topic Re: Self-weight of Structure in Structural Bridge Design Forum

Self-weight of Structure

Anonymous — Fri, 05 Apr 2019 05:22:08 GMT

Afternoon All

I am designing a precast, pre-stressed concrete bridge with no topping slab. I'm using the detailed analysis tool in ASBD 2019 as the bridge has come complicated geometry to it.

When looking at adding loads to the bridge, I can't work out how to ask the program to calculate the self-weight. I understand that if you've created design beams it will do it for you, however I seem unable to create a design beam using a single cross-section. An error box appears saying that the section is incomplete.

Thanks in advance.

Tom

I understand that once you have created a design beam you can ask ASBD to automatic

Re: Self-weight of Structure

dave_geeves — Sun, 07 Apr 2019 14:13:08 GMT

Hi, I think the simplest process is to add a nominal insitu slab of say 10mm by 10mm (possibly smaller but me careful of ill conditioning). This will have very little effect on the analysis results and will allow volume loads to be created. If this has answered your query please mark this post as a solution so that others can find it more easily. Regards Dave Geeves

Re: Self-weight of Structure

Anonymous — Mon, 08 Apr 2019 01:17:45 GMT

Thanks very much for that Dave, will give it a shot.

Re: Self-weight of Structure

dave_geeves — Mon, 08 Apr 2019 13:11:36 GMT

Hi Tom,

I should have added that you could assign a “design section” to th structural members instead of a “design beam” and still use the member volume loads to define the self weight.

Regards

Dave Geeves.

Re: Self-weight of Structure

Anonymous — Wed, 10 Apr 2019 09:06:05 GMT

Thanks Dave

Do you mean manually calculate the SW load through using the area of the cross-section and multiplying by the weight?

I've tried your other method and it seems to have worked well, thanks for that. However, is there any way to copy across these load cases so they can be used in compilations? I understand you can transfer results back to the design beam but I can't see how to find the graphics (in the detailed model) displaying:

- The deflections for serviceability compilation cases.

- The total reaction loads for piers.

I guess what I'm getting at is that I'd like to see how the structure performs as a whole (in the detailed analysis) compared to individual design beams.

Cheers

Tom

Re: Self-weight of Structure

simon_hooper — Thu, 09 May 2019 17:36:21 GMT

Hi Thomas

Just picking up on this thread. You may have found by now, File | Results is the command to give access to the full structural analysis results.

Regarding SW load, Dave was suggesting you can use the structure loads type "Beam Member Load - Beam Element Load" and set the "Load Value" type to volume. The force value specified is the value per unit volume of the member to which the load is applied.

Simon

Re: Self-weight of Structure

Anonymous — Tue, 26 May 2020 10:06:18 GMT

Hello,

I am trying to check the vertical deflections of the bridge just taking into account the self weight of the structure but I am not sure if the analysis does consider the SW in the calculations or you have to add the load manually.

The problem is that I can´t set the results just to show the SW reactions if I don´t add a specific SW load.

Any thoughts?

Thanks