Load cases and Load Combinations

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vamsio
Posts: 6
Joined: Sat May 09, 2020 8:34 am

Load cases and Load Combinations

Post by vamsio » Sun Jun 07, 2020 9:47 am

How we can analyze a structure for different load cases (say dead load and wind load) and their combinations?

I tried by creating different time series in same py file(refer below code). with same load im getting displacement 4 times more in Time series 2 compared to Time series 1

what can be the reason?


# create TimeSeries
timeSeries("Linear", 1)

# create a plain load pattern
pattern("Plain", 1, 1)

load(5, 1, 0, 0)
# ------------------------------
# Start of analysis generation
# ------------------------------

# create SOE
system("BandSPD")

# create DOF number
numberer("RCM")

# create constraint handler
constraints("Plain")

# create integrator
integrator("LoadControl", 1.0)

# create algorithm
algorithm("Linear")

# create analysis object
analysis("Static")


# perform the analysis
analyze(1)
print(nodeDisp(5,1))

print("SERIES 2")
wipeAnalysis()
# create TimeSeries
timeSeries("Linear", 2)

# create a plain load pattern
pattern("Plain", 2, 2)

load(5, 1, 0, 0)
# ------------------------------
# Start of analysis generation
# ------------------------------

# create SOE
system("BandSPD")

# create DOF number
numberer("RCM")

# create constraint handler
constraints("Plain")

# create integrator
integrator("LoadControl", 1.0)

# create algorithm
algorithm("Linear")

# create analysis object
analysis("Static")


# perform the analysis

analyze(1)
print(nodeDisp(5,1))

mhscott
Posts: 444
Joined: Tue Jul 06, 2004 3:38 pm
Location: Corvallis, Oregon USA
Contact:

Re: Load cases and Load Combinations

Post by mhscott » Tue Jun 09, 2020 7:14 am

You end up with two loads applied and after two time steps with linear time series, you get four times the displacement. You will need to use 'Constant' time series for gravity loads. Or 'Linear' time series but you have to reset the time to zero before you apply time varying loads.
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