EUROCODES. Background and Applications. EN 1991 Eurocode 1: Actions on structures. Dissemination of information for training workshop

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1 Dissemination of information for training workshop February 2008 Brussels EN 1991 Eurocode 1: Actions on structures Organised by European Commission: DG Enterprise and Industry, Joint Research Centre with the support of CEN/TC250, CEN Management Centre and Member States

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3 Tuesday, February 19 Palais des Académies EN Eurocode 1: Actions on structures Baron Lacquet room 9:00-9:10 Introduction by chairman H. Gulvanessian CEN/TC250 9:10-9:45 Introduction to EN 1991 N. Malakatas Ministry of Environment, Physical Planning & Public Works of Greece 9:45-10:30 EN N. Malakatas Ministry of Environment, Physical Planning & Public Works of Greece 10:30-11:00 Coffee 11:00-11:45 EN P. Formichi University of Pisa 11:45-12:45 EN S. O. Hansen Svend Ole Hansen ApS 12:45-14:00 Lunch 14:00-14:35 EN M. Holicky Czech Technical University in Prague 14:35-15:10 EN P. Formichi University of Pisa 15:10-15:40 Coffee 15:40-16:30 EN A. Vrouwenvelder TNO 16:30-17:30 EN J.-A. Calgaro CGPC, CEN/TC250 Chairman 17:30-18:00 Discussion and close M. Tschumi SBB-CFF-FFS All workshop material will be available at

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5 INTRODUCTION TO EN 1991 N. Malakatas Ministry of Environment, Physical Planning & Public Works of Greece

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7 LINKS BETWEEN THE Introduction to EN 1991 (Eurocode 1: Actions on structures) EN 1990 EN 1991 Structural safety, serviceability and durability Actions on structures Dr-Ing. Nikolaos E. Malakatas Head of Department - Ministry of Environment, Planning and Public Works - GREECE Chairman of CEN/TC250/SC1 EN 1992 EN 1993 EN 1994 EN 1995 EN 1996 EN 1999 EN 1997 EN 1998 Design and detailing Geotechnical and Seismic design Past and future of the EN 1991 (and the other Eurocodes) Parts and implementation of EN 1991 Time Period 1980 s Phase Technical preparation under EC Steering Committee CEN/TC250 Chairman CEN/TC250/SC1 Chairman Part of Eurocode 1 : Actions on structures Title (Subject) Issued EN General actions Densities, selfweight, April 2002 imposed loads for buildings EN General actions Actions on structures November 2002 exposed to fire EN General actions Snow loads July /2000 ENV (under CEN) Dr Breitschaft (until 1993) Dr Lazenby Dr Menzies EN General actions Wind actions April 2005 EN General actions Thermal actions November / ? EN (under CEN) Implementation Maintenance Harmonization Dissemination Further development Prof. Bossenmeyer Prof. Calgaro Prof. Gulvanessian Dr Malakatas EN General actions Actions during June 2005 execution EN General actions Accidental actions July 2006 EN Traffic loads on bridges September 2003 EN Actions induced by cranes and July 2006 machinery EN Silos and tanks May 2006 Partitioning of the NDPs among the Eurocodes Types of NDPs in the Eurocodes Type 1: Value (s) of (a) parameter (s). Type 2: Reference to some set of values table (s). Type 3: Acceptance of the recommended procedure, choice of calculation approach, when alternatives are given, or introduction of a new procedure. Type 4: Country specific data (geographical, climatic, etc.). Type 5: Optional National chart (s) or table (s) of a parameter. Type 6: Diagram (s). Type 7: References to non-contradictory complementary information to assist the user to apply the Eurocodes. Type 8: Decisions on the application of informative annexes. Type 9: Provision of further, more detailed information. Type 10: Reference to information Type 1 Type 2 Type 3 Type 4 Type 5 Type 6 Type 7 Type 8 Type 9 Type 10 1

8 EN : Densities, self-weight, imposed loads for buildings Forward Section 1 General Section 2 Classification of actions Section 3 Design situations Section 4 Densities of construction and stored materials Section 5 Self-weight of construction works Section 6 Imposed loads on buildings Annex A (informative) Tables for nominal density of construction materials, and nominal density and angles of repose for stored materials. Annex B (informative) Vehicle barriers and parapets for car parks EN : Actions on structures exposed to fire Forward Section 1 General Section 2 Structural Fire design procedure Section 3 Thermal actions for temperature analysis Section 4 Mechanical actions for temperature analysis Annex A (informative) Parametric temperature-time curves Annex B (informative) Thermal actions for external members Simplified calculation method Annex C (informative) Localised fires Annex D (informative) Advanced fire models Annex E (informative) Fire load densities Annex F (informative) Equivalent time of fire exposure Annex G (informative) Configuration factor EN : Actions on structures exposed to fire ( cont.) EN : Snow loads Forward Section 1 General Section 2 Classification of actions Section 3 Design situations Section 4 Snow load on the ground Section 5 Snow load on roofs Section 6 Local effects EN : Snow loads (cont.) EN : Snow loads (cont.) Annex A (normative) Design situations and load arrangements to be used for different locations Annex B (normative) Snow load shape coefficients for exceptional snow drifts Annex C (informative) European Ground Snow Load Maps Annex D (informative) Adjustment of the ground snow load according to the return period Annex E (informative) Bulk weight density of snow 2

