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Eurocodes Essential Guide | Snow | Structural Steel
Description: Part-3
Professor Haig Gulvanessian CBE, Civil Engineering
and Eurocode Consultant
This chapter gives a brief summary of the scope, field of application and
difference within UK practice for each Part of EN 1991.
EN 1991 (Eurocode 1: Actions on structures) provides comprehensive information and guidance on all actions that it is normally necessary to consider
in the design of buildings and civil engineering works. The European Union
initiated the preparation of EN 1991 in 1985. All Parts have been published
as have all the corresponding UK national annexes. This chapter describes the
scope of Eurocode 1 and its main provisions.
EN 1991 comprises 10 Parts as shown in Table 1.1. The background to
these ten Parts is comprehensively described by Gulvanessian, Formichi and
Calgaro [1] and Calgaro, Tchumi and Gulvanessian [2]. The Parts are referred
to in this chapter by their designated EN numbers. These Parts will provide
the actions for use with EN 1990 Eurocode: Basis of structural design, and
EN 1992–EN 1999 as appropriate, for design and verification on the basis of
overall principles given in EN 1990.
Difference between EN 1991 and the UK system of loading codes
Each Part of EN 1991 gives unique guidance on a particular type of action.
Within each Part, guidance is provided for buildings and other construction
works, e.g. bridges. This is different to the British Standard system of loading
codes where the codes are based on the type of structure, e.g. BS 6399 for
buildings and BS 5400 for bridges.
Table 1.1. The Parts of Eurocode 1: Actions on structures
Accidental actions due to impact and explosions
Definition of actions in EN 1990
In EN 1990 and EN 1991, actions are classified by their:
variation in time – permanent, variable or accidental;
origin – direct or indirect;
spatial variation – fixed or free; and
nature and/or structural response – static or dynamic.
Actions are described by a model, its magnitude being represented in the most
common cases by one scalar, e.g. vehicle axle spacing, and its magnitude is
commonly represented by a single scalar. The scalar may adopt several representative values, e.g. a dominant (leading) or non-dominant (accompanying)
action. Several scalars are used for multi-component action. More complex
representations are required for fatigue and dynamic actions.
Table 1.2 gives examples of the classification of actions with regard to variation in time.
The term single action is also used to define an action which is statistically
independent in time and space from any other action acting on the structure.
The self-weight of a structure can be represented by a single characteristic
value, (Gk), provided the variability of G is small, and it can be calculated on
the basis of the nominal dimensions and the mean unit mass. If the variability
of G is not small and the statistical distribution is known, two values are
used: an upper value (Gk,sup) and a lower value (Gk,inf). More information on
this subject has been given by Ostlund [3].
Table 1.2. Classification of actions
a) Self-weight of
structures, fittings and
c) Water and soil
d) Indirect action, e.g.
c) Impact from vehicles
Indirect action, e.g.
e) Actions due to traffic
Arbitrary point-in-time value Q
Combination value y 0Qk
Frequent value y 1Qk
Quasi-permanent value y 2Qk
Figure 1.1. Representative values
7 0.S. Table 1. The combination value.3 0. the quasi-permanent value.5 0. y factors for buildings y0 y1 y2 0. y0Qk.70 0.S. The quasi-permanent value. Iceland.3 (reproduced from EN 1990).bsigroup.3 0 Finland.1). for sites located at altitude H £ 1000 m A.7 0.5 0 0. Remainder of CEN Member States. y2Qk. 0. It is used for the verification of ultimate limit states and irreversible serviceability limit states.50 0. y2 for buildings are shown in Table 1.7 01 0. Qk.0 0. is used for verification of ultimate limit states involving accidental actions and reversible limit states.5 0 Action Imposed loads in buildings. category (see EN 1991-1-1) Category A: domestic. for sites located at altitude H > 1000 m A. the combination value.com/transition © BSI British Standards Institution .62 0.6 0.5 in the UK national annex.5 0.7 1. takes account of the reduced probability of simultaneous occurrence of the most unfavourable values of several independent variable actions.7 0.6 0.2 0 Temperature (non-fire) in buildings (see EN 1991-1-5) 0. Norway.20 0.50 0. is also used for ultimate limit state verification involving accidental actions and for reversible serviceability limit states. y2Qk. The recommended values of y0.70 0.3 0. y1Qk.50 0.7 0.6 0.20 0 Wind loads on buildings (see EN 1991-1-4) 0.7 0.7 0.3. The frequent value.20 0. the frequent value.L. • • • • the characteristic value. y1Qk. vehicle weight £ 30 kN Category G: traffic area.8 0. 0.7 in the UK national annex. 45 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.Eurocode 1: Actions on structures A variable action has the following representative values (see Figure 1. for more details go to: http://shop. 30 kN < vehicle weight £ 160 kN Category H: roofs Snow loads on buildings (see EN 1991-1-3) 1 2 0. y0Qk. Sweden Remainder of CEN Member States.6 0.9 0.7 0. y1.L. residential areas Category B: office areas Category C: congregation areas Category D: shopping areas Category E: storage areas Category F: traffic area.
The guidance given in EN 1991-1-1 on densities is generally similar to that contained in BS 648 which will be withdrawn. which is covered by Part 1. a range of values is provided. cladding. EN 1991-1-1. As an example.3).com/transition © BSI British Standards Institution . roofs. b) the self-weight of structural elements and whole structures and some fixed non-structural items.The essential guide to Eurocodes transition Information on combining Actions for particular design situations is given in the Chapter on EN 1990 for both ultimate and serviceability limit states. ‘Table A.4 Construction materials-metals’ is shown in Table 1.1: Densities.bsigroup. finishes and fixed services. which are therefore described as nominal values. floors. For materials where the bulk weight density has significant variability according to its source. gives comprehensive tables for densities of construction and stored materials. c) imposed loads on floors and roofs of buildings (but excluding snow. partitions. EN 1991-1-1 Eurocode 1: Part 1. Self-weight of structural elements Methods are provided for assessing the self-weight of construction elements in buildings. walls. Densities of construction and stored materials Differences in the national codes of the CEN Member States imposed constraints on the development of this part of Eurocode 1. for more details go to: http://shop.4. self-weight and imposed loads Scope and field of application EN 1991-1-1 covers the assessment of actions for use in structural design due to: a) the density of construction materials and stored materials. e.g. 46 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. They are therefore called nominal densities but can be treated as characteristic values when determining self-weights. in its Annex A. It was not possible to describe the densities of the construction or stored materials as either mean or characteristic values since both of these terms imply some understanding of the underlying statistical distribution of the densities.
0 to 72.com/transition © BSI British Standards Institution .0 to 85.0 83. the self-weight of movable partitions may be taken into account by a uniformly distributed load. which should be added to the imposed loads of floors.0 112.0 to 89.0 kN/m wall length: qk = 1. Table A. for more details go to: http://shop. For both traffic and railway bridges. Provided that a floor allows a lateral distribution of loads. 47 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. the determination of the self-weight of construction elements including coating.4 – Construction materials-metals (from EN 1991-1-1) Materials Density g (kN/m3) Metals Aluminium Brass Bronze Copper Iron.5 71.0 87. • for movable partitions with a self-weight £ 2.4.0 to 114.Eurocode 1: Actions on structures Table 1.5 kN/m2. To determine the upper and lower characteristic values of self-weight of waterproofing. services and other non-structural elements is also explained.0 As in BS 6399-1. This defined uniformly distributed load is dependent on the self-weight of the partitions as follows: • for movable partitions with a self-weight £ 1. surfacing and other coatings for bridges.0 kN/m wall length: qk = 0. wrought Lead Steel Zinc 27.8 kN/m2. cast Iron.bsigroup. loads due to movable partitions are treated as imposed loads but in a slightly different way and there is no minimum load on floors of offices. where the variability of their thickness may be high. • for movable partitions with a self-weight £ 3.0 to 85.5 76.2 kN/m2.0 kN/m wall length: qk = 0.0 to 72.0 77.0 83. qk.0 71.0 to 78. a deviation of the total thickness from the nominal or other specified values should be taken into account for which recommended values are given.
88 0.60 0.5. social. Additionally. The difference in reduction factors aA and an are shown in Tables 1.6 respectively which are reproduced from Designers’ Guide to Eurocode 1: Actions on Buildings [1].5 and 1.The essential guide to Eurocodes transition Imposed loads on buildings Table 4 of EN 1991-1-1 gives characteristic values of loads for floors and roofs for the following categories of occupancy and use: • residential. • roofs. Reduction factor aA for floors (EN 1991-1-1 versus national annex) A (m2) aA (EN 1991-1-1) y0 = 0. Table 1. • helicopter landing areas. for columns and walls the total imposed loads from several storeys may be multiplied by the reduction factor an (where an is a function of y0 and the number of stories n).84 0. aA is a function of y0 and the floor area A. • barriers and walls having the function of barriers. • garage and vehicle traffic. • areas for storage and industrial activities including actions induced by forklifts and other transport vehicles.96 0. The UK national annex does not allow the use of these reduction factors and specifies the use of the reduction factors in BS 6399-1.7 aA (UK national annex for EN 1991-1-1) 40 80 120 160 240 0. provided that the area is classified according to EN 1991-1-1 6.60 0.bsigroup. and accessible roofs for maintenance purposes. Formichi and Calgaro [1].76 48 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. commercial and administration areas. A reduction factor aA may be applied to the qk values for imposed loads given in EN 1991-1-1 for floors. commercial and administration areas (categories A to D as described in Table 4 of EN 1991-1-1).59 0.92 0.com/transition © BSI British Standards Institution . for more details go to: http://shop. social. The basis for the determination of the characteristic loads is given by Gulvanessian.1 into the categories residential.75 0.63 0.
which will also provide background information. with a value recommended within the range.6 0.6 0.g.78 0. Reduction factor an for imposed loads from several storeys (EN 1991-1-1 versus national annex) n an (EN 1991-1-1) y0 = 0. There remain some topics (e. EN 1991-1-2 Eurocode 1: Part 1.6 0. for more details go to: http://shop.9 0.85 0.Eurocode 1: Actions on structures Table 1. It is intended that EN 1991-1-2 is used with 49 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.7 0.6 0.82 0.9 0.6 0.7 an (UK national annex for EN 1991-1-1) 1 2 3 4 5 6 7 8 9 10 1 1 0. Most of the characteristic values for imposed loads are given in ranges. PD 6688-1-1.6 Implications for practice in the UK The scope of BS EN 1991-1-1 is greater than for the appropriate UK national codes (BS 6399-1 and BS 648).8 0. and these topics will feature in a complementary document published by BSI.com/transition © BSI British Standards Institution . EN 1991-1-1 used together with the national annex will not alter current practice in the UK.8 0.6.79 0. and the UK national annex generally specifies the values given in BS 6399-1. vertical loads on parapets and values for actions for storage and industrial use) which are not covered as comprehensively in BS EN 1991-1-1 when compared to BS 6399.bsigroup.76 1 0.77 0.2: Actions on structures exposed to fire Scope and field of application EN 1991-1-2 covers the actions to be used in the structural design of buildings and civil engineering works where they are required to give adequate performance in fire exposure.
bsigroup. Annex F (informative) Equivalent time of fire exposure. 50 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. for more details go to: http://shop. For fire design. Section 3 Actions for temperature analysis (thermal actions). EN 1991-1-2 [4] contains the following main sections: • • • • • • • • • • Section 2 Structural fire design procedure. i. Annex B (informative) Thermal actions for external members – simplified calculation method.e. Essentially the objective is to limit risk to life from fire by meeting the following performance requirements of the structure: • to maintain load bearing function during the relevant fire exposure. In addition to the foreword and Section 1 ‘General’. The Parts 1–2 of material Eurocodes EN 1992 to EN 1996 and EN 1999 that deal with passive fire protection of construction works made of different materials represent an extension of the basic document EN 1991-1-2. Annex C (informative) Localized fires. Basic approaches in EN 1991-1-2 As indicated in Figure 1. • to meet deformation criteria where the separating or protecting function of the construction may be impaired by structural deformation in the fire. no integrity or insulation failure during the relevant fire exposure where fire compartmentalization is required. [5] and [6]. fire actions are the dominant action.The essential guide to Eurocodes transition EN 1990 and with the Parts on structural fire design in Eurocodes 2 to 6 and 9 [4]. The prescriptive approach uses nominal fires (standard temperature/time curves) to determine the thermal actions.2. Annex D (informative) Advanced fire models. two possible methods are given in EN 1991-1-2 to determine thermal actions due to fire: the prescriptive approach and the performance-based approach. Annex G (informative) Configuration factor. Section 4 Actions for structural analysis (mechanical actions). EN 1991-1-2 provides general guidance and actions for the structural design of buildings exposed to fire.com/transition © BSI British Standards Institution . • to maintain separating function. Annex A (informative) Parametric temperature/time curves. Annex E (informative) Fire load densities.
Eurocode 1: Actions on structures Design procedures Performance-based code (physical thermal actions) Prescriptive rules (nominal fire) Selection of fire development models Analysis of a member Analysis of a structural part Analysis of entire structure Analysis of a member Analysis of a structural part Analysis of entire structure Figure 1. and to demonstrate that the structure.com/transition © BSI British Standards Institution . of these parameters. They use so-called parametric temperature/time curves or the equivalent time of fire exposure approach. However. using fire safety engineering. or its members. will give adequate performance in a real building fire. At the present time it is possible to undertake a procedure for determining adequate performance which incorporates some. informative annexes provide models for more realistic calculation of thermal actions. where the procedure is based on a nominal fire (standard temperature/time curve). ‘Parametric fire’ is a general term which covers fire evolution more in line with real fires and takes into account the main parameters which influence 51 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.bsigroup. refers to thermal actions based on physical and chemical parameters (parametric temperature/time curves). For the first time in an international standard. the required periods of fire resistance may be specified in such a way that the features and uncertainties considered by performance-based approach described previously are taken into account (though not explicitly). if not all. for more details go to: http://shop.2. Design procedures in EN 1991-1-2 The performance-based approach.
This Part does not provide all the data needed to allow a performance-based structural fire design. As indicated in Figure 1. type of construction. However. The design value is either based on a national fire load classification or a survey of fire loads combined with partial factors to take account of fire consequences. fire load and size of openings. EN 1991-1-2 does require consideration of risks of fire in the wake of other accidental actions.com/transition © BSI British Standards Institution . a structural fire design analysis should follow these steps: • • • • selection of the relevant design fire scenarios. for more details go to: http://shop.bsigroup. Parametric temperature/time curves therefore vary mainly with building size. Actions due to fire are classified as accidental actions and should be combined with mechanical actions using combination rules provided in EN 1990 for the accidental design situation. Post-fire situations after the structure has cooled down need not be considered in fire design.2. Post-fire situations after the structure has cooled down are not within the scope of the document. determination of the corresponding design fires. In accordance with clause 2 of EN 1991-1-2.The essential guide to Eurocodes transition the growth of fires. The combined occurrence of a fire in a building and an extremely high level of mechanical loads are assumed to be very small. Selection of the relevant design fire scenarios and corresponding design fires should be done on the basis of general principles of risk analysis taking into account possible risks due to other accidental actions. The design fire should usually be applied only to one fire compartment. Simultaneous occurrence with other independent accidental actions need not be considered. A further informative annex of this Eurocode gives guidance on the determination of fire load densities using ‘the global fire safety concept’. Design procedure Design fire scenarios Structural fire design involves thermal actions due to fire as well as mechanical actions. 52 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. calculation of the mechanical behaviour of the structure exposed to fire. calculation of temperature evolution within the structural members. fire frequency and active fire safety measures [6]. the thermal actions may be determined using either prescriptive rules (nominal fire) or physical based rules (parametric thermal curves).
Eurocode 1: Actions on structures Temperature analysis should take into account the position of fire in relation to the structural member and separating walls.d. three design requirements should be generally verified.d. In accordance with clause 2 of EN 19911-2.d.bsigroup. Depending on particular conditions.d ≥ tfi.t ≥ Efi.requ where tfi.d is the design value of material temperature.t is the design value of the load effect of the relevant actions in the fire situation at time t. and is the design value of the critical material temperature A number of computational tools and software products are available to verify the three design conditions above. Mechanical analysis The analysis of mechanical behaviour of a member should consider the same duration as the temperature analysis.d.d where Qd Qcr.t where Rfi. The time requirement is given by the inequality: tfi. and tfi. for more details go to: http://shop. the analysis may be based on a nominal temperature curve without a cooling phase of full duration of the fire.requ is the required fire resistance time Considering bearing capacity of a structural member the following condition is applied Rfi.d is the design value of the fire resistance time. in some cases the material temperature should also be checked using the condition Qd £ Qcr.com/transition © BSI British Standards Institution . In addition to the design criteria expressed by the previous expressions. 53 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.t is the design value of resistance of the member in the fire situation at time t. and Efi.
The UK national annex to EN 1991-1-2 refers to a complementary document. • snow loads on bridges.3: Snow loads Scope and field of application EN 1991-1-3 provides guidance for the calculation of: • snow loads on roofs which occur in calm or windy conditions. UK) and continental climates. However. It does not generally apply to sites at altitudes above 1500 m.bsigroup. and by snow sliding down a pitched roof onto snow guards. • loads on roofs which occur where there are obstructions. • significant alterations to existing buildings and structures. EN 1991-1-3 Eurocode 1: Part 1. BS EN 1991-1-3 applies to sites at altitudes to 1500 m (the limit in BS 6399-2 is 500 m). The basis of EN 1991-1-3 has been described elsewhere [1]. The scopes of BS EN 1991-1-3 and BS 6399-2 (those relating to snow loads) are similar. • loads due to snow overhanging the cantilevered edge of a roof. EN 1991-1-3 applies to: • snow loads in both maritime (i. Generally. the national annex will ensure that current UK practice is safeguarded.The essential guide to Eurocodes transition Implementation for practice in the UK Passive fire resistance is now fully covered by the Structural Eurocodes. • new buildings and structures. for more details go to: http://shop. which will provide background information to the national annex. Format for taking account of climatic variation Both the initial deposition and any subsequent movements of snow on a roof are affected by the presence of wind. [7].e.com/transition © BSI British Standards Institution . PD 6688-1-2. In design the general lack of data on the combined action of wind and snow is normally overcome by considering one 54 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.
carried by another weather system driven by wind and where there may be several repetitions of these events 55 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. • For maritime weather systems where all the snow usually melts and clears between the individual weather systems and where moderate to high wind speeds occur during the individual weather system. for more details go to: http://shop.g.bsigroup. This situation requires the separate consideration of either uniform snow load or a drift load as the two are not expected to occur together. before any redistribution of snow due to other climatic actions. by the action of the wind. Continental weather systems are associated with multiple snow events which occur where snow is more persistent and where snow falling in calm conditions may be followed by further snow. in the UK. Drifted snow load on the roof Load arrangement which describes the snow load distribution resulting from snow having been moved from one location to another location on a roof. e. affected only by the shape of the roof. Undrifted snow load on the roof Load arrangement which describes the uniformly distributed snow load on the roof.g. • For continental weather systems where the snow that falls is more persistent and where snow falling in calm conditions may be followed by further snow.com/transition © BSI British Standards Institution . For snow loads the load arrangement for these situations are described below. carried by another weather system driven by wind and there may be several repetitions of these events before there is any significant thawing. EN 1991-1-3 provides different rules for ‘maritime’ and ‘continental’ weather systems. Owing to the climatic variability across Europe. Maritime weather systems are associated with single snow events which occur in regions where the snow fall is considered to be associated with a weather systems of about 3 to 4 days’ duration and where there is a reasonable expectation that the snow deposited on roofs will thaw between the arrival of one weather system and the next. The alternatives apply for specific locations.Eurocode 1: Actions on structures or more critical design situations. e.
the UK is divided into zones. i.com/transition © BSI British Standards Institution . Exceptional snow drifts (in maritime climates. In these situations the accumulations are combined into a single load case.The essential guide to Eurocodes transition before significant thawing. UK). snow loads may be treated as accidental actions. e. where isolated and extremely infrequent very heavy snow falls have occurred ii. For the two following conditions. This is different to the snow map in BS 6399 in which the snow load on the ground is determined through isopleths. Exceptional snow load on the ground in some regions. It is usually determined from records of snow load or snow depth measured in well-sheltered areas. In the BS EN 1991-1-3 snow map. The characteristic value is defined as the value with an annual probability of exceedance 0. Thus snow loads on roofs for the persistent/transient design situations are determined as follows: s = miCeCt sk where: 56 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. An expression is given to determine the snow load on the ground which depends upon the zone number and the altitude of the site.bsigroup. for more details go to: http://shop. particularly southern Europe. It is left to the national annex to specify which should be used for a particular region. Characteristic value of snow load on the ground The snow load on the ground is that assumed to occur in perfectly calm conditions. The snow load on the roof is affected by the topography of the site and the amount of heat loss through the roof and EN 1991-1-3 makes provision for adjustment of the roof snow load using an exposure and thermal coefficient factors.02.g. Method of assessment of snow load on the roof The snow load on the roof is determined by multiplying the characteristic value of the snow load on the ground by a snow load shape coefficient m.
