alberto

Calculation of wind loads & Eurocode 1

42 posts in this topic

What do you think about the calculation of the wind loads according to Eurocode 1 (EN 1991 1-4)?

I think that this procedure is very complicated even for a portal frame...

BS and DIN were much easier to use!

Do you know which design software can automatically generate wind loads subjected to buildings according to Eurocodes?

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I agree with you alberto! It is really very complicated to calculate wind loads according to Eurocodes...

I think that one of the best design software for this purpose is Nemetschek's Scia.

You can also use this online free application!

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I have spreadsheet solutions that implement the UK NAD methods and data. I also know that Strusoft FEM design and STRAP, to name but two FEM suites, have EC1 wind loading functionality. The latest version of Strusoft (11) allows one to define 'covers' that transmit the pressures to a frame and allow the geometric calculation to be performed but I haven't explored it in detail yet.

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Cook; a UK, if not international, authority on wind, gave an amusing account of some of the committee sessions when drafting the wind code. It highlights the different attitudes to regulation and practice in different parts of Europe. It seems that some nations want plenty of codified rules and data and others want practically none, with the majority forming a spectrum in between these extremes. I seem to remember he singled out the Swiss representative who expressed the view that all Swiss engineers were competent so did not need any rules! Perhaps that's a harsh interpretation but illustrative of the great difficulty of harmonising a set of standards.

Something like wind must be one of the most difficult areas. After all, concrete and steel vary little - like some wines, they 'travel well' - but wind climate must vary a great deal. The UK and western France are greatly influenced by the Atlantic depressions but further East, the predominant effects may have different origins. This explains why the UK NAD has quite a lot or material in it and makes a lot of use of the nationally determined parameters and methods.

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I don't like the fact that a building subjected to wind loads is divided to strips and zones with different pressure coefficients.

Because of this both FEA simulation and hand calculation are becoming more complicated!

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I have spreadsheet solutions that implement the UK NAD methods and data. I also know that Strusoft FEM design and STRAP, to name but two FEM suites, have EC1 wind loading functionality. The latest version of Strusoft (11) allows one to define 'covers' that transmit the pressures to a frame and allow the geometric calculation to be performed but I haven't explored it in detail yet.

Andy,

Did you write the spreadsheet solution or is it available in the UK?

Bob

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Bob, you can find Andy's spreadsheet about wind loads according to Eurocode 1 here!

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Yes, I wrote the spreadsheets - in fact still writing them, as they are a never-ending task as I continually try to improve and debug them. Be careful if you use them and keep an eye on the calculation - there is always room for improvement! I wrote them for my own use and I correct and improve them as I go - feel free to adapt them as you wish. They are created as individual calculations for various aspects of design in a way that they can be copied and pasted into another spreadsheet to form a coherent set of calculations. Excel works well for this.

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Yes, I wrote the spreadsheets - in fact still writing them, as they are a never-ending task as I continually try to improve and debug them. Be careful if you use them and keep an eye on the calculation - there is always room for improvement! I wrote them for my own use and I correct and improve them as I go - feel free to adapt them as you wish. They are created as individual calculations for various aspects of design in a way that they can be copied and pasted into another spreadsheet to form a coherent set of calculations. Excel works well for this.

Andy

Thanks I was not able to open it, I only have Excel 2000, will it convert?

Bob

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Hi Bob,

The spreadsheet itself will be OK in whatever version of Excel you use I think, but the add-ins that are needed to drive it are specifically 2007-2010 compatible. If you can find someone who will lend you a few minutes use of a PC with 2010 or 2007 then you could open the add-ins in the VBA editor and save them as 'xla' rather than 'xlam'. You should then be able to install the add-ins in 2000. Then you may need to also change the links in the link editor to 'see' the new xla files. Alternatively, you could extract what code you need from the VBA and paste it into your spreadsheet as custom functions.

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Hi Andy

I can't install the addons for your spreadsheet.

I am on Win 7 and have browed to c:\Users but there is no "All Users" folder so I went to create one but I get prompted that one already exists but I can't see it! Any ideas?

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I am in the process of writing a spreadsheet to work out the Co (orography coefficients). I was wondering if anyone has done one that I can check mine against and also has anyone worked out a way of calculating the Cr(z) (roughness factor) as the national annex states that the expressions in the main code are not to be applied and the graphs are meant to be used.

Could really do with some guidance so that I know I'm doing it right lol.

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Excel 2003-2007 may work better...

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I am in the process of writing a spreadsheet to work out the Co (orography coefficients). I was wondering if anyone has done one that I can check mine against and also has anyone worked out a way of calculating the Cr(z) (roughness factor) as the national annex states that the expressions in the main code are not to be applied and the graphs are meant to be used.

I didn't know that UK's NA suggests a different procedure to calculate cr(z)...

Could really do with some guidance so that I know I'm doing it right lol.

You could upload your spreadsheet here so that I and probably the other members of the forum can check it!

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post-67-14570089610414_thumb.png

Because traffic load is so predominant for small (and medium) bridges it's waste of time to calculate wind so accurately (and it leaves lot of room for mistakes as well). Wind load (edit. pressure) can be given with really simple table above, the difference with accurate value is miniscule. Again sorry for the language. Naturally for larger bridges wind loads are calculated separately.

