Dir. nodal mass for dynamic analysis: inclined solar plates

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tguha
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Joined: Tue Jul 18, 2017 8:44 am
Location: NexTracker

Dir. nodal mass for dynamic analysis: inclined solar plates

Post by tguha » Fri Sep 15, 2017 11:27 am

Hello,
I am trying to carry out a transient analysis under wind loading on a solar racking system in which the solar modules are inclined at 30 degree to the horizontal plane (ground), the x-z plane. The problem is 3 dimensional with 6 degrees of freedom. The y-axis is vertical to the ground (direction of gravity loading is negative y) and z-axis (on the x-z plane) is along the longitudinal direction of the structure (i.e. along the larger dimension of the racking system). In other words, the solar modules are not co-aligned to any of the global x, y and z axes rather inclined 30 degrees to the ground. The wind force time histories (uplift and downforce) are expected to act normal to the solar modules, meaning the forces can be resolved along x (sin component) and y (cos component) axes. There are no wind forces acting along the z (longitudinal axis) direction of the structure. As mentioned, the self weight of the system is expected to act in the negative y direction. Under the circumstances, for transient analysis, do I have to assign mass (Self weight/g) along both x and (neg.) y direction for all the 700 nodes that I have in the model?? Since the cross sectional properties of the elements and their mass densities making up the whole structure vary across the structure (I have about 8 different section types), do I have to individually calculate the mass (Self weight of the element/g)of each of the connecting elements and then equally distribute the mass into the connecting nodes along x and y direction?? If yes, this does seem a pain staking process for 500 odd elements and 700 nodes. Also, as I understand, on top of that, do I also have to define a constant time series and a gravity load pattern to apply the total self weight of the entire structure in the neg. y direction?? Is my understanding correct?? I appreciate all your inputs to the problem.

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