As an example. case (i) indicates the un-drifted load arrangement and cases (ii) and (iii) indicate the drifted load arrangements. The specific exclusions are: 57 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. EN 1991-1-4 Eurocode 1: Part 1. • land-based structures. Implications for practice in the UK EN 1991-1-3 is very similar to BS 6399-2 and should not provide any problems to the UK engineer. However. for more details go to: http://shop. their components and appendages. In the diagrams. EN 1991-1-3 provides shape coefficients for mono-pitch. EN 1991-1-3 does not provide prescriptive clauses for certain small building roofs as BS 6399-2 does.com/transition © BSI British Standards Institution . • bridges with spans of not more than 200 m (subject to certain limitations based on dynamic response criteria).4: Wind actions Scope and field of application BS EN 1991-1-4 is applicable to: • building and civil engineering works with heights up to 200 m.Eurocode 1: Actions on structures mi sk Ce Ct is the snow load shape coefficient is the characteristic value of snow load on the ground is the exposure coefficient is the thermal coefficient Snow load shape coefficients The different snow load coefficients to be considered in design relate to different climatic conditions (maritime and continental) and are given for both the un-drifted and the drifted load arrangements. multi-pitched and cylindrical roofs and coefficients for drifting at abrupt changes in roof height and at obstructions on roofs for both maritime and continental climate areas. duo-pitched.bsigroup. Figure 1.3 shows snow load shape coefficients for continental and maritime climates.
Snow load shape coefficients (a) for continental climates and (b) for maritime climates • • • • • • lattice towers with non-parallel chords.5m1(a1) m1(a2) Case (iii) m1(a1) 0.The essential guide to Eurocodes transition Case (i) m1(a1) m1(a2) Case (ii) 0. bridge deck vibration from transverse wind turbulence. modes of vibration higher than the fundamental mode. The contents of EN 1991-1-4 are as follows: Section 1 General Section 2 Design situations Section 3 Modelling of wind actions Section 4 Wind velocity and velocity pressure Section 5 Wind actions 58 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.3. for more details go to: http://shop.com/transition © BSI British Standards Institution . guyed masts and guyed chimneys.bsigroup. cable supported bridges. torsional vibrations of buildings.5m1(a2) a1 a2 (a) Case (i) m1(a1) m1(a2) m1(a2) Case (ii) Case (iii) m1(a1) a1 a2 (b) Figure 1.
They may also act directly on the internal surface of open structures. The response of structures is calculated from the peak velocity pressure. the force and pressure coefficients and the structural factor cscd·qp depends on the wind climate. when large areas of structures are swept by the wind. friction forces acting tangentially to the surface may be significant. Pressures act on areas of the surface resulting in forces normal to the surface of the structure or of individual cladding components.bsigroup. the terrain roughness and orography.e. The wind actions calculated using EN 1991-1-4 are characteristic values. a wind action is represented by a simplified set of pressures or forces whose effects are equivalent to the extreme effects of the turbulent wind.Eurocode 1: Actions on structures Section 6 Structural factor cscd Section 7 Pressure and force coefficients Section 8 Wind actions on bridges Annex A (informative) Terrain effects Annex B (informative) Procedure 1 for structural factor cscd Annex C (informative) Procedure 2 for structural factor cscd Annex D (informative) Graphs of cscd for common building forms Annex E (informative) Vortex shedding and aeroelastic instabilities Annex F (informative) Dynamic characteristics of structures Modelling of wind actions The nature of wind actions is that they fluctuate with time and act directly as pressures on the external surfaces of enclosed structures and. the response of the structure). depends on the size. also act indirectly on the internal surfaces. The basic values are characteristic values having annual probabilities of exceedence of 0. The effect of the wind on the structure (i. qp. 59 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. which is equivalent to a mean return period of 50 years. They are determined from the basic values of wind velocity or the velocity pressure. In EN 1991-1-4. because of porosity of the external surface. EN 19911-4 covers dynamic response due to along-wind turbulence in resonance with the along-wind vibrations of a fundamental flexural mode shape with constant sign.02. shape and dynamic properties of the structure. Additionally. at the reference height in the undisturbed wind field. and the reference height.com/transition © BSI British Standards Institution . for more details go to: http://shop.
003 1 I Lakes or flat and horizontal area with negligible vegetation 0.01 and without obstacles 1 II Area with low vegetation such as grass and isolated obstacles (trees.0 where vb vb. and is determined from the expression below 60 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.0. at 10 m above ground level in open country terrain with low vegetation such as grass and isolated obstacles with separations of at least 20 obstacle heights (Terrain Category II. see Table 1. suburban terrain.The essential guide to Eurocodes transition Table 1.0 cdir cseason is the basic wind velocity is the fundamental value of the basic wind velocity. vb.3 5 IV Area in which at least 15% of the surface is covered with 1.com/transition © BSI British Standards Institution . is the characteristic 10 min mean wind velocity.1 of EN 1991-1-4. and is the season factor The mean wind velocity vm(z) at a height z above the terrain depends on the terrain roughness and orography and on the basic wind velocity. buildings) with separations of at least 20 obstacle heights 0. vb.bsigroup. Terrain categories and terrain parameters Terrain category z0 (m) zmin (m) 0 Sea or coastal area exposed to the open sea 0.0 buildings and their average height exceeds 15 m 10 The terrain categories are illustrated in Annex A. irrespective of wind direction and time of year.7). Wind velocity and velocity pressures The basic wind velocity shall be calculated from the expression below: vb = cdir cseason vb. permanent forest) 0. as defined above is the directional factor.05 2 III Area with regular cover of vegetation or buildings or with isolated obstacles with separations of maximum 20 obstacle heights (such as villages. for more details go to: http://shop. The UK national annex provides a map on this basis. The fundamental value of the basic wind velocity.7.
the effects should be taken into account using the orography factor co. • Terrain categories III and IV have been considered together to give a single terrain category referred to as town terrain.7.bsigroup.com/transition © BSI British Standards Institution . The upwind terrain may be considered up to a distance of 10 times the height of the isolated orographic feature. • Terrain categories I and II have been considered together to give a single terrain category referred to as country terrain. taken as 1. cr(z).3. The determination of cr(z) is dependent upon: • z0 the roughness length.2 of EN 1991-1-4. Ground roughness The roughness factor.Eurocode 1: Actions on structures vm (z) = cr (z)co (z) where cr(z) is the roughness factor. There are three terrain categories in the UK national annex: • Terrain category 0 is referred to as sea terrain.) increases wind velocities by more than 5%. cliffs etc. • the ground roughness of the terrain upwind of the structure in the wind direction considered.g. hills. EN 1991-1-4 gives z0 and zmin values for the terrains which are described here in Table 1. given in 4. for more details go to: http://shop.3. and co(z) is the orography factor. The effects of orography may be neglected when the average slope of the upwind terrain is less than 3°. 61 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.3 of EN 1991-1-4. • All inland lakes extending more than 1 km in the direction of wind and closer than 1 km upwind of the site should be treated as sea. accounts for the variability of the mean wind velocity at the site of the structure due to: • the height above ground level.0 unless otherwise specified in 4. • zmin the minimum height defined previously for the particular terrain. Terrain orography Where orography (e.
