## Vertical loads from wind action moments in plane

Figure 6.3 Lateral stability against wind loads N-S

Check relative stiffness of lift shaft and wall A to determine share of load on wall A.

Lift shaft: ILs = 2.44 / 12 - 2.04 / 12 - 0.2 x 1.63 / 12 = 1.36 m4

. Wall A takes = 1.41 / (1.41 + 1.36) = 51% of wind load. Check shear centre to resolve the effects of torsion. Determine centre of reaction of lift shaft

 Area X Ax 2.4 x 2.4 = 5.76 1.2 6.912 -2.0 x 2.0 = -4.00 1.2 -4.800 -1.6 x 0.2 = -0.32 2.3 -0.732 1.44 1.38

' Includes storeys supporting Categories A (residential & domestic), B (office), C (areas of congregation) and D (shopping) but excludes E (storage and industrial), F (traffic), G (traffic) and H (roofs).

Figure 6.4 Lift shaft

x = Ax / A = 1.38 / 1.44 = 0.956 m i.e. from face of lift shaft to CoG of shaft

Shear centre, Cw of walls, from centreline of wall A

or = 12.56 + 2.80 - 0.05 = 15.31 from east end of building

Figure 6.5 Shear centres

Note: centre of action and shear centre (almost) coincide. .'. There is no torsion to resolve in the stability system for wind in a N-S direction. (Had there been significant torsion this would have been resolved into +/- forces in a couple based on the shear walls.)

### Figure 6.5 Shear centres

Note: centre of action and shear centre (almost) coincide. .'. There is no torsion to resolve in the stability system for wind in a N-S direction. (Had there been significant torsion this would have been resolved into +/- forces in a couple based on the shear walls.)

* Assuming centreline of wall A is 50 mm to right hand side of grid.

Wall A takes 51% of wind load so characteristic wind load on wall A, Wk = 51% x wk x ix = 51% x 1.1 x 30.7 = 17.2 kN / m

Figure 6.6 Wall A - wind loads N-S

.'. at just above ground floor, characteristic inplane moment in wall A, Mk

Resolving into couple using 1 m either end of wall*, characteristic wind load in each end, Wk

Figure 6.6 Wall A - wind loads N-S

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### Responses

• tesfay
How to consider wind load for wall?
8 years ago