9 EN : Wind actions EN : Wind actions (cont.) Forward Section 1 General Section 2 Design situations Section 3 Modelling of wind actions Section 4 Wind velocity and velocity pressure Section 5 Wind actions Section 6 Structural factor c s c d Section 7 Pressure and force coefficients Section 8 Wind actions on bridges EN : Wind actions (cont.) EN : Wind actions (cont.) Annex A (informative) Terrain effects Annex B (informative) Procedure 1 for determining the structural factor c s c d Annex C (informative) Procedure 2 for determining the structural factor c s c d Annex D (informative) c s c d values for different types of structures Annex E (informative) Vortex shedding and aeroelastic instabilities Annex F (informative) Dynamic characteristics of structures EN : Thermal actions EN : Thermal actions (cont.) Forward Section 1 General Section 2 Classification of actions Section 3 Design situations Section 4 Representation of actions Section 5 Temperature changes in buildings Section 6 Temperature changes in bridges Section 7 Temperature changes in industrial chimneys, pipelines, silos, tanks and cooling towers Annex A (normative) Isotherms of national minimum and maximum shade air temperatures. Annex B (normative) Temperature differences for various surfacing depths Annex C (informative) Coefficients of linear expansion Annex D (informative) Temperature profiles in buildings and other construction works 3

10 Forward EN : Actions during execution Section 1 General Section 2 Classification of actions Section 3 Design situations and limit states Section 4 Representation of actions Annex A1 (normative) Supplementary rules for buildings Annex A2 (normative) Supplementary rules for bridges Annex B (informative) Actions on structures during alteration, reconstruction or demolition EN : Accidental actions Forward Section 1 General Section 2 Classification of actions Section 3 Design situations Section 4 Impact Section 5 Internal explosions Annex A (informative) Design for consequences of localised failure in buildings from an unspecified cause Annex B (informative) Information on risk assessment Annex C (informative) Dynamic design for impact Annex D (informative) Internal explosions - D.1 : Dust explosions in rooms, vessels and bunkers - D.2 : Natural gas explosions - D.3 : Explosions in road and rail tunnels EN : Accidental actions EN : Accidental actions EN : Traffic loads on bridges Forward Section 1 General Section 2 Classification of actions Section 3 Design situations Section 4 Road traffic actions and other actions specifically for road bridges Section 5 Actions on footways, cycle tracks and footbridges Section 6 Traffic actions and other actions specifically for railway bridges EN : Traffic loads on bridges (cont.) Annex A (informative) Models of special vehicles for road bridges Annex B (informative) Fatigue life assessment for road bridges assessment method based on recorded traffic Annex C (normative) Dynamic factors 1 + φ for real trains Annex D (normative) Basis for the fatigue assessment of railway structures Annex E (informative) Limits of validity of load model HSLM and the selection of the critical universal train from HSLM-A Annex F (informative) Criteria to be satisfied if a dynamic analysis is not required Annex G (informative) Method for determining the combined response of a structure and track to variable actions Annex F (informative) Load models for rail traffic loads in transient design situations 4

11 EN : Traffic loads on bridges (cont.) EN : Traffic loads on bridges (cont.) EN : Traffic loads on bridges (cont.) EN : Traffic loads on bridges (cont.) EN : Actions induced by cranes and machinery EN : Silos and tanks Forward Section 1 General Section 2 Actions induced by hoists and cranes on runway beams Section 3 Actions induced by machinery Annex A (normative) Basis of design - Supplementary clauses to EN 1990 for runway beams loaded by cranes Annex B (informative) Guidance for crane classification for fatigue Forward Section 1 General Section 2 Representation an classification of actions Section 3 Design situations Section 4 Properties of particulate solids Section 5 Loads on the vertical walls of silos Section 6 Loads on silo hoppers and silo bottoms Section 7 Loads on tanks from liquids 5

12 EN : Silos and tanks (cont.) EN : Silos and tanks (cont.) Annex A (normative) Basis of design Supplementary paragraphs to EN 1990 for silos and tanks Annex B (normative) Partial factors and combinations of actions on tanks Annex C (informative) Measurements of properties of solids for silo load evaluation Annex D (informative) Evaluation of properties of solids for silo load evaluation Annex E (informative) Values of the properties of particulate solids Annex F (informative) Flow pattern determination Annex G (informative) Alternative rules for pressures in hoppers Annex H (informative) Actions due to dust explosions Background Documents and other supporting material Almost all Eurocodes represent the state-of-the-art in the respective scientific and technical field at the time of their drafting The scientific and technical basis of EN 1991 included mainly : - the systematic review of the existing relevant national codes and practices - consideration of relevant international standards (e.g. ISO Standards) or codes (e.g. JCSS Model Codes) - recent (prenormative) research results (e.g. European Snow Map) - calibration of load models based on probabilistic approaches and appropriate measurements (e.g. traffic loads for road bridges) Background Documents and other supporting material (cont.) - Well-established relevant international literature Strictly speaking, as Background Documents (BD) are considered all of the aforementioned material that has been taken into account by the relevant Project Team, during the drafting of the Eurocodes. All other relevant material, including literature, workshops and seminars, handbooks, guides and books or articles, are considered to be additional information and supporting material. A typical example are the 5 handbooks prepared in the framework of a Leonardo Da Vinci European Project (Handbook 3 is very closely linked to EN 1991, since it is dedicated to Action Effects on Buildings, and Handbook 4 is dedicated to the Design of Bridges ). This material is accessible on the Eurocodes website. Background Documents and other supporting material (cont.) The uploading of the Background Documents (BD) for EN 1991 is under way by the Secretary of EN/TC250/SC1. Until recently BD have been uploaded for the following Parts of EN 1991 : - EN EN EN EN EN and Handbooks 1 to 5 Additional information can also be found in the relevant websites, e.g. and other links (e.g. NSO et al.) Present and Future of the EN 1991 Finalising the preparation of some Corrigenda (target date June 2008) Detecting the eventual need for some Amendments (target date June 2009) On national level : Full implementation. Several countries have already issued their national standard EN 1991, but uploading of the NDPs in the ad-hoc data base of JRC Ispra goes on at a slow pace Prospects for the future : - Extending the snow map and other climatic data to cover the new EU Member States - Including eventually the ISO Standards on Waves and Currents and on Atmospheric Icing - Extending the Eurocodes to include glass and FRPs 6

