EN DK NA:2007

Transcription

1 EN DK NA:2007 National Annex to Eurocode 5: Design of timber structures - Part 1-1: General - Common rules and rules for buildings Foreword In connection with the incorporation of Eurocodes into Danish building legislation to replace the Danish structural codes of practice, this National Annex was prepared in to implement Eurocode 5 in Denmark. Scope This National Annex lays down the conditions for the implementation of the Eurocode. Contents This National Annex specifies the national choices prescribed in Denmark. The national choices may be in the form of nationally applicable values, an option between methods given in the Eurocode, or the addition of supplementary guidance. This National Annex addresses: Clauses where national choices have been made; All clauses where national choices have been possible; Bibliography: Overview of all National Annexes prepared. Page 1 of 10

2 Clauses where national choices have been made (2)P Assignment of loads to load-duration classes Examples of assignment of loads to load-duration classes in Denmark appear from Table 2.2. Table 2.2 Examples of determination of load-duration classes Load-duration class Permanent Long-term Medium-term Short-term Instantaneous Examples of loads self-weight silo action storage areas, Category E, see DS/EN other variable actions - snow loads - variable loads on concrete forms - variable loads on scaffolding and transient structures - short-term forces due to temperature and moisture actions - accidental load - wind actions - impact forces, including impact allowance - random person load (concentrated load) on roofs and similar loads - mooring forces from ships - short-term action on quays - braking and acceleration forces - wave and ice pressures. Page 2 of 10

3 (1)P Assignment of structures to service classes Examples of structures assigned to the service classes indicated in (2)P, (3)P and (4)P: Service class 1 - structures in heated buildings where moisture is not added to the air, e.g. dwellings, offices and shops. Service class 2 - structures in ventilated, not permanently heated buildings, e.g. weekend cottages, unheated garages and storehouses; - ventilated structures protected against precipitation, e.g. ventilated roof structures. Service class 3 - structures in moist rooms; - structures exposed to precipitation or water, including concrete forms and outdoor scaffolding; - timber frames for felted roofs if these are not designed in such a way that they may be assigned to Service class (1)P Partial factors for material properties γ M Instead of Table 2.3 in EN , the following shall be used: Ultimate limit states (1)P The following partial factors for shall be used for ultimate limit states for persistent and transient design situations. Structures (IN SITU) Glued laminated timber, LVL and panels γ M = 1,30γ 3 Solid timber γ M = 1,35γ 3 Connections, e.g. with dowel type fasteners γ M = 1,35γ 3 Connections, e.g. with glued bolts and splice connections γ M = 1,50γ 3 Connections made with punched metal plate fasteners γ M = 1,35γ 3 The partial factors are determined in accordance with the DK National Annex to EN 1990, Annex F, where γ M = γ 1 γ 2 γ 3 γ 4. γ 1 γ 2 γ 3 γ 4 takes into account the type of failure takes into account the uncertainty related to the design model takes into account the extent of inspection takes into account the variation of the strength parameter or resistance. When determining γ 1 the following type of failure should be applied: Page 3 of 10

4 Assumed types of failure for the determination of γ 1 Structures Glued laminated timber, LVL and panels Solid timber Connections, e.g. with dowel type fasteners Connections, e.g. with glued bolts and splice connections Connections made with punched metal plate fasteners Warning of failure without spare resistance Warning of failure without spare resistance Warning of failure without spare resistance No warning Warning of failure without spare resistance (2) The following values of γ 3, depending on the level of inspection, should be used. Sub-partial factor γ 3 depending on the level of inspection Inspection Tightened Normal Relaxed level γ 3 0,95 1,0 1,10 Factory-made elements such as structural timber elements and prefabricated timber members made with punched metal plate fasteners may be assigned to the tightened inspection level. Other elements should be assigned to the normal inspection level. (3)P The following partial factors shall be used in Denmark for ultimate limit states for accidental design situations γ M = 1, (8) Double tapered, curved and pitched cambered beams Expression (6.55) should be applied, using the following definition: p d is the uniformly distributed load acting on the top of the beam at the ridge in the direction of the beam axis. If the uniformly distributed load acts away from the beam axis??, the last term of expression (6.55) changes its sign. 7.2(2) Limiting values for deflections Instead of Table 7.2 of EN , the limiting values for deflections specified in the table below should be used. Page 4 of 10

