Internal Wind Pressure on balustrade 2

[Jandra11]

Guys I need your help. the consultant is asking me to add the internal wind pressure to the original horizontal live load. our company already fabricated the balustrade but if we comply with the consultant's comment some of the section will change. Does this internal wind pressure(0.25kPa) is additive load? How can I prove to him that those load should not act concurrently? Thank you in advance.

 

[Settingsun]

Check your code's load combinations. They usually have a reduced live load when combined with wind.

 

[Agent666]

Look at the load combinations you are required to apply in accordance with your code for ultimate and serviceability cases. Often wind and live are considered in one case, but usually the live load is some portion like 0.4 times the full live. Wind wouldn't be additive to the full horizontal live load.

Saying that I don't think I've ever considered the internal wind in addition to the live load as its hard to see at 0.4Q how this case would govern.

 

[Jandra11]

thanks, I get your point but we are using Eurocode.it will be 1.35DL+1.5LL + 1.0 WL

 

[MIStructE_IRE]

The world has gone mad. Personally I have ignored this in the past - rightly or wrongly!

 

[Jandra11]

As per my personal opinion, this 0.5kpa is to check the integrity of some architectural works which don't have any load requirements. And it should not be acting concurrently with other live loads? or do I miss anything?

 

[MIStructE_IRE]

You could argue that the amount of people required to impose such a significant horizontal imposed load on a balustrade in the first place would in fact shelter it from any additional wind...

I think its an unreasonable load combination in reality particularly indoors.. There is a hoarding design manual “hoardings - a guide to good practice” which covers the load combination externally but they take a minumum ‘working’ wind which even externally is considered at around 0.2kpa when applied in conjunction with the UDL.

 

[dianium500]

What kind of structure are you designing for? Is it an evacuation route where they would have to pass the railings during a wind event? I am curious as to why they would want you to consider that combination.

 

[patswfc]

Jandra,

I wouldnt normally combine these loads either, but if you are being asked to do this (i suppose technically correct to eurocodes) then the combinations do allow for a reduction.

ULS Combinations
With handrail load the leading variable the combination would be 1 or 1.35DL + 1.5 Handrail Live load + 0.75 Wind Load (1.5 * psi0 factor of 0.5 for wind as the non leading variable)
With wind load the leading variable the combination would be 1 or 1.35DL + 1.5 Win load + 1.05 Wind Load (1.5 * psi0 factor of 0.7 for Handrail Live as the non leading variable)

Similar reductions are appropriate for SLS Characteristic combinations, with further reductions if you are checking deflections under Frequent or Quasi-permanent SLS combinations, as these use lower psi1 or psi 2 factors.

Does this help you make the design work?

What handrail load are you designing for and what wind load are you now being asked to add to this? Is the balustrade solid catching all of this wind or open, reducing the wind load on the posts?

 

[patswfc]

This should read

With wind load the leading variable the combination would be 1 or 1.35DL + 1.5 Wind load + 1.05 Handrail Live Load (1.5 * psi0 factor of 0.7 for Handrail Live as the non leading variable)

Also the psi factors i've shown are based on the UK national annex. The default value in the main eurocode is 0.6 for psi0 for wind. Your national annex (if not designing for use in the UK) may be different.