1、BRITISH STANDARD BS 7385-2: 1993 Evaluation and measurement for vibration in buildings Part 2: Guide to damage levels from groundborne vibrationBS7385-2:1993 This British Standard, having been prepared under the direction of the General Mechanical Engineering Standards Policy Committee, was publishe
2、d under the authority of the Standards Board and comes into effect on 15 November 1993 BSI 02-1999 The following BSI references relate to the work on this standard: Committee reference GME/21 Draft for comment 92/86081 DC ISBN 0 580 22188 1 Committees responsible for this British Standard The prepar
3、ation of this British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/21, upon which the following bodies were represented: Electricity Association Federation of Civil Engineering Contractors Imperial College of Science and T
4、echnology Institute of Sound and Vibration Research Institution of Mechanical Engineers Lloyds Register of Shipping Ministry of Defence Open University Power Generation Contractors Association (BEAMA Ltd.) Railway Industry Association of Great Britain Sira Test and Certification Ltd. Society of Brit
5、ish Aerospace Companies Limited University of Manchester The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Association of Consulting Engineers British Coal Corporation British Railways Board British Society for Strain Measurements Departmen
6、t of the Environment (Building Research Establishment) Department of Trade and Industry (National Engineering Laboratory) Department of Transport (Transport Research Laboratory) Health and Safety Executive Heriot-Watt University Institute of Acoustics Institute of Explosives Engineers Institution of
7、 Environmental Health Officers University of Leeds Amendments issued since publication Amd. No. Date CommentsBS7385-2:1993 BSI 02-1999 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1 Scope 1 2 References 1 3 Definitions 1 4 Characteristics of building vibration
8、 2 5 Factors to be considered in building response 2 6 Measurement of vibration 3 7 Assessment of vibration 4 Annex A (informative) Cracking in buildings 7 Annex B (informative) Data to record during a survey 8 Annex C (informative) Building damage due to soil compaction 9 Figure 1 Transient vibrati
9、on guide values for cosmetic damage 6 Table 1 Transient vibration guide values for cosmetic damage 5 List of references Inside back coverBS7385-2:1993 ii BSI 02-1999 Foreword This Part of BS 7385 has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee.
10、It should be considered together with BS7385-1:1990 Guide for measurement of vibrations and evaluation of their effects on buildings. More detailed consideration of the methodology for measurement, data analysis, reporting and building classification is given in BS7385-1, to which the reader is refe
11、rred for further guidance beyond the basic principles given here. A British Standard does not purport to include all the necessary 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
12、 from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 10, 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 ame
13、ndment table on theinside front cover.BS7385-2:1993 BSI 02-1999 1 Introduction Groundborne vibration from sources such as blasting, piling, machinery or road/rail traffic can be a source of concern for occupants of buildings in the vicinity. This concern can lead to a need to assess the effect of th
14、e imposed vibration on the building structure to ascertain whether damage could occur. This Part of BS7385 provides guidance on the assessment of the possibility of vibration-induced damage in buildings due to a variety of sources. There is a lack of reliable data on the threshold of vibration-induc
15、ed damage in buildings both in countries where national standards already exist and in the UK. This Part of BS7385 has been developed from an extensive review of UK data, relevant national and international documents and other published data. Although a large number of case histories was assembled i
16、n the UK database1, very few cases of vibration-induced damage were found. It has been necessary therefore, to refer to the results of experimental investigations carried out in other countries into vibration-induced damage thresholds. This Part of BS7385 sets guide values for building vibration bas
17、ed on the lowest vibration levels above which damage has been credibly demonstrated. It is intended to provide a standard procedure for measuring, recording and analysing building vibration together with an accurate record of any damage occurring. 1 Scope This Part of BS 7385 gives guidance on the l
18、evels of vibration above which building structures could be damaged. It identifies the factors which influence the vibration response of buildings, and describes the basic procedure for carrying out measurements. Vibrations of both transient and continuous character are considered. A method of asses
19、sment which takes into account the characteristics of the vibration, the building and the measured data is given. It is appropriate for the types of investigation given in BS7385-1, but for detailed engineering analysis, criteria other than the vibration levels may need to be considered. Only the di
20、rect effect of vibration on buildings is considered. The indirect effects on the building structure due to ground movement, the movement of loose objects within buildings, the possibility of damage to sensitive equipment and the effect of vibration on people are outside the scope of this Part of BS7
21、385. There is a major difference between the sensitivity of people in feeling vibration and the onset of levels of vibration which damage the structure. Levels of vibration at which adverse comment from people is likely are below levels of vibration which damage buildings, except at lower frequencie
22、s. The evaluation of human exposure to vibration in buildings is covered in BS6472. This Part of BS 7385 does not consider the many other causes of cracking in buildings; cracking commonly occurs in buildings whether they are exposed to vibration or not (see annex A). Damage due to earthquakes, air
23、overpressure, wind or the sea are also outside the scope of this Part of BS7385. It is applicable only to vibration transmitted through the ground and not to vibration set up by machinery within a building. Chimneys, bridges and underground structures such as chambers, tunnels and pipelines are not
24、covered. 2 References 2.1 Normative references This Part of BS 7385 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriate points in the text and the publications are listed on page10. Subsequent amendments to, or
25、revisions of, any of these publications apply to this Part of BS7385 only when incorporated in it by updating or revision. 2.2 Informative references This Part of BS 7385 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of
26、 this standard are listed on page10, but reference should be made to the latest editions. 3 Definitions For the purposes of this Part of BS7385, the following definitions apply. 3.1 peak particle velocity (p.p.v.) the maximum instantaneous velocity of a particle at a point during a given time interv