13 THANK YOU FOR YOUR ATTENTION 7

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15 EN N. Malakatas Ministry of Environment, Physical Planning & Public Works of Greece

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17 Use of EN Eurocode 1: Actions on structures Part 1-1: General actions - Densities, self-weight, imposed loads for buildings Dr-Ing. Nikolaos E. Malakatas Head of Department - Ministry of Environment, Planning and Public Works - GREECE Chairman of CEN/TC250/SC1 Gives design guidance and actions for the structural design of buildings and civil engineering works, including the following aspects : - densities of construction materials and stored materials - self-weight of construction elements, and - imposed loads for buildings Is intended for Clients, Designers, Contractors and Public Authorities Is intended to be used with EN 1990 (Basis of Structural Design), other parts of EN 1991 (Actions) and EN 1992 to EN 1999 (Materials Eurocodes) for the design of structures. LINKS BETWEEN THE Programme of implementation of EN EN 1990 EN 1991 EN 1992 EN 1993 EN 1994 EN 1995 EN 1996 EN 1999 EN 1997 EN 1998 Structural safety, serviceability and durability Actions on structures Design and detailing Geotechnical and Seismic design Received positive vote as EN in April 2002 (Supersedes ENV : 1995) Published by CEN in July 2002 Confirmed in 2007 for a further period of 5 years Implementation on a national level in the Member States (National Standard EN and National Annex) still in process Withdrawal of conflicting standards probably by 2009/2010 Contents of EN Foreword Section 1 General Section 2 Classification of Actions Section 3 Design Situations Section 4 Densities of Construction and Stored Materials Section 5 Self-weight of Construction Works Section 6 Imposed Loads on Buildings Annex A (Informative) Tables for Nominal Density of Construction Materials, and Nominal Density and Angles of Repose for Stored Materials Annex B (Informative) Vehicle Barriers and Parapets for Car Parks Scope of EN Design guidance and actions for the structural design of buildings and civil engineering works, including: - densities of construction materials, additional materials for bridges and stored materials (Section 4 & Annex A), - self-weight of construction elements (Section 5), and - imposed loads for building floors and roofs (Section 6), according to category of use : - residential, social, commercial and administration areas; - garage and vehicle traffic areas (for gross vehicle weight < 160 kn); - areas for storage and industrial activity; - roofs; - helicopter landing areas. Actions on silos and tanks caused by water or other materials are dealt in EN Snow load on roofs is dealt in EN

18 Classification of actions Classification of actions (cont.) (Reminder from EN 1990) Variation in time: Permanent, Variable or Accidental Origin: Direct or Indirect Spatial Variation: Fixed or Free Nature and/or structural response: Static or Dynamic Self-weight of construction works: generally a Permanent Fixed action, however If Variable with time then represented by upper and lower characteristic values, and If Free (e.g. moveable partitions) then treated as an additional imposed load. Ballast and earth loads on roofs/terraces: Permanent with variations in properties (moisture content, depth) during the design life being taken into account. Classification of actions (cont.) Imposed loads (on buildings) : generally Variable Free actions, however loads resulting from impacts on buildings due to vehicles or accidental loads should be determined from EN Imposed loads for bridges are given in EN Also : Imposed loads generally Quasi-static actions and allow for limited dynamic effects in static structures, if there is no risk of resonance. Actions causing significant acceleration of structural members are classified as Dynamic and need to be considered via a dynamic analysis However for fork-lift trucks and helicopters additional inertial loads from hoisting and take-off/landing are accounted for through a dynamic magnification factor φ applied to appropriate static load values Design situations Permanent loads The total self-weight of structural and non-structural members is taken as a single action when combinations of actions are being considered Where it is intended to add or remove structural or nonstructural members after construction critical load cases need to be identified and taken into account. Water level is taken into account for relevant design situations, as is the source and moisture content of materials in buildings used for storage purposes. Design situations Imposed loads Probabilistic aspects Where areas are likely to be subjected to different categories of loadings, the critical load case needs to be identified and considered When imposed loads act simultaneously with other variable actions (e.g. wind, snow, cranes or machinery) the total of those imposed loads may be considered as a single action. However, for roofs of buildings, imposed loads should not be considered to act simultaneously with snow loads or wind actions. Self-weight may be usually determined as a product of the volume and the density, which both as random variables that may be described by normal distributions, with a mean value very close to their nominal value. Imposed loads are usually described by a Gumbel distribution, although Gamma distributions may also be used for the sustained (long-term) loads and exponential distributions for the intermittent (short-term) loads. 2