orography coefficient. Iv. • for cladding elements with a natural frequency > 5 Hz. The value of cscd may be taken as 1.3 5 × H if f > 0. It should be noted that procedures for determining some of the parameters (e. • for circular cross-section chimneys with a height < 60 m and not more than 6.05 A = Base of upwind orography 1.4) that indicates where orography may be significant.05 H/2 H H/2 Upwind slope f > 0. terrain category.0 in the following cases: • for buildings with a height < 15 m. Significance of orography The UK national annex gives a diagram (see Figure 1. • for framed buildings with structural walls of < 100 m and not more than 4 times the in-wind depth.The essential guide to Eurocodes transition 0. cr(z).3 Hill or ridge Downwind slope > 0.5 × Ld if f < 0.5 times the diameter.8.5 × Le if f < 0.com/transition © BSI British Standards Institution . 62 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.05 H/2 H H/2 Escarpment Figure 1. for more details go to: http://shop. roughness coefficient.bsigroup. turbulence intensity.3 1.g.3 Downwind slope < 0. structural factor. cscd) are different in the UK national annex.6 × H if f > 0. Shaded areas show where orography is significant. co(z). A summary of recommended calculation procedures for the determination of wind actions is given in Table 1.4.
ze Terrain category Characteristic peak velocity pressure. wi = qpcpi Clause 7 Clause 7 5.3 4. • Field of application: span length < 200 m. e.bsigroup.3. Recommended (EN 1991-1-4) calculation procedures for the determination of wind actions Parameter Subject reference in EN 1991-1-4 Peak velocity pressure. e.2 (3) cs accounts for the non-simultaneous occurrence of peak pressure cd accounts for the vibrations of the structure due to turbulence Wind action on bridges Clause 8 of EN 1991-1-4 covers wind actions on bridges and the limitations are given below.1 4.g.1 (1) 5. Fw. Iv Mean wind velocity.1 4.g. • Only applies to single decks (but multiple spans).2 (2) 5. qp Basic wind velocity.Eurocode 1: Actions on structures Table 1. Fw. cr(z) 4. • Simplified procedure for force in x-direction Fw = qp (ze )cf Aref (cs cd ) 63 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. cpe External wind pressure. cpi External pressure coefficient.2 (2)P Clause 7 Table 4. calculated from force coefficients Wind force. fixings and structural parts Internal pressure coefficient.com/transition © BSI British Standards Institution .4 4. height above ground < 200 m. cscd Wind force.8.3. for cladding. for overall wind effects Structural factor. calculated from pressure coefficients 6 5. co(z) Roughness coefficient.1 (2) Wind forces on structures. we = qpcpe Internal wind pressure.3.2 Wind pressures. for more details go to: http://shop.0. vm Orography coefficient. qp Turbulence intensity. • Road and rail bridges < 40 m span can normally be considered to be static and cscd may be taken as 1. vb Reference height.5 (1) 4.
The effects on UK practice should prove neutral. Characteristic values of thermal actions are provided for the design of structures which are exposed to daily and seasonal climatic changes. The national annex to BS EN 1991-1-4. for more details go to: http://shop. when the deformation is restrained. which uses substantial information from BS 6399-2. warm and cold storage facilities.5: Thermal actions Scope and field of application EN 1991-1-5 gives principles.The essential guide to Eurocodes transition where qp(ze) is the peak velocity pressure at height ze. EN 1991-1-5 Eurocode 1: Part 1.5 is that the temperature distribution within a cross-section leads to a deformation of the element and/or. e.g. chimneys.bsigroup. cf Implications for practice in the UK The scope of BS EN 1991-1-4 is much wider than BS 6399-2. which in the UK are given in a number of other British Standards and design guides. cooling towers. will refer to a complementary document. and is the force coefficients. rules and methods of calculating thermal actions on buildings. which will give background information to the national annex and other essential advice. In some cases. tanks. bridges and other structures including their structural components. Underlying philosophy The underlying philosophy of Part 1.g. there is no equivalent UK standard.com/transition © BSI British Standards Institution . The characteristic values of isotherms of national minimum and maximum shade air temperatures are provided in the form of maps or in other forms in the national annexes. 64 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. the occurrence of stresses in the element. silos. PD 6688-1-4. as it includes wind actions on other structures. dynamic response of certain buildings. Principles for determining thermal actions for claddings and other appendages on the building are also provided. Structures in which thermal actions are mainly a function of their use (e. hot and cold services) are also treated.
either by the provision of expansion joints or by including the effects in the design. a non-linear temperature distribution. EN 1991-1-5 splits the temperature distribution within an individual structural element into the following four essential components (see Figure 1. Classification and representation of thermal actions Thermal actions are classified as variable free actions and are indirect actions. Thermal actions on buildings due to climatic and operational temperature changes need to be considered in the design of buildings where there is a possibility of the ultimate or serviceability limit states being exceeded due to thermal movement and/or stresses.bsigroup. Representation of constituent components of a temperature profile EN 1991-1-5 gives procedures for load bearing structures to be checked to ensure that thermal effects do not cause over-stressing of the structural elements. a linearly varying temperature component about the z-z axis.Eurocode 1: Actions on structures Figure 1.com/transition © BSI British Standards Institution . for more details go to: http://shop. Temperature changes in buildings This section of EN 1991-1-5 provides general guidelines and advice on matters which should be considered. 65 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. a linearly varying temperature component about the y-y axis.5): • • • • a uniform temperature component. The characteristic values given are generally 50 year return values.5.