-BG

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I didn't know that UK's NA suggests a different procedure to calculate cr(z)...

Well in the British national annex (N.A.2.11) it says, "BS EN 1991-1-4:2005 Expressions (4.4) and (4.5) do not apply". I don't know whether it is different in your national annex.

I will upload it when it allows me to... It says I need to have three posts before uploading and downloading.

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I should be able to download and upload spreadsheets now, so I will get it on here for you to have a look at.

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jamalsid: Sorry - just seen your post!

Have you got the settings in Explorer set to display system and hidden folders? The 'All users' folder should exist or you should be able to add it. I have updated my addins a bit since the last upload. If you want them, or more help, let me know. You could send a message through the forum messaging.

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Hi Ion,

This is quite a relieve to see this msg. I will have a look at Andy's Spreadsheet. We just got our new loading codes here in South Africa, it has changed quite a bit from what it was due to the process of adopting the EU design methods.

Kind Regards!

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Bob, you can find Andy's spreadsheet about wind loads according to Eurocode 1 here!

My primary reason for joining this forum was to be able to download Andy's spreadsheet.

This is the first of the 3 posts that I need to make in order to qualify to do the download!

Our Windowmaker software for window manufacturers includes some wind load calculations, but it assumes that a Pascal value for the wind pressure is already known. Sometimes it is not known and needs to be calculated. We have no wish to reinvent the wheel on this and would rather point interested customers in the direction of an existing solution.

So my question is 'Can we give them copies of the spreadsheet (once I've downloaded it), or do we need to persuade them to all come and register and post on this site?'.

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Hello Windowmaker and welcome!

You could send a personal message to Andy asking questions about his spreadsheet.

BR,

Ion

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Hello Windowmaker and welcome!

You could send a personal message to Andy asking questions about his spreadsheet.

BR,

Ion

Thanks Ion, I've now done that.

So onto my 2nd post.

We have supplied our Windowmaker software to 75 countries worldwide.

Besides Europe, we have been particular active in Canada, USA, India, Australia and China.

What are the similarities/differences between the European standards and those elsewhere, especially in the above countries?

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To all - important:

Ah! A quick disclaimer is needed.

My spreadsheets were originally created by me for personal use and use in my work under the assumption that I would be the only user and would know what's going on and would be able to adjust and develop them as and when required. I uploaded them on the understanding that they were for others' personal use too and as an aid to learning and developing their own.

They are certainly not for direct commercial use.

However, I am more than happy to share them with anyone for personal use and educational purposes, or even for others developing their own applications who might like to avoid 're-inventing the wheel' by using some of the calculations or VBA code - but on the assumption that they properly debug, test and correct it as necessary.

If this is done on a small scale, then I am happy to supply them free of charge. If large scale commercial use is envisaged, then I think it's fair to ask for some recompense.

The spreadsheets are compiled as a fairly extensive set of 'building blocks' of calculations that can be used separately or linked together to form larger blocks of calculations. They are not generally 'stand alone' applications with a single application on one worksheet (or workbook).

They rely on Excel addins, also uploaded, that contains quite a large set of VBA code giving many custom functions that can be used in Excel to make new calculations and they are used in the Eurocode calculations in the example workbooks.

There is a lot of work in them - years, on and off - but I would not consider them sufficiently debugged and tested to allow them for general release. Neither can I accept liability for them for that reason.

The calculation of wind loading is a case that can be very complex as wind loading is sensitive to many factors that cannot concisely be compiled into a spreadsheet of reasonable size. That is not to say that a simplified version could not be constructed to deal with particular cases like cladding or windows. Even so, a spreadsheet application could be misused or used incorrectly by an unsuspecting user without the necessary training. An example of this might be, say, where the user fails to identify the effect of some local topography near a site.

I originally posted this, but it's been suggested that it might be better to send to you as a private message.

My primary reason for joining this forum was to be able to download Andy's spreadsheet.

This is the first of the 3 posts that I need to make in order to qualify to do the download!

Our Windowmaker software for window manufacturers includes some windload calculations, but it assumes that a Pascal value for the wind pressure is already known. Sometimes it is not known and needs to be calculated. We have no wish to reinvent the wheel on this and would rather point interested customers in the direction of an existing solution.

So my question is 'Can we give them copies of the spreadsheet (once I've downloaded it), or do we need to persuade them to all come and register and post on this site?'.

The workbooks and addins are constantly under development and I make periodic updates, corrections and improvements. They are presently on my Dropbox site, are 'synced' daily with my live versions and I can allow people to have a link if they want to download them.

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We have supplied our Windowmaker software to 75 countries worldwide. Besides Europe, we have been particular active in Canada, USA, India, Australia and China.

What are the similarities/differences between the European standards and those elsewhere, especially in the above countries?

There are some significant differences in the calculation of wind load in the UK NAD compared to other NAD's and the general, 'vanilla flavour', code. One of the main reasons is that the UK wind climate is different from that predominant in the continent, away from the Atlantic coasts. There are some other more subtle reasons and I would recommend anyone to read through Cook's handbook on EN 1991-1-4.

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