19 Densities of construction and stored materials Characteristic values of densities of construction and stored materials should generally be used. (If there is a significant scatter - e.g. due to their source, water content etc. an upper and a lower value should be used). Where only mean values are available, they should be taken as characteristic values in the design. Mean values for a large number of different materials are given in EN Annex A. For materials not in Annex A either: - the characteristic value of density needs to be determined in the National Annex, - a reliable direct assessment is carried out (eventually according to EN 1990 Annex D). Self-weight of construction works Generally represented by a single characteristic value calculated from nominal dimensions, characteristic values of densities and including, where appropriate, ancillary elements, e.g. non-structural elements and fixed services, weight of earth and ballast. Non-structural elements include : - roofing; - surfacing and coverings; - partitions and linings; - hand rails, safety barriers, parapets and curbs; - wall cladding; - suspended ceilings; - thermal insulation; - fixed services Self-weight of construction works (cont.) Fixed services include : - equipments for lifts and moving stairways; - heating, ventilating and air conditioning equipment; - electrical equipment; - pipes without their contents; - cable trunking and conduits Loads due to movable partitions are treated as imposed loads, but an equivalent uniformly distributed load may be used. Self-weight of construction works (cont.) Additional provisions specific for bridges : For ballast on railway bridges or fill above buried structures the upper and lower characteristic values of densities should be taken into account. The upper and lower characteristic values of the ballast depth should be considered as deviating from the nominal depth by ± 30%. The upper and lower characteristic values of the thickness due to waterproofing, surfacing and other coatings should be considered as deviating from the nominal value by ± 20% (if a post-execution coating is included in the nominal value) otherwise +40% and 20%, respectively. The upper and lower characteristic values of the self-weight of cables, pipes and service ducts should be considered as deviating from the mean value by ± 20%. Imposed loads on buildings Characteristic values of imposed loads for floors and roofs for the following types of occupancy and use: - residential, social, commercial and administration areas - garage and vehicle traffic - areas for storage and industrial activities - roofs - helicopter landing areas - barriers and walls having the function of barriers. Representation of actions Imposed loads on buildings are those arising from occupancy and the values given include : - normal use by persons; - furniture and moveable objects; - vehicles; - rare events such as concentrations of people and furniture, or the moving or stacking of objects during times of re-organisation and refurbishment Floor and roof areas in buildings are sub-divided into 11 categories according to use; loads specified are represented by uniformly distributed loads (UDL), concentrated loads, line loads or combinations thereof. Heavy equipment (e.g. in communal kitchens, radiology or boiler rooms) are not included in EN (To be agreed with the Client and/or the relevant Authority). 3

20 Main Categories of Use : Categories of use Residential, social, commercial and administration areas -4 categories (A, B, C and D) Areas for storage and industrial activities -2 categories (E1 and E2) Garages and vehicle traffic (excluding bridges) -2 categories (F and G) Roofs -3 categories (H, I and K) Residential, social, commercial and administration areas Table 6.1 Categories of use Category Specific use Example A Areas for domestic and Rooms in residential buildings and houses; residential activities bedrooms and wards in hospitals; bedrooms in hotels and hostels kitchens and toilets. B Office areas C Areas where people may congregate (with the exception of areas defined under category A, B and D 1) ) C1: Areas with tables, etc e.g. areas in schools, cafes, restaurants, dining halls, reading rooms, receptions C2: Areas with fixed seats, e.g. areas in churches, theatres or cinemas, conference rooms, lecture halls, assembly halls, waiting rooms, railway waiting rooms. C3: Areas without obstacles for moving people, e.g. areas in museums, exhibition rooms, etc. and access areas in public and administration buildings, hotels, hospitals, railway station forecourts C4:Areas with possible physical activities, e.g. dance halls, gymnastic rooms, stages. D Shopping areas D1: Areas in general retail shops C5:Areas susceptible to large crowds, e.g. in buildings for public events like concert halls, sports halls including stands, terraces and access areas and railway platforms. D2: Areas in department stores. 1) Attention is drawn to (2), in particular for C4 and C5. See EN 1990 when dynamic effects need to be considered. For Category E, see Table 6.3 NOTE 1. Depending on their anticipated uses, areas likely to be categorised as C2, C3, C4 may be categorised as C5 by decision of the client and/or National annex. Imposed loads on floors, balconies and stairs in buildings Additional loading from movable partitions Table 6.2 Imposed loads on floors, balconies and stairs in buildings Categories of loaded areas qk [kn/m 2 ] Category A - Floors 1,5 to 2,0 - Stairs 2,0 to 4,0 - Balconies 2,5 to 4,0 Category B Category C - C1 - C2 - C3 - C4 - C5 2,0 to 3,0 2,0 to 3,0 3,0 to 4,0 3,0 to 5,0 4,5 to 5,0 5,0 to 7,5 Qk [kn] 2,0 to 3,0 2,0 to 4,0 2,0 to 3,0 1, 5 to 4,5 3,0 to 4,0 2,5 to 7,0 (4,0) 4,0 to 7,0 3,5 to 7,0 3,5 to 4,5 Category D -D1 -D2 4,0 to 5,0 4,0 to 5,0 3,5 to 7,0 (4,0) 3,5 to 7,0 NOTE: Where a range is given in this table, the value may be set by the National annex. The recommended values, intended for separate application, are underlined. qk is intended for the determination of general effects and Qk for local effects. The National annex may define different conditions of use of this Table. Provided that a floor allows a lateral distribution of loads, the self-weight of movable partitions may be taken into account by a uniformly distributed load q k which should be added to the imposed loads of floors obtained from Table 6.2 (Cat. A to D). This load depends on the self-weight of the movable partitions, as follows : - self-weight < 1 kn/m, q k = 0,5 kn/m 2-1 kn/m < self-weight < 2 kn/m, q k = 0,8 kn/m 2-2 kn/m < self-weight < 3 kn/m, q k = 1,2 kn/m 2 Load arrangements Floors, beams and roofs Mid span bending moment of a floor structure Chess board arrangement Simplification in EN Load arrangements (cont.) For the design of a floor structure within one storey or a roof, the imposed load shall be applied as a free action at the most unfavourable part of the influence area. Effect of actions that cannot exist simultaneously should not be considered together (EN 1990). For the design of a column loaded from several storeys, load assumed to be distributed uniformly. For local verification concentrated load Q k acting alone should be considered. Reduction factors α A (for floors, beams and roofs) and α n (for columns and walls) may be applied, but factors ψ and α n should not be considered together. 4

