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British Standard A single copy of this British Standard is licensed to Giorgio Cavalieri on March 05, 2001 This is an uncontrolled copy. Ensure use of the most current version of this standard by searching British Standards Online at bsonline.techindex.co.uk BRITISH STANDARD BS 6779-2 1991 Incorporating Amendment No. 1 Highway parapets for bridges and other structures Part 2 Specification for vehicle containment parapets of concrete construction Licensed Copy Giorgio Cavalieri, ALSTOM, 5-Mar-01, Uncontrolled Copy. BSI BS 6779-21991 This British Standard, having been prepared under the direction of the Road Engineering Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 28 February 1991 BSI 06-1999 The following BSI references relate to the work on this standard Committee reference RDB/18 Draft for comment 89/15659 DC ISBN 0 580 19025 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Road Engineering Standards Policy Committee RDB/- to Technical Committee RDB/18, upon which the following bodies were represented Aluminium Federation Association of Consulting Engineers British Cement Association British Railways Board British Steel Industry Convention of Scottish Local Authorities County Surveyors’ Society Department of Transport Fencing Industry Association Institution of British Engineers Institution of Civil Engineers Institution of Highways and Transportation Royal Automobile Club Royal Society for the Prevention of Accidents The following body was also represented in the drafting of the standard, through subcommittees and panels Department of Transport Transport and Road Research Laboratory Amendments issued since publication Amd. No.DateComments 7057April 1992Indicated by a sideline in the margin Licensed Copy Giorgio Cavalieri, ALSTOM, 5-Mar-01, Uncontrolled Copy. BSI BS 6779-21991 BSI 06-1999i Contents Page Committees responsibleInside front cover Forewordii Section 1. General 0Introduction1 1Scope1 2Definitions1 3Symbols2 4Designation of vehicle parapets3 Section 2. General design 5Levels of containment4 6Vehicle impact loading4 7Wind loading5 8Parapet heights5 9Front face profile, freedom from projections and joint treatment5 10Durability6 11Design 7 12Prevention of composite action between the parapet and main structure11 13Ends of parapets11 14Movement joints in parapets11 Section 3. Construction 15Materials and workmanship13 16Surface finish13 Figure 1 Dimensional parameters for reinforced concrete parapets6 Figure 2 Alternative joint details7 Figure 3 Possible diagrammatic arrangement of a precast reinforced concrete parapet10 Figure 4 Shear transfer arrangement used in the tested parapets12 Table 1 Designation of vehicle parapets2 Table 2 Equivalent static nominal loads for in situ and precast concrete parapets applicable to panel lengths L 1.5 m to 3.5 m4 Table 3 Value of fL ultimate limit state7 Table 4 Values of fk and m8 Publications referred toInside back cover Licensed Copy Giorgio Cavalieri, ALSTOM, 5-Mar-01, Uncontrolled Copy. BSI BS 6779-21991 ii BSI 06-1999 Foreword This Part of BS 6779 is one of a series prepared under the direction of the Road Engineering Standards Policy Committee. The other Part already published in the series is Part 1 Specification for vehicle containment parapets of metal construction. The other Part so far planned in the series is Part 3 Specification for vehicle containment parapets of combined metal and concrete construction. 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 from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 14, 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. Licensed Copy Giorgio Cavalieri, ALSTOM, 5-Mar-01, Uncontrolled Copy. BSI BS 6779-21991 BSI 06-19991 Section 1. General 0 Introduction 0.1 This Part of BS 6779 specifies requirements for the design and construction of concrete parapets, intended to provide specific levels of vehicle containment on highways. These parapets are installed on bridges, retaining walls or other structures. Parapets of metal or of combined concrete and metal are not covered in this Part of BS 6779. 0.2 The specification requirements are based upon the results of tests on panels of 2.1 m and 3.0 m lengths and it is considered reasonable to extrapolate to include panel lengths from 1.5 m to 3.5 m. Designers wishing to use panel lengths outside these limits will have to their own judgement as to making further extrapolation in the light of the individual circumstances. 0.3 The design of free standing panels and of panels having adequate shear transfer arrangements are covered. 