5 Table Limitation of deflections Structure Load w inst w net,fin Where limitation of the deflection of structures is necessary, the following frequently used deflections may be used as a basis. Structures in roofs or over small buildings Roof trusses Large glued laminated timber structures in roofs and their supports With camber Large glued laminated timber structures in roofs and their supports Without camber Snow loads 0,72 kn/m 2 l/400 - Self weight l/400 - Characteristic snow loads l/500 - Wind l/250 - Self weight l/400 - Self weight and imposed l/200 0 load Self weight and imposed load l/300 - The deflection of the structures mentioned below should not exceed the values stated. Floor structures in multistorey buildings Floor joints of residential buildings, e.g. single family hourse Concentrated load 1,0 kn 1,7 mm - 1,5 kn/m 2 l/ (2) Limiting values for vibrations The maximum ratio between w and F, where w is the instantaneous vertical deflection due to a vertical concentrated static force F applied anywhere on the floor should fulfil w a mm/kn F (0.1) and the unit impulse velocity v should fulfil ( f -1) 1 v b ζ m/(ns²) (0.2) where: a = 4 mm/kn b= 50 m/(ns 2 ) Page 5 of 10

6 (4) Nailed timber-to-timber connections: Rules for nails in end grain The paragraph should be replaced by: Smooth nails in end grain should not be assumed to have any lateral load-bearing capacity. For annular ringed nails according to EN in end grain, the lateral load-bearing capacity should be taken as 1/3 of the capacity specified for annular ringed nails driven in perpendicular to the grain, provided that: the nailed connection is subject to lateral action only; at least 3 annular ringed nails are used; the applicable requirements for minimum thicknesses, edge distances and minimum distances of nailed connections are fulfilled; the nail point penetration in the end grain is at least 10d; the connection can be assigned to service class 1 or service class (7) Nailed timber-to-timber connections: Species sensitive to splitting Addition: For timber with a moisture content less than 10% at the time of erection, the recommendation in EN should be observed. Predrilling may be omitted in timber with a moisture content exceeding 10% and for nails with a diameter smaller than 5 mm or a side length smaller than 3,5 mm (1) Bracing modification factors for beam or truss The following Danish modification factor values in Table 9.2 for the determination of stiffness and resistance of stabilising structures are recommended: Table 9.2 Factor Value s ky 3,0 k f,1 80 k f,2 100 k f,3 60 The following should furthermore be added: Where at least 8 equal, closely spaced solid timber members in compression are supported by closely spaced transverse bracings, e.g. braced by battens, half of the bending stiffness and the bending strength of the timber members may be used to resist and transfer a d. For less than 8 members, n/16 of the bending stiffness and the bending strength should be used. Page 6 of 10

7 The accumulated force in the transverse bracing member supporting n members in compression should at least be taken as: F akku = nf d - but no more than 3F d. where F ad. is the design stabilising force according to (3) (3) Erection of trusses with punched metal plate fasteners: maximum bow Maximum bow = +/- l /500, but no more than +/- 45 mm from the symmetry plane. See Figure where l is the span of the truss (4) Erection of trusses with punched metal plate fasteners: maximum vertical deviation Maximum deviation from the vertical symmetry plane +/- 45 mm, but no more than +/- h/100 measured locally on the truss. See Figure where h is the truss height. Max. bow length l Max. deviation from vertical plane height h Figure Maximum bow and deviation from vertical alignment Page 7 of 10