27、alBS7385-2:1993 2 BSI 02-1999 NOTEWhereas the disturbance caused by a vibration source propagates away from that source with a certain wave velocity, ground particles oscillate with a variable particle velocity. At a given location along the propagation path the motion may be defined in terms of thr
28、ee mutually perpendicular components (usually vertical, transverse and longitudinal or radial). In order to ensure that the peak particle velocity is correctly measured, all three components have to be measured simultaneously. 3.2 peak component particle velocity the maximum value of any one of thre
29、e orthogonal component particle velocities measured during a given time interval 3.3 dynamic magnification the motion measured at a given point (usually in the structure) divided by the motion measured at a reference point (usually at the base of the structure or on the foundation) NOTE 1The dynamic
30、 magnification is not necessarily greater than 1 (values less than 1 indicating a reduction of vibration levels). NOTE 2In common practice the dynamic magnification is based on a comparison of values of p.p.v. from time histories, and is therefore frequency independent. The dynamic magnification doe
31、s however vary with frequency and, when based upon a comparison of spectral peaks, is called a spectral magnification or amplification. 4 Characteristics of building vibration 4.1 Duration The structural response of a building can be significantly affected by the duration of the vibration to which i
32、t is exposed. The time characteristic of various vibration forcing functions is given in Table 1 of BS7385-1:1990 and 3.2 of BS7385-1:1990. The limit above which damage may be caused for vibration of a continuous nature may need to be lower than the corresponding limit for transient vibration. If th
33、e building is exposed to continuous vibration for a sufficient time (which is dependent on frequency and damping of the structure), it is possible for dynamic magnification to occur if a resonant frequency of the structure is close to the excitation frequency. The possibility of fatigue of building
34、materials would also arise if a vibration source causes a sufficient number of stress reversals, however, no substantiated cases are known to have arisen from groundborne vibration. 4.2 Frequency range Typical frequency ranges covering the dominant structural response to various sources of vibration
35、 are given in Table 1 of BS7385-1:1990. The lowest frequency originating from man-made sources included in this Part of BS7385 is 1Hz and the highest frequency expected from either machinery or close-in construction blasting in hard ground is1000Hz, however a more limited range of 4Hz to250Hz is usu
36、ally encountered in buildings. For the purpose of selecting guide values from those given in this Part of BS7385, it is the frequency of the input vibration to the building which is of relevance. 4.3 Sources of vibration Sources of vibration which are considered include blasting (carried out during
37、mineral extraction or construction excavation), demolition, piling, ground treatments (e.g. compaction), construction equipment, tunnelling, road and rail traffic and industrial machinery. 5 Factors to be considered in building response 5.1 General The response of a building to groundborne vibration
38、 is affected by the type of foundation, underlying ground conditions, the building construction and the state of repair of the building. 5.2 Foundation type and ground conditions The interaction between the ground and the foundation of the structure can have a major effect on building response. The
39、geology of the ground between the vibration source and the building also affects the input frequency spectrum to the building. In general stiffer foundations result in higher natural frequencies of the building-soil system and higher input frequencies are often associated with harder ground. Categor
40、ies of foundations and types of soils are given in annex A of BS7385-1:1990. The strain imposed on a building at foundation level is proportional to the p.p.v. but is inversely proportional to the propagation velocity of the shear or compression waves in the ground2. Since the propagation velocity i
41、ncreases with ground stiffness, a higher p.p.v. measured with harder ground conditions may induce the same strain (cracking potential) as a lower p.p.v. measured with softer ground, provided that it occurs significantly far away from a resonance3. Thus where a structure closely follows the movement
42、of the ground, it may be possible to allow a higher p.p.v. with hard ground conditions.BS7385-2:1993 BSI 02-1999 3 5.3 Type and construction of building The strains induced in a building by a given vibration excitation will depend upon the dynamic characteristics of the particular type of building,
43、i.e.,the natural frequencies, mode shapes and damping. Natural frequencies are determined by the geometry of the building and the components, the degree of fixity of these components in the structure and the stiffness and mass of each component. Older, low-rise masonry structures tend to have higher
44、 natural frequencies in comparison with modern lightweight, flexible and taller buildings. Higher levels of strain will result when excitation frequencies are close to natural frequencies. A classification of buildings is given in annex A of BS7385-1:1990, with an indication of the relative resistan
45、ce to vibration. 5.4 Building components Individual building components such as walls, floors, beams or ceilings have natural frequencies which are usually higher than the frequencies of the building as a whole, and are therefore more susceptible to excitation at resonance by continuously operating
46、machinery, than the building as a whole. In assessing the effect of vibration on building components it should be noted that the dynamic stresses corresponding to a p.p.v. of 10mm/s, range typically from only 0.4% to 2.3% of the allowable design stress for some specific building materials4. A method
47、 of estimating peak stress from p.p.v. is given in annex B of BS7385-1:1990. 6 Measurement of vibration 6.1 General The general principles for measuring vibration in buildings are given in BS7385-1:1990. Guidance on specific measurements to be carried out for the purpose of assessing the possibility
48、 of vibration-induced damage are given in 6.2 to 6.6. 6.2 Quantity to be measured Peak particle velocity has been found to be the best single descriptor for correlating with case history data on the occurrence of vibration-induced damage. Cracking occurs however, due to excessive structural strain,
49、due to either distortion as the building follows movement of the ground or ground motion which causes inertial loading of the building2. In some situations, therefore, it may be appropriate to measure strain directly. The preferred method of measuring p.p.v. is to record simultaneously unfiltered time histories of the three orthogonal components of particle velocity, which allows any desired value to be extracted at a later stage. Where it has been demonstrated that time histories are consistent, then, as indicated in6.1 of BS7385-1:1990, it may be adequate to chara