0.4 Containment levels are related to defined vehicle impacts and normal and high levels of containment are specified. A low level of containment, used in Part 1 of this series for the design of metal parapets in certain circumstances, is not considered appropriate to concrete construction. Appendix A to Part 1 of this series outlines the derivation of design forces in relation to containment levels. The normal level of containment specified in BS 6779 is considered to offer a reasonable level of protection under all but the most exceptional cases. 0.5 The main objectives of the s of parapet defined in this Part of BS 6779 are a to provide specified levels of containment to limit penetration by errant vehicles; b to protect highway users and others in the vicinity by redirecting errant vehicles with minimum deceleration forces on to a path as close as possible to the line of the parapet and to reduce the risk to the vehicle of overtopping the parapet and of overturning. 0.6 It is possible in the case of concrete parapets to give theoretical design criteria to produce satisfactory designs. This is because the dynamic response of such rigid structures is relatively predictable. In consequence full scale acceptance testing, as required for metal parapets in Part 1 of BS 6779; is not necessary. 1 Scope This Part of BS 6779 specifies requirements for the design and construction of in situ and precast concrete parapets which are designed to provide specified levels of containment for vehicles on highways. The requirements for minimum panel length and for the prevention of composite action with the main structure limit the direct application in the case of bridge decks to those of 7.5 m and greater span. As they are of solid construction they also provide effective pedestrian protection without modification. Parapets are to be prevented from acting compositely with the main structure by dividing them into panels. Parapets designed to act compositely as part of the main structure are outside the scope of this Part of BS 6779 as are prestressed concrete parapets, parapets of metal construction and parapets of combined concrete and metal design. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS 6779 the following definitions apply. 2.1 vehicle restraint system an installation to provide a level of containment for errant vehicles to limit damage or injury to users of the highway 2.2 highway parapet a barrier at the edge of a bridge, or on top of a retaining wall or similar structure, associated with a highway 2.3 safety fence an installation, provided for the protection of users of the highway, consisting of horizontal beams mounted on posts 2.4 safety barrier an installation, provided for the protection of users of the highway, that is continuously in contact with its supporting foundation 2.5 transition system an arrangement for connecting dissimilar and/or different capacity protective systems 2.6 front face of a parapet the face nearest to the traffic Licensed Copy Giorgio Cavalieri, ALSTOM, 5-Mar-01, Uncontrolled Copy. BSI BS 6779-21991 2 BSI 06-1999 2.7 outer face of a parapet the opposite face to the front face 2.8 main structure any part of the bridge, retaining wall or similar structure upon which the parapet is mounted 2.9 adjoining paved surface the paved area on the traffic side of a parapet, immediately adjacent to the base of a parapet 2.10 datum for height considerations the highest level of footway, verge, carriageway or any other part of the road construction within 1.5 m of, and on a line at right angles to, the front face NOTEThis will normally be the adjoining paved surface. 2.11 anchorage that part contained within the main structure to which the parapet is directly fixed by means of the attachment system NOTEFor example, a cast-in anchorage cradle in a reinforced concrete deck beam. 2.12 attachment system the system of attachment of the parapet to the anchorage, usually consisting of holding-down bolts 2.13 top of front face of a parapet notional or actual point at a transverse section where the horizontal projection through the highest point intercepts the plane of the front face 2.14 shear transfer an arrangement for transferring horizontal shear between adjacent panels across the vertical joint 2.15 vehicle parapet highway parapet that acts as a vehicle restraint system 2.16 vehicle pedestrian parapet vehicle parapet with safety provisions for pedestrians and animals 3 Symbols The following is a list of the symbols used in this Part of BS 6779 to represent variables. Other symbols used for designation purposes are listed in Table 1. Table 1 Designation of vehicle parapets DNominal bolt diameter mm fkCharacteristic or nominal strength of the material HVertical distance from top of parapet to the horizontal section where shear force is considered m LLength of parapet panel