21 Reduction factors α n and α A Factors ψ i α n 2 + ( n 2) ψ = n 0, α A 5 = ψ 7 0 A0 + A (Reminder from EN 1990) Actions ψ 0 ψ 1 ψ 2 α n 1 n) 0,90.9 ( n) 2( n0,8 ) 0.8 n) 0,70.7 n1) ČR (C, D) CEN, DE UK FR (C, D) 0,60.6 ( n) FR (A, B) 0,5 0.5 ČR (A, B) n α A 1 A) 0,90.9 N( A) N1( A) 0,80.8 ) A) 0,70.7 A) 1( A) 2( A0,6 ) 0.6 FI ČR (C, D) ČR (A, B) CEN DE (A, B) FR UK DE (C, D) A [m 2 ] 0, A Imposed Cat. A, B 0,7 0,5 0,3 Imposed Cat. C, D 0,7 0,7 0,6 Imposed Cat. E 1,0 0,9 0,8 Snow 0,5-0,7 0,2-0,5 0,0-0,2 Wind 0,6 0,2 0,0 Temperature 0,6 0,5 0,0 Reduction factor α A for floors A (m 2 ) α A (EN α A (EN with ψ o = 0,7) with ψ o = 1,0) 40 0,75 0, ,63 0, ,59 0, ,56 0, ,54 0,76 Reduction factor α n for columns n α A (EN with ψ o = 0,7) 1 1,00 2 1,00 3 0,90 4 0,85 5 0,82 6 0,80 7 0,79 8 0,78 9 0, ,76 Imposed loads on floors due to storage Actions induced by forklifts Table 6.3 Categories of storage and industrial use Category Specific Use Example E1 Areas susceptible to accumulation of goods, including access areas Areas for storage use including storage of books and other documents E2 Industrial use Table 6.4 Imposed loads on floors due to storage Categories of loaded areas q k [kn/m 2 ] Q k [kn] Category E1 7,5 7,0 NOTE The values may be changed if necessary according to the usage (see Table 6.3 and Annex A) for the particular project or by the National annex. qk is intended for the determination of general effects and Qk for local effects. The National annex may define different conditions of use of Table 6.4. Forklifts and transport vehicles Forklifts are classified into 6 classes via their hoisting capacity, which is reflected in other characteristics such as weight and plan dimensions. For each class, a static axle load is defined which is then increased by a dynamic (multiplication) factor φ dependent on whether the forklift has solid (φ = 2,00)or pneumatic (φ = 1,40) tyres. That factor is intended to account for the inertial effects caused by acceleration and deceleration of the hoisted load. Where transport vehicles move on floors, either freely or guided by rails, the actions need to be determined from the pattern of the vehicle s wheel loads. The static value of those wheel loads is determined from permanent weights and pay loads and the spectra of loads should be used to define appropriate combination factors and fatigue loads. 5

22 Actions induced by forklifts Garages and vehicle traffic areas Table 6.8 Imposed loads on garages and vehicle traffic areas Categories of traffic areas Category F Gross vehicle weight: 30kN Category G 30kN < gross vehicle weight 160 kn q k [kn/m 2 ] q k 5,0 Q k [kn] Q k Q k NOTE 1 For category F q k may be selected within the range 1,5 to 2,5 kn/m 2 and Q k may be selected within the range 10 to 20 kn. NOTE 2 For category G, Q k may be selected within the range 40 to 90 kn NOTE 3 Where a range of values are given in Notes 1 & 2, the value may be set by the National annex. The recommended values are underlined. Category F (e.g. garages, parking areas, parking halls) Category G (e.g. access routes, delivery zones, zones accessible to fire engines) Categorization of roofs Imposed loads on roofs of Cat. H Categories of loaded area (of a roof) : Category H Accessible for normal maintenance and repair only Category I Accessible with occupancy according to categories A to G Category K Accessible for special services e.g. helicopter landing areas Table 6.10 Imposed loads on roofs of category H Roof q k [kn/m 2 ] Q k [kn] Category H q k Q k NOTE 1 For category H q k may be selected within the range 0,0 to 1,0 kn/m2 and Q k may be selected within the range 0,9 to 1,5 kn. Where a range is given the values may be set by the National Annex. The recommended values are: q k = 0,4 kn/m 2, Q k = 1,0kN NOTE 2 q k may be varied by the National Annex dependent upon the roof slope NOTE 3 q k may be assumed to act on an area A which may be set by the National Annex. The recommended value for A is 10m 2, within the range of zero to the whole area of the roof. NOTE 4 See also (1) The minimum values given in Table 6.10 do not take into account uncontrolled accumulations of construction materials that may occur during maintenance Separate verifications to be performed for Q k and q k, acting independently Imposed loads on roofs of Cat. K for helicopters Horizontal loads on partition walls and parapets Table 6.11 Imposed loads on roofs of category K for helicopters Table 6.12 Horizontal loads on partition walls and parapets Loaded areas Category A qk [kn/m] qk Class of Helicopter Take-off load Q of helicopter Take-off load Q k Dimension of the loaded area (m x m) Category B and C1 Categories C2 to C4 and D Category C5 qk qk qk Category E qk HC1 HC2 Q 20 kn 20 kn < Q 60 kn Q k = 20 kn Q k = 60 kn 0,2 x 0,2 0,3 x 0,3 Category F See Annex B Category G See Annex B NOTE 1 For categories A,B and C1, qk may be selected within the range 0,2 to 1,0 (0,5) NOTE 2 For categories C2 to C4 and D qk may be selected within the range 0,8 kn/m to -1,0 kn/m The dynamic factor φ to be applied to the take-off load Q k to take account of impact effects may be taken as φ = 1,40 NOTE 3 For category C5, qk may be selected within the range 3,0 kn/m to 5,0 kn/m NOTE 4 For category E qk may be selected within the range 0,8 kn/m to 2,0 kn/m. For areas of category E the horizontal loads depend on the occupancy. Therefore the value of qk is defined as a minimum value and should be checked for the specific occupancy. NOTE 5 Where a range of values is given in Notes 1, 2, 3 and 4, the value may be set by the National Annex. The recommended value is underlined. NOTE 6 The National Annex may prescribe additional point loads Qk and/or hard or soft body impact specification for analytical or experimental verification. 6

