SIST EN 13224:2012
(Main)Precast concrete products - Ribbed floor elements
Precast concrete products - Ribbed floor elements
This document identifies the requirements, the basic performance criteria and evaluation of conformity for precast ribbed elements made of reinforced or prestressed normal weight concrete, used in floors or roofs. The elements consist of a top and/or bottom slab and one or more (usually two) ribs; transverse ribs may also be present.
Some examples of precast elements considered in this document are shown in Annex A.
Specific requirements for minor floor elements are listed in the Annex B.
This document covers terminology, performance criteria, tolerances, relevant physical properties, test methods and aspects of transport and erection.
This document does not cover load bearing capacity determined by testing.
Betonfertigteile - Deckenplatten mit Stegen
Dieses Dokument legt die Anforderungen, die grundlegenden Eigenschaften und die Verfahren zur Konformitätsbewertung für vorgefertigte Deckenplatten mit Stegen aus Stahlbeton oder Spannbeton fest, die für Decken oder Dächer eingesetzt werden. Die Deckenplatten bestehen aus einer oberen Platte und/oder einer unteren Platte sowie einem Steg oder mehreren (üblicherweise zwei) Stegen. Querstege können ebenfalls vorhanden sein. Beispiele für vorgefertigte Deckenplatten, die in diesem Dokument behandelt werden, sind in Anhang A dargestellt. Besondere Anforderungen an untergeordnete Deckenplatten sind in Anhang B angegeben. In diesem Dokument werden Begriffe, Leistungskriterien, Toleranzen, die maßgebenden physikalischen Eigenschaften, Prüfverfahren und Regelungen zu Transport und Montage festgelegt. Die versuchsgestützte Bemessung ist nicht Gegenstand dieses Dokumentes.
Produits préfabriqués en béton - Eléments de plancher nervurés
La présente norme spécifie les prescriptions, les critères relatifs aux performances de base et l'évaluation de
conformité pour les éléments nervurés préfabriqués en béton de granulats courants armé ou précontraint,
utilisés pour les planchers ou les toitures. Les éléments sont composés d'une dalle supérieure et/ou inférieure
et d'une ou de plusieurs (généralement deux) nervures ; des nervures transversales peuvent également être
présentes.
Quelques exemples d'éléments préfabriqués traités dans la présente norme sont donnés dans l'Annexe A.
Les prescriptions particulières pour les petits éléments de plancher sont énumérées dans l'Annexe B.
La présente norme couvre la terminologie, les critères de performance, les tolérances, les propriétés
physiques pertinentes, les méthodes d'essai ainsi que des aspects relatifs au transport et à la mise en oeuvre.
La présente norme ne couvre pas la capacité portante déterminée par les essais.
Montažni betonski izdelki - Rebraste etažne plošče
V tem dokumentu so opredeljene zahteve, osnovna merila učinkovitosti in ocena skladnosti montažnih rebrastih plošč iz prednapetega ali armiranega normalno težkega betona, ki se uporabljajo za tla ali strehe. Sestavljene so iz zgornje in/ali spodnje plošče ter vsaj enega rebra (običajno iz dveh); prisotna so lahko tudi prečna rebra.
Nekaj primerov montažnih plošč iz tega dokumenta je prikazanih v dodatku A.
Posebne zahteve za manjše etažne plošče so navedene v dodatku B.
Ta dokument zajema izrazje, merila učinkovitosti, tolerance, ustrezne fizikalne lastnosti, preskusne metode ter vidike transporta in postavitve.
