1、PD 6696-2:2007Background paper to BS EN 1994-2 and the UK National Annex to BS EN 1994-2ICS 91.010.30; 91.080.10; 91.080.40; 93.040NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWPUBLISHED DOCUMENTLicensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 25/03/2008 08:16, Uncontro
2、lled Copy, (c) BSIPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2007ISBN 978 0 580 58645 3The following BSI references relate to the work on this standard:Committee reference B/525/4Publication historyFirst pu
3、blished December 2007Amendments issued since publicationAmd. no. Date Text affectedPD 6696-2:2007Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 25/03/2008 08:16, Uncontrolled Copy, (c) BSI BSI 2007 iPD 6696-2:2007ContentsForeword iiIntroduction 11 Scope 12 Design values of material or produc
4、t properties BS EN 1994-2:2005, 2.4.1.2 (2)P 13 Structural analysis 24 Ultimate limit states (ULS) member design 35 Shear connection 56 Rules for transverse filler beams BS EN 1994-2:2005, 6.3.1 (1) 8Bibliography 9List of figuresFigure 1 Geometry for block connectors with hoops 7Summary of pagesThis
5、 document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 9 and a back cover.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 25/03/2008 08:16, Uncontrolled Copy, (c) BSIPD 6696-2:2007ii BSI 2007ForewordPublishing informationThis Published Document is published by BS
6、I and came into effect on 31 December 2007. It was prepared by Subcommittee B/525/4, Composite structures, in collaboration with Subcommittee B/525/10, Bridges, under the authority of Technical Committee B/525, Building and civil engineering. A list of organizations represented on this committee can
7、 be obtained on request to its secretary.Relationship with other publicationsThis Published Document is a background paper that gives non-contradictory complimentary information for use in the UK with the Eurocode BS EN 1994-2 and its UK National Annex.Presentational conventionsThe provisions in thi
8、s document are presented in roman (i.e. upright) type. Its recommendations are expressed in sentences in which the principal auxiliary verb is “should”.The word “may” is used in the text to express permissibility, e.g. as an alternative to the primary recommendation of the Clause. The word “can” is
9、used to express possibility, e.g. a consequence of an action or an event.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 cannot confer i
10、mmunity from legal obligations.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 25/03/2008 08:16, Uncontrolled Copy, (c) BSI BSI 2007 1PD 6696-2:2007IntroductionWhen there is a need for guidance on a subject that is not covered by the Eurocode, a country can choose to publish documents that co
11、ntain 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 1994-2.1 Scope This Published Document contains non-contradictory complementary information and add
12、itional guidance for use in the UK with BS EN 1994-2:2005 and its UK National Annex. This published document gives information and guidance on the design of components of composite steel and concrete bridges; it does not cover assessment. This Published Document does not fully cover cable-supported
13、bridges.This Published Document does not cover the detailing of components for seismic design or the design of parapets, safety fences and other ancillary items.2 Design values of material or product properties BS EN 1994-2:2005, 2.4.1.2 (2)PThe definition of design compressive stress, fcd, differs
14、in BS EN 1994-2:2005 from that in BS EN 1992-2:2005 since the parameter ccis omitted. Where reference is necessary to BS EN 1992-2:2005 for design of reinforced concrete elements, such as the local design of a deck slab, the definition of design compressive stress in BS EN 1992-2:2005, 3.1.6 should
15、be adopted for such verifications, with ccas given in the National Annex to BS EN 1992-2:2005. This value is 0,85 for flexural and axial compression, and so is consistent with the factor 0,85 in BS EN 1994-2:2005, 6.2.1.2 (1) and 6.7.3.2 (1). Where stress in concrete is checked under the combined ef
16、fects of local and global actions, the check should be in accordance with BS EN 1994-2:2005 if the concrete is acting as part of a composite section in the direction concerned, and otherwise in accordance with BS EN 1992-2:2005. (See PD 6687-2 1).)1)In preparation. Licensed Copy: Wang Bin, ISO/EXCHA
17、NGE CHINA STANDARDS, 25/03/2008 08:16, Uncontrolled Copy, (c) BSIPD 6696-2:20072 BSI 20073 Structural analysis3.1 Imperfections BS EN 1994-2:2005, 5.3Allowances for imperfections are covered in BS EN 1994-2:2005, 5.3. Imperfections in common planarity of bearings should be allowed for in the analysi