In these figures ‘heating’ 66 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. It groups bridge superstructures into three groups: Group 1 Group 2 Group 3 Steel deck on steel box. Guidance is provided for determining the characteristic value of the vertical temperature component. heating and cooling of a bridge deck’s upper surface will result in maximum positive (top surface warmer) and maximum negative (bottom surface warmer) temperature variation. truss or plate girders. which are similar to the corresponding figures of BS 5400. • use of different materials with different thermal expansion coefficients and heat transfer. over a prescribed period of time. The rules provided apply to bridge decks that are exposed to daily and seasonal climatic effects. for more details go to: http://shop. For approach 1 (the linear approach). guidance is provided on the determination of the minimum/maximum bridge temperatures from the minimum/maximum shade air temperatures.com/transition © BSI British Standards Institution . The characteristic value of the uniform temperature component depends on the minimum and maximum effective temperatures which a bridge will achieve over a prescribed period of time. EN 1991-1-5 states that all thermal actions should be assessed by the uniform temperature component and the linear temperature components. Temperature changes in bridges EN 1991-1-5 treats the temperature changes in bridges in very much more detail than in buildings. For approach 2 (the non-linear approach) recommended values of vertical temperature differences for bridge decks are given in three figures. • use of different shapes of cross-section with different uniform temperature. Two approaches are provided. Rules for determining these values for the three groups of bridges (both road and rail) and for adjusting these values to take into account varying thicknesses of surfacing are given. and either approach 1 (vertical linear component) or approach 2 (vertical temperature components with non-linear effects) may be used.bsigroup.The essential guide to Eurocodes transition Volume changes and/or stresses due to temperature changes may also be influenced by: • shading of adjacent buildings. Concrete deck on steel box. For the three groups of bridges. truss or plate girders. Concrete slab or concrete deck on concrete beams or box girders.
The UK national annex to EN 1991-1-5 stipulates the use of approach 2. For structures in contact with heated gas flow or heated material (e.com/transition © BSI British Standards Institution .6: Actions during execution Scope and field of application EN 1991-1-6 covers assessment of actions. They are required to be provided in the project specification for a 50 year return period. chimneys. Temperature changes in industrial chimneys and pipelines EN 1991-1-5 provides quantifiable values for thermal actions in chimneys and pipelines resulting from climatic effects.g. for more details go to: http://shop.bsigroup. • accidental temperature distribution from failures in operation. Regarding bridges. PD 6688-1-5. Characteristic values of maximum and minimum flue gas temperatures are not given. Implications for practice in the UK The guidance in this part.Eurocode 1: Actions on structures refers to conditions such that solar radiation and other effects cause a gain in heat through the top surface of the bridge deck. due to the variation of shade air temperature and solar radiation. pipelines and silos) the following thermal actions are defined: • temperature distribution for normal process conditions. It requires the values of operating process temperature to be obtained from the project specification. including those actions 67 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. combinations of actions and environmental influences during the execution stage. EN 1991-1-6 Eurocode 1: Part 1. is not covered in UK loading standards. which will provide background information to the national annex. ‘cooling’ refers to conditions such that heat is lost from the top surface of the bridge deck as a result of re-radiation and other effects. The national annex to BS EN 1991-1-5 will refer to a complementary document. the guidance in EN 1991-1-5 and the UK national annex is very similar to current practice. Conversely. in particular the guidance relating to building structures.
Accidental actions for buildings and bridges which may lead to collapse or damage during execution are described and the need to check the relevant limit states is defined. Other ultimate limit states design situations. the anticipated duration of the stage of execution under consideration’. propping and bracing. or greater than. and may include: 68 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. fitness for use and/ or aesthetic appearance in the final stage have to be avoided. e. accidental and seismic situations.g. The serviceability limit states for the selected design situations during execution need to be verified. need to be considered. e. climatic actions. as appropriate. The criteria associated with the serviceability limit states during execution should take into account the requirements for the completed structure. for more details go to: http://shop.The essential guide to Eurocodes transition applied to auxiliary construction works. The design situations should take into account the likelihood for any corresponding return periods of variable actions.g. Recommended return periods of climatic actions are given depending on the nominal duration of the relevant design situation. in accordance with EN 1990. The safety of people on construction sites is not within the scope of EN 1991-1-6. The need to consider seismic actions is described. for use in structural design of buildings and bridges. e.bsigroup. EN 1991-1-6 requires that any selected transient design situation be associated with ‘a nominal duration equal to. Design situations during execution EN 1991-1-6 gives guidance on identification of transient design situations. scaffolding. Representation of actions Actions during execution are classified in accordance with EN 1990.com/transition © BSI British Standards Institution . Operations which can cause excessive cracking and/or early deflection during execution and which may adversely affect the durability.g. Further information on these is given by Gulvanessian. Formichi and Calgaro [1].
for more details go to: http://shop. i. extreme erosion or rock falls. intentional imposed deformations and settlements. storage movable items. and thus provides new codified information for the profession. It recommends design values for the most common cases of accidental actions from impact and explosion. are not in the scope of the EN 1991-1-7.Eurocode 1: Actions on structures • those actions that are not construction loads. non-permanent equipment. i.bsigroup. accumulation of waste materials. EN 1991-1-7 Eurocode 1: Part 1. self-weight. 69 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.com/transition © BSI British Standards Institution . and atmospheric ice loads. and • construction loads The representation of those actions that are not construction loads are defined. cranes). warfare or malicious damage.e. temperature and shrinkage actions. snow and water actions.e.g.7: Accidental actions due to impact and explosions Scope and field of application EN 1991-1-7 describes safety strategies for accidental design situations. wind. are given and specific principles and rules are included for construction loads for buildings and bridges. it gives design models and also details provisions which may be used as alternatives to design verifications. loads from parts of structure in temporary states. • • • • • • site visitors and personnel with hand tools. It also provides more advanced impact and explosion design concepts. or natural phenomena such as tornadoes. Approaches for taking construction loads into account. movable heavy machinery and equipment (e. pre-stressing. External explosion. Implications for practice in the UK The guidance provided in this document does not have a UK equivalent.
• the provisions for preventing or reducing the hazard and the exposure of the structure to the hazard. Accidental actions are required to be taken into account. causes and consequences. It requires there to be a reasonable probability that the structure will not be damaged to an extent disproportionate to the original cause. Additional strategies are defined which may be used singly or in combination as measures which may be used to control the risk of accidental actions – these are based on a classification of consequences of failure as follows: 70 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. Localized damage due to accidental action may be acceptable.g.com/transition © BSI British Standards Institution . some explosions and impact. Formichi and Calgaro [1]. • the probability of occurrence of the initiating event. EN 1991-1-7 recognizes that no structure can be expected to resist all actions arising from an extreme cause and that residual risk will be present in practice. • strategies based on limiting the extent of localized failure.7 has been described in more detail by Gulvanessian. e. It describes: • the procedure for risk analysis to identify extreme events. Design situations EN 1991-1-7 recommends two strategies to be considered for accidental design situations as follows: • strategies based on identified accidental actions. • the safety precautions required to maintain acceptable safety by using measures to reduce the probability of the consequences of the accidental event. • the acceptable level of risk. EN 1991-1-7 defines the general principles that can be used in the analysis of accidental design situations.The essential guide to Eurocodes transition Underlying philosophy The selected accidental design situations should be sufficiently severe and varied so as to encompass all conditions which can be reasonably foreseen. for more details go to: http://shop. depending on: • the possible consequences of damage.bsigroup. With regard to the previous strategies. The philosophy of Part 1.
com/transition © BSI British Standards Institution . For structures in category 3. Structures classified as category 1 require no specific consideration in design of the effects of explosions. The general rules for connections and interaction between elements given in Eurocodes 2 to 9 are assumed to provide adequate safeguards. • impact from ships on supporting substructures. depending upon the specific circumstances of the structure in question.7 requires that the structure is designed to resist the accidental actions either using simplified analysis for key elements based upon equivalent static load models or by applying prescriptive design/detailing rules. the use of a risk analysis together with hazard identification is recommended. • category 3 (large consequences) where more extensive study (e. 71 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. Accidental actions due to impact Impact actions are defined and collision forces given for: • impact from vehicles on walls of buildings and supporting substructures for bridges. hazard identification. • category 2 (medium consequences) where. Accidental actions due to explosions EN 1991-1-7 covers accidental actions arising from gas explosions in buildings. for more details go to: http://shop.g. • impact from derailed trains. For structures classified for category 2 and 3. Part 1.bsigroup. • impact from fork lift trucks. • impacts from vehicles on the underside of buildings and on bridge superstructures. risk analysis) is required. • hard landings by helicopters on roofs. a simplified analysis by static equivalent action models or the application of prescriptive design/detailing rules is made.Eurocode 1: Actions on structures • category 1 (limited consequences) where no specific consideration of accidental actions is required.
