despite that, I have tried many methods to solve the issue of abnormal stress values around weld joints but all didn't work. why? I applied 100 KN lateral force at the top and fixed the model from sides. the von mises stress is of order 1e10. also, I observed that the maximum stress localized around the welding toe and it seem that the stress doesn't transfer to the other areas although large deformation occurs in such areas as you may observe in the attached figure ??

the methods that I tried to solve the models and did not work are

1. reducing the contact stiffness factor to 0.01.

2. changing boundary and loading conditions.

3. coarsening the mesh at welding joints to overcome the singularity.

4. turning on large deformation option

5. using material properties other than default steel structure properties.

6. slicing and mapping in order to improve the meshing quality.

7. using part option in order to avoid contact issues.

Now, I wonder what shall I do to avoid the solve the problem.

the warnings that appear after solution completes are

1. the maximum contact stiffness is too big...... (in case if used contact options)

2. the deformation is large compared to the model bounding box,....

3. an iterative solver was used for this model.

the model that run to solution and contains the results has been attached for anyone wants to check it. it is ansys workbench 16.1.