Variable actions imposed loads General

Imposed loads are divided into categories. Those most used in concrete design are shown in Table 2.1.

Table 2.1

Variable actions: categories

Table 2.1

Variable actions: categories

Category

Description

A

Areas for domestic and residential activities

B

Office areas

C

Areas of congregation

D

Shopping areas

E

Storage areas and industrial use (including access areas)

F

Traffic and parking areas (vehicles < 30 kN)

G

Traffic and parking areas (vehicles > 30 kN)

H

Roofs (inaccessible except for maintenance and repair)

I

Roofs (accessible with occupancy categories A - D)

K

Roofs (accessible for special services, e.g. for helicopter landing areas)

Notes

1 Category J is not used.

2 For forklift loading refer to BS EN 1991-1-1 Cl. 6.2.3.

2.4.2 Characteristic values

Characteristic values for commonly used imposed loads are given in Tables 2.2a to 2.2g

Variable actions, category A: domestic and residential 6.2 & NA.3>

Variable actions, category A: domestic and residential 6.2 & NA.3>

Sub

Example

Imposed loads

category

qk (kN/m2)

Qk (kN)

A

Areas for domestic and residential activities

A1

All usages within self-contained dwelling units Communal areas (including kitchens) in small" blocks of flats

1.5

2.0

A2

Bedrooms and dormitories, except those in self-contained single family dwelling units and in hotels and motels

1.5

2.0

A3

Bedrooms in hotels and motels; hospital wards; toilet areas

2.0

2.0

A4

Billiard/snooker rooms

2.0

2.7

A5

Balconies in single-family dwelling units and communal areas in small" blocks of flats

2.5

2.0

A6

Balconies in hostels, guest houses, residential clubs. Communal areas in larger" blocks of flats

Min.b 3.0

2.0c

A7

Balconies in hotels and motels

Min.b 4.0

2.0c

Key

a Small blocks of flats are those with < 3 storeys and < 4 flats per floor/staircase. Otherwise they are considered to be 'larger' blocks of flats

b Same as the rooms to which they give access, but with a minimum of 3.0 kN/m2 or 4.0 kN/m2

c Concentrated at the outer edge

Table 2.2b Variable actions, category B: offices

Sub

Example

Imposed loads

category

qk (kN/m2)

Qk (kN)

B

Office areas

B1

General use other than in B2

2.5

2.7

B2

At or below ground floor level

3.0

2.7

Table 2.2c

<BS199

Variable actions, category C: areas of congregation

6.1, 6.2

Subcategory

Example

Imposed loads

qk (kN/m2)

Qk (kN)

C

Areas of congregation

C1

Areas with tables

C11

Public, institutional and communal dining rooms and lounges, cafes and restaurants (Note: use C4 or C5 if appropriate)

2.0

3.0

C12

Reading rooms with no book storage

2.5

4.0

C13

Classrooms

3.0

3.0

C2

Areas with fixed seats

C21

Assembly areas with fixed seating a

4.0

3.6

C22

Places of worship

3.0

2.7

C3

Areas without obstacles for moving people

C31

Corridors, hallways, aisles in institutional type buildings, hostels, guest houses, residential clubs and communal areas in larger■b blocks of flats

3.0

4.5

C32

Stairs, landings in institutional type buildings, hostels, guest houses, residential clubs and communal areas in largerb blocks of flats

3.0

4.0

C33

Corridors, hallways, aisles in otherc buildings

4.0

4.5

C34

Corridors, hallways, aisles in otherc buildings subjected to wheeled vehicles, including trolleys.

5.0

4.5

C35

Stairs, landings in otherc buildings subjected to crowds

4.0

4.0

C36

Walkways - Light duty (access suitable for one person, walkway width approx 600 mm)

3.0

2.0

C37

Walkways - General duty (regular two-way pedestrian traffic)

5.0

3.6

C38

Walkways - Heavy duty (high-density pedestrian traffic including escape routes)

7.5

4.5

C39

Museum floors and art galleries for exhibition purposes

4.0

4.5

C4

Areas with possible physical activities

C41

Dance halls and studios, gymnasia, stagesd

5.0

3.6

C42

Drill halls and drill roomsd

5.0

7.0

C5

Areas subjected to large crowds

C51

Assembly areas without fixed seating, concert halls, bars and places of worshipd,e.

5.0

3.6

C52

Stages in public assembly areasd

7.5

4.5

Key

a Fixed seating is seating where its removal and the use of the space for other purposes is improbable

b Small blocks of flats are those with < 3 storeys and < 4 flats per floor/staircase. Otherwise they are considered to be 'larger' blocks of flats

c Other buildings include those not covered by C31 and C32, and include hotels and motels and institutional buildings subjected to crowds

d For structures that might be susceptible to resonance effects, reference should be made to NA.2.1

e For grandstands and stadia, reference should be made to the requirements of the appropriate certifying authority.