The essential guide to Eurocodes transition Implications for practice in the UK Although aspects of accidental actions are covered in BS 6399-1 and BS 5400. The UK design engineer will be familiar with the design requirements of this part although risk assessments will be required for category 3 structures. which has also been used in Approved Document A of the Building Regulations. pedestrian actions and rail traffic which include. Specific models are given for verification of fatigue.com/transition © BSI British Standards Institution . which will give background information to the national annex.g. and on loads on parapets. It also includes guidance on combinations with non-traffic loads on road and railway bridges. Road traffic actions and other actions specifically for road bridges Load models Road traffic actions are represented by a series of load models which represent different traffic situations and different components (e. EN 1991-2 Eurocode 1: Part 2: Traffic loads on bridges Scope and field of application EN 1991-2 [8] specifies imposed loads (models and representative values) associated with road traffic. The national annex to BS EN 1991-1-7 refers to a complementary document. acceleration and accidental forces. A categorization scheme concerning the robustness of buildings. is from BS EN 1991-1-7 Annex A. Actions for the design of road bridges with individual spans less than 200 m and with carriageway widths not greater than 42 m are defined in EN 1991-2. for more details go to: http://shop. 72 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. when relevant. The load models for vertical loads are as follows. in particular to risk assessments on impacts to supporting structures for bridges. horizontal force) of traffic action. dynamic effects and centrifugal. braking. PD 6688-1-7. BS EN 1991-1-7 comprehensively covers the topic of accidental actions in one document.bsigroup.
It is the main loading model and consists of two systems: – double axle concentrated loads (tandem system. braking and acceleration forces and centrifugal forces. for general and local verifications of the structure. Fatigue load models For verifications of resistance to fatigue. climatic actions) acting on the bridge.bsigroup. b) Load model 2: a single axle load applied on specific tyre contact areas which covers the dynamic effects of normal traffic on very short structural elements. EN 1992-2 also provides advice on dispersal of concentrated loads. The derivation is discussed elsewhere [9]. This model should be considered and is intended only for general verifications of the structure. The various load models are combined into five groups which are then combined with non-traffic loads (e. horizontal forces. This model is intended for general and local verifications of the structure. having a weight density per square metre obtained by multiplying a characteristic value by an adjustment factor. c) Load model 3: a set of assemblies of axle loads representing special heavy vehicles (e. for more details go to: http://shop.Eurocode 1: Actions on structures a) Load model 1: concentrated and uniformly distributed loads. This model should be separately considered and is only intended for local verifications. 73 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. This model is intended to be used only as required by the client. – uniformly distributed loads (UDL system).com/transition © BSI British Standards Institution . TS).g. The UK national annex specifies the special vehicles currently used in UK practice.g. for industrial transport) which may travel on routes permitted for abnormal loads. The UK national annex increases the applicability of the loaded lengths for this model (from 200 m to 1500 m) and gives alternative values for the uniformly distributed loads. d) Load model 4: a crowd loading. five fatigue load models of vertical forces are provided for use depending on the verification level selected from the relevant Eurocodes 2–9. which cover most of the effects of the traffic of lorries and cars.
Pedestrian.com/transition © BSI British Standards Institution . • load model number 2: concentrated load (10 kN recommended). for more details go to: http://shop. Accidental actions The section on road bridges also provides guidance on: • accidental actions including: – actions from vehicles on the bridge. Non-accidental actions due to rail traffic are given for: • vertical loads: four load models LM 71. ‘unloaded train’ and HSLM (high speed load model).The essential guide to Eurocodes transition The UK national annex gives alternatives to fatigue load model 4 and restrictions to use for fatigue load model 2. • action on parapets. represent the effects of real traffic. The load models are combined into two groups which are then combined with non-traffic loads (e. cycle actions and other actions specifically for footbridges Vertical load models and representative values for pedestrian and cycle traffic are defined using the following load models: • load model number 1: uniformly distributed load. • load model number 3: service vehicle. • load models on embankments. [10]. climatic actions) acting on the bridge. 74 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. LM SW (associating two sub-models SW/0 and SW/2). The load models are not deemed to describe the real loads: they have been defined so that their effects.g. with a dynamic magnification taken into account separately.bsigroup. Rail traffic actions and other actions specifically for rail bridges EN 1991-2 covers the static effects of standard rail traffic operating over the standard-gauge or wide-gauge European mainline-network [2].
Each of the mixes is based on an annual traffic tonnage of (25 × 106) tonnes. PD 6688-2. which will give background information to the national annex. Other accidental actions which arise from severance of overhead line equipment and from road traffic must also be considered in design. Centrifugal forces therefore depend on the loaded length of the bridge and on the maximum permissible speed. For the consideration of centrifugal forces. the relevant authority may specify a different life and traffic mix. • centrifugal forces. 75 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. Accidental actions arising from derailment on bridges are required to be taken into account so that the damage to the bridge is limited to a minimum.Eurocode 1: Actions on structures • vertical loads for embankments and for earth pressure (for the sake of simplicity concentrated or linear vertical loads are replaced by distributed loads). Fatigue assessment is for a life of 100 years. • load effects from catenaries and other overhead line equipment attached to the structure. • dynamic effects. • acceleration and braking forces. for more details go to: http://shop. EN 1991-2 recognizes that heavy traffic does not operate at high speeds whereas high speed passenger trains have light axle loadings.com/transition © BSI British Standards Institution .bsigroup. The deformations and vibrations caused by the passage of rail traffic have to be limited for safety and passenger comfort. Implications for practice in the UK The national annex to BS EN 1991-2 will refer to a complementary document. Fatigue damage assessment is required for all elements subjected to fluctuations of stress. • aerodynamic effects as a result of passing trains. Details of the service trains and traffic mixes and the dynamic enhancement are given. Alternatively. Prevention of overturning or collapse of the bridge is a design requirement. • nosing force. Guidance is provided on all the topics mentioned.