23 Annex A (informative) : Nominal densities and angles of repose Table A.1 - Construction materials-concrete and mortar Table A.2 - Construction materials-masonry Table A.3 - Construction materials-wood Table A.4 - Construction materials-metals Table A.5 - Construction materials- other materials Table A.6 - Bridge materials Table A.7 - Stored materials - building and construction Table A.8 - Stored products agricultural Table A.9 - Stored products - foodstuffs Table A.10 - Stored products - liquids Table A.11 - Stored products - solid fuels Table A.12 - Stored products - industrial and general Annex B (informative) : Vehicle barriers and parapets for car parks The force in kn acting on 1,5 m of a barrier : δ c δ b m v F = 0,5 m v 2 / (δ c + δ b ) [kn] the deformation of the vehicle (mm) the deformation of the barrier (mm) the gross mass of the vehicle (kg) the velocity of the vehicle (m/s) 200 F [kn] 100 δ c =100 mm δ c =200 mm δ c =50 mm δ c For vehicles < 2500 kg: m = 1500 kg, v = 4,5 m/s, δ c = 100 mm. Backgound Documents and other supporting material Message for the near future A more general reference to Background Documents (BD) and related supporting material has been included and presented in the Introduction to EN The BD on the imposed loads on floors and roofs is already uploaded on the relevant website. Handbook 3 (Action Effects for Buildings) and Handbook 4 (Design of Bridges) of the Leonardo Da Vinci Pilot Project for the Development of Skills Facilitating the Implementation of Structural Eurocodes are considerd to be an appropriate first approach for the deeper understanding of EN Since a few years various books are being available (e.g. the Thomas Telford collection of Guides) Please try on a national level to finalise and issue the National Annex and upload the NDPs in the ad-hoc data base of JRC Ispra (if not already done so) THANK YOU FOR YOUR ATTENTION 7

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25 EN P. Formichi University of Pisa

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27 Brussels, February 2008 Dissemination of information workshop 1 Scope of the presentation Brussels, February 2008 Dissemination of information workshop 2 EN 1991 Eurocode 1: Actions on structures Part 1-3 General actions Snow Loads Paolo Formichi Department of Structural Engineering University of Pisa - Italy Description of EN Eurocode 1: Part 1-3: Snow Loads Background research for snow maps for Europe, Accidental (exceptional) loads, Shape Coefficients, Combination Factors, etc. Examples Background research Background research Brussels, February 2008 Dissemination of information workshop 3 Many clauses of EN are based on the results of a research work, carried out between 1996 and 1999, under a contract specific to this Eurocode, to DGIII/D3 of the European Commission. Brussels, February 2008 Dissemination of information workshop 4 The research results are contained in two final reports. They were identified four main research items: study of the European ground snow loads map investigation and treatment of exceptional snow loads study of conversion factors from ground to roof loads definition of ULS and SLS combination factors for snow loads. EN Field of application EN Field of application Brussels, February 2008 Dissemination of information workshop 5 Brussels, February 2008 Dissemination of information workshop 6 EN provides guidance for the determination of the snow load to be used for the structural design of buildings and civil engineering works for sites at altitudes under 1500m. In the case of altitudes above 1500m advice may be found in the appropriate National Annex. EN does not give guidance on the following specialist aspects of snow loading: impact loads due to snow sliding off or falling from a higher roof; additional wind loads resulting from changes in shape or size of the roof profile due to presence of snow or to the accretion of ice; loads in areas where snow is present all the year; loads due to ice; lateral loading due to snow (e.g. lateral loads due to dirfts); snow loads on bridges

28 Brussels, February 2008 Dissemination of information workshop 7 Contents of EN Classification of actions Foreword Section 1: General Section 2: Classification of actions Section 3: Design situations Section 4: Snow load on the ground Section 5: Snow load on roofs Section 6: Local effects ANNEX A: Design situations and load arrangements to be used for different locations ANNEX B: Snow load shape coefficients for exceptional snow drifts ANNEX C: European Ground Snow Load Maps ANNEX D: Adjustment of the ground snow load according to return period ANNEX E: Bulk weight density of snow Brussels, February 2008 Dissemination of information workshop 8 Actions due to snow are classified, in accordance with EN 1990, as: Variable: action for which the variation in magnitude with time is neither negligible nor monotonic Fixed: action that has a fixed distribution and position over the structure. Static: action that does not cause significant acceleration of the structure or structural members Classification of actions Definition of Exceptional snow load on the ground Brussels, February 2008 Dissemination of information workshop 9 Brussels, February 2008 Dissemination of information workshop 10 For particular conditions may be treated as accidental actions: action, usually of short duration but of significant magnitude, that is unlikely to occur on a given structure during the design working life Exceptional snow load on the ground load of the snow layer on the ground resulting from a snow fall which has an exceptionally infrequent likelihood of occurring Exceptional snow load on the ground Exceptional snow drifts Exceptional snow load on the ground Exceptional snow load on the ground Brussels, February 2008 Dissemination of information workshop 11 In some regions, particularly southern Europe, isolated very heavy snow falls have been observed resulting in snow loads which are significantly larger than those that normally occur. Including these snowfalls with the more regular snow events for the lengths of records available may significantly disturb the statistical processing of more regular snowfalls Gumbel probability paper: Pistoia (IT) N of recorded years = 51 N of no snowy winters = 26 s m = Max. snow Load = 1.30 kn/m 2 50yrs load incl. Max Load = 1.00 kn/m 2 s k = 50yrs load excluded Max Load = 0.79 kn/m 2 k = s m /s k = 1,65 Brussels, February 2008 Dissemination of information workshop 12 The National Annex should specify the geographical locations where exceptional ground snow loads are likely to occur.? When the maximum ground snow load is to be considered as exceptional? If the ratio of the largest load value to the characteristic load determined without the inclusion of that value is greater than 1.5 then the largest value should be treated as an exceptional value According to this definition over 2600 weather stations from 18 CEN countries (1997), in 159 they were registered exceptional ground snow loads.