Ta dokument ne vključuje nosilnosti, ki se določi s preskušanjem.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Betonfertigteile - Deckenplatten mit StegenProduits préfabriqués en béton - Eléments de plancher nervurésPrecast concrete products - Ribbed floor elements91.100.30Beton in betonski izdelkiConcrete and concrete productsICS:Ta slovenski standard je istoveten z:EN 13224:2011SIST EN 13224:2012en,fr,de01-februar-2012SIST EN 13224:2012SLOVENSKI
STANDARDSIST EN 13224:2004+A1:20071DGRPHãþD
SIST EN 13224:2012
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 13224
November 2011 ICS 91.100.30 Supersedes EN 13224:2004+A1:2007English Version
Precast concrete products - Ribbed floor elements
Produits préfabriqués en béton - Eléments de plancher nervurés
Betonfertigteile - Deckenplatten mit Stegen This European Standard was approved by CEN on 1 October 2011.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 13224:2011: ESIST EN 13224:2012
EN 13224:2011 (E) 2 Contents Page Foreword .4Introduction .61 Scope .72 Normative references .73 Terms, definitions, and symbols .73.1 Terms and definitions .74 Requirements .84.1 Material requirements .84.2 Production requirements .84.3 Finished product requirements .84.3.1 Geometrical properties .84.3.2 Surface characteristics . 104.3.3 Mechanical resistance . 104.3.4 Resistance and reaction to fire . 114.3.5 Acoustic properties . 114.3.6 Thermal properties . 114.3.7 Durability . 114.3.8 Other requirements. 115 Test methods . 125.1 General . 125.2 Tests on concrete . 125.3 Measuring of dimensions and surface characteristics . 126 Evaluation of conformity . 126.1 General . 126.2 Type testing . 126.3 Factory production control . 126.4 Finished products . 127 Marking and labelling . 138 Technical documentation . 13Annex A (informative)
Examples of elements . 14Annex B (normative)
Minor floor elements . 16B.1 General . 16B.2 Additional requirements for minor floor elements . 16B.2.1 General . 16B.2.2 Dimensions . 16B.2.3 Minimum strength of concrete . 17B.3 Special rules for minor floor elements . 17B.3.1 Bearing length . 17B.3.2 Transverse load distribution . 18B.3.3 Detailing . 18Annex C (informative)
Unintended negative moments . 20Annex D (informative)
Thermal maps . 23Annex E (informative)
Transverse load distribution . 27Annex F (informative)
Diaphragm action . 28SIST EN 13224:2012
EN 13224:2011 (E) 3 Annex ZA (informative)
Clauses of this European Standard addressing the provisions of the EU Construction Products Directive . 29ZA.1 Scope and relevant characteristics . 29ZA.2 Procedure for attestation of conformity of precast ribbed floor elements . 31ZA.2.1 System of attestation of conformity . 31ZA.2.2 EC Certificate and Declaration of conformity . 32ZA.3 CE marking and labelling. 33ZA.3.1 General . 33ZA.3.2 Declaration of geometrical data and material properties (method 1) . 35ZA.3.3 Declaration of product properties (method 2) . 37ZA.3.4 Declaration of compliance with a given design specification provided by the client (method 3a) . 39ZA.3.5 Declaration of compliance with a given design specification provided by the manufacturer according to the client's order (method 3b) . 41Bibliography . 43 SIST EN 13224:2012
EN 13224:2011 (E) 4 Foreword This document (EN 13224:2011) has been prepared by Technical Committee CEN/TC 229 “Precast concrete products”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 2012, and conflicting national standards shall be withdrawn at the latest by August 2013. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 13224:2004+A1:2007. Significant technical changes compared to the previous version are: a) change in the scope to also cover elements with bottom slab (as shown in Annex A); b) deletion of the requirement on planarity (in 4.3.1.1 and 5.2); c) deletion of the requirement on camber or sag (in 4.3.1.1 and 5.2); d) addition of a rule for elements without shear reinforcement in 4.3.3.3; e) adoption of the new template for Annex ZA. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of the Construction Products Directive (89/106/EEC) of the European Union (EU). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. This standard is one of a series of product standards for precast concrete products. For common aspects, reference is made to EN 13369: Common rules for precast products, from which also the relevant requirements of the EN 206-1: Concrete — Part 1: Specification, performances, production and conformity are taken. The references to EN 13369 by CEN/TC 229 product standards are intended to make them homogeneous and to avoid repetitions of similar requirements. Eurocodes are taken as a common reference for design aspects. The installation of some structural precast concrete products is dealt with by EN 13670:2009 Execution of concrete structures. In all countries it can be accompanied by alternatives for national application. The programme of standards for structural precast concrete products comprises the following standards, in some cases consisting of several parts: EN 1168, Precast concrete products — Hollow core slabs EN 12794, Precast concrete products — Foundation piles EN 12843, Precast concrete products — Masts and poles SIST EN 13224:2012
