I'd like to analyze a cabled truss structure with opensees which includes both bar and cable elements. As I know bar elements are under tension and compression but cable materials are just under tension. First, how can I define a cable element with pre-stressed value, second, how can I intermix both bar element stiffness and cable stiffness to analyze it nonlinearly ? I know how to define a bar element in opensees but how about a cable element?
Any comment would be appreciated
Thanks in advacne
Hi. Hope I can help you.
(i) Try EPP material in OpenSees. The yield stress in compression can be defined as zero. For cable, I suggest that you can try coroTruss element.
(ii) I can not understand your question.
Hi,
I think an eigenvalue analysis may not be possible with the cable element. for similar problem of spring in compression I used same beam element with moment and polar moment of inertia as very low values and mass density also as very low values so that the member fundamental frequency in bending and torsion are more than the cut off fraquency. also at one of the suitable ends of the member, release the rotational DOF and keep only the translatory DOF connected. Once you complete the response spectrum analysis while checking the cable element subtract and add the axial force obtained from the response spectrum analysis to the pre tension in the cable. you will find that the tension has reduced and increased. see that the tension is not reduced to zero and that it is not more that the capacity of the cable for earthquake condition
Thank you so much dear Zhongkui and Arun for giving me some leads to follow. I will test them and report soon.
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