Design of inclined concrete wall 1

[ranawaseem]

Hi guyz!
How would you design a concrete inclined wall? in ETABS we cannot assign piers to inclined walls..So the other way i think is to use moment contours...but how to design by moment contours?

A wall has 2 out of plane bending moments, 2 out of plane shear components, 1 in plane shear and moment...so if i think to solve this in PCA column as a column then how to convert 2 out of plane bending moments and shears into 1 out of plane bending moment of column? Do I have to use Mmax and Mmin in ETABS or just M11 and M22...Please suggest!

 

[hokie66]

Ever think of using good old pencil, paper, and calculator?

 

[ukengineer58]

Hokie sounds like a case of someone trying to use a computer to solve a problem they dont understand. i agree

 

[ranawaseem]

I agree i dont know about the problem but does any one has got the courage to teach me something?

Or if this is a very basic problem then atleast suggest me something to read....or atleast some tips? anyone?

 

[fcu45]

Hi Rana
As mentioned above, manual calculation can help you here.
I assume you are designing a retaining wall.

So I suggest you to read the retaining walls chapter in this book:
"Principles of Geotechnical Engineering" by Braja M. Das

Good luck

 

[ranawaseem]

i am not designing a retaining wall...i have skewed geometry....a box type roof in plan dimensions are 20m x 20m and height is 12 m....now the wall is slanted so i cannot design this in etabs. because you cannot assign piers to slanted walls..

now my wall will bend under horizontal loads in 2 curvatures...like a slab (2 way) under gravity loads....so i get 2 out of plane moments M11 and M22

the problem is axial force interaction as i have floor supported on these walls..

so how can i design my walls for this interaction?

one thought was to design it as a column...provided that my wall aspect ratios make it one way slab? but its not...its behaviour is 2 way...

so i thought to design it for axial force plus 1 out of plane bending moment (m11) as a columm....and then make another design for the same column for the same axial force and m22...

this will give me conservative design i think...

similary i was thinking to resolve 2 out of plane shear force components of walls namely V12 and V13 to one component by doing SRSS of both and get the value of Vmax or i can directly read this value from ETABS....

as this shear force is parabolic in nature so i can take the average by diving Vmax by 1.5...and apply it to the column design

as in column and wall there is no problem for in-plane moment or shear so that is not an issue....

is my approach correct?...thats all

 

[msquared48]

After you do the manual calculations, shoot the Architect.

Seriously, just apply basic and very conservative concrete design engineering principles. Do not be conservative here or try to cut corners.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[BAretired]

In which direction and how much is the inclination? Are you using Rankine, Coulomb or some other theory for active earth pressure? How high is the retaining wall? What type of soil do you have? Is the groundwater table considered to occur within the height of the retaining wall? What do you mean by piers and why do you wish to assign them to the inclined retaining wall?





BA

 

[BAretired]

I wrote my last post before I read your explanation. Perhaps a sketch or two would help.

BA

 

[slickdeals]

@Ranawaseem,

You should manually check your results in situations such as this one. However, in ETABS, you can define "section cuts", which will give you integrated forces that you will use for design. The only painful part is assigning these section cuts and getting the results.

Also, you will have to manually mesh (explicit) the shell elements in order to be able to calculate the forces.

Another basic (less sophisticated) way to do a sanity check is to define a grillage of frame elements in the model. Then use a membrane element as the "skin" to transfer wind loads to these. That way you will get the moments/shears/axial loads and can be designed as a member with axial/flexural loads.

 

[ranawaseem]

I like slickdeals idea of grillage system...

@BA Retired...i am not designing a retaining walls...please read above...

Some more ideas and if possible some reference of plate analysis with moments and axial forces will surely help...

Thanks all

 

[BAretired]

An inclined wall with axial compression produces horizontal loads, so there could be a problem with stability under gravity loading. If you want any useful help, provide a sketch showing your situation.

BA