EN 13224:2011 (E) 5 EN 13224, Precast concrete products — Ribbed floor elements EN 13225, Precast concrete products — Linear structural elements EN 13693, Precast concrete products — Special roof elements EN 13747, Precast concrete products — Floor plates for floor systems EN 13978, Precast concrete products — Precast concrete garages EN 14843, Precast concrete products — Stairs EN 14844, Precast concrete products — Box culverts EN 14991, Precast concrete products — Foundation elements EN 14992, Precast concrete products — Wall elements EN 15037, Precast concrete products — Beams for beam-and-block floor systems This standard defines in Annex ZA the application methods of CE marking to products designed using the relevant EN Eurocodes (EN 1992-1-1 and EN 1992-1-2). Where, in default of applicability conditions of EN Eurocodes to the works of destination, design Provisions other than EN Eurocodes are used for mechanical strength and/or fire resistance, the conditions to affix CE marking to the product are described in ZA.3.4. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
SIST EN 13224:2012
EN 13224:2011 (E) 6 Introduction The evaluation of conformity given in this standard refers to the completed precast elements which are supplied to the market and covers all the production operations carried out in the factory. For design rules and resistance to fire, reference is made to EN 1992-1-1 and EN 1992-1-2. Additional complementary rules are provided where necessary. 4.3.3 and 4.3.4 include specific provisions resulting from the application of EN 1992-1-1, and EN 1992-1-2 rules made specific for the concerned product. The use of these provisions is consistent with a design of works made with EN 1992-1-1 and EN 1992-1-2. SIST EN 13224:2012
EN 13224:2011 (E) 7 1 Scope This document identifies the requirements, the basic performance criteria and evaluation of conformity for precast ribbed elements made of reinforced or prestressed normal weight concrete, used in floors or roofs. The elements consist of a top and/or bottom slab and one or more (usually two) ribs; transverse ribs may also be present. Some examples of precast elements considered in this document are shown in Annex A. Specific requirements for minor floor elements are listed in Annex B. This document covers terminology, performance criteria, tolerances, relevant physical properties, test methods and aspects of transport and erection. This document does not cover load-bearing capacity determined by testing. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1990:2002, Eurocode: Basis of structural design EN 1991-1-6:2005, Eurocode 1 — Actions on structures — Part 1-6: General actions — Actions during execution EN 1992-1-1:2004, Eurocode 2: Design of concrete structures — Part 1-1: General rules and rules for buildings EN 1992-1-2:2004, Eurocode 2: Design of concrete structures — Part
1-2: General rules — Structural fire design EN 13369:2004, Common rules for precast concrete products 3 Terms, definitions, and symbols 3.1 Terms and definitions For the purposes of this document, the terms and definitions given in EN 1992-1-1:2004 and EN 13369:2004 and the following apply. 3.1.1 ribbed precast concrete element precast unit consisting in a slab stiffened by one or more ribs 3.1.2 minor floor element ribbed precast floor elements having limited dimensions, which are in compliance with Annex B SIST EN 13224:2012
EN 13224:2011 (E) 8 4 Requirements 4.1 Material requirements For general aspects, reinforcing and prestressing steel, inserts and connectors, the relevant subclauses of EN 13369:2004, 4.1 shall apply. For constituent materials of concrete EN 206-1 applies. In particular, the ultimate tensile and tensile yield strength of steel shall be considered. 4.2 Production requirements The production of precast ribbed elements shall comply with the requirements in EN 13369:2004, 4.2. NOTE In addition to EN 13369:2004, 4.2.2 for cast-in-situ concrete considered to act compositely with precast units in the structural resistance (e.g. structural top layer), the minimum strength class is C 20/25. In particular, the compressive strength of concrete shall be considered. For minor floor elements, strength classes shall comply with B.2.3. 4.3 Finished product requirements 4.3.1 Geometrical properties 4.3.1.1 Production tolerances Complementary to EN 13369:2004, 4.3.1.1 the following tolerances shall apply (Figure 1). SIST EN 13224:2012
EN 13224:2011 (E) 9
Figure 1 — Reference points for standard check of tolerances DIMENSION PERMITTED DEVIATION (mm) Skewness (θ) ± 15 Lateral bow (ε ) ± 10 or L/1 000 (whichever is greater) Angular deviation of ribs (δ) ± 15 Methods of measurements are given in 5.3. For prestressed elements the values of tolerance in lateral bow (ε) and angular deviation of ribs (δ) can be increased by 50 %; this includes the effect of prestressing tolerances. For minor floor elements according to Annex B, the permitted deviation on length is ± 25 mm. 4.3.1.2 Minimum dimensions EN 13369:2004, 4.3.1.2 shall apply. 4.3.1.3 Longitudinal connections If the precast units are connected along their longitudinal edges by means of a cast in situ mortar or concrete joint, the minimum joint width shall be at least 30 mm at the top to allow satisfactory casting. The joint face shall be provided with at least one groove. The size shall be appropriate with regard to the shear resistance of the grout. If tie bars are to be anchored within the joint, the joint width at the tie bar level shall be at least three times the diameter of the bar to enable a satisfactory bond and a complete encasing of the bar. If welded connections are used, the connection devices should be designed in order to allow an easy compensation of camber and erection deviations and welding execution. SIST EN 13224:2012
