Draft

14.4LateralDe
ections 259

SIDESWAY

P

Figure14.28: Side-Sway De
ectionfromUnsymmetricalVerticalLoad,(LinandStotesbury

14.4.5 TrussedFrame

48 Thecantilever de
ectiondueto columnshorteningandlengthening(producedby overturning

moment) is usuallyof secondaryimportanceuntil thebuildingis some40 storiesor higher,Fig.

??.

H

H

H

H

Dc

1

2

3

4

P 1

C C

T C

T

D

a

a

h

c

SH

d

d

1

Figure14.29:AxialElongationandShorteningof a TrussFrame,(LinandStotesbury1981)

49 Thetotalde
ection
atCis givenby

= 

P P L

AE

(14.47)

where:Pis theforcein any member dueto loadingonthewholesystem,Lis thelengthof the

member,AandEthecorrespondingcrosssectionalareaandmodulusof elasticity,Ptheforce

in thesamemember dueto a unit(1)forceappliedin thedirectionof thede
ectionsought,

andat thepoint in question.

50 Alternatively, we canneglecttheweb deformationandconsideronlytheaxialdeformations

in thecolums:



t+c

a

h

t+c = 2

T h

AE

(14.48)