1、PUBLISHED DOCUMENTRecommendations for the design of structures to BS EN 1991-1-7PD 6688-1-7:2009This publication is not to be regarded as a British Standard. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPD 6688-1-7:2009 PuBliSheD DocumenTPublishi
2、ng and copyright informationThe BSi copyright notice displayed in this document indicates when the document was last issued. BSi 2008iSBn 978 0 580 53003 6icS 91.010.30The following BSi references relate to the work on this Published Document: committee reference B/525/1Publication historyFirst publ
3、ished December 2008Amendments issued since publicationDate Text affected Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPuBliSheD DocumenT BSI 2008 iPD 6688-1-7:2009ContentsForeword iiintroduction 11 Scope 12 non-contradictory complementary informa
4、tion 1Bibliography 9List of tablesTable 1 equivalent static design forces due to vehicular impact on members supporting foot and cycle track bridges over or adjacent to roads 3Table 2 consequence factor for foot and cycle track bridges 3Table 3 Vertical sag curve compensation 7Summary of pagesThis d
5、ocument comprises a front cover, an inside front cover, pages i to ii, pages 1 to 10, an inside back cover and a back cover.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPD 6688-1-7:2009ii BSI 2008PuBliSheD DocumenTForewordPublishing informationTh
6、is Published Document is published by BSi and came into effect on 31 December 2008. it was prepared by Subcommittee B/525/1, Actions (loadings) and basis of design, under the authority of Technical committee B/525, Building and civil engineering structures. A list of organizations represented on thi
7、s committee can be obtained on request to its secretary.Relationship with other publicationsThis Published Document gives non-contradictory complimentary information for use in the uK with BS en 1991-1-7:2006 and its uK national Annex.Use of this documentThis publication is not to be regarded as a B
8、ritish Standard.As a guide, this Published Document takes the form of guidance and recommendations. it should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading.Any user claiming compliance with this Published Docume
9、nt is expected to be able to justify any course of action that deviates from its recommendations.Presentational conventionsThe provisions in this Published Document are presented in roman (i.e. upright) type. its recommendations are expressed in sentences in which the principal auxiliary verb is “sh
10、ould”.Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.The word “should” is used to express recommendations of this Published Document. The word “may” is used in the text to express permissibility, e.g. as an al
11、ternative to the primary recommendation of the clause. The word “can” is used to express possibility, e.g. a consequence of an action or an event.notes and commentaries are provided throughout the text of this Published Document. notes give references and additional information that are important bu
12、t do not form part of the recommendations. commentaries give background information.Contractual and legal considerationsThis publication does not purport to include all the necessary provisions of a contract. users are responsible for its correct application.Compliance with a Published Document cann
13、ot confer immunity from legal obligations.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPuBliSheD DocumenT BSI 2008 1PD 6688-1-7:2009IntroductionWhen there is a need for guidance on a subject that is not covered by the eurocode, a country can choo
14、se to publish documents that contain non-contradictory complementary information that supports the eurocode. This Published Document provides just such information and has been cited as a reference in the uK national Annex to BS en 1991-1-7:2006.NOTE This Published Document refers to design values f
15、or accidental actions. In the UK National Annexes to BS EN 1990:2002 Annex A1 and Annex A2, the safety factors for accidental actions are equal to 1. Therefore the nominal value and the design value for accidental actions are numerically the same. The nominal values and design values of an action ar
16、e defined in BS EN 1990:2002 1.5.2.2 and 1.5.3.21 respectively.1 ScopeThis Published Document gives non-contradictory complementary information for use with BS en 1991-1-7:2006 and its uK national Annex.2 Non-contradictory complementary information2.1 Strategies and rules BS EN 1991-1-7:2006, 3.1(2)
17、 Note 12.1.1 For road bridges and foot and cycle track bridges2.1.1.1 The following provisions should be considered in the design of road bridges and foot and cycle track bridges in order to reduce the risk of a heavy Goods Vehicle (hGV) impact on a support causing bridge collapse:Preventing direct
18、impacts on the supports, for example by a) protecting supports with very high containment level barriers as defined in BS en 1317-2. This provision has the added benefit that it will reduce the risk to hGV drivers and the drivers of other vehicles on the same carriageway, by re-directing vehicles sa
