1、 ISO 2016 Timber structures Test methods Floor vibration performance Structures en bois Mthodes dessai Comportement vibratoire des planchers INTERNATIONAL STANDARD ISO 18324 First edition 2016-04-01 Reference number ISO 18324:2016(E) ISO 18324:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECT
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4、8324:2016(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms 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 Shak
5、er test procedure . 5 5.3.3 Impact test procedure . 7 5.4 Modal analysis . 9 6 Measur ement of static deflection under a c onc entr at ed 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 ISO 2016 All rights re
6、served iii Contents Page ISO 18324:2016(E) 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
7、 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 Elect
8、rotechnical 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 o
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12、llowing URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 165, Timber structures.iv ISO 2016 All rights reserved ISO 18324:2016(E) Introduction Dynamic properties of timber structures are of critical importance to designers since they govern how these st
13、ructures 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 occup
14、ants 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 impul
15、se (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 u
16、sed 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 liste
17、d 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 da
18、mping 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 theory of modal testing and ana
19、lysis has been well documented in Reference. 4This 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 t
20、hat 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. ISO 2016 All rights reserved v Timber structures Test methods Floor vibration perf
21、ormance 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 vi
22、bration 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 me
23、asured 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 propert
24、ies 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 the
25、ory of modal testing and analysis has been well documented in Reference 4. 2 Normative references There are no normative references in this document. 3 T erms a nd definiti ons For the purposes of this document, the following terms and definitions apply. 3.1 coherence function indicator of the degre
26、e 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 i
27、n 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 w
28、hich 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
29、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. INTERNATIONAL ST ANDARD ISO 18324:2016(E) ISO 2016 All rights reserved 1 ISO 18324:2016(E) 3.5 leakage effect on measured
30、 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
31、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 struct
32、ure (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
33、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 Fr
34、equency 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
35、vibration modes. Specifically, this clause focuses on two techniques of exciting the out-of-plane 2 ISO 2016 All rights reserved ISO 18324:2016(E) 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 flo
36、or. 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 required for modal testing shall consist of
37、three major items: 1) an exciter for inducing vibration; 2) transducers for measuring the time history signal of excitation force and the vibration response; 3) a signal analyser for recording and analysing the time signals and extracting the desired information from the analysis results. Figure 1 i
38、llustrates the layout of a modal test system using a shaker as the exciter. NOTE 1 This figure was a modification of the original figure in Reference 4. Figure 1 Layout of a modal test system using a shaker as the exciter 5.2.1 Exciter, shall be provided to initiate vibration in a structure. General
39、ly, a satisfactory exciter for floor testing shall have the following capabilities: a) Sufficient energy to induce floor vibration so that the modal testing measurements made over the entire frequency range of interest has an adequate signal-to-noise ratio without exciting a nonlinear response; b) A
40、 suitable excitation waveform with frequency content that covers the frequency range of interest. The exciter shall be either a shaker or an unattached impact device. 5.2.1.1 Attached exciter shaker, shall be an electro-dynamic, electro-hydraulic, or piezoelectric vibration exciter attached to the t
41、est floor. The shaker shall be attached to a selected location on the floor during testing to continuously apply the excitation to the floor. 5.2.1.2 Unattached exciter impact device, an instrumented hammer with a built-in force transducer or an impact device with a separate force transducer placed
42、on a floor shall be used as the unattached exciter. The impact system shall have sufficient energy and appropriate surface contact characteristics to excite all the frequencies that are of interest. Specific requirements on the impact characteristics are given in 5.3.3. ISO 2016 All rights reserved
43、3 ISO 18324:2016(E) 5.2.2 Transducer and mounting 5.2.2.1 Transducer, for modal testing, both excitation and response signals are required. The transducer shall have sufficient sensitivity and capacity to cover the frequency range of interest and low noise-to-signal ratio, and be insensitive to extr
44、aneous environmental effects, such as temperature, humidity, shock, rough field working conditions, etc. It shall also be sufficiently light that its presence on the test floor does not change the dynamic characteristics of the floor. The vibration response shall be measured using accelerometers. A
45、procedure to evaluate any possible influence of mass of transducer is given in 5.3.1.3. 5.2.2.2 Transducer mounting, for an instrumented hammer, the force transducer is built into the hammer. The technique of mounting a force transducer onto a shaker is specified in 5.3.2.1, along with the shaker mo
46、unting technique. The accelerometer shall be rigidly attached to the floor structure. For floors with carpet overlaid on wood-based subfloor, a special mounting base that penetrates the carpet to the subfloor shall be used. The accelerometer shall be attached to the upper face of the base plate of t
47、he tripod. A tripod with a heavy metal base plate and pinned legs that can penetrate through the carpet to the subfloor has been found to work well. 5 For timber floors with floating flooring as finishing or a floating heavy topping, the accelerometer shall be attached to the underside of the floor.
48、 5.2.3 Signal analyser, shall be used to process the time signals and shall use the fast fourier transform (FFT) method to convert the time domain signals into frequency domain. For signal analysers that also acquire the data, the equipment shall have at least two input channels for acquiring the ex
49、citation force signal and the floor response signal simultaneously. The sampling frequency shall be at least twice the highest frequency of interest to capture all the target natural frequencies of the test floor. As a minimum, the outputs of the signal analyser shall include the FRF and coherence function. 5.3 Test procedures 5.3.1 General requirements and principles The following principles shall be followed when performing the test procedure: The locations for exciter and response measurement shall be selected in such a way t
