Converting batter and slope to inches of setback per course 2

[Bagman71]

Hello Folks-

I'm in need of some math help. I would love to be able to give a rough idea of how much setback in inches is required per course of segmental retaining blocks to achieve a certain batter. For example, if I want to build a wall at an 8:1 batter how much setback in inches per course is required to achieve this? My units are 5" high, if that matters. I've been out of high school too long I think - I can't deduce the proper formulas!

Thanks for any help you all can offer!

 

[BigH]

Take a pencil and paper and an engineering scale. Make a starting point. Make a line projecting upwards at 1H:8V; start drawing in your 5 inch layer courses and measure the setback required. You don't need math for this one!

 

[Bagman71]

Ok that's a definite option! I guess I can go to an engineer supply and grab a scale- as you call it- is my lack of experience showing yet? If I did want to apply a formula, do you have any idea how I could do it? I'd like to be able to do it for all batters, from 1:1 up to at least 1H:10V. I figured a formula would be faster- and it seems more elegant

Thanks very much for your help and prompt reply- very generous.

 

[cvg]

spreadsheet is better

if your course is exactly 5 inches thick, than setback is 5/8 inches

 

[PEinc]

Check the details for the particular block you are using. Often, the block has a built-in offset feature that automatically sets a particular wall batter. Talk to the block manufacturer or supplier.

http://www.PeirceEngineering.com

 

[Bagman71]

Thanks folks-

So cvg- what's the formula there? Is it the obvious-which would be unit height over vertical rise? So setback on a 1H:2V would be 5/2 or 2 1/2"? Spreadsheet is the way to go, I agree. And I should be frank-I am the distributor, but the unit height CAN vary, so the manufacturer has not provided any standard setback based on the 5" I have provided. We have standardized it to avoid confusion.

 

[cvg]

slope and batter for architects and civil engineers is expressed in rise over run. assuming 8V:1H, for every 8 inches of rise (vertical) you get 1 inch of run (horizontal). so for 5 inches of rise you get 5/8 inches of run. Note that batter is usually expressed as vertical to horizontal and slope is expressed just the opposite.

 

[msquared48]

Batter is 1 foot horizontal for every 8 feet of height.

For a 5" high block, the setback in inches would be
12(5/96) = 5/8" as CVG said.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[BigH]

@Bagman71 - you don't have an engineering scale?? Mmmm

@therest - I am on vacation While this was an "easy" one, I sometimes just like to point out that things could be designed before personal computers! One of my university professors was asked to confirm that the top piece of the St Louis Arch would fit - the day before it was to be placed. He did the whole exercize graphically and said it would - and it did!

 

[FixedEarth]

Try the following books- They have your answers plus they will be a good reference for future projects:

http://www.amazon.com/Measuring-Marking-Layout-Builders-Guide/dp/1561583359/ref=pd_sim_sbs_b_6

http://www.amazon.com/DEWALT-Construction-Math-Quick-Check/dp/111112857X/ref=pd_sim_sbs_b_2

The Trigonometry chapter, specifically the inverse Tangent function. The inverse of the Tangent when measured from the bottom of the wall for 8:1 batter will give you Inv. Tangent = (8/1) which is equal to 82.875 Degrees. The horizontal setback depends on this angle and the block height. So for the 82.875 Deg. & 5 inch height, the setback is 5.0/Tan 82.875 = 0.625 inch or 5/8"

Let us try 12:1 and an 8" block. Inv. Tangent (12/1)= 85.2364 Deg. Setback is 8/Tan 85.2364 = 0.667 or 2/3" and so on.

 

[Drumchaser]

Bagman

I agree with PEinc...the manufacturer/supplier will provide details, and stnd. drawings on how the wall should be constructed.

What is the height of your wall, and does it have a leveling pad?
The modular block walls we are familiar with sometimes have to match the existing ground on the final course, which causes the leveling pad to be placed with step-ins/step-ups in order to tie-in the existing features. This can be tricky.

 

[fattdad]

it's 5/8ths!

Come on guys. . .

f-d

¡papá gordo ain’t no madre flaca!