deflection types

Hi everybody,

I´ve got some questions:

I need to know if Karamba calculates the instant deflection of a beam or the deflection along a certain period of time (e.g. 5 years)

I´m using reinforced concrete, is the material homogenous for the calculation or there is a division between steel and concrete?

And the last one, is it possible to export results to an Excel sheet or another format?

Thanks in advance,

Patricia

Replies to This Discussion

Permalink Reply by Karamba3D on October 27, 2014 at 1:26am

Hi Patricia,

Karamba 1.0.5 calculates the deformation assuming linear elastic material behavior. In order to allow for creep, shrinkage and cracking in reinforced concrete you can reduce the Young's Modulus by a factor. For reinforced concrete slabs the influence of shrinkage, creep and cracking can be approximated as follows:

max_f ~ 1.2*(1+phi_inf)/0.6*f_c

here max_f is the maximum deflection at time t=infinite, 1.2 is a factor that takes account of shrinkage, phi_inf is the creep factor (phi_inf~2.5 inside buildings, phi_inf~0.7*2.5 outside of buildings) and 1/0.6 allows for cracking.

Thus the factor for Young's Modulus is

0.6/(1.2*(1+phi_inf)).

The above relation can be found in 'Beton im Hochbau - Handbuch für den konstruktiven Vorentwurf', A. Pauser, Verlag Bau + Technik, Düsseldorf, 1998.

Karamba 1.0.5 assumes an isotropic material for beams. This is normally sufficient for analyzing and designing reinforced concrete structures.

Karamba 1.0.5 offers the possibility to export models via the DAfSt-format which can be read by Robot, RFem and other FE-packagers. However the DAfSt-format does not support shells. Using VB- or C# scripts one has full access to the model properties (see the Karamba Hacker's guide) which can be used to write custom exporters.

Best,

Clemens

Permalink Reply by Patricia Edith Camporeale on October 27, 2014 at 5:12am