m Q* Design load kN QkNominal load kN R* Design resistance S* Design load effect fLPartial load factor f3Partial factor for load effect mPartial factor on material strength vbMinimum ultimate tensile strength of bolt material N/mm2 yaMinimum yield strength of anchorage material N/mm2 ItemDesignationClause ref. aLevels of containment N Normal level of containment H High level of containment 5 5.1 5.2 bHeight above datum 1.00 1 m height 1.25 1.25 m height 1.50 1.50 m height etc. 8 cType Without shear transfer I In situ concrete P Precast concrete With shear transfer i In situ concrete p Precast concrete 11.3.9 NOTEExamples of designation N/1.00/I indicates an in situ concrete parapet of 1 m height, of normal level of containment, with no shear transfer arrangement. H/1.50/p indicates a precast concrete parapet of 1.50 m height, of high level of containment, with shear transfer arrangement. Licensed Copy Giorgio Cavalieri, ALSTOM, 5-Mar-01, Uncontrolled Copy. BSI BS 6779-21991 BSI 06-19993 4 Designation of vehicle parapets For the purposes of an abbreviated description, vehicle parapets shall be designated by three characters indicating a level of containment; b height of parapet; c type of parapet. Designation details are set out in Table 1. NOTECompatible designations for metal parapets are given in BS 6779-1. Licensed Copy Giorgio Cavalieri, ALSTOM, 5-Mar-01, Uncontrolled Copy. BSI BS 6779-21991 4 BSI 06-1999 Section 2. General design 5 Levels of containment 5.1 Normal level of containment Normal level of containment shall be that required to resist penetration from the following vehicle impact characteristics NOTEThe normal level of containment is that suitable for general use. 5.2 High level of containment High level of containment shall be that required to resist penetration from the following vehicle impact characteristics NOTE 1The high level of containment is for use only in extremely high risk situations. NOTE 2Some authorities, notably British Rail, have specific requirements which should be determined for parapets on structures over their property. For applications over or adjacent to railways, reference should be made to British Rail or other appropriate railway authority. 6 Vehicle impact loading NOTEThe results of a series of impact tests carried out on concrete parapets have been analysed to produce the equivalent static loads and design s set out in clauses 6 and 11. 6.1 General The parapet shall be designed to resist loading appropriate to the designated level of containment using the equivalent static nominal loadings from Table 2. 6.2 Attachment systems and anchorages for precast concrete parapet panels 6.2.1 Attachment systems and anchorages shall be designed to resist the loadings given in 11.2.2. 6.2.2 In addition, when considering anchorage and attachment systems for high containment, the following nominal loads shall be considered in combination with the loadings in 6.2.1 to give the most severe effect a a nominal horizontal longitudinal load of 72 kN applied at the top of the front face of the panel and unily distributed over a length of 3 m or the panel length if less; b a nominal downward vertical load of 175 kN unily distributed over a horizontal length of 3.0 m at the top of the front face of the parapet. 6.3 Main structure The loads due to vehicle collision with parapets, and which are considered locally in the design of the elements of the parapet supporting structure and globally on main structures including bridge superstructures, bearings and substructures, shall be as specified in Department of Transport Standard BD 37/88. Table 2 Equivalent static nominal loads for in situ and precast concrete parapets applicable to panel lengths L 1.5 m to 3.5 m VehicleSaloon car Mass1 500 kg Height of centre of gravity 600 mm Angle of impact20 Speed113 km/h 70 mile/h VehicleFour axle rigid tanker or equivalent Mass30 000 kg Height of centre of gravity 1.8 m Angle of impact20 Speed64 km/h 40 mile/h Parapet containment levelPanel nominal bending momenta Panel nominal shearbPanel joint nominal shear transferc kN/panelkN Normald without shear transfer provision between panels High with shear transfer provision between panelse High without shear transfer provision between panels 50 kN over 1.0 m 180 40L kN/panel 210 40L kN/panel 80L 90 50H L 110 50H L 110 a The bending moment to be resisted produced by applying transversely a horizontal, continuous, unily distributed nominal load to the top of the panel. b The nominal shear force to be resisted by any transverse section of a panel. c Minimum ultimate transverse shear resistance to be provided within the top 1.2 m of the panel wall. d Shear transfer pr
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