1 Kul Finite element method II – Vibration of a four storey building

2 Model to be constructed Model the columns in the building as deformable bodies and the floor as rigid bodies. The aim is to obtain the first three natural frequencies of the building. t H d W L X Y Z

3 In the Part –module: Create material geometries Create partitions for –Separation of columns into bolts and nuts-washers –Easy construction of columns and floor components

4 Create a beam (3D, deformable, wire, planar) in the Part –module.

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6 Take the stiffening effect of the nuts and washers into account. Divide the beam into three different parts using Datum points and Partition edge.

7 Create a shell element (3D, deformable, shell, planar) in the Part –module. (Rigid body will be assigned later)

8 Create a surface partition in the Part –module for easy construction of the assembly.

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10 In the Property –module: Create material profiles for steel and aluminum Create and assign sections –Two for the steel beam: a) beam and b) nuts and washers –One for the shell element

11 Determine steel as the material for beams in the Property –module.

12 Define aluminum as the material for shell in the Property –module.

13 Take the stiffening effect of the nuts and washers into account. Determine the profiles for the different parts of the beam in the Property –module.

14 Create and assign the profile for the shell element in the Property –module.

15 Assemble the parts in the Assembly –module. Create a new part from the assembly using the Merge –function. Operations Rotate and Translate instance as well as Linear pattern are useful.

16 Go back to the Property –module and assign beam orientations and shell/membrane normal to the components of the merged assembly. Assign beam orientation - Note that n1 is perpendicular to x-axis of the beam Assign shell/membrane normal

17 Define a new step for the linear perturbations in the Step –module. Select Step Manager → Procedure Type → Linear Perturbations → Frequency Select number of eigenvalues requested, e.g. 5.

18 Define each floor as rigid bodies in the Interaction – module. First, create reference points RP on each floor, e.g. RP1,... Then, create constraint and tie each RP to corresponding floor.

19 Take into account fixed boundary condition in the Load – module. In the case of rigid bodies the boundary condition is applied to the reference point.

20 Define the element size and mesh the structure in the Mesh –module.

21 Submit and run the analysis for in the Job –module.

22 See your results and determine the first three natural frequencies using Step/Frame (under Results)

23 See your results and determine the first three natural frequencies using Step/Frame (under Results)