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Journal ArticleDOI

Wind-induced vibrations and building modes

01 Aug 1966-Bulletin of the Seismological Society of America (GeoScienceWorld)-Vol. 56, Iss: 4, pp 793-813

AbstractThis paper outlines the methods that have been used to determine the frequencies and modes of vibration of multistory buildings from their wind-induced vibrations. Three buildings of ten, thirty-eight and forty-seven stories were investigated. A simple theoretical model was used to calculate the frequencies of vibration of the buildings; the model was based on the assumption that there was no joint rotation in the building frames. A comparison of the theoretical and measured values of the frequencies showed that this simple model was a realistic representation of only the smaller building. It is concluded that a model that includes joint rotation would be more realistic for the taller buildings. Auto-correlation and power spectrum analysis of the vibration records were used to obtain an estimate of the damping characteristics of the buildings. The values obtained were 1 to 3 per cent of the critical amount of damping.

Topics: Vibration (53%), Normal mode (51%)

Summary (1 min read)


  • Thc three buildings investigated have been c.onstructc~c1 ~vithiil the last five years-One of the buildings, the Sir Alcsaildcr Cam~~bcll Buildiilg is the headquarters of the Cunndi:ul Post Office Dcp:u.tilleilt 211 Ottawa; the other two buildiilgs, the Cnnacliail Imperial I3~1lli of Com~ncrcc Builcliitg ant1 CIll IIouhe, arc 1oc.atctl 011 Dor-c11estc.r Boulevard i~t 3101ltre~~l.
  • \Trllcii the vibrntioli had becil built up to a suitable lcvel, thc motion was allon~cd to dccny and thc dampingv:\lue was again obini~icd by the logarithmic decrement mcthod.
  • This assuillptioil was made, togcthcr i~ith the further assuinptioll that a11 thc Inasscs of cach floor for n give11 building were eclual.


  • The wind records havc bceil stcacly on each occasion when readings have bccn taken froill the aiiemonleter, a fact that could be related to its isolatcd position.
  • The claillpirig valucs obtained by these mcthocls arc shoxvn in Table 4 -Tllc ~ncastued and theoretical valucs of the pcriotls of tlic fulidaillclital inodcs of lateral vibration of the buildiiigs are sho~vii in the first two lilies of T~~blc 5.
  • The ~ne:~surecl results in Tablc 1 show that the ratios of tlic natural frccluerlcies of vibration to the fundanlentnl freciuency :ire of the o~,cler 1, 3, 5, 7, etc. 31oclc shapes of buildings :Ire also inlportant in carthqualic engineering design l~ccause they cletermine t'lic manner in which eart'llqualic loatls are distributed thl~ougli the kicight of the st,ructure.
  • One of the best ways of achicviag this knomledgc is to continue the comparison of the predictions of theory with the nleasurecl dy~ian~ic ~haractcristics of buildings.

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Publisher’s version / Version de l'éditeur:
Bulletin of the Seismological Society of America, 56, 4, pp. 793-813, 1966-07-01
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Wind-induced vibrations and building modes
Ward, H. S.; Crawford, R.
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NRC Publications Record / Notice d'Archives des publications de CNRC:

the ~arth(l~:lli~ :111d wintl resihtant clcsig~l of
is impera-
tive that every opportunity should be talie~l to try to unclcrstand tho dynamic hc-
llaviour of buildi~~gs. HOUSILC~ aid 13racly
have studied exiitillg information,
and have co~ic.ludcd that
of the existing empiricxl formulae used
codes to determine the periods of vibration of buildings can 1,c in error by as inuch
per cent.
Another c.onclusion was that soillc inoclcrn steel frame builcliilgs behave esseriti:~lly
they had rigid floor girc1el.s. Calculi~tiolls have bee11 made to t,est this assump-
tion for the buildii~gs dcscribccl
this p:~prr, ancl it is sho~vil that fair agreement
was obtui~lcd for the ten-story building, but that there ~vas an overcstimatiorl of the
fundamental frequency of the order of
per cent for the multi-story structures.
Some possible causes for the discrepancy arc discussed, and the measured values are
comparcd with sonlc of the dcrivccl formulae obt:~ined by Hous~ler and Brady.
There is
perhaps less l~no~vn about the damping properties of buildings th;~n of
t~ny other clyil:~mic c11ar:~ctcristic. Ail attempt has been made to determine damping
values froin the rccorcls of the wild-iilducctl vibrations of the building by two meth-
ods: power spectrum :ulalysis and auto-correlatioll a~lalysis.
one instance the rc-
sults have been compared with those obtained by inail-induced vibrations. The
incthods need to be applied to illore builclillgs before general co~lclusioris c:~n be
drawl, but the initial fi~idiiigs iiltlic~atc damp~ng values of the ordcr of
per cent
of criticsal.
Thc three buildings investigated have been c.onstructc~c1 ~vithiil the last five years-
One of the buildings, the Sir Alcsaildcr Cam~~bcll Buildiilg is the headquarters of
the Cunndi:ul Post Office Dcp:u.tilleilt
Ottawa; the other two buildiilgs, the Cn-
nacliail Imperial I3~1lli of Com~ncrcc Builcliitg ant1 CIll IIouhe, arc 1oc.atctl
c11estc.r Boulevard i~t 3101ltre~~l.
ft, c~lcvcn bays by thrcc b:~ys ill pl;ul di-
mcnsio~l, ant1
in. high. Tllcrc :we trrl floors :~bovc grouncl, including
house ancl oile b:lselncilt; arlcl
yl~ical sto1.y height is
ill. The h:~nic ;lnd floor
slabs :~i.c rciriforc~ccl conc.i3dc, and the cxtcrnal I\-:dls arc 11011-load-bc:~ri~ig 4-h~. or
8-in. bric.1; ~valls.
Tllc buildii~g rcsls
groups of piles
diitmdcr, e:~cl1 of
toils y,
that pass through
ft of gravel and s:lild to solid liinesto~lc rocsli.
Tllc colum~ls :we rcc-tar~gular
oricutcd so that the stiffest usis is parallel to the
loilg clinlcnsiorl of tllc builcli~~g; the colu~nils arc s~pprosim:ltcly twicac as stiff about
this asis as they arc about the one at right angles to it. The c~olum~l stift'iic~ss is
proximately cdolistalit Roil1 the fou~~tlation lo the
floor, where the values :we
approximately 11:llvctl a~itl Illen ~tlnniil colistailt lo the roof.
ft by
scvcil b:lys
1,y four bays iri plaii,
above the street lcvcl. There arc
:~bovc ground lcvcl wit11 a typical story height of
ill., cxcocpt for the first floor
aiid the five ~nec~hailic.:~l floors
the fifteeilth floor level arid the top.
structwc thi*cc floors in tlcptll covers thc entire site of
1Yic building is fo~~~idctl
bed r0c.1;
ft brlonr street level, with footi~lgs desig~~rd

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