Stress Analysis - Nastran - overview

[NachitoMax]

Hi

for an internal project i wanted to run an analysis on some concrete that a family member has had carried out that, in my construction experience, doesnt look that good. Apart from the fact that the concrete base spans a large width, it is only 4in thick, spans about 4 metres and is supported on an existing concrete wall on one side to 3 concrete pillars at 200mm x 200mm on the other. The platform height is 4 metres, the pillars sit atop an existing concrete base of 150mm thick. on top of the platform is a roof platform to the exact same size @3 metres height. There is also a recently added 4 x 2 steel I beam added as the platform dips about 75mm. The hole for the I beam has been made in the centre column directly under the platform...

I think there is a risk of it failing but wanted to run an analysis to sense check.

Does anyone here have enough experience with Stress Analysis or Nastran that can guide me through a typical setup and what i need to be doing in order to get a reasonable result? like a step by step?

do i do this in a block model part or do i need an assembly?

if an assembly, do the members need to be separated or all 1 merged part?

do i need to add gravity load?

do i need to add steel in the column or is there a setting / material that can be used or is it assumed?

Any help is greatly received

Thanks