DIAGONAL STRAP BRACING FORMULA?

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Andrew G
Andrew G's picture
DIAGONAL STRAP BRACING FORMULA?
SoftPlan Version:
13

I'm a novice when it comes to formulas and currently trying to write one that will report on bulk quantities of diagonal strap bracing required for a custom wall type which includes arbitrary Solids to represent metal strap bracing. Our company purchases 30 x 0.8 mm metal strap bracing at a rate of $2.15 / kg with each kg containing 5.5 lineal meters.

First I started with the Lumber Format and entered 5500 in the Order Length box and created a Lumber Pricing Table (see Image 3) called "metal_strap" which contains the order length and price per lineal meter. However SL didn't like it because the combine options are set to cut lengths between 1800 and 6000 with increments of 300 to suit order lengths for Studs, Lintels, etc.

Instead, the Custom Formula I created (see Images 1 & 2) is cutting from smaller lengths and when I replace the @length variable with 5.5m, it reports (incorrectly) that all lengths are 5.5m to be cut from 5.7m.

How do I get SoftList to cut from only 5.5m lengths as per the Lumber Pricing Table?

Thanks in advance!

 
Bill Wimberley
Bill Wimberley's picture
Strapping

Perhaps taking a more simple approach. Let's assume all of your straps are exactly 5.5m in length. The first thing to do would be to determine what walls get the straps and how many straps would be used. So say for instance all exterior stud framed walls are strapped. Maybe you figure 1 strap for walls up to 12' in length and 2 straps for walls over 12'. So then you would just need to create a formula that looks at the walls and first determines if it is an exterior wall. If it is then what is the length. If the length is 12' or less then add 1 strap at 5.5m. If the wall is greater than 12' then add 2 straps at 5.5m.

Is this close to what you are trying to accomplish? I would need to know what you are trying to do more than how you have tried to do it.

Bill is the owner and maintainer of SoftPlanTuts.com

Andrew G
Andrew G's picture
Lineal lengths

Hi Bill,

That is sort of what I'm trying to do, except get a more accurate length, and in turn, mass result on the report.

Ultimately, if it could show the total lineal length of strapping for the job, eg. 17m, divided by 5.5m / kg = 4 kg, on the report like so,

Material

Description

Qty

Units

Cost

Metal Strap Bracing

30 x 0.8 x 17m

4

kg

2.15

that would be ideal, but I'm not sure if dividing lineal by X amount is possible?

Thanks again.

Bill Wimberley
Bill Wimberley's picture
strapping

Hello Andrew. What I need to know is what walls get the strapping. For example is it just certain wall types? Will all walls have just 1 strap? If some walls would have multiple straps what criteria determines how many straps would be used? Do wall lengths factor in? Will all straps be the same length regardless of wall height?

Once I know what criteria determines where the strapping is used I can look at how to count them.

Andrew G
Andrew G's picture
Hi Bill,

Hi Bill,

Thanks again for the quick replies.

The criteria is based on wall types I've named "90mm Strap Bracing Wall" and "70mm Strap Bracing Wall" with materials Solid A and Solid B representing the opposing straps.

Minimum length of strap bracing is 1.8m, maximum length 2.7m. So for wall lengths (minus opening widths) 1.8m to less than 3.6m, 1 strap. For wall lengths 3.6m to less than 5.4m, 2 straps, etc. Maximum wall length would be 18m, with 10 straps.

All straps would be in the same range of 1.8m to 2.7m long each regardless of wall height.

Cheers!

Bill Wimberley
Bill Wimberley's picture
Strapping

Andrew, forget for a moment about SoftPlan and your specialty "Strap Bracing" walls. Referring to the actual physical house...what walls are to receive the strapping? Interior walls? Exterior walls? Siding walls? Masonry walls? All walls? You most likely do not need any special "strapping wall" definitions. There are numerous other ways to select walls.

What criteria determines number and length of straps? For instance 1 strap for each 3m length of wall? Again, I am talking about the actual house, not your special walls. If you were to write out a formula that describes the length of the straps and how many straps go in a wall what would that formula look like? Can you provide a sketch showing the strapping and how the lengths and quantities are determined?

The formula to calculate the strapping should be pretty simple once I understand how the strapping is used on the actual house.

Andrew G
Andrew G's picture
Formula

Hi Bill,

To answer your questions for the house,

All walls, both Exterior with siding outside, and Interior with plasterboard both sides, to receive strapping.

For each 1.8m length of wall, provide 1 strap.

Perhaps the formula would look something like,

@wall_length=length-door_width-window_width
if between(@wall_length,1800mm,3600mm) or @wall_length=1800mm
   @strap_length=hypot(wall_height,@wall_length)
   if within(@strap_length,1800mm,2700mm)
      set_dimens(millimeters,millimeters,millimeters)
      lumber(@strap_length/5500,0.8,30,@strap_length,metal_strap)
   endif
endif
?

I've attached a sketch of the subject house with the strapping locations.

Hope this helps.

Andrew G
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Sketch

Oops. Sorry - forgot to attach the elevation of the strap.

ChrisStewart
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I do not know if there is a

I do not know if there is a Softlist variable that will give you wall length between windows.

 

It seems to me that you will either have to just average -based on total linear feet of wall

 

or if you need to be exact than:

 

make a symbol for the strapping and use that to write the formula

 

so the symbol is nothing more than a vertical plane or solid which has a length and height and would be inserted onto the drawing manually and strapping would be calculated based on the length and height of each instance.   

 

 

Bill Wimberley
Bill Wimberley's picture
Bracing

As Chris said a symbol might be one way to do it.

I don't have version 13 so I am thinking of options that may not even exist in version 13. But can you check on something for me? Switch over to SoftList Mode. It is one of the additional modes like Drawing, Electrical, etc. Look in SoftList mode and see if there is the ability to draw Takeoff polygons. If so then that might be the easiest way to go. Basically you would draw a line over each area of the wall where you want to have the bracing. Then you would create a formula that takes the lengths of these Takeoff polygons and calculates the bracing.

ChrisStewart
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That would be easier but I

That would be easier but I think that Takeoff did not show up until v2014

 

Bill Wimberley
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Takeoff

It was there in version 14 but I don't know about 13.

Andrew G
Andrew G's picture
It looks like there is no

It looks like there is no SoftList or Takeoff mode available in V13 :(

ChrisStewart
ChrisStewart's picture
I guess I am further behind

I guess I am further behind than I imagined.

 

Anyway, in either case each strapping location needs to be drawn individually so while you could save a few minutes if you had the Takeoff tool it is easy enough to do with a symbol.