29 Brussels, February 2008 Dissemination of information workshop 13 Definition of Exceptional snow drift Design Situations Exceptional snow drift load arrangement which describes the load of the snow layer on the roof resulting from a snow deposition pattern which has an exceptionally infrequent likelihood of occurring These load arrangements (treated in Annex B of EN ) may result from wind redistribution of snow deposited during single snow events. Localised snow concentrations may develop at obstructions and abrupt changes in height, leaving other areas of the roof virtually clear of snow. Brussels, February 2008 Dissemination of information workshop 14 Different climatic conditions will give rise to different design situations. The four following possibilities are identified: - Case A: normal case (non exceptional falls and drifts) - Case B1: exceptional falls and non exceptional drifts - Case B2: non exceptional falls and exceptional drifts - Case B3: exceptional falls and drifts. The national competent Authority may choose in the National Annex the case applicable to particular locations for their own territory. Design Situations Snow load on the ground Brussels, February 2008 Dissemination of information workshop 15 Brussels, February 2008 Dissemination of information workshop 16 Section 4 of EN Snow load on the ground Accidental: refers only to exceptional conditions Persistent: Conditions of normal use Transient: temporary conditions (e.g. execution or repair) Snow load on the ground Snow load on the ground Brussels, February 2008 Dissemination of information workshop 17 The snow load on the roof is derived from the snow load on the ground, multiplying by appropriate conversion factors (shape, thermal and exposure coefficients). Brussels, February 2008 Dissemination of information workshop 18 s k is intended as the upper value of a random variable, for which a given statistical distribution function applies, with the annual probability of exceedence set to 0,02 (i.e. a probability of not being exceeded on the unfavourable side during a reference period of 50 years). For locations where exceptional ground snow loads are recorded, these value must be excluded from the data sample of the random variable. The exceptional values may be considered outside the statistical methods. The characteristic ground snow loads (s k ) are given by the National Annex for each CEN country.

30 Brussels, February 2008 Dissemination of information workshop 19 Snow load on the ground Snow load on the ground Needs for harmonization Development of European ground snow load map Inconsistencies at borders between existing national maps; Different procedures for measuring snow load (mainly ground snow data): snow depths + density conversion, water equivalent measures, direct load measures; Different approaches for statistical data analysis (Gumbel, Weibull, Log-normal distributions). The research developed a consistent approach Produced regional maps (Annex C of EN ) Snow load with Altitude relationship Zone numbers & altitude functions Geographical boundaries! Brussels, February 2008 Dissemination of information workshop 20 For maps in Annex C of EN the following common approach has been followed: Statistical analysis of yearly maxima, using the Gumbel Type I CDF (best fitting in the majority of data points); LSM for the calculation of the best fitting regression curve; Both zero and non zero values have been analysed according to the mixed distribution approach ; Approximately 2600 weather stations consistently analysed; Regionalization of CEN area (18 countries 1997) into 10 climatic regions; Smoothing of maps across borderlines between neighbouring climatic regions (buffer zones 100 km). Snow load on the ground Snow load on the ground Brussels, February 2008 Dissemination of information workshop European regions, with homogeneous climatic features Brussels, February 2008 Dissemination of information workshop 22 Alpine Region Snow load at sea level (France, Italy, Austria, Germany and Switzerland) Snow load on the ground Snow load on the ground Brussels, February 2008 Dissemination of information workshop 23 Zone 4 Brussels, February 2008 Dissemination of information workshop 24 Alpine Region Snow load at sea level Zone 3 Zone 2 Zone 1 z = Zone number given on the map A = site altitude above Sea Level [m]

31 Brussels, February 2008 Dissemination of information workshop 25 Snow load on the ground Snow load on the ground - Example Brussels, February 2008 Dissemination of information workshop 26 Map for Mediterranean region Annex C EN (geographical boundaries) Zone 1 Med. Zone 1 Alp. Zone 2 Zone 3 Italian National Annex (administrative boundaries) Italian ground Snow load Map: - 4 different zones (3 Med. + 1 Alpine) - Administrative boundaries (110 provinces) - 4 Altitude correlation functions Ground Snow Load kn/m Zone 1 alp Zone 1 med Zone 2 Zone Altitude [m] Example of calculation of ground snow load at a given location: Inputs: - zone n. 3 - altitude = 600m a.s.l. s k = 1,30 kn/m 2 Other representative values of ground snow loads Other representative values of ground snow loads Brussels, February 2008 Dissemination of information workshop 27 Brussels, February 2008 Dissemination of information workshop 28 j 1 Combination valueψ 0 s k γ "+" γ Q,iψ 0,iQ G, jgk, j γ PP"+" γ Q,1Qk,1"+" i>1 k,i Eq EN 1990 Frequent value ψ 1 s k The frequent value ψ 1 s k is chosen so that the time it is exceeded is 0,10 of the reference period. Gk, "+" P"+" ψ Q "+" ψ 2,iQ j 1,1 k,1 j 1 i> 1 k,i Eq. 6.15b EN 1990 The combination factor ψ 0 is applied to the snow load effect when the dominating load effect is due to some other external load, such as wind. Based upon the available data ψ 0 values were calculated through the Borges-Castanheta method. Quasi-permanent value ψ 2 s k The quasi-permanent value ψ 2 s k (used for the calculation of long-term effects) is usually chosen so that the proportion of the time it is exceeded is 0,50 of the reference period. ψ 1 and ψ 2 values were calculated from daily data series available at 59 weather stations representative of all 10 different climatic regions. Gk, "+" P"+" ψ 2,iQ j j 1 i> 1 k,i Eq. 6.16b EN 1990 Other representative values of ground snow loads Treatment of exceptional loads on the ground Brussels, February 2008 Dissemination of information workshop 29 Brussels, February 2008 Dissemination of information workshop 30 Maps given in National Annexes are determined without taking into account exceptional falls? How to determine design values for accidental ground snow loads? For locations where exceptional loads may occur (National Annex), the ground snow load may be treated as accidental action with the value: s Ad = C esl s k Where: C esl (set by the National Annex) - recommended value = 2,0 s k = characteristic ground snow load at the site considered Gk, j"+" P"+"Ad"+"( ψ 1,1 orψ 2,1) Qk,1"+" ψ 2,iQk,i Eq. 6.11b j 1 i> 1 EN 1990

