Linear Static bolted structure - Bolted connections hard to understand results

[MarceloDeTomasi6989]

Hi, I have been working on a structured bridge like which it is composed of bolted 3 sections through flanges, which the outside sections are identical. I run the Linear Static analysis and get satisfactory results. I have refined the mesh by reducing by 10% each of the 4 times, to check if the results converged. That was relative ok.

I need to validate the structural bolts sizes that joint the flanges in 6 locations. Each flange has 12 bolts. 

I have added the Bolts connectors and the results start to be all over the place. I have also added the pre-tension axial load and make thing worse. I have changed the DECOMPMETHOD=PCGLSS to PSS but still not good.

So which will be the best approach to validate the bolts sizes using bolts connection or other alternative solution.

Proposed Bolts AS1110 Class 10.9 M24 - 190.45kN Pretension - Tensile Strength = 1040 MPa ; Yield Stress = 940 MPa ; Proof Load Stress = 830 MPa min-AJAX Fasteners

IV 2019.1.1 - Nastran In-Cad Version 2019.1.0.200 / Nastran 2019 Version 13.1.0.185

Any help is welcome. Thanks in advance. Marcelo.

[David.Short.]

Hi @MarceloDeTomasi6989,

Thanks for posting. Please can you explain a little more where you want to apply bolts. From the picture that you sent I cannot see where the bolts are supposed to go.

Also it may be useful to upload the model such that we can have a play around with the setup and try and get things running.

Thanks a lot,

David