte t( uni'(r! "n c(ncentr"te &("# "re i#cu##e* In the #ec(n &e##(n, "rche# in

    %ener"& "n three hin%e "rche# in "rticu&"r "&(n% with i&&u#tr"ti)e e"!&e# "re e&"ine* In

    the &"#t tw( &e##(n# (' thi# !(u&e, tw( hin%e "rch "n hin%e&e## "rche# "re c(n#iere*

    Structure !"y $e c&"##i'ie int( ri%i "n e'(r!"$&e #tructure# eenin% (n ch"n%e in

    %e(!etry (' the #tructure whi&e #u(rtin% the &("* Ri%i #tructure# #u(rt etern"&&y "&ie

    &("# with(ut "reci"$&e ch"n%e in their #h"e /%e(!etry0* Be"!# tru##e# "n 'r"!e# "re

    e"!&e# (' ri%i #tructure#* Un&i.e ri%i #tructure#, e'(r!"$&e #tructure# uner%( ch"n%e# in

    their #h"e "cc(rin% t( etern"&&y "&ie &("#* H(we)er, it #h(u& $e n(te th"t e'(r!"ti(n#

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    61/89

    WWW#6/D7!8T&/93U$#'"M

    "re #ti&& #!"&&* ="$&e# "n '"$ric #tructure# "re e'(r!"$&e #tructure#* ="$&e# "re !"in&y u#e t(

    #u(rt #u#en#i(n r(('#, $ri%e# "n c"$&e c"r #y#te!* They "re "( u#e in e&ectric"&

    tr"n#!i##i(n &ine# "n '(r #tructure# #u(rtin% r"i( "ntenn"#* In the '(&&(win% #ecti(n#, c"$&e#

    #u$:ecte t( c(ncentr"te &(" "n c"$&e# #u$:ecte t( uni'(r! &("# "re c(n#iere*

    The shape assumed by a rope or a chain (with no stiffness) under the action of external

    loads when hung from two supports is known as a funicular shape. Cable is a funicular

    structure. It is easy to visualize that a cable hung from two supports subected to external

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    62/89

    WWW#6/D7!8T&/93U$#'"M

    load must be in tension (vide !ig. "#.$a and "#.$b). %ow let us modify our definition of

    cable. & cable may be defined as the structure in pure tension having the funicular shape of

    the load.

    A# #t"te e"r&ier, the c"$&e# "re c(n#iere t( $e er'ect&y '&ei$&e /n( '&eur"& #ti''ne##0 "n

    ineten#i$&e* A# they "re '&ei$&e they ( n(t re#i#t #he"r '(rce "n $enin% !(!ent* It i# #u$:ecte t(

    "i"& ten#i(n (n&y "n it i# "&w"y# "ctin% t"n%enti"& t( the c"$&e "t "ny (int "&(n% the &en%th* I' the

    wei%ht (' the c"$&e i# ne%&i%i$&e "# c(!"re with the etern"&&y "&ie &("# then it# #e&' wei%ht i#

    ne%&ecte in the "n"&y#i#* In the re#ent "n"&y#i# #e&' wei%ht i# n(t c(n#iere*

    =(n#ier " c"$&e "# &("e in Fi%* 81*3* Let u# "##u!e th"t the c"$&e &en%th# "n #"% "t /0 "re .n(wn*

    The '(ur re"cti(n c(!(nent# "tAC.E"n, c"$&e ten#i(n# in e"ch (' the '(ur #e%!ent# "n three

    #"% )"&ue#2 " t(t"& (' e&e)en un.n(wn +u"ntitie# "re t( $e eter!ine* Fr(! the %e(!etry, (ne c(u&

    write tw( '(rce e+ui&i$riu! e+u"ti(n# /,KKyx330 "t e"ch (' the (int "n.CA,,,Ei*e* " t(t"&(' ten e+u"ti(n# "n the re+uire (ne !(re e+u"ti(n !"y $e written 'r(! the %e(!etry (' the c"$&e*

    F(r e"!&e, i' (ne (' the #"% i# %i)en then the r($&e! c"n $e #(&)e e"#i&y* Otherwi#e i' the t(t"&

    &en%th (' the c"$&e i# %i)en then the re+uire e+u"ti(n !"y $e written "#

    Cale su9ected to uniform load.

    ="$&e# "re u#e t( #u(rt the e" wei%ht "n &i)e &("# (' the $ri%e ec.# h")in% &(n% #"n#*

    The $ri%e ec.# "re #u#ene 'r(! the c"$&e u#in% the h"n%er#* The #ti''ene ec. re)ent#

    the #u(rtin% c"$&e 'r(! ch"n%in% it# #h"e $y i#tri$utin% the &i)e &(" !()in% ()er it, '(r "

    &(n%er &en%th (' c"$&e* In #uch c"#e# c"$&e i# "##u!e t( $e uni'(r!&y &("e*

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    63/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    64/89

    WWW#6/D7!8T&/93U$#'"M

    Consider a cable which is uniformly loaded as shown in !ig "#."a

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    65/89

    WWW#6/D7!8T&/93U$#'"M

    'ue to uniformly distributed load the cable takes a parabolic shape. owever due to its

    own dead weight it takes a shape of a catenary. owever dead weight of the cable is

    neglected in the present analysis.

