staged construction analysis with additional load

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jwoong
Posts: 2
Joined: Fri Feb 25, 2011 6:53 pm
Location: Seoul, South Korea

staged construction analysis with additional load

Post by jwoong » Mon Sep 14, 2020 5:06 pm

Hello,
I attached my simple truss analysis input.
In the first stage, I applied -1000 downward, and I got reaction 500 at both supports. It is OK.
In the second stage, I also applied -1000 downward, and I got reaction 2000 at both supports.
It is double of the correct reaction 1000.
Please let me know how to modify the input to get correct answer.

# Applied load
pattern Plain 1 Linear { load 1 0 -1000 0 0 0 0 }

# Analysis generation
constraints Plain
numberer Plain
system ProfileSPD
integrator LoadControl 1.0
algorithm Linear
analysis Static

analyze 1
puts "##### STAGE 1 - finished #####";

pattern Plain 2 Linear { load 1 0 -1000 0 0 0 0 }

analyze 1
puts "##### STAGE 2 - finished #####";
Last edited by jwoong on Tue Mar 23, 2021 1:01 am, edited 1 time in total.

mhscott
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Location: Corvallis, Oregon USA
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Re: staged construction analysis with additional load

Post by mhscott » Mon Sep 14, 2020 8:56 pm

Your time series are linear, so the load increases every time you analyze and advance to a new step.

xinyue
Posts: 4
Joined: Fri Oct 11, 2019 5:52 pm

Re: staged construction analysis with additional load

Post by xinyue » Wed Sep 30, 2020 5:25 pm

You ended up with a psedo time =2.0 for both loads applied. To correct this, you should make the first load constant and reset time to zero before applying the second load so that the second analysis will start from time 0. Hope this helps!

fmk
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Re: staged construction analysis with additional load

Post by fmk » Mon Oct 05, 2020 8:24 pm

i.e. end of file should look like the following with the loadConst added:

analyze 1
puts "##### STAGE 1 - finished #####";

loadConst -time 0.0

pattern Plain 2 Linear { load 1 0 -1000 0 0 0 0 }

analyze 1
puts "##### STAGE 2 - finished #####";

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