Acceleration, bridge

Hi Karamba

I’m currently working on a bridge project (pilot project – a space frame construction) where we have used Grasshopper and Galapagos in connection with Karamba. Our main goal for this project is to find an optimized shape of the bridge, and in order to do this we have added following parameters: The curve shape of the bridge, the cross sections, the bridge height and width, the location of the connecting bridge and a few other parameters – I think we have 40-50 parameters (I know it is to many :) ).

Our design criteria’s for the bridge are as following (collected in one fitness function):

Utilization, stress check < 100% (done manually in Grasshopper by using the sectional forces from Karamba)
A minimum allowable natural frequency (the frequency is calculated by Karamba)
A maximum allowable acceleration (planned to be calculated by an expression in grasshopper)

When the three criteria are met, the fitness function will try to reduce the weight of the bridge as much as possible.

My main question is about the acceleration. Before we can calculate the accelerations we need the node point (the location) for the maximum deflection of the mode shape (ex. mode 1). Is this in any way possible?

If we have the location for the maximum deflection, we can add a load in exactly that point and hereby calculate the maximum acceleration.

Besides the main problem I also have a minor problem by showing the deformation:

Deformation for the 1^st mode shape – no problem, deformation figure is shown: