×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Composite action in slab of timber and concrete, deflection

Composite action in slab of timber and concrete, deflection

Composite action in slab of timber and concrete, deflection

(OP)
I have modelled a composite floor slab of 200 mm timber with 120 mm concrete on top (also called a TCC). I am trying to verify the deflection given by Abaqus with the analytical solution given by the "gamma method". My problem is i can not get close enough results. My Abaqus result show a midspan deflection of 6 mm while the gamma method shows a deflection of 3.3 mm. Any guidance will be very appreciated!

I first want to study 100% composite action. In the gamma method i use gamma equals to 1 and in Abaqus i set the connection between the concrete and timber surface to "tie".

Dimensions:
Concrete: 8x2.4x0.12 m
Timber: 8x2.4x0.2 m

Material data:
Concrete
E-modulus: 33 Gpa
Poisson: 0.2

Timber
E1: 12GPa
E2: 0.5 GPa
E3 0.9 GPa
Nu: 0.3
G12: 600 MPa
G13: 600 MPa
G23: 60 MPa

Load and BC:
Load: 3500 N/m2
BC: Pinned in one end and locked in Z in one end (simply supported).


RE: Composite action in slab of timber and concrete, deflection

I haven't done any timber and concrete composites, but I've done alot of steel and concrete composite beams. For those, we transform the concrete into a equivalent area of steel by dividing by the modular ratio (Esteel/Econcrete) to calculate the moment of inertia. Then we'd use calculated I and the E for the material that wasn't transformed (in our case, steel) to calculate the deflection.

RE: Composite action in slab of timber and concrete, deflection

(OP)
Could you elaborate a bit? If i have concrete height 0.12 and timber 0.2 with Ec=33GPa and Et=12GPa, the modular ratio becomes: Ec/Et=12/33=0.3636... How do i use the ratio to transform the timber part to a concrete part?

RE: Composite action in slab of timber and concrete, deflection

You would multiply the width of the timber by .3636, maintaining the height, to model it as an equivalent area of concrete, in order to do the section properties calculations. The I and S that you get, would be equivalent to a section that was all concrete. Then you can calculate the deflection using the I you calculated for the transformed section and Ec.

Edit: That assumes that the timber and concrete actually make a composite section, i.e. there is a rigid connection between the two with enough shear capacity for them to act as a single piece. Otherwise, you just calculate the bending stiffness using Ic*Ec and It*Et and sum them.

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close