BS 6611-1985 Guide to evaluation of the response of occupants of fixed structures especially buildings and offshore structures to low-frequency horizontal motion (0 063 Hz to 1 Hz).pdf

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1、BRITISH STANDARD BS6611:1985 Guide to Evaluation of the response of occupants of fixed structures, especially buildings and offshore structures, to low-frequency horizontal motion (0.063Hz to1Hz) UDC 534.838.3:534.831-6:612.014.45BS6611:1985 This BritishStandard, having been prepared under the direc

2、tionof the General Mechanical Engineering Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 31May1985 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference GME/21 Draft for comment82/73918 DC ISBN 0 580 14492

3、5 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the General Mechanical Engineering Standards Committee (GME/-) to Technical Committee GME/21, upon which the following bodies were represented: British Internal Combustion Engine Manufacturers

4、Association British Ship Research Association British Steel Corporation Department of Trade and Industry (National Engineering Laboratory) Electricity Supply Industry in England and Wales Engineering Equipment and Materials Users Association Institute of Sound and Vibration Research Institution of E

5、lectronic and Radio Engineers Institution of Mechanical Engineers Ministry of Defence Motor Industry Research Association Power Generation Association (BEAMA Ltd.) Society of British Aerospace Companies Limited Society of Environmental Engineers United Kingdom Atomic Energy Authority Amendments issu

6、ed since publication Amd. No. Date of issue CommentsBS6611:1985 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 0 Introduction 1 1 Scope and field of application 1 2 References 2 3 Response criteria 2 4 Measurement of motion in existing structures 2 Annex A Assessme

7、nt of structural vibration with respect to human response 4 Bibliography 8 Figure 1 Suggested satisfactory magnitudes of horizontal motion of buildings used for general purposes (curve1) and of off-shore fixed structures (curve2) 6 Figure 2 Average (curve2) and lower threshold (curve1) of perception

8、 of horizontal motion by humans 7 Table Acceleration/frequency values at the one-third octave points for the curves in Figure 1 and Figure 2 5 Publications referred to Inside back coverBS6611:1985 ii BSI 12-1999 Foreword This BritishStandard has been prepared under the direction of the General Mecha

9、nical Engineering Standards Committee. The guidance contained in this standard is technically equivalent to ISO6897:1984 “Guidelines for the evaluation of the response of occupants of fixed structures, especially buildings and off-shore structures, to low-frequency horizontal motion(0,063 to1Hz)”, w

10、hich was prepared by Technical Committee ISO/TC108 of the International Organization for Standardization (ISO) and in the development of which the United Kingdom played an active part. The only difference is that this standard refers to BS6472 where the International Standard refers to ISO2631. For

11、ease of reproduction the text of the International Standard has been used, amended to incorporate the difference outlined above. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as

12、 a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Attention is drawn to the bibliography of supporting data included in this standard and it is recommended that reference is also made to ISO2041 “Vibration and shock Vocabulary”

13、and ISO5805 “Mechanical vibration and shock affecting man Vocabulary”. BS3015 “Glossary of terms relating to mechanical vibration and shock” is a British Standard related to ISO2041, but there is no BritishStandard corresponding to ISO5805. A British Standard does not purport to include all the nece

14、ssary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1

15、to10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6611:1985 BSI 12-1999 1 0 Introduction Until this century, buildings were seldom more t

16、han a few storeys high and the few tall buildings which did exist were usually of a heavy gravity design which did not readily respond to wind or other forces. Also, tall buildings constructed in the late nineteenth century and early this century generally had vertical load-bearing frames with massi

17、ve granite infills which provided another generation of unresponsive buildings. This history of unresponsive building structures has led people to expect buildings to provide nearly stationary accommodation, even under storm conditions, and the occupants of buildings are prepared to accept only extr

18、emely low levels of motion. In contrast to these unresponsive structures, more modern buildings have tended, for reasons of economy of space, foundation requirements, material outlay, speed of erection and elegance, to be formed from more slender sections such that these much lighter buildings are m

19、ore responsive to dynamic forces than their predecessors. This BritishStandard proposes magnitudes of low-frequency horizontal motion that should produce only minimum adverse comment from people working or living in buildings. Similarly, off-shore fixed structures were, until recently, generally of

20、a non-habitable form or of an unresponsive design. Modern mineral exploitation and production structures founded on the seabed are of such large proportions and subject to such extreme wind and wave action that the dynamic response of both the overall structures and their component parts has become

21、the focus of much attention from the view-point of the motion transmitted to those operating and living on the structures. Also, although outside the scope of this BritishStandard, the structural integrity, material fatigue and operation of off-shore fixed structures in storm conditions receive much

22、 attention. This BritishStandard therefore proposes magnitudes of low-frequency horizontal motion which should prove satisfactory to those living on and operating off-shore fixed structures. Allowances are made for the fact that wind and waves shall be expected to cause motion of these structures wh

23、ich, in addition, are generally manned by trained personnel who are prepared to accept some degree of motion so long as it does not present a health hazard or interfere with the efficient operation of the installation. Often the likely motion of a planned structure has to be calculated in order to a

24、ssess the probable response, to the vibration, of those who will use the structure. The probable motion of a proposed structure can generally be found by structural dynamics using the structure stiffness and mass, the wind or wind and wave spectra, the structure shape, aspect and roughness, and the

25、appropriate topographical parameters. Wind tunnel and wave tank studies using aerodynamic and fluid dynamic models can also be used to determine the likely motion of structures. In some forms of tall building construction, poor construction joints allow inter-storey drift in the structure and, when

26、assessing the probable response of such structures, an allowance should be made for the effects of inter-storey movements. Guidance on satisfactory magnitudes of vibration for specific situations is given in the Annex. 1 Scope and field of application 1.1 This BritishStandard relates to typical resp

27、onses of people to the horizontal motion of structures in the frequency range0,063 to1Hz. The recommendations are categorized in accordance with the use of the structures and, in the case of off-shore fixed structures, with the nature of work being carried out. Injury of occupants due to structural

28、vibration is outside the scope of this BritishStandard. 1.2 Whole-body motion caused by structural vibrations induced by infrequent external environmental forces is considered separately from whole-body motion resulting from structural vibrations caused by frequently occurring force actions. Frequen

29、tly occurring force actions may arise from external sources, machinery or structure services such as elevators, fans, air conditioners, heating units and plumbing. Both perceptible magnitudes of low-frequency horizontal motion of structures and magnitudes likely to raise minimum adverse comment are

30、included. NOTE 1Visual perception of building motion, the influence of torsional oscillations of structures and the effects of noise may influence the subjective response to vibrations of structures but no quantitative assessment is made. NOTE 2Blasting, earthquakes and similar events are excluded f

31、rom the scope of this BritishStandard. NOTE 3An off-shore fixed structure is one founded on the sea bed, such as a gravity platform or a steel jacket with a piled foundation. Floating structures, tension leg and articulated platforms are excluded from the scope of this BritishStandard. NOTE 4In buil

32、dings, the response of people is for a normal adult population and, although it is known that levels of vibration considered acceptable vary with age groups and sex, no definite correction factors can be put forward at present to adjust the acceleration magnitudes for these influences. On off-shore

33、fixed structures, the recommendations only apply to trained personnel.BS6611:1985 2 BSI 12-1999 NOTE 5This BritishStandard applies to horizontal motion of structures as perceived by human beings in any posture, sitting, standing or reclining. 2 References The title of the publication referred to in

34、this standard is given on the inside back cover. 3 Response criteria 3.1 This BritishStandard considers three categories of human response to the vibration of structures: a) basic threshold effects (see3.5 and clauseA.3); b) intrusion, alarm and fear which may be associated with minor or major adver

35、se comment levels (see3.3, 3.4 and notes1 and2 in3.6); c) interference with activities (see3.4, 3.5 and clauseA.2). 3.2 The criterion for infrequently induced low-frequency horizontal building vibrations caused by storms is the alarm experienced by the occupants of the structure category b) above. T

36、he level of adverse comment due to such alarm is dependent upon the return period, the shorter the interval between occurrences the higher the level of adverse comment, and on the time over which motion of a particular intensity is sustained for each occurrence. The perception of motion is assumed t

37、o be sensed through proprioceptive cues or the vestibular organs rather than through visual cues. The presence of even very small torsional vibrations may greatly influence subjects in their assessment of the acceptability of the vibration of a structure (seeA.1.3 and note2 inA.3.2). 3.3 In building

38、s used for general purposes, the criterion is that probably not more than2% of those occupying the parts of the building where the motion is greatest comment adversely about the motion caused by the peak10min of the worst wind storm with a return period of5 years or more. In regions where wind storm

39、 recurrence patterns are not well defined, a longer return period should be used. Present shortage of data prevents the definite stipulation of acceleration/frequency curves for storms with a return period of less than5 years. Guidance on the expected level of adverse comment for such storms is curr

40、ently limited to that given in note3 in3.6. 3.4 For off-shore fixed structures where non-routine or skilled manual operations are carried out, the criteria for infrequently induced low-frequency horizontal motion of such structures are related to the performance of those engaged in the operations (s

41、ee clauseA.2). 3.5 The criteria for regularly occurring horizontal building motions are related to the perception thresholds of horizontal motion for average and for sensitive humans, that is to the average and lower thresholds. 3.6 The criteria for regularly occurring horizontal motion of structure

42、s at frequencies greater than1Hz are given in BS6472. NOTE 1The buildings are assumed to be properly clad and acoustically insulated so that significant sounds caused by the wind and by building motions are minimized to the occupants. If this were not the case, the satisfactory magnitudes may be red

43、uced since the effect of noise on the occupants is to influence the subjective response to the motion. NOTE 2People long accustomed to living in some forms of low rise buildings, such as two-storey flexible wooden frame houses, are sometimes prepared to accept magnitudes of motion due to regularly r

44、ecurring events, such as wind action or the passage of heavy vehicles, which cause alarm in occasional visitors. Conversely, occupants of high-rise buildings do not readily adapt to motions which cause them alarm on the first occurrence. NOTE 3For a storm with a one-year return period which causes t

45、he magnitudes of motion recommended as satisfactory for a five-year return period, the adverse comment level from people occupying the parts of the building where motion is greatest is estimated to be12%. It is tentatively suggested that to obtain a probable adverse comment level of2% for storms wit

46、h a one-year return period, the suggested satisfactory acceleration magnitudes would be0,72times those for a five-year return period. NOTE 4In general, it may be assumed that the motions of duration less than10min associated with wind storms are not sufficiently severe to impress significantly the m

47、emory of individuals. Where the exposure period is shorter than10min, vibration amplitudes which are vividly remembered are generally a product of seismic activity. NOTE 5During the peaks of wind storms, accelerations much in excess of the suggested satisfactory magnitudes will occur for short perio

48、ds but these higher levels, briefly experienced, are not considered to make any great contribution to the memory of the storm except where momentary vibrations are in the extreme category mentioned in note4. Short periods of higher acceleration which occur during the worst10 consecutive minutes of t

49、he storm occurrence are accounted for in the r.m.s. value of the vibration of the structure for the storm peak (seenote1 in4.5). 4 Measurement of motion in existing structures 4.1 Motion measurements to determine the magnitude and direction of the greatest horizontal acceleration should be made on a structural surface supporting the human body at the point of entry to the human subject. Under some conditions, measurements may have to be made on some surface other than at the point of entry of the vibration to the human subjects. In such cases, transfer functions need to