F r

Notes

1 Depending on the magnitude of gk, qk length AB and BC, yGkinf Sk (= 1.0 gk) may be more critical for span moment.

2 The magnitude of the load combination indicated are those for Exp. (6.10) of BS EN 1990. The worse case of Exp (6.10a) and Exp (6.10b) may also have been used. 3: Presuming supports A and B were columns then the critical load combination for Column A would be as Figure 2.18. For column B the critical load combination might be either as Figure 2.17 or 2.18._

Figure 2.18

ULS: maximum span moment AB

c) Serviceability limit state (SLS) of deformation: (quasi-permanent Loads) i) For maximum deformation at C

Figure 2.19

SLS: maximum deformation at C

Figure 2.19

SLS: maximum deformation at C

ii) For maximum deformation AB

* Msumdrlg o+fice aria

Note

Quasi-permanent load combinations may also be used for calculations of crack widths or controlling cracking, i.e. the same load combinations as shown in Figures 2.19 and 2.20 may be used to determine SLS moment to determine stress in reinforcement. The characteristic and/or frequent combinations may be appropriate for other SLS limit states: for example, it is recommended that the frequent combination is used to determine whether a member has cracked or not.

Figure 2.20

SLS maximum deformation AB

Example 2.11.4 Overall stability (EQU)

For the frame shown in Figure 2.21 identify the various load arrangements to check overall stability (EQU) against overturning. Assume that the structure is an office block and that the loads qk2 and qk3 may be treated as arising from one source.

Figure 2.21 Frame configuration

Permanent action, favourable

Accompanying variable action

Permanent action, favourable

0.9

rv-VSrv-vv^

Permanent action, favourable

0.9

i-y-v-v^

Lead variable action = y^ - ' Permanent action, unfavourable s V ,1>; -1.1

Lead variable action = y^ -1,5 . Permanent action, unfavourable - Y -,= 1-1

7777 A

Accompanying variable action = Y~ l.y c t,05 Permanent action, unfavourable = - 1.1 <i,.

Lead variable action = y^ - ' Permanent action, unfavourable s V ,1>; -1.1

Lead variable action = y^ -1,5 . Permanent action, unfavourable - Y -,= 1-1

7777 S

5ee Table 2.7 for values of Vfj

Figure 2.22

Frame with floor variable action as leading variable action b) Treating the roof load as the leading variable action (EQU)

Figure 2.23

Frame with roof variable action as leading variable action

Figure 2.23

Frame with roof variable action as leading variable action c) Treating wind as the leading variable action (EQU)

0.9 a,

0.9 0t2

7777

7777

Figure 2.24

Frame with wind as lead variable action

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