EN 13224:2011 (E) 10 4.3.1.4 Concrete cover For the protection against corrosion EN 13369:2004, 4.3.7 shall apply. For minor floor elements see Annex B. 4.3.2 Surface characteristics EN 13369:2004, 4.3.2 shall apply. 4.3.3 Mechanical resistance 4.3.3.1 General EN 13369:2004, 4.3.3.1 to 4.3.3.5 shall apply except 4.3.3.4. For minor floor elements see Annex B. For transverse distribution of loads see Annex E. For diaphragm actions see Annex F. 4.3.3.2 Transient situations For transient situations, EN 13369:2004, 4.3.3.6 shall apply. Unless compensating devices are used during lifting, each suspension point should be verified on the basis that only two are being active. In the erection phases in which the access of workers on the elements can be expected, the construction loads of EN 1991-1-6 shall be considered and the supports for safety devices shall withstand the appropriate horizontal force, placed in the most unfavourable position of the upper side of the protection rail. 4.3.3.3 Shear reinforcement It is allowed to omit the transversal shear reinforcement where it is not required by the resistance to loads or fire verification provided adjacent units are connected. At least the minimum shear reinforcement according to EN 1992-1-1:2004, 9.2.2 shall be provided in the anchorage zone of prestressing tendons, unless a greater area is required by the relevant verification. This minimum shear reinforcement is not required for ribbed elements used for roofs, provided the spalling stress in the webs is lower than the tensile strength of concrete at time of prestress release. In ribs with a thickness not exceeding 120 mm the shear reinforcement may be shaped in one leg only, placed in the middle plane of the rib and properly anchored beyond the main reinforcement. 4.3.3.4 Shear and negative moments In elements without shear reinforcement, negative moments and unintended restraining effects at the supports should be considered in the design of the elements and in the detailing of the connections at the supports in order to prevent possible restraint cracks which can initiate shear failure near the support. Two methods to deal with negative or unintended fixing moments are applicable: detailing the connection in such a way that these negative moments will not occur; SIST EN 13224:2012
EN 13224:2011 (E) 11 design by calculations. Design methods to consider negative or unintended moments are given in Annex C. 4.3.3.5 Longitudinal shear EN 1992-1-1:2004, 6.2.4 shall apply. If the composite action with a cast on site topping is considered, the manufacturer shall declare the type of roughness of the surface according to EN 1992-1-1:2004, 6.2.5. 4.3.4 Resistance and reaction to fire 4.3.4.1 Resistance to fire Fire resistance dealing with load bearing capacity R, integrity E and insulation I of ribbed floor elements, expressed in terms of classes, shall be declared following EN 13369:2004, 4.3.4.1 and 4.3.4.2. Load bearing classification R by calculation can be carried out using the thermal maps given in Annex D. Load bearing classification R by tabulated data may be made on the basis of data given in EN 1992-1-2 using beam data for the ribs and slab data for the slab, respectively. NOTE If the option of tabulated data is selected, as they do not take into account the actual position of the reinforcement nor the actual load level, they usually lead to an over dimensioning of the cross section. 4.3.4.2 Reaction to fire For reaction to fire, EN 13369:2004, 4.3.4.4 shall apply. 4.3.5 Acoustic properties EN 13369:2004, 4.3.5 shall apply. 4.3.6 Thermal properties EN 13369:2004, 4.3.6 shall apply. 4.3.7 Durability EN 13369:2004, 4.3.7 shall apply. 4.3.8 Other requirements 4.3.8.1 Safety in handling EN 13369:2004, 4.3.8.1 shall apply. 4.3.8.2 Safety in use EN 13369:2004, 4.3.8.2 shall apply. SIST EN 13224:2012
EN 13224:2011 (E) 12 5 Test methods 5.1 General EN 13369:2004, Clause 5 shall apply, with the following rules. 5.2 Tests on concrete EN 13369:2004, 5.1 shall apply. 5.3 Measuring of dimensions and surface characteristics EN 13369:2004, 5.2 shall apply with the following additional rules (see Figure 1): Skewness (θ): (for elements having rectangular shape only): measure the distance of points 5 and 15 from straight lines normal to the straight line 1-11, containing respectively the points 1 and 11; Lateral bow (ε): measure the distance of points 6 and 10 from straight lines respectively 1-11 and 5-15; Angle deviation of the rib (δ): measure the distance of points 2 and 12 (4 and 14) from straight lines normal to the lines 16-20 (17-21), containing respectively the points 16 and 20 (17 and 21). 6 Evaluation of conformity 6.1 General EN 13369:2004, 6.1 shall apply. 6.2 Type testing EN 13369:2004, 6.2 shall apply. 6.3 Factory production control NOTE The missing numbers correspond to the clauses of EN 13369 included in the general references made in this subclause. EN 13369:2004, 6.3 shall apply. 6.4 Finished products In addition to items 3 to 5 of D.4.1 of Table D.4 of EN 13369:2004, the check of Table 1 shall be performed. SIST EN 13224:2012