Guidance for the determination of the following load arrangements is provided: • vertical loads from monorail hoist blocks underslung from runway beams. • overhead travelling cranes. for more details go to: http://shop.The essential guide to Eurocodes transition EN 1991-3 Eurocode 1: Part 3: Actions induced by cranes and machinery Scope and field of application EN 1991-3 specifies actions. When not supplied by the crane manufacturer: • dynamic amplification factors are given for vertical loads and advice is included on treating wind actions for cranes located outside buildings. Actions induced by cranes Actions induced by cranes comprise actions from hoists. The background to the methods has been described elsewhere [12]. • dynamic amplification factors and a method of calculating the drive force on a driven wheel are given. crabs and cranes on runway beams. • horizontal loads from overhead travelling cranes. Crane supporting structures are divided into two categories: • underslung trolleys on runways. crabs and cranes on runway beams and static and dynamic actions induced in supporting structures by machinery. • multiple crane action.bsigroup. • horizontal loads from monorail hoist blocks underslung from runway beams.com/transition © BSI British Standards Institution . Guidance is included on obtaining horizontal 76 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. • vertical loads from overhead travelling cranes. The methods prescribed are compatible with the provisions of EN 13001-1 [11] to facilitate the exchange of data with crane suppliers. self-weights and imposed loads (models and representative values) associated with hoists. Actions induced by cranes are classified as variable and accidental actions and are represented by various models.
the advice is limited to structures supporting rotating machines which induce dynamic effects in one or more planes. The scope is restricted to: 77 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. Guidance is given on the calculation of characteristic values of actions for normal service and accidental conditions and on determining movements caused by dynamic forces. variable and accidental. Actions induced by machinery are classified as permanent. for more details go to: http://shop. stairs.Eurocode 1: Actions on structures loads and the guide force caused by skewing and the horizontal force caused by acceleration or deceleration of the crab. Accidental actions. Variable actions from machinery during normal service are dynamic actions caused by accelerating masses. Fatigue damage equivalent loads are used to classify fatigue actions in relation to a load effect history parameter according to EN 13001-1.com/transition © BSI British Standards Institution . platforms and guard rails. which may be considered to occur. Advice is also included on taking account of temperature effects in the determination of loads on access walkways.bsigroup. Guidance is given on accidental actions due to buffer forces related to crane movement and movements of the crab and tilting forces. Permanent actions during service include the self-weight of all fixed and movable parts and static actions from service. EN 1991-4 Eurocode 1: Part 4: Actions in silos and tanks Scope and field of application EN 1991-4 [13] gives general principles and rules for determining actions arising from the storage of bulk materials and liquids in silos and tanks. short circuit or lack of synchronization between generators and machines and impact effects from pipes on shutting down. Actions due to machinery For machinery. are those due to accidental magnification of the eccentricity of masses.
com/transition © BSI British Standards Institution . Rules are given for calculating storage loads due to particulate materials in tall silos. for more details go to: http://shop. and with discharge devices which do not cause shock or eccentricities beyond the given limitations. Particulate material properties are obtained by a simplified approach which takes account of horizontal/vertical pressure ratio and coefficient of wall friction. Prevention of dust explosions by choice of proper maintenance and cleaning.The essential guide to Eurocodes transition • silos with limited eccentricity of inlet and outlet. accidental actions and situations arising from explosions. use of safe electronic equipment and careful use of welding is advocated.bsigroup. where appropriate. with small impact effects caused by filling. Consideration of fatigue is required where the silo or tank is subjected to more than one load cycle per day. • tanks with liquids stored at normal atmospheric pressure. Background Initial studies of codes and recommendations found mainly in Member States covering loads in silos and tanks led to work initiated by ISO being adopted in 1987 as the starting point for the preparation of Part 3 [14]. • silos containing particulate materials which are free-flowing and have a low cohesion. seismic actions and fire. Attention is drawn to the inherent variability of stored materials and the simplifications in the load models. empirical parameters were used. Advice is given on measures which may be used to limit or avoid potential damage from dust explosions. Limitation of concrete cracking at the serviceability limit state is required for silos to be used for storage of water sensitive materials. or by testing. vehicle impact. Design situations The design situations to be considered include maximum possible filling and. 78 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition. The classical Janssen theory for filling was adopted as a basis. squat silos and homogenizing silos and silos with a high filling velocity. For discharge and special cases. The selection of structural form to give low sensitivity to load deviations is given as a principle and loads due to particulate materials have to be calculated for filling and discharge.
Progress in Structural Engineering and Materials. volume 1 (4). volume 74. IABSE Reports. IABSE Reports. Progress in Structural Engineering and Materials. and Prat M. volume 74. J. Delft. 1996. and Grosmann D. 1996 [10] Gandil J. Delft. Delft. Designers’ Guide to Eurocode 1: Actions on Buildings.B. Conference. J. Part 2: Load effects. References and recommended reading [1] Gulvanessian H. EC1: Silos and tanks. Tshumi M.. Conference. It is intended primarily for use with Eurocodes 2–9 for structural design and verification on the basis of the overall principles for limit state design given in EN 1990 Basis of Structural Design. ‘Metal silos’.bsigroup. et al Input data for the natural fire design of building structures. pp443-451 [8] Calgaro J. Progress in Structural Engineering and Materials. volume 74. Eurocode 1: Part 2. IABSE Reports. 1998. ‘Snow loading: Scientific basis. Thomas Telford.. IABSE Reports.M. London. 1996 [11] EN 13001 Cranes – Safety – Design – General – Part 1: General principles and requirements. Davos. problems and challenges’.. [4] Twilt L. Conference. Delorme F.. Designers’ Guide to Eurocode 1: Actions on Bridges. Calgaro. Conference. volume 1 (4). 2009 [2] Calgaro J. 1992 [5] Schleich J. volume 1 (4). [9] Bruls A. London. 1996 [6] Twilt L. Delft. and Gulvanessian H.Eurocode 1: Actions on structures Conclusions EN 1991 Eurocode 1. [12] Sedlacek G. Actions. 2010 [3] Ostlund L.2: Actions on structures exposed to fire. and Kersken-Bradley M. Delft. Conference. EC1: Actions on structures exposed to fire. volume 74. Conference. pp428-435 [14] Nielsen J. 1996 [7] Sanpaolesi L.A. 1992 79 This complimentary chapter is brought to you by Eurocodes PLUS our online tool that helps with the Eurocodes transition.A. volume 74. 1998.. volume 65. Delft. pp452-461. and Calgaro J. 1996 [13] Rotter. Thomas Telford. Railway traffic actions and combination with other variable actions. IABSE Reports.com/transition © BSI British Standards Institution . ‘Loads on bridges’.A. IABSE Reports. Conference. EC1: Actions induced by cranes. et al..A.A. Formichi P. volume 74. IABSE Reports. IABSE Reports. Conference. Actions on Structures gives comprehensive information on all actions that should normally be considered in the design of building and civil engineering structures. volume 65. for more details go to: http://shop. Mathieu H. and Vognier P. ENV 1991: Part 3: The main models of traffic loads on road bridges. Tchumi M. Davos. 1998.
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2nd term project 1 personal essay
api-272849846
2A.pile Caps
Septian Brandalzx