Uniform snow load from snow drift (triangular load)

[SFares]

Hello All,

I have attached a Prime 9 sheet. I am trying to calculate  the uniform load on several members resulting from triangular snow load. i have included my instructions as to what needs to be accomplished. 

Thank you for your assistance!

Sam

[NickKemaev]

И так?

[SFares]

Hello Nick,

I’m not sure if what you did is correct. Could you please send me the sheet or a screenshot of your work, and make sure the units are in US units?

Thanks,

Sam

[Werner_E · Accepted solution]

I don't understand why you think that that last value should be zero

With your function you simply connected two points by a straight line which also extends beyond the points

If your intention was that the function value should be zero for all values of s beyond 18 ft, you simply would have to add a third value larger than the last and with the very same function value.

Now you get

To automate what you did manually step by step you could create a vector containing the sum of all S-values up to

and use this vector of sums as function argument (vectorization not mandatory here but its good to be on the safe side)

To automate the 'Trib' values you could use

But for obvious reasons (every element is the arithmetic mean of the corresponding S-value and its successor but the last value in the S vecor has no successor)  this vector has one element less than the rest and so you would not be able to multiply the 9-element vector with the 8-element vector Trib.

But you sure can multiply the first 8 values

Not sure if that's what you had in mind

maybe you wanted SSum to be used when calculating the Trib vector and not S.joist? You have to know what you need

Anyway, P9 sheet attached

[SFares]

Thank you so much, Werner!

What  I have is snow drift, which is a triangular load. I was focusing first on Drift #1. As shown below, the snow is maximum at support zero then it decreases to zero. So support 4 and 5 get no snow drift, and that's why i said , the snow drift is zero beyond the snow drift length.

you stated "S-value and its successor but the last value in the S vector has no successor)  this vector has one element less than the rest", I agree with your observation.  believe i need to make and adjustment as to what happen ends at a support or somewhere in between. the load calculation will be different. i will have a follow up question later.

Regards,

Sam

[Fred_Kohlhepp]

So your drift is triangular in two dimensions?

And the section of the drift at each joint changes?

[SFares]

Hi Fred,

Yes, its a corner drift. Depending on the magnitudes of the intersection drifts, the supporting member might have a uniform snow load from drift#1 and an additional triangular drift from drift#2. What i sent earlier and Werner helped me with, will work well if the spacing among the members is uniform. I modified the sheet ,and using  Werner provided, but i still have few minor issues. i will attach the sheet now and i have some questions inside the sheet-P9 in red text. I can also post the question as  a new topic.

Thanks

Sam

[SFares]

Hello Werner,

I will make a new post regarding this topic now.  What i sent before and you helped with will work well if the spacing among the members. For the case when the spacing among the supports are not equal,  I modified the sheet you sent me and added few more things. Depending on the magnitudes of the intersection drifts, Drift1 and 2, the supporting member might have a uniform snow load from drift#1 and an additional triangular drift from drift#2.  I still have few "minor" issues.  I have some questions inside the sheet-P9 in red text. 

Thank you!

Sam