ISO 4866:1990(E) Licensed copy:HALCROW GROUP LTD, 27/01/2009, Uncontrolled Copy, © <strong>BSI</strong> Figure 1 — Categories of the types of data 8 © <strong>BSI</strong> 01-1999
ISO 4866:1990(E) Licensed copy:HALCROW GROUP LTD, 27/01/2009, Uncontrolled Copy, © <strong>BSI</strong> 9.2 Types of <strong>in</strong>vestigation For many of the parameters of <strong>in</strong>terest, listed <strong>in</strong> 9.1 a) to g), the choice of <strong>in</strong>strumentation, its location with<strong>in</strong> the build<strong>in</strong>g, the type of record<strong>in</strong>g device <strong>and</strong> the number of data channels or measurement po<strong>in</strong>ts desired, the duration of monitor<strong>in</strong>g <strong>for</strong> the phenomena <strong>and</strong> the speed of data collection will immediately be decided. The outl<strong>in</strong><strong>in</strong>g of <strong>in</strong>strumentation requirements <strong>in</strong> clause 6 <strong>and</strong> annex C has been arranged <strong>in</strong> such a way as to facilitate the selection of <strong>in</strong>strumentation to meet particular requirements. Beyond this it is important to del<strong>in</strong>eate the degree of sophistication to be applied to the <strong>in</strong>vestigation. Instruments which characterize the vibration environment by a s<strong>in</strong>gle quantity, such as those used <strong>in</strong> connection with human response <strong>and</strong> mach<strong>in</strong>e condition, may be used <strong>in</strong> a prelim<strong>in</strong>ary survey so long as the limited frequency responses are taken <strong>in</strong>to account. For the purposes of this International St<strong>and</strong>ard, a prelim<strong>in</strong>ary assessment, a monitor<strong>in</strong>g program, a field survey <strong>and</strong> a detailed eng<strong>in</strong>eer<strong>in</strong>g analysis are under consideration. 9.2.1 Prelim<strong>in</strong>ary assessment Situations may arise where an assessment has to be made of vibration problems by desk study alone, usually be<strong>for</strong>e field measurements. Empirical methods can be used to estimate response provided that data on the source parameters <strong>and</strong> build<strong>in</strong>g response characteristics, such as fundamental frequency <strong>and</strong> damp<strong>in</strong>g, are available. 9.2.2 Exploratory monitor<strong>in</strong>g Very limited measurement of vibration on a build<strong>in</strong>g or over an area can <strong>in</strong>dicate the existence of a problem requir<strong>in</strong>g further <strong>in</strong>vestigation. High errors are not uncommon <strong>and</strong> this fact has to be kept <strong>in</strong> m<strong>in</strong>d. (See also f<strong>in</strong>al paragraph <strong>in</strong> 9.2.3.) 9.2.3 Field survey A field survey would consist of a limited number (see also 7.1) of vibration measurement locations <strong>in</strong> order to assess the vibration severity often <strong>in</strong> comparison with values stipulated <strong>in</strong> codes or regulations. In the case of vibrations which can be reproduced <strong>for</strong> a sufficient time, the same transducers can be used <strong>for</strong> the different po<strong>in</strong>ts keep<strong>in</strong>g a reference po<strong>in</strong>t at the foundation level near the source. As regards exploratory monitor<strong>in</strong>g (see 9.2.2) <strong>and</strong> field surveys, measurements should be of an accuracy compatible with the uncerta<strong>in</strong>ties implicit <strong>in</strong> the vibration <strong>in</strong>dices <strong>and</strong> empirical relationship used. S<strong>in</strong>gle parameter <strong>in</strong>dices, such as peak particle velocity or peak acceleration <strong>and</strong> r.m.s, values, need, generally, only to be known to with<strong>in</strong> ± 10 % at the 68 % confidence level. 9.2.4 Eng<strong>in</strong>eer<strong>in</strong>g analysis When complex structures of vital importance are be<strong>in</strong>g subjected to vibration excitation of a magnitude that requires serious consideration of the consequences, the structural behaviour needs to be assessed <strong>in</strong> a more detailed way. Instrumentation <strong>for</strong> monitor<strong>in</strong>g the time history should be mounted at a number of locations to ensure that specific values <strong>for</strong> that structure are not exceeded. If the ground-to-foundation transfer function is of concern, simultaneous record<strong>in</strong>g outside <strong>and</strong> on the foundation should be carried out. The record<strong>in</strong>g position on the foundation is at a po<strong>in</strong>t on the ma<strong>in</strong> wall at ground floor level or the basement. The number of measur<strong>in</strong>g po<strong>in</strong>ts <strong>and</strong> their location have to be def<strong>in</strong>ed <strong>and</strong> modified accord<strong>in</strong>g to the characteristics of the build<strong>in</strong>g <strong>and</strong> the observations noticed dur<strong>in</strong>g monitor<strong>in</strong>g. The natural frequencies of build<strong>in</strong>gs should be determ<strong>in</strong>ed, if possible. In the case of vibrations which can be reproduced <strong>for</strong> a sufficient time, the same transducers can be used <strong>for</strong> the different po<strong>in</strong>ts keep<strong>in</strong>g a reference po<strong>in</strong>t at the foundation level near the source. For structures of vital importance, response analysis should be carried out as well as an estimate of structure load<strong>in</strong>g. A full eng<strong>in</strong>eer<strong>in</strong>g analysis requires a system which would enable frequency to be estimated to ± 1 % <strong>and</strong> damp<strong>in</strong>g to ± 10 %. 9.3 Report<strong>in</strong>g of control activities The style of report<strong>in</strong>g should be consistent with the type of <strong>in</strong>vestigation (see 9.2), but as a m<strong>in</strong>imum the report should <strong>in</strong>clude the follow<strong>in</strong>g: a) Risk analysis 1) Description of the source. 2) Type <strong>and</strong> condition of build<strong>in</strong>g, <strong>in</strong> accordance with annex A. 3) Purpose of the measurement. 4) Reference to the st<strong>and</strong>ard be<strong>in</strong>g used <strong>and</strong> type of <strong>in</strong>vestigation. b) <strong>Measurement</strong>s 1) Position of transducer <strong>and</strong> manner of coupl<strong>in</strong>g. 2) Type <strong>and</strong> make of transducer, signal condition<strong>in</strong>g <strong>and</strong> record<strong>in</strong>g equipment. 3) Calibration factors <strong>for</strong> the <strong>in</strong>strumentation system. 4) Frequency range <strong>and</strong> l<strong>in</strong>earity. 5) Assessment of the sources of error. © <strong>BSI</strong> 01-1999 9