Wind load underside of elevated buildings (BS EN 1991-1-4) 2

[mte12]

Was looking in BS EN 1991-1-4, for wind load to underside of buildings, but could not find anything.

For comparison, AS 1170.2 has the following in Section 5.4.1:
For the underside of elevated buildings, Cp,e shall be taken as 0.8 and –0.6. For buildings with less elevation above ground than one-third of the height, use linear interpolation between these values and 0.0, according to the ratio of clear unwalled height underneath first floor level to the total building height.

 

[HTURKAK]

Eng. MTE ,
I looked ASCE 7- 16 and apparently the same pressure coefficients specified and are adopted from Standards Australia

29.4.2.3 Undersides of Isolated Elevated Circular Bins, Silos,and Tanks. External pressure coefficients Cp for the underside
of elevated circular bins, silos, or tanks with clearance height, C, above ground less than or equal to the solid cylinder height, H,shall be taken as 0.8 and −0.6.

C29.4.2.3 Undersides of Isolated Elevated Circular Bins,Silos, and Tanks. This section specifies the external pressure
coefficients, Cp, for the underneath sides of circular bins, silos,and tanks.

EC (EN 1991-1-4 ) does not specify wind load to underside of building.

I will suggest you to adopt the same figures ( 0.8 and −0.6) . You may post more details to get better responds.

P.S. : I did not encounter with such a case .






Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[JStephen]

A quick search turned up a similar question here:

https://collaborate.asce.org/standards-exchange/discussion/wind-loads-for-elevated-beach-house

I don't see anything in ASCE 7-16, as noted, but there are hundreds of "beach houses" up and down the coast, so presumably some sort of assumption is normally made. Especially given they are in high-wind, high-exposure locations.

 

[mte12]

Thanks HTURKAK, JStephen.

Will allow for pressures under base. For information, structure is a cladded truss, 30m from ground level.

 

[HTURKAK]

A sketch with dimensions will help to get the problem. Consider ( 8.3.3 Wind forces on bridge decks in z-direction.)



Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[mte12]

Thanks HTURKAK, section 8.3.3 for bridges indicates coefficients up to +/-0.9.

Dimensions are shown for information.

 

[HTURKAK]

In your case , the clear height underneath the structure 30 m , it is pretty high . My approach would be , to select the more stringent figures stated at section 8.3.3 for bridges or flat roof coefficients .

I would like to hear others' thoughts on this subject.





Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[mte12]

Thanks again HTURKAK.