Hi!who could help me about a wood structure analysis with Karamba?

Replies to This Discussion

Permalink Reply by Karamba3D on September 10, 2015 at 1:42am

Before starting a statical calculation it's a good idea to deal with some fundamental questions like where and how is the structure supported and which loads need to be taken into account.

From your pictures it seems as though the wood structure serves as a cladding for an inner core. In that case the main loads would be dead-weight and wind. The wood structure sits on a brick wall which supports it vertically. The main issue seems to be horizontal stabilization. In case the inner shaft can be used for that then only dead weight remains to be taken care of.

There is a component called 'ElementFelting' in Karamba which you might find helpful to model the connections between the wood elements via short beam pieces.

Best,

Clemens

Permalink Reply by oldstory on September 10, 2015 at 3:53am

Clemens, thank you for your reply! I assume the wood struture can be supported by six cantilever steel pillars that hinged to the concrete core, in fact, the core is a old water tank. The dead load is self-weight of the wood structure. Because the wood beams are overlap lay by lay rather than connect in the horizon direction, so I am puzzled how to build a simplified analysis model. The image attached is the axis of wood beam, you can see the axes are not connect on same height and they are staggered. I will try the 'elementfelting' component, if you have better advice, please let me know。Thank you again!! 

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Permalink Reply by oldstory on September 13, 2015 at 3:13am

Clemens, I tried 'ElementFelting'component , and get some small vetical columns at the apparent intersections of axis of beams, in fact, the small column is  not exist between upper-beam and lower-beam, they are just overlaping but their axes are not connected by column.  So I thought the structure analysis model can not represent the true structure. Could you give me some suggestions? Thank you very much!!

Permalink Reply by Karamba3D on September 14, 2015 at 12:05am

Oldstory, you can use the small elements to model the connections between your wooden beams. From the cross section forces in those elements you can e.g. derive an appropriate design for the connection details. In case you know the mechanical characteristics of your wooden joints it is possible to model those by introducing joints with springs at the connection elements.

Best,

Clemens

Permalink Reply by oldstory on September 14, 2015 at 1:34am

Clemens, thank you! According your suggestion, would I assume the small elements are wood matierial columns and the section is intersection of upper-beam's shape and lower-beams shape, or they are small steel bolts?

Another issue puzzled me is ElementFelting component break the each beam into three segments at the small elements and ignore the beam is actually a whole wood beam, I don't know if it will effect the accuracy of analysis. 

Best,

Oldstory

Permalink Reply by Karamba3D on September 14, 2015 at 11:28pm

The small elements simulate the contact between the wooden beams. They can have any material and cross section as long as they keep the wood parts in place.

The fact, that the wooden beams are split into several lines does not affect the result - they are assumed to be rigidly connected.

Best,

Clemens

Permalink Reply by oldstory on September 14, 2015 at 11:45pm

En. I got it. thanx! It means I don't need to set any joint connect at the nodes of small elenents, just put it default. Right?

Permalink Reply by Karamba3D on September 19, 2015 at 3:36am

You should place a rotation joint at the connection element unless you are sure that you can achieve a rigid connection where the wood beams meet.

Best,

C.