8 Overview of possible national choices The list below identifies the clauses where national choices are possible and the applicable/not applicable informative annexes. Furthermore, this National Annex refers to additional (non-conflicting) information that may be of assistance to the user of the Eurocode. National choice Clause (2)P (1)P 2.4.1(1)P Comment National assignment National assignment National partial factors 6.4.3(8) Guidance 7.2(2) Guidance 7.3.3(2) Guidance (4) Danish rules for nails in end grain (7) Addition (7) No changes (1) National values (3) Recommended Danish practice (4) Recommended Danish practice Annex A Annex B Annex C Annex D Applicable Applicable Applicable Applicable Page 8 of 10

9 Additional (non-conflicting) information (4) Minimum overlap of punched metal plate fasteners Where a punched metal plate fastener utilises no more than 80% of its load-bearing capacity, the requirement for minimum overlap of one third of the height of the timber member may be disregarded. It should be verified that the timber is not subject to splitting. NOTE - This guidance is based on the Danish requirements for increased insulation thicknesses and the associated increased timber dimensions. Page 9 of 10

10 Bibliography List of all National Annexes EN 1990 DK NA:2007 National Annex to Eurocode 0 Basis of structural design EN DK NA:2007 National Annex to Eurocode 1: Actions on structures Part 1-1: General actions Densities, selfweight, imposed loads for buildings EN DK NA:2007 National Annex to Eurocode 1: Actions on structures Part 1-2: General actions Actions on structures exposed to fire EN DK NA:2007 National Annex to Eurocode 1: Actions on structures Part 1-3: General actions Snow loads EN DK NA:2007 National Annex to Eurocode 1: Actions on structures Part 1-4: General actions Wind actions EN DK NA:2007 National Annex to Eurocode 1: Actions on structures Part 1-5: General actions Thermal actions EN DK NA:2007 National Annex to Eurocode 1: Actions on structures Part 1-6: General actions Actions during execution EN DK NA:2007 National Annex to Eurocode 1: Actions on structures Part 1-7: General actions Accidental actions EN DK NA:2007 National Annex to Eurocode 2: Design of concrete structures - Part 1-1: General rules and rules for buildings EN DK NA:2007 National Annex to Eurocode 2: Design of concrete structures - Part 1-2: General rules Structural fire design EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-1: General rules and rules for buildings EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-2: General rules Structural fire design EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-3: General rules - Supplementary rules for cold-formed members and sheeting EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-4: General rules - Supplementary rules for stainless steels EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-5: Plated structural elements EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-6: Strength and stability of shell structures EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-7: Plated structures subject to out of plane loading EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-8: Joints EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures Part 1-9: Fatigue EN DK NA:2007 National Annex to Eurocode 3: Design of steel structures - Part 1-10: Material toughness and throughthickness properties EN DK NA:2007 National Annex to Eurocode 4: Design of composite steel and concrete structures - Part 1-1: General rules and rules for buildings EN DK NA:2007 National Annex to Eurocode 4: Design of composite steel and concrete structures - Part 1-2: General rules Structural fire design EN DK NA:2007 National Annex to Eurocode 5: Design of timber structures - Part 1-1: General - Common rules and rules for buildings EN DK NA:2007 National Annex to Eurocode 5: Design of timber structures - Part 1-2: General Structural fire design EN DK NA:2007 National Annex to Eurocode 6: Design of masonry structures - Part 1-1: General rules for reinforced and unreinforced masonry structures EN DK NA:2007 National Annex to Eurocode 6: Design of masonry structures - Part 1-2: General rules Structural fire design EN DK NA:2007 National Annex to Eurocode 6: Design of masonry structures - Part 2: Design considerations, selection of materials and execution of masonry EN DK NA:2007 National Annex to Eurocode 7: Geotechnical design - Part 1: General rules EN DK NA:2007 National Annex to Eurocode 9: Design of aluminium structures - Part 1-1: General rules EN DK NA:2007 National Annex to Eurocode 9: Design of aluminium structures Part 1-2: Structural fire design EN DK NA:2007 National Annex to Eurocode 9: Design of aluminium structures Part 1-3: Fatigue Page 10 of 10