Table 2.2d

Variable actions, category D: shopping areas

Subcategory

Example

Imposed loads

qk (kN/m2)

Qk (kN)

D

Shopping areas

D1

Areas in general retail shops

4.0

3.6

D2

Areas in department stores

4.0

3.6

Table 2.2e <BS 199

Variable actions, category E: storage areas and industrial use (including access areas) Tables

NA.4 &

Subcategory

Example

Imposed loads

qk (kN/m2)

Qk (kN)

E

Storage areas (including access areas)

E1

Areas susceptible to accumulation of goods including access areas

E11

General areas for static equipment not specified elsewhere (institutional and public buildings)

2.0

1.8

E12

Reading rooms with book storage, e.g. libraries

4.0

4.5

E13

General storage other than those specified'

2.4/m

7.0

E14

File rooms, filing and storage space (offices)

5.0

4.5

E15

Stack rooms (books)

2.4/m (min. 6.5)

7.0

E16

Paper storage and stationery stores

4.0/m

9.0

E17

Dense mobile stacking (books) on mobile trolleys in public and institutional buildings

4.8/m (min. 9.6)

7.0

E18

Dense mobile stacking (books) on mobile trucks in warehouses

4.8/m (min. 15.0)

7.0

E19

Cold storage

5.0/m (min. 15.0)

9.0

E2

Industrial use

See PD 6688[22]

Forklifts Classes FL1 to FL6

See BS 1991-1-1 Tables 6.5 and 6.6

Key a Lower bound value given. More specific load values should be agreed with client

Table 2.2f

Variable actions, categories F and G: traffic and parking areas

Table 2.2f

Variable actions, categories F and G: traffic and parking areas

Subcategory

Example

Imposed loads

qk (kN/m2)

Qk (kN)

F

Traffic and parking areas (vehicles < 30 kN)

Traffic and parking areas (vehicles < 30 kN)

2.5

5.0

G

Traffic and parking areas (vehicles > 30 kN)

Traffic and parking areas (vehicles > 30 kN)

5.0

To be determined for specific use

Roofs are categorized according to their accessibility.. Imposed loads for roofs <55 en 1991-1-1 that are normally accessible are generally the same as for the specific use and 6.3.4 & NA> category of the adjacent area. Imposed loads for roofs without access are given in Table 2.2g.

Variable actions, category H, I and J: roofs Tables 6.9, 6.10, ^1 & NA.7>

Subcategory

Example

Imposed loads

(kN/m2)

Qk (kN)

H

Roofs (inaccessible except for maintenance and repair)

Roof slope, a°

< 30°

0.6

0.9

30° < a < 60°

0.6(60 - a) / 30

< 60°

0

I

Roofs (accessible with occupancy categories A - D)

Categories A -

As Tables 2.2a to 2.2d according to specific use

K

Roofs (accessible for special services, e.g. for helicopter landing areas)

Helicopter class HC1 (< 20 kN) (subject to dynamic factor 0 = 1.4)

20

Helicopter class HC2 (< 60 kN)

60

2.4.2.2 Movable partitions

The self-weight of movable partitions may be taken into account by a uniformly distributed load qk which should be added to the imposed loads of floors as follows:

■ For movable partitions with a self-weight of 1.0 kN/m wall length: qk = 0.5 kN/m2.

■ For movable partitions with a self-weight of 2.0 kN/m wall length: qk = 0.8 kN/m2.

■ For movable partitions with a self-weight of 3.0 kN/m wall length: qk = 1.2 kN/m2.

Heavier partitions should be considered separately. 2.4.3 Reduction factors

2.4.3.1 General

Roofs do not qualify for load reductions. The method given below complies with the < bs EN 1991-1-1 UK National Annex but differs from that given the Eurocode. 6.3.1.2 (10),

A reduction factor for imposed loads for area aA may be used and should be determined using aA = 1.0 - A / 1000 > 0.75 (NA.1) < bs EN 1991-1-1

A is the area (m2) supported with loads qualifying for reduction (i.e. categories nA> A to E as listed in Table 2.1).

2.4.3.3 Number of storeys

A reduction factor for number of storeys an, may be used and should be determined using an = 1.1 - n / 10 for 1 < n < 5 an = 0.6 for 5 < n < 10

where n = number of storeys with loads qualifying for reduction (i.e. categories A to D as listed in Table 2.1).

According to the UK NA, aA and an may not be used together.

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Responses

  • marie
    How to apply imposed load reduction according to eurocode?
    8 years ago
  • gladys
    Is imposed load same as variable load?
    1 year ago
  • peter tuhkasaari
    How to use variable load for slabs in storage structure EC2?
    2 months ago

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