Grasshopper

algorithmic modeling for Rhino

# Glulam Simulation

Hi all,

Am attempting to simulate a glulam structure for a project we have in school...

Specifically the product we're working with is

GL32h HASSLACHER NORICA TIMBER

E (Number) Young's Modulus [kN/cm2] of the material :1370.0

G (Number) Shear Modulus [kN/cm2] of the material : 85.0

gamma (Number) Specific weight [kN/m3] of material : 4.2183

alphaT (Number) Coefficient of thermal expansion [1/C°] of the material: -

fy (Number) Yield strength [kN/cm2] of the material.

2.9 COMPRESSION

2.25 TENSION

Have input these values into Karamba but however a singular stiffness matrix error is returned from the Analyse THI & THII components. I understand that this is due to the G value having to be between E/2 and E/3. Is there however any way to get around this though? To simulate the actual characteristics as closely as possible

Thanks!

Kendrick

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### Replies to This Discussion

Hi Glulam.
This error occures when the structures is ill-conditionated.
Check the support and also the release in the beam element.
If you post your definition, we can have a look and give you a suggest.
Cheers
Marco

Hi Kendrick,

at the moment (version 1.2.2) there is this limitation for the transverse shear stiffness you mention. In version 1.3.0 this limitation will be lifted.

The shear stiffness influences the results only in case of very compact beams.

Best,

Clemens

Hey Clemens,

what would then my options be if I wanted to analyse a block glulam bridge section which is also curved in top view? I modelled the curvature with a polyline but I'm wondering about the accuracy of the calculation when my shear modulus is unrealistic.

Also, since I'm already asking, is there a way to display values of a moment/force diagram only at a specific point and not the entire range?

Cheers,
Matej

Hey Matej,

in Karamba 1.3.0 the problem with the transverse shear stiffness will be solved.

With the 'BeamForces'-component you can retrieve the cross section forces in multiple points along the beam axis. You could then interpolate the values to get a specific cross section force component at an arbitrary position.

Best,

Clemens

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