Structural Analysis - Automatic Loading Combinations On a Model

[natalierr]

Hi, 

I am quite new to Robot so am a bit unsure about some features. I have tried to find the answer to this online but haven't been able to so far. 

I am in the process of completing a project focusing on the optimisation of a bridge. After some advice and amazing help on this after posting a query, my model is complete.

I now need to apply load combinations to find the maximum stresses in beams, so I can decrease or increase sizes of members accordingly. My design needs to satisfy Eurocode requirements. 

Using this https://knowledge.autodesk.com/support/robot-structural-analysis-professional/learn-explore/caas/Clo... I found that you can automatically apply 'Eurocode code combinations'.

However, it is not clear to me what load combinations they're using, even when expanding the description to include 'code combination components'.

My questions are:

1) Is there a way of getting a more detailed description of what these load patterns are? Do they include the axle forces etc specified in the different load cases in Eurocode 1991-2:2003? Do they include the idea of one lane of the bridge being fully loaded, but the other half not (as this can change where max stresses or moments occur)?

2) When you produce calculations from these loadings, such as 'deflection' or 'stress' etc, is the data calculated for each beam the worst case out of all load combinations for that particular beam? I.e. is that the maximum possible deflection or maximum possible stress that beam will experience according to Eurocode loadings, out of all possible combinations? 

3) My bridge deck has a layer of asphalt that is not included on the model as a component, but I added as a load per m^2 equal to the weight of the asphalt.

Is there a way of adding this to the model so when the 'Eurocode combinations' are ran, it includes this extra weight? Or do I need to model this as a plate and add a custom material with the properties of the asphalt, so it is automatically included in the 'self-weight' load case?

Sorry if these questions aren't clear, I have tried to make them as clear as possible but please let me know if you are unsure what I mean/they don't make much sense!

Thank you in advance for your time/help,

Natalie

[Simau · Accepted solution]

@natalierr 

Here some replies to your questions :

1) Do they include the idea of one lane of the bridge being fully loaded, but the other half not (as this can change where max stresses or moments occur)?

It depends on how you created this load. No, if you created only one load for the whole bridge deck. To get what you expect you must create separate loads each one in each half of the bridge, then when generating combinations with these loads use operator « or (incl) »

2) When you produce calculations from these loadings, such as 'deflection' or 'stress' etc, is the data calculated for each beam the worst case out of all load combinations for that particular beam? I.e. is that the maximum possible deflection or maximum possible stress that beam will experience according to Eurocode loadings, out of all possible combinations? 

Yes, that’s correct

3) My bridge deck has a layer of asphalt that is not included on the model as a component, but I added as a load per m^2 equal to the weight of the asphalt.

Is there a way of adding this to the model so when the 'Eurocode combinations' are ran, it includes this extra weight? Or do I need to model this as a plate and add a custom material with the properties of the asphalt, so it is automatically included in the 'self-weight' load case?

Add asphalt to the bridge deck panel as a dead load using

[natalierr]

Thank you so much @Simau this was extremely useful!