19、fely onto the carriageway after impact. This provision should be seen as part of the design of the bridge.Designing the supports in the form of multiple columns so that b) a support can withstand impact damage to a struck column, and even its loss, without the deck above becoming unstable.Designing
20、the deck structure of road bridges in a form so that c) even the loss of part of a support would not result in the collapse of the bridge. For foot and cycle track bridges, adequate restraint to the deck should be provided to prevent the deck from being removed from the support due to an hGV impact
21、on the deck.Designing the individual column supports so that they can d) withstand an hGV impact without losing their ability to support the bridge.2.1.1.2 Provisions 2.1.1.1b) and 2.1.1.1c) should be part of general design practice. however they do not ensure that collapse cannot Licensed Copy: Wan
22、g Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPD 6688-1-7:20092 BSI 2008PuBliSheD DocumenToccur, although they do minimize the risk in most cases. in some situations, however, where both the risk of collapse and the consequences are high, further provisions, such a
23、s 2.1.1.1a) and 2.1.1.1d) may be justified. however, the use of very high containment level barriers 2.1.1.1a) is more cost effective and if practicable should be the method of choice.2.2 Complete collapse BS EN 1991-1-7:2006, 3.1(2) Note 5 For road structurescollapse of lighting columns, close circ
24、uit television (ccTV) poles, cantilevered traffic signal mast arms, cantilevered and portal sign/signal gantries may be acceptable where the consequences for safety are not significant. consideration should be given to passive safety as defined in BS en 12767, and/or the provision of safety barriers
25、.2.3 Level of acceptable risk BS EN 1991-1-7:2006, 3.2(1) Note 3 For road bridges and foot and cycle track bridges2.3.1 The design of bridge support structures should ensure that the risks of an hGV striking a bridge support and causing structural collapse are as low as reasonably practicable (AlARP
26、) taking account of site conditions.2.3.2 The AlARP objective is achieved by selecting an appropriate design impact criterion for each support according to the risks at that support on the basis of its risk ranking factor (see nA to BS en 1991-1-7:2006, NA.2.11.2.3).2.4 Consequences Classes BS EN 19
27、91-1-7:2006, 3.4 (2) NoteFor the design of buildings the categorization (consequences classes 1, 2a, 2b and 3) should be as given in Table A.1 of BS en 1991-1-7:2006.For bridges, the consequence class should be established on a project specific basis.2.5 Accidental actions on lightweight structures
28、BS EN 1991-1-7:2006, 4.1(1) Note 12.5.1 Impact on supporting substructures For foot and cycle track bridgesThe static design forces due to vehicular impact on members a) supporting structures over or adjacent to roadways should be in accordance with BS en 1991-1-7:2006, 4.3.1.impact loads for foot a
29、nd cycle track bridgesb) The nominal collision loads are given in Table 1, together 1) with their direction and height of application, and should be considered to act horizontally on bridge supports. Supports should be capable of resisting the main and residual load components acting simultaneously.
30、 The rules for Fdxand Fdy, are contained in nA to BS en 1991-1-7:2006, NA.2.14. The Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPuBliSheD DocumenT BSI 2008 3PD 6688-1-7:2009controlling class of road is the road under the bridge, i.e. the road th
31、at is carrying the hGV that might impact on the support.The static design forces given in Table 1 should be 2) multiplied by an adjustment factor Fain accordance with the nA to BS en 1991-1-7:2006, NA.2.11.2.4. The selection of the adjustment factor is based on the risk assessment procedure given in
32、 nA to BS en 1991-1-7:2006, NA.2.11.2.3.in all cases the main and residual design loads should not be 3) less than the minimum robustness requirements specified in Table 1.Table 1 Equivalent static design forces due to vehicular impact on members supporting foot and cycle track bridges over or adjac
33、ent to roadsForce Fdxin the direction of normal travelForce Fdyperpendicular to the direction of normal travelPoint of application on bridge supportkn knFootbridgesmain and Residual load components applied to plinthAs road bridge, depending on road class below bridge (see Table nA.1 of nA to BS en 1
34、991-1-7:2006)Residual load component150 150 At the most severe point between 1 m and 3 m above carriageway levelFootbridges: minimum forces for robustness main load component 150 150 At the most severe point between 0,75 m and 1,5 m above carriageway levelResidual load component75 75 At the most sev
35、ere point between 1 m and 3 m above carriageway levelRisk Ranking Procedure for foot and cycle track bridge supportsc) The risk ranking procedure should be the same as that set out 1) in nA to BS en 1991-1-7:2006, NA.2.11.2.3, except that the consequence factor F8 given in nA to BS en 1991-1-7:2006,
36、 NA.2.11.2.3.11, is to be replaced by Table 2.Table 2 Consequence factor for foot and cycle track bridgesBridge usage F8i) Rarely used e.g. in rural locations and sparsely populated areas0,1ii) lightly used e.g. in sub-urban locations 0,5iii) Generally used e.g. in urban areas 1iv) heavily used e.g.