32 Brussels, February 2008 Dissemination of information workshop 31 Snow load on roofs Snow load on roofs Section 5 of EN Snow load on roofs Brussels, February 2008 Dissemination of information workshop 32 The snow the snow layers on a roof can have many different shapes depending on roof s characteristics: its shape; its thermal properties; the roughness of its surface; the amount of heat generated under the roof; the proximity of nearby buildings; the surrounding terrain; the local meteorological climate, in particular its windiness, temperature variations, and likelihood of precipitation (either as rain or as snow). Snow load on roofs Load arrangements Snow load on roofs Load arrangements Brussels, February 2008 Dissemination of information workshop 33 In absence of wind, or with very low wind velocities (<2 m/s) snow deposits on the roof in a balanced way and generally a uniform cover is formed UNDRIFTED LOAD ARRANGEMENT Brussels, February 2008 Dissemination of information workshop 34 With wind speeds in the range of 4 to 5 m/s, much of the snow is deposited in areas of aerodynamic shade DRIFTED SNOW LOAD ARRANGEMENT Aerodynamic shade wind wind Model in wind tunnel wind velocity of 4m/s Snow load on roofs Load arrangements Snow load on roofs Load arrangements Brussels, February 2008 Dissemination of information workshop 35 For situations where the wind velocity increases above 4 5 m/s snow particles can be picked up from the snow cover and redeposited on the lee sides, or on lower roofs in the lee side, or behind obstructions on the roof. DRIFTED SNOW LOAD ARRANGEMENT wind Brussels, February 2008 Dissemination of information workshop 36 EXCEPTIONAL DRIFTS In maritime climates (e.g. UK and Eire), where snow usually melts and clears between the individual weather systems and where moderate to high wind speeds occur during the individual weather system, the amount of the drifted load is considered to be of a high magnitude compared to the ground snow load, and the drifted snow is considered an exceptional load and treated as an accidental load using the accidental design situation (Annex B of EN ). wind Model in wind tunnel for multi - pitched roof wind velocity > 5 m/s Model in wind tunnel for multi - pitched roof wind velocity > 5 m/s

33 Brussels, February 2008 Dissemination of information workshop 37 w Snow load on roofs Snow load on roofs Load arrangements Brussels, February 2008 Dissemination of information workshop 38 Snow load on the roof (s) is determined converting the characteristic ground snow load into an undrifted or drifted roof load for persistent/transient and, where required by the National Annex, accidental design situations by the use of: an appropriate shape coefficient which depends on the shape of the roof; considering the influence of thermal effects from inside the building and the terrain around the building. For the persistent / transient design situations i.e. no exceptional snow falls or drifts: s = μ i C e C t s k (5.1 EN ) For the accidental design situations, where exceptional ground snow load is the accidental action: s = μ i C e C t s Ad (5.2 EN ) For the accidental design situations where exceptional snow drift is the accidental action and where Annex B applies: s = μ i s k (5.3 EN ) Snow load on roofs Shape coefficients Snow load on roofs Shape coefficients Brussels, February 2008 Dissemination of information workshop 39 EN gives shape coefficients for the following types of roofs (non exceptional drifted cases): Brussels, February 2008 Dissemination of information workshop 40 Annex B of EN gives shape coefficients for the following types of roofs (exceptional drifted cases): Multi-span Monopitch Pitched Cylindrical Roofs abutting and close to taller construction works Roofs abutting and close to taller construction works Drifting at projections, obstructions and parapets Multi-span Snow load on roofs Shape coefficients Snow load on roofs Shape coefficients Brussels, February 2008 Dissemination of information workshop 41 Values for shape coefficients μ i given in EN are calibrated on a wide experimental campaign, both in situ and in wind tunnel. 1,49 1,92 Average = 1,67 Brussels, February 2008 Dissemination of information workshop 42 Roof abutting and close to taller construction works μ s is for snow falling from the higher roof (α>15 ) μ w is the snow shape coefficient due to wind: μ w = (b 1 +b 2 )/2h < γ h /s k γ = 2 kn/m < μ w < 4 l s = 2h 5m < l s < 15m 10,00 9,00 30 wind μ w 8,00 7,00 6,00 5,00 4,00 3,00 b 1 = 8,0 m b 2 = 10,0 m s k = 0,8 kn/m 2 2,00 1,00 Multi-span drifted case 0,00 0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0 h [m]