ISO 18324:2016

INTERNATIONAL ISO
STANDARD 18324
First edition
2016-04-01
Timber structures — Test methods —
Floor vibration performance
Structures en bois — Méthodes d’essai — Comportement vibratoire
des planchers
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Measurement of natural frequencies and modal damping ratios .2
5.1 General . 2
5.2 Apparatus . 3
5.3 Test procedures . 4
5.3.1 General requirements and principles . 4
5.3.2 Shaker test procedure . 5
5.3.3 Impact test procedure . 7
5.4 Modal analysis . 9
6 Measurement of static deflection under a concentrated load. 9
6.1 General . 9
6.2 Apparatus .10
6.3 Test procedure .11
7 Environmental condition of test site .11
8 Test report .12
Bibliography .13
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 165, Timber structures.
iv © ISO 2016 – All rights reserved

Introduction
Dynamic properties of timber structures are of critical importance to designers since they govern
how these structures respond to seismic, wind and in-service human-induced dynamic excitation.
Seismic and wind can cause structural failure, while in-service human-induced motion generally causes
serviceability problems related to human discomfort; this is also true to wind-induced building motion.
Since occupants are constantly in contact with the floor system, vibration serviceability of floor systems
is often of concern to designers of timber structures. Vibrational performance of a timber floor can
be assessed using parameters such as natural frequencies, damping ratios, dynamic responses to an
impulse (dynamic displacement, velocity, and acceleration), and static deflection under a concentrated
load. These parameters have been found to correlate well with human perceptions. Among these
parameters, natural frequencies, damping ratios, and static deflection under concentrated load
are commonly used to evaluate timber floor vibrational performance. Design procedures have been
developed, and in some cases implemented in design standards, for assessing vibration serviceability
of timber floors. These design procedures usually include criteria for floor response parameters, such
as those listed above, and mathematical procedures to calculate these parameters. As an alternative
to calculation, it is also necessary to provide standardized procedures to measure these parameters
experimentally. This is the prime motive for the development of this ISO test standard.
Natural frequencies and damping ratios of a test system can be measured using modal testing. ISO
published a series of International Standards on the application of modal testing and analysis to
determine natural frequencies, modal damping ratios, and other dynamic properties of an object. The
[4]
theory of modal testing and analysis has been well documented in Reference. This International
Standard provides practical procedures that can be applied either in the laboratory or in the field to
measure natural frequencies, modal damping ratios and static deflection under a concentrated load of
a timber floor. It is assumed that users of the International Standard have the necessary equipment and
fundamental knowledge to perform modal testing.
This International Standard does not address acceptance criteria for vibrational serviceability.
INTERNATIONAL STANDARD ISO 18324:2016(E)
Timber structures — Test methods — Floor vibration
performance
1 Scope
This International Standard specifies test procedures to measure natural frequencies, modal damping
ratios and static deflection under a concentrated load of laboratory or field timber floors. These
parameters have been found to correlate well with human perception to timber floor vibration
response caused by human-induced excitation under normal use. It is intended that the test procedures
can be applied in lieu of calculation to quantify some or all of the above parameters that are used to
evaluate the vibrational serviceability of the test floor. The subsequent use of the measured parameters
to evaluate vibrational serviceability is, however, outside the scope of this International Standard.
ISO published a series of International Standards on the application of modal testing and analysis to
determine natural frequencies, modal damping ratios, and other dynamic properties of a structure. For
the measurement of dynamic parameters such as natural frequencies and modal damping ratios, modal
testing is proposed in this International Standard. It is assumed that the test operators possess the
required equipment and fundamental knowledge to perform such a test. The theory of modal testing
and analysis has been well documented in Reference [4].
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
coherence function
indicator of the degree of linearity at each frequency component between the input and output signals,
i.e., the noise level at each frequency component in the frequency response function (FRF) spectrum
Note 1 to entry: The value of coherence function is one when there is no noise in the signal, and zero for pure
noise in the measured signals.
3.2
damping
parameter relating to the dissipation of energy, or more precisely, to the conversion of the mechanical
energy associated with a vibration to a form that is unavailable to the vibration
3.3
natural frequency
frequency, associated with a vibration mode (3.12), at which a system naturally vibrates once it has
been set into motion with a transient excitation
3.4
frequency response function
response function expressed in frequency domain and normalized to the input force
Note 1 to entry: It is the summation of each mode in the modal space. It shows the response of a system to be a
series of peaks. Each peak with identifiable centre-frequency is the natural frequency of the system vibrating as
if it was a single degree-of-freedom system.
3.5
leakage
effect on measured frequency due to truncating the infinite time response signal during Discrete
Fourier Transform
3.6
modal damping ratio
damping ratio associated with a vibration mode (3.12)
3.7
modal testing
measurement of the frequency response function (3.4)
3.8
modal analysis
process of determining the natural frequencies (3.3), modal damping ratios (3.6), and mode shapes (3.9)
of a structure (floor) for the vibration modes (3.12) in the frequency range of interest from the frequency
response function (3.4)
3.9
mode shape
pattern of movement (i.e., dynamic displacement, velocity, acceleration) of a structure (floor) for a
vibration mode (3.12)
3.10
nodal point
point of zero displacement on a vibrating system of a mode shape (3.9) associated with a vibration
mode (3.12)
3.11
vibration
oscillation of a system about its equilibrium position
3.12
vibration mode
vibration behaviour of a system or object that is characterized by its natural frequency (3.3), modal
damping ratio (3.6) and mode shape (3.9)
Note 1 to entry: The free vibration of a continuous structure such as floor system contains a summation of an
infinite number of vibration modes.
4 Abbreviated terms
FFT Fast Fourier Transform
FRF Frequency Response Function
5 Measurement of natural frequencies and modal damping ratios
5.1 General
This clause specifies the general procedure of applying modal testing and analysis described in
ISO 7626 to timber floors to determine their natural frequencies and damping ratios associated with
the vibration modes. Specifically, this clause focuses on two techniques of exciting the out-of-plane
2 © ISO 2016 – All rights reserved

vibration of a floor. One technique uses a shaker that is attached to the test floor, and the other uses an
impact device that is not attached to the floor.
NOTE A general understanding of the theoretical basis of modal testing is expected in order to apply
the procedures described in this clause. This understanding can be acquired by consulting relevant text, e.g.
Reference [4].
5.2 Apparatus
The equipment requir
...