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8/13/2019 Cretu Tulei Ghindea
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Outline
Effect of human activities on building
floors
Vibration limitation in code provisions
Case study
Conclusions
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Effect of human activities on
building floors
Long-span floors
Educational areas Commercial areas Factories
Light materials
strength damping
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Effect of human activities on
building floors
Ordinary buildings:
moderate spans
stiff r. c. floors
f 10 - 14 Hz
Special buildings: long spans
light and flexible composite floors
f f of dynamic actions/human activities
No discomfort to the
building occupants
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Effect of human activities on
building floors
Dance
Walk of people
Malfunction of
electro-mechanicalequipments
Aerobics Disturbing vibrations
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Effect of human activities on
building floors
Jogging: ~ 2.5 Hz
Walk: 1.62.4 Hz
Running: ~3 Hz
Frequencies of equivalent harmonic excitation
1 cycle
(beat of music)
1 second
Group
weight
Fo
rce
Time
Dance
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Effect of human activities on
building floors
10% g: people doing aerobics
0.5% g: sitting/lying persons
2% g: people standing in stores/
sitting near a dance floor
Unacceptable accelerations:
Acceptable accelerations:
Floor vibrations - Occupants comfort
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Effect of human activities on
building floors
steady accelerations > 20% g
Fatigue phenomenon
Floor collapse
Resonance
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Vibration limitation in code
provisions
National Buildings Code of Canada: floor dynamic analysis for f1< 6 Hz
Eurocode 5, Design of timber structures: floors with timber beams in residential buildings
special investigations for f1< 8 Hz
WORKSHOP Eurocodes: Background and
Applications Eurocode 4. Serviceability limitstates of composite beamsHanswille, G., Brussels, 2008: floor dynamic analyses for f1< 7.5 Hz
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Vibration limitation in code
provisions
Vibration limitation in code
provisions
SSEDTA CD Release 2001: Structural
Steelwork Eurocodes: Development of a Trans-
National Approach, EC3, lecture 03, 2001:
f1> 3 Hz for floors with normal access
f1> 5 Hz for gymnastics and dancing halls
certain stiffness small deflections SLS
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Vibration limitation in code
provisions
Vibration limitation in code
provisions
Standard ISO10137,
Basis for the Design
of StructuresServiceability of
Buildings against
Vibrations, ISO,Geneva, 1992
0.04
0.2
1
5
25
1 2 4 8 16 32
PeakAcceleration[%Gra
vity]
Frequency [Hz]
ISO Baseline Curvefor RMS acceleration
Offices, Residences
Indoor Footbridges, Shooping
Malls, Dining and Dancing
Rythmic Activities,Outdoor Footbridges
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Vibration limitation in code
provisions
Vibration limitation in code
provisions
ALLEN, D.E., PERNICA, G., Control of
Floor Vibration, Construction Technology
Update No. 22, National Research Councilof Canada, 1998:
residential and office buildings
floor PGA < 0.5% g
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Case study
r.c. slabthmed= 12 cm
C24/30: Ec= 325 N/mm2
steel beamsHEA450S235
2 m
2 m
14 m
14 mr.c. walls
perimeter beams
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Case study
Analyses results:
natural frequencies;
maximum deflections.
Models of the composite floor:
M1: equalized with a grid of steel beams;
M2: fixed on the boundary;
M3: elastically supported by the perimeter beams
and r.c. walls.
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Case study
M2 M3
fixedfixed
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Case study
M1, M2, M3
Concrete stiffness: non-degraded degraded
Loads: dead load p1= 6.8 kN/m
2
live load p2= 3 kN/m2(rooms)
p2= 4 kN/m2 (corridors)
CE CE==CE CE==*
CE
CE= 0.5
*
CE
CE= 0.5
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Case study
M1, M2, M3
Load combinations (EC1):
SLS:
LC1: q1= p1
LC2: q2= p1+ 0.4 p2 LC3: q3= p1+ p2
ULS:
LC4: q4= 1.35 p1+ 1.5 p2
lk,1,1
n
1j
jk,QG
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Case study
Floor modal shapes M1
dead + live load (q3) /
f1= 10.19 Hz f2= 19.44 Hz
CE CE==CE CE==
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Case study
Floor modal shapes M2
dead + live load (q3) /
f1= 10.82 Hz f2= 20.1 Hz
CE CE==CE CE==
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Case study
Floor modal shapes M3
dead + live load (q3) /
f1= 7.69 Hz f2= 14.84 Hz
CE CE==CE CE==
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Case study
Maximum deflections of the floor, dmax[mm]
LC q1 q2 q3 q4
Model M1
= 0 6.30 7.40 9.00 12.50
2.60 3.10 3.80 5.20
3.00 3.60 4.30 6.10
Model M22.40 2.79 3.50 4.80
2.50 2.90 3.60 5.00
Model M3
4.32 5.13 6.28 8.80
5.52 6.50 7.95 11.15
CE
CE
*
CE
CE
*
CE
CE
*
CE
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Case study
First natural frequency of the floor, f1[Hz]
q1
q1q1
q1
q1
q1
q1
q2
q2q2
q2
q2q2
q2
q3
q3q3
q3
q3
q3
q3
q4
q4q4
q4
q4
q4
q4
0
2
4
6
8
10
12
14
M1 M1 M2 M3 M1 M2 M3
Frequency[Hz]
Modeltype
Minimumacceptable
frequency [3]
7.5
*
CE0EC CE
Minimumacceptable
frequency [6]
NBCWS-EC4
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Case study
Approximate formula for the first frequency of acomposite floor:
f1limiting >> deformability conditiongenerally applied in floor designing,
M3 ( )
max1d20f
350ldd amax
mm8dmax mm4035014000da
*
CE CE= 0.5*
CE CE= 0.5
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Conclusions
Check of dynamic characteristics is mandatory.
f1 beam depth storey clear height
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Conclusions
Physico-mechanical characteristics of the
materials, especially of the concrete, are different
of those considered in analyses.
Experimental measurements in situ are
absolutely necessary.
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Thank you for your attention!