    Example 31.1

    'etermine reaction components at & and * tension in the cable and the sag of the cableshown in !ig. "#.+a. %eglect the self weight of the cable in the analysis

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    66/89

    WWW#6/D7!8T&/93U$#'"M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    67/89

    WWW#6/D7!8T&/93U$#'"M

    ,ince there are no horizontal loads horizontal reactions at & and * should be the same.Taking moment about E yields

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    68/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    69/89

    WWW#6/D7!8T&/93U$#'"M

    T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    70/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    71/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    72/89

    WWW#6/D7!8T&/93U$#'"M

    UNIT-5 SPCE T!USSES

    Tetr"her(n2 #i!&e#t e&e!ent (' #t"$&e #"ce tru## /#i !e!$er#, '(ur :(int#0 e"n $y "in%

    8 !e!$er# "n 1 :(int e"ch ti!e

    Deter!in"cy "n St"$i&ity

    $ r 8: un#t"$&e

    $ r K 8: #t"tic"&&y eter!in"te /chec. #t"$i&ity0 $

    r 8: #t"tic"&&y ineter!in"te /chec. #t"$i&ity0

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    73/89

    WWW#6/D7!8T&/93U$#'"M

    >r(ceure '(r An"&y#i#

    Meth( (' Secti(n#

    Meth( (' ;(int#

    6umerical eam)le

    In the '(&&(win% e"!&e we #h"&& c(n#truct the intern"& '(rce# i"%r"!# '(r the %i)en in Fi%* 6

    #"ce 'r"!e #tructure* The intr(uce %&($"& c((rin"te #y#te! i# #h(wn in the #"!e 'i%ure*

    The intr(uce &(c"& c((rin"te #y#te!# (' the i''erent e&e!ent# (' the #"ce 'r"!e "re

    re#ente in Fi%* P* The tyic"& #ecti(n# where the intern"& '(rce# !u#t $e c"&cu&"te, in (rer t(

    c(n#truct the re&e)"nt i"%r"!#, "re nu!$ere 'r(! 1 t( 6 in the #"!e 'i%ure* The tyic"&

    #ecti(n# "re &"ce "t &e"#t "t the $e%innin% "n "t the en (' e"ch e&e!ent /#e%!ent0 (' the

    'r"!e* The intern"& '(rce# i"%r"!#, in the &i!it# (' e"ch e&e!ent, c(u& $e eri)e $y u#in% the

    c(rre#(nin% re'erence "n $"#e i"%r"!#*

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    74/89

    WWW#6/D7!8T&/93U$#'"M

    Internal *orces

    In (rer t( ($t"in the intern"& '(rce# "t " #eci'ie (int, we #h(u& !".e #ecti(n cut

    erenicu&"r t( the "i# (' the !e!$er "t thi# (int* Thi# #ecti(n cut i)ie# the #tructure in tw(

    "rt#* The (rti(n (' the #tructure re!()e 'r(! the "rt int( c(n#ier"ti(n #h(u& $e re&"ce

    $y the intern"& '(rce#* The intern"& '(rce# en#ure the e+ui&i$riu! (' the i#(&"te "rt #u$:ecte t(

    the "cti(n (' etern"& &("# "n #u(rt re"cti(n#* A 'ree $(y i"%r"! (' either #e%!ent (' the

    cut !e!$er i# i#(&"te "n the intern"& &("# c(u& $e eri)e $y the #i e+u"ti(n# (' e+ui&i$riu!

    "&ie t( the #e%!ent int( c(n#ier"ti(n*

    e #h"&& #.i the eri)"ti(n (' intern"& '(rce# in #ecti(n 1 'r(! Fi%* 6, $ec"u#e they c"n $e eri)e

    with(ut "ny tr(u$&e#* Let u# %( irect t( the intern"& '(rce# in #ecti(n 3* I' we "## " #ecti(n cut "t

    (int 3 the #"ce 'r"!e wi&& $e #e"r"te "# #h(wn in Fi%* 1* The (#iti)e irecti(n# (' intern"&

    '(rce#, in "cc(r"nce with the intr(uce &(c"& c((rin"te #y#te! '(r the !e!$er#

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    75/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    76/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    77/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    78/89

    WWW#6/D7!8T&/93U$#'"M

    E+ui&i$riu! (' the :(int#

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    79/89

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    80/89

    WWW#6/D7!8T&/93U$#'"M

    Nu!eric"& E"!&e-3

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    81/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    82/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    83/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    84/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    85/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    86/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    87/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    88/89

    WWW#6/D7!8T&/93U$#'"M

    WWW#6/D7!8T&/93U$#'"M6T;!M

  • 7/25/2019 CE2351 SA 2 Lecture Notes

    89/89