37、 at motorway services with shared facilities or access to major public assembly facilities such as schools, sports stadiums, public transportation facilities, etc.5Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPD 6688-1-7:20094 BSI 2008PuBliSheD D
38、ocumenTAdjustment factor d) Fafor Table 1The adjustment factor 1) Fashould be applied to Table 1 but should not be applied to the minimum robustness requirement. The threshold value, used to determine whether the risk to the piers is high or normal, Tcas described below is defined for the individual
39、 project. unless otherwise specified for the individual project, the value of Tcmay be taken as 2,4.if the Risk Ranking Factor 2) Rdefor the design of a support of a foot or cycleway bridge is greater than Tc, the adjustment factor Fashould be taken as 1. A robust plinth of 1,5 m height should be pr
40、ovided to carry the support and to resist the main and residual load components given in Table 1. The support and the connection from the support to the plinth should be designed for the residual load component specified for footbridges in Table 1.if the Risk Ranking Factor 3) Rdefor the design of s
41、upport of foot and cycleway bridge is less than or equal to Tc, the adjustment factor Fashould be taken as 0,5. A robust plinth of 1,5 m height should be provided to carry the support and to resist 50% of the main and residual load components given in Table 1. The support and the connection from the
42、 support to the plinth should be designed for 50% of the residual load component specified for footbridges in Table 1.Ramps and stairs of footbridges, whose removal would not affect e) the overall integrity of the structure, need not be designed for collision loading. however they should be designed
43、 to meet the minimum robustness requirements given in Table 1.impact provisions where safety barriers in compliance with f) BS en 1317 are provided, as set out below.if the risk ranking factor 1) Rdefor the design of a support of a foot or cycleway bridge is greater than Tc, possible options are as
44、follows.A very high containment level barrier with full working i) width may be provided to protect the support (without a 1,5 m robust plinth).A very high containment level concrete rigid barrier ii) without full working width may be provided to protect the support (without a 1.5 m robust plinth).
45、A minimum lateral clearance of 400 mm should be provided between the back face of the barrier and the front face of the support. The support and the connection from the support to the plinth should be designed for the residual load component specified for footbridges in Table 1.For cases i) to ii) a
46、bove, the support should be designed iii) for the minimum robustness requirement specified for foot and cycle track bridges in Table 1.if the risk ranking factor 2) Rdefor the design of a support of a foot or cycleway bridge is less than or equal to Tc, possible options are as follows.A higher conta
47、inment level barrier with full working i) width may be provided to protect the support (without a 1,5 m robust plinth).Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 12/05/2009 07:05, Uncontrolled Copy, (c) BSIPuBliSheD DocumenT BSI 2008 5PD 6688-1-7:2009A higher containment level concrete r
48、igid barrier ii) without full working width may be provided (without a 1,5 m robust plinth). A minimum lateral clearance of 400 mm should be provided between the back face of the barrier and the front face of the support. The support should be designed for 50% of the residual load component specifie
49、d for footbridges in Table 1.2.5.2 Impact on superstructures For lightweight road structuresThe vehicle collision loads on superstructures are not applicable to the superstructure of foot/cycle track bridges, gantries, and lighting columns, as these structures are required to have headroom exceeding the applicable limit to reduce the likelihood of impact owing to their lightweight nature. however adequate restraint on the deck of foot/cycle track bridges should be provided to prevent the deck being removed from the support under the acti