18、s of torsional moments and reactions for torsionally stiff superstructures and should be compatible with the tolerances, which the designer should specify, and the construction method and sequence used.3.2 Creep and shrinkage BS EN 1994-2:2005, 5.4.2.2The partial factor for shrinkage should be obtai
19、ned from BS EN 1992-1-1:2004, 2.4.2.1. Where cracking has been considered in analysis in accordance with BS EN 1994-2:2005, 5.4.2.3 (2) or 5.4.2.3 (3) the same cracked zone may be considered in calculation of shrinkage secondary effects.3.3 Pre-stressing by tendons BS EN 1994-2:2005, 5.4.2.7The stra
20、in in the tendons at failure may be calculated from a non-linear global analysis of the structure. If this is done, checks should be made to ensure that conventional “conservative” assumptions, such as ignoring the tensile strength of concrete, do not have the effect of increasing the tendon strain
21、and hence the ultimate strength. The effects of tension stiffening should be considered in global analysis where they adversely affect the resistance at the critical section.3.4 Combinations of local and global action effects in deck slabs BS EN 1994-2:2005, 5.4.4 (1)The flexural effects of local an
22、d global loads in deck slabs in the longitudinal direction should be combined for serviceability verifications, but, where elastic global analysis is used, need not be combined for checks for ultimate limit states other than fatigue. Where a check of the combined effects of local and global loads is
23、 not made at the ultimate limit state, concrete compressive stresses should be limited to the value given in BS EN 1992-2:2005, 7.2 (102) at the serviceability limit state, regardless of actual concrete exposure class.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 25/03/2008 08:16, Uncontrol
24、led Copy, (c) BSI BSI 2007 3PD 6696-2:20073.5 Classification of cross-sections BS EN 1994-2:2005, 5.5For beams with moment and axial compression, section classification should be determined considering the actual combination of bending and axial compression. The resulting section classification shou
25、ld be used in evaluating the effects of both bending and axial force. For simplicity, the section classification may be determined for axial compression alone. For Class 1 and 2 cross-sections, the cross-section resistance may be verified in accordance with BS EN 1994-2:2005, 6.7.2. Alternatively, C
26、lass 1 and 2 cross-sections may be checked using the linear interaction given in BS EN 1993-1-1:2005, 6.2.1 equation (6.2).For beams with moment and axial tension, section classification should be determined considering the actual combination of bending and axial tension. For simplicity, the section
27、 classification may be determined for the bending moment alone. 4 Ultimate limit states (ULS) member design4.1 Elastic resistance to bending BS EN 1994-2:2005, 6.2.1.5The elastic resistance moment, Mel,Rdis defined in BS EN 1994-2:2005, 6.2.1.4 (6). In calculating Mel,Rd, the stresses from the prima
28、ry effects of shrinkage should be included, unless they may be neglected in accordance with BS EN 1994-2:2005, 6.2.1.5 (5).4.2 Resistance to vertical shear BS EN 1994-2:2005, 6.2.2The effect of torsion on the shear plastic resistance and shear buckling resistance should be considered in accordance w
29、ith BS EN 1993-2:2006, 6.2.7.4.3 Resistance to vertical shear Additional rules for beams in bridges BS EN 1994-2:2005, 6.2.2.5 (3)In should be noted that in the final sentence of the Note to BS EN 1994-2:2005, 6.2.2.5 (3), cphas the sign convention of compression positive as defined in BS EN 1992-2:
30、2005, 6.2.2 (101). cpshould therefore be taken as negative if tensile, but not less than cp,0, where the recommended value of cp,0= 1,85 N/mm2. (See Ehmann and Kuhlman 2006 1.) Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 25/03/2008 08:16, Uncontrolled Copy, (c) BSIPD 6696-2:20074 BSI 2007
31、4.4 Bending and vertical shear BS EN 1994-2:2005, 6.2.2.4 (3)In applying the interaction in BS EN 1993-1-5:2006, 7.1, should be taken as MEd/Mpl,Rdfor the cross-section at the stage being checked. MEdis the greatest value anywhere in the cross-section of iWi, where iis the total accumulated stress a
32、t an extreme fibre and Wiis the elastic modulus of the effective section at the same fibre at the time considered. need not however be taken as less than 1, derived by considering accumulated stress. (See Hendy and Johnson, 2006 2.)4.5 Bending, shear and axial force For beams with sections in Class
33、1 or 2, 3.5 of this document applies but the yield strength of the web should be reduced, following section classification, to (1 )fydwhere is defined in BS EN 1994-2:2005, 6.2.2.4 (2).For beams with sections in Class 3 or 4, the interaction between bending, shear and axial force should be considere
34、d in accordance with BS EN 1993-1-5:2006, 7.1. In applying BS EN 1993-1-5:2006, 7.1, the following apply.a) MEdis the greatest value anywhere in the cross-section of iWi, where iis the total accumulated stress from bending moments only at an extreme fibre and Wiis the elastic modulus of the effectiv
