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!