How to add a sequence cyclic load (force then displacement Cycles) and obtain hysteresis curves ?

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Moh.Sarwat
Posts: 2
Joined: 16 May 2020, 03:06

How to add a sequence cyclic load (force then displacement Cycles) and obtain hysteresis curves ?

Post by Moh.Sarwat »

I am modelling a experimental test of steel coupling beam with cyclic loads to obtain (shear-strain and shear-chord rotation) hysteresis curves. I need help to know: How to add a sequence cyclic load start with force cycles following by displacement cycles to get this hysteresis loops ?

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seismosoft
Posts: 743
Joined: 06 Jul 2007, 04:55

Re: How to add a sequence cyclic load (force then displacement Cycles) and obtain hysteresis curves ?

Post by seismosoft »

You can do this in two ways:
1) The easier is to use the static time-history analysis type, with a combination of force and displacement time-history loads. The force loading should be zero in the second part of the analysis and the displacement load should be zero in the first part of the analysis. Note however that this might not be feasible in the cases when the DOFs, where the displacement loads are applied in the second phase, need to be free to deform in the first part
2) With pushover analysis, using a sequence of load control and response control phases in opposite directions, i.e. (i) load control +X, (ii) load control -X, (iii) response control, +X, (iv) response control -X etc.

In any case, note that typically a static time-history analysis with displacement hysteretic loads should normally be sufficient in most cases of tests.
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Moh.Sarwat
Posts: 2
Joined: 16 May 2020, 03:06

Re: How to add a sequence cyclic load (force then displacement Cycles) and obtain hysteresis curves ?

Post by Moh.Sarwat »

Thank you for your quick response, I had tried the first way and i got a warning message at the beginning of the analysis said: "node n1_B4 is already loaded in the z direction.the last load in this direction is cancelled"

Attached are pictures for the assigned cyclic loads , and the warning message that i got
https://we.tl/t-bJJkINPmhi

This link is for the seismostruct model if you could check it and advice me for this issue
https://we.tl/t-mHcPAcdHvf

Thank you in advance

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seismosoft
Posts: 743
Joined: 06 Jul 2007, 04:55

Re: How to add a sequence cyclic load (force then displacement Cycles) and obtain hysteresis curves ?

Post by seismosoft »

As I explained in my previous message, you cannot apply on the same DOF simultaneously a displacement and a force time history.
You might want to try with the pushover analysis with a sequence of phases.
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