35、e section at the same fibre at the time considered.b) The plastic bending resistance Mpl,Rdin the interaction expression in BS EN 1993-1-5:2006, 7.1 (1) should be reduced in accordance with BS EN 1993-1-5:2006, 7.1 (4) to Mpl,N,Rd.c) The resistance Mf,Rdshould be reduced by the factor given in BS EN
36、 1993-1-5:2006, 5.4 (2), in accordance with BS EN 1993-1-5:2006, 7.1 (4). For composite beams in hogging zones, this factor should be replaced by:where Asis the area of the longitudinal reinforcement in the top slab.4.6 General methods for buckling of members and frames BS EN 1994-2:2005, 6.4.3Later
37、al and lateral torsional buckling of members subject to bending and axial load may be verified using one of the following methods:a) the general method given in BS EN 1994-2:2005, 6.4.3.1;b) second order analysis with modelled imperfections in accordance with BS EN 1994-2:2005, 5.2 and 5.3. Imperfec
38、tions for beams in the plane of bending should be based on those for curve d in BS EN 1993-1-1:2005, Table 5.1 and any specified precamber should also be included in the analysis model.11()Edf1 f2 yf M0 s sd1/NAA Af+Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 25/03/2008 08:16, Uncontrolle
39、d Copy, (c) BSI BSI 2007 5PD 6696-2:2007c) the simplified method given in BS EN 1994-2:2005, 6.4.3.2 and linear interaction according to:where:MII,Edis the moment in the plane of the web, including additional moments from in-plane second-order effects;Nb,Rdis the lateral flexural buckling resistance
40、 of the beam under axial force. Nb,Rdshould be determined from BS EN 1993-2:2006, 6.3.4.2 by multiplying the stress required for lateral buckling of the compression flange by the area of the entire beam cross sectional area relevant to the stage being checked;Mb,Rdis the lateral torsional buckling r
41、esistance of the beam determined from BS EN 1993-2:2006, 6.3.4.2.In calculating Nb,Rdand Mb,Rdfor Class 4 cross-sections, effective sections should be used in accordance with BS EN 1993-1-5:2006, 4.3.4.7 Transverse forces on webs BS EN 1994-2:2005, 6.5The rules in BS EN 1993-1-5:2006, Section 6 may
42、also be conservatively applied to the composite flange where the load is applied through the concrete slab. The concrete slab should be ignored in the calculation of the effective loaded length, ly, other than in determining the length of stiff bearing, ss. In determining ss, a spread of load throug
43、h the concrete slab of 1:1 may be assumed. (See Hendy and Murphy 3.)5 Shear connection5.1 Influence of tension on shear resistance BS EN 1994-2:2005, 6.6.3.2The interaction between stud shear force, PEd, and stud tension, Ften, may be checked using the following expression:(Ften/0,85PRd)5/3+ (PEd/PR
44、d)5/3u 1,0(See Johnson and Buckby 1986 4.) 5.2 Spacing of connectors BS EN 1994-2:2005, 6.6.5.5For wide compression flanges, the limits to transverse spacing of shear connectors given in BS EN 1994-2:2005, 9.4 (7) also apply.II,EdEdb,Rd b,Rd1, 0MNNM+ -Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STAN
45、DARDS, 25/03/2008 08:16, Uncontrolled Copy, (c) BSIPD 6696-2:20076 BSI 20075.3 Design resistance to longitudinal shear BS EN 1994-2:2005, 6.6.6.2Interaction of longitudinal shear and transverse bending should be considered for the reinforcement crossing shear surfaces of type b-b and c-c in BS EN 19
46、94-2:2005, Figure 6.15 where the transverse bending induces tension in the bottom reinforcement. In such cases, the reinforcement requirements for shear and moment should be fully added. For surfaces of type d-d, an interaction need not be considered providing the haunch reinforcement Abhis not assu
47、med to resist the bending moment.Where a slab is in direct transverse tension, the reinforcement requirements for the tension should be fully combined with that for longitudinal shear on planes a-a, b-b and c-c. (See Hendy and Johnson 2006 2.) 5.4 Design resistance of block connectors with hoops BS
48、EN 1994-2:2005, 1.1.3 (3)The shear resistance of a block connector with hoops in normal weight concrete and height of block, 0,5b1, not exceeding four times its thickness, lb, may be taken as:where:Ac0is the area of the front surface of the block connector, equal to 0,5b1d1;b1and d1are shown in Figu
49、re 1;Ac1is the design distribution area at the rear surface of the adjacent connector, equal to 0,5b2d2;b2and d2are shown in Figure 1 and should be in accordance with BS EN 1992-1-1:2004, 6.7 as follows:b2u b1+ h and b2u 3b1; d2u d1+ h and d2u 3d1;Ac0and Ac1should be of similar shape.The shear resistance of a block connector with hoops in lightweight aggregate concrete may be taken as:where: is obtained from BS EN 1992-1-1:2004, Table 11.1.Vertical tie reinforcement to control