EN 13224:2011 (E) 13 Table 1 — Finished product inspection Subject Method Purpose Frequency Main dimensions See 5.2 Conformity with drawings and specified tolerances 1 every 10 elements or 1 every casting line Skewness Lateral bow Angle deviation of the rib See 5.2 Conformity with drawings and specified tolerances Every month Slippage of tendons Appropriated check /measurement Conformity with
EN 13369:2004, 4.2.3.2.4 Only if release is not gradual Surface appearance
Visual inspection In case of doubt, check according to EN 13369:2004, J.4 Conformity with specified tolerances Every element 7 Marking and labelling EN 13369:2004, Clause 7 shall apply. NOTE For CE marking see Annex ZA. 8 Technical documentation The detailing of the element, with respect to geometrical data and complementary properties of materials and inserts, shall be given in technical documentation, which includes the construction data, such as the dimensions, the tolerances, the layout of reinforcement, the concrete cover, the surface characteristics (when relevant), the expected transient and final support conditions and lifting conditions. The composition of technical documentation is given in Clause 8 of EN 13369:2004.’ SIST EN 13224:2012
EN 13224:2011 (E) 14 Annex A (informative)
Examples of elements Some examples of cross-sections of precast elements considered in this document are shown in Figure A.1. The elements can be simply supported, or connected longitudinally on or with the supports, achieving total or partial continuity. They can also be designed with half joints at the ends, in order to reduce the total thickness. According to the different situations, the elements can be: placed on site without transversal connections, eventually supporting secondary elements between them (isolated members); provided with steel plates at their lateral edges to be connected together at their top flanges by welded shear connectors; shaped in form of shear keys at their lateral edges to be connected together by cast in situ shear joints, and/or be provided with steel plates for welded connections on site; provided with a cast in situ reinforced concrete topping. Such topping, if effectively restrained to the precast elements by bond, with or without steel reinforcement projecting from the elements, may be taken into account in the resistant section. Combinations of the preceding cases are also possible. According to the different arrangement of connections, the elements can be: able to act as a diaphragm in order to transfer horizontal forces to the bracing elements (cases b), c), d) and a) if the secondary elements are adequately connected); able to transfer vertical shear from heavier loaded elements to the surrounding ones (cases c), d) and b) if the welded connection is arranged in an appropriate way). SIST EN 13224:2012
EN 13224:2011 (E) 15
a)
b)
c)
d)
e)
f)
g) Figure A.1 — Examples of some forms of ribbed floor elements SIST EN 13224:2012
EN 13224:2011 (E) 16 Annex B (normative)
Minor floor elements B.1 General In view of their use as specified in B.2.1, minor floor elements may be designed in the lower consequences class of EN 1990:2002, B.3.1. In this case, they shall be in compliance with the additional requirements and special rules of this annex. Design, production and application of minor floor elements, according to these special rules, is only allowed if manufacturing takes place under strict production control. B.2 Additional requirements for minor floor elements B.2.1 General Minor floor elements are ribbed precast floor elements with limited dimensions, used only for a suspended floor with a maximum below air space of 1 000 mm between the floor and the ground, which are in compliance with the additional requirements of B.2.2 and B.2.3. NOTE According to consequences classes stated in 1990:2002, B.3.1, taking into account the use stated above, some special design rules are given for these products. Examples of some forms of minor floor elements are given in Figure B.1.
Figure B.1 — Possible forms of minor floor elements B.2.2 Dimensions Minor floor elements shall comply with the following dimensions (referred to the concrete-element, without thermal insulation): span of the elements ≤ 8 000 mm; height of the elements ≤ 400 mm; width of the ribs ≥ 60 mm; spacing between ribs ≤ 1 200 mm; SIST EN 13224:2012
EN 13224:2011 (E) 17 thickness of the slab: for Lx ≤ 950 mm: ≥ 50 mm; for Lx > 950 mm: ≥ Lx/15; cantilever (Lc) ≤ 600 mm; thickness of cantilever slab ≥ Lc/8 or 50 mm; for Lx and Lc: see Figure B.2. The span/height ratio of minor floor elements shall be such that the time dependent deformation due to the quasi-permanent loads shall not exceed 3/1 000 of the span. In case of stone-like (plaster or brittle finish or other non-flexible) partitions, the additional deflection (after the execution of partitions) shall not exceed 2/1 000 of the span.
Figure B.2 — Notations B.2.3 Min
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