Concrete beam/slab/wall example

Hi,

1) Does anyone have an example of concrete beam/slab/wall including a simple calculation of the rebar percentage? I want to do the simple calculations inside grasshopper interface. Not with a external software.

2) Is there a possibility in Karamba to use spring supports? E.g. for calculating a slab on soil.

Thanks in advance.

Halim

Replies to This Discussion

Permalink Reply by Karamba3D on August 2, 2016 at 2:07pm

Hi Halim,

for a beam with rectangular cross section under uniaxial bending, no axial force and the case that the concrete compression zone is not governing the design (i.e. is not utilized to the limit) a common formula for calculating the reinforcement quantity is As = Msd/(0.9*d*fyd). Here 'Msd' is the design bending moment, 'd' the effetive depth i.e. distance between the centroid of the reinforcement and the compressed edge of the cross section and 'fyd' the design strength of the rebars (e.g. 43.5[kN/cm2] for reinforcement steel BSt500). For biaxial bending, compressive or tensile normal force or other cross section shapes the corresponding relations can become quite complex but can be found in standard textbooks.

Regarding reinforcement design formulas for slabs and walls the book 'Plates and FEM - Surprises and Pitfalls' by Johan Blaauwendraad might be helpful (see chapter 16: 'Reinforcement Design Using Linear Analysis').

In Karamba you can generate spring supports by attaching joints with arbitrary stiffness characteristics to the end of fully fixed beams.

Best,

Clemens

Permalink Reply by Halim Yilmaz on August 3, 2016 at 1:35am

Hi Clemens,

Thank you for your response.

Best,

Halim

Permalink Reply by Halim Yilmaz on August 19, 2016 at 3:04am

Hi Clemens,

Is it also possible to generate spring supports for shells?

Best,
Halim

Permalink Reply by Karamba3D on August 22, 2016 at 11:56am

Hi Halim,

in Karamba 1.2.1 there is no direct way. A workaround would be to connect the nodes of the shell via springs to supports. However one has to take into account the area of influence of each node. Thus for a constant modulus of subgrade reaction and an irregular shell mesh the spring stiffnesses will vary from node to node.

Best,

Clemens

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