×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Smearing rebar material properties

Smearing rebar material properties

Smearing rebar material properties

(OP)
Is there an equation to smear the modulus of elasticity of rebar on a solid element.

I have a 3D model of a concrete structure and only the concrete is modeled as an isotropic material.  The natural frequency is coming out to be too low.  I wanted to smear the stiffness of rebar without changing the element type to a concrete element.  Is there a easy way of doing this.

Thanks,

RE: Smearing rebar material properties

rh142:

E(composite)=E(concrete) AREA(concrete) + E(steel) AREA(steel)

and

AREA(concrete)=1.0-AREA(steel)

AREA(steel) = % steel expressed as a decimal i.e. 1%=.01

Ed.R.

RE: Smearing rebar material properties

Unless the rebar is closely spaced enough and in an even mesh pattern (including vertically), you may have to switch to an orthotropic brick so that you can differentiate material properties along the element axes.  For instance, if the rebar is running along the x- and y-axes, but not the z-axis, you will need to increase the x- and y-moduli, but not the z-modulus.

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
Magnitude The Finite Element Analysis Magazine for the Engineering Community

RE: Smearing rebar material properties

EdR,

Don't you mean the following:

E(composite)=  

    E(concrete) AREA(concrete) + E(steel) AREA(steel)
                  TOTAL AREA

??


RE: Smearing rebar material properties

(OP)
thanks for all your responses, for the orthotropic material will the shear modulus change the same way? What about poisson's ratio?

GregLocock,
I don't understand the neutral axis if its being modeled with solid elements

Thanks,

RE: Smearing rebar material properties

JAE:

Nope...By defining the Area's as I did the total area becomes 1.0 and you don't have to consider the total area of each element.....

rh142:

It's probably a decent first approximation to use the same idea for the shear modulus...Once you have E and G Poisson's ratio's are defined.....You may have to look up the orthotropic (anisotropic?) relationships between E, G, and Nu....

Greg:

True if bending is present...Typically when using this technique the element size is controlled so that the smeared properties are representative of each region (and as Garland said also in each direction) ...Thus if bending was present one would have multiple elements, each with a different % of steel, to represent the various regions....The technique can be extended to bending elements by extending the "transformed section method" of composite materials but it becomes complicated.....


Ed.R.

RE: Smearing rebar material properties

EdR - thanks...I missed that % that you were using.

RE: Smearing rebar material properties

Ah OK, I was thinking beam elements, not bricks.

Cheers

Greg Locock

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources