Change the section of the member during analysis

[ybala]

The existing building should be rehabilitated. How can I apply the gravity loads to the existing structure;then, change the sections of the columns and apply the seismic loads to the retrofitted building?

[mhscott]

You can use the parameter and updateParameter commands. The parameter command depends heavily on the type of element and section models you are using.

# e.g., identify moment of inertia of element 1 as a parameter
# this assumes a beam-column element is used with elastic sections
# if you are using other section models, e.g., fiber, this command would change
parameter 1 element 1 I

# change the value of parameter 1 to a new value, e.g., 210.0
updateParameter 1 210.0

[ybala]

Thanks so much for the response. Would you please give an example using fiber sections for the element and apply the parameter and updateParameter commands to change the sections?

[mhscott]

To change a geometric property of a fiber section, you have to use one of the "canned" fiber section commands

section WFSection2d (http://opensees.berkeley.edu/wiki/index ... ge_Section)

parameter 3 element 1 param

The valid entries for param in the above command are

overall depth "d" -- parameter 3 element 1 d
flange width "bf"
web thickness "tw"
flange thickness "tf"

Take a look at the setParameter method of the WideFlangeSectionIntegration class for valid strings

http://opensees.berkeley.edu/WebSVN/fil ... ration.cpp



section RCSection2d (http://opensees.berkeley.edu/wiki/index.php/RC_Section)

The valid entries for param are

overall depth "d"
overall width "b"
cover "cover"
area of each rebar on top layer "Atop"
area of each rebar on bottom layer "Abot"
area of each rebar on sides "Aside"

Have a look at the setParameter method of the RCSectionIntegration file

http://opensees.berkeley.edu/WebSVN/fil ... ration.cpp

[ybala]

Thanks.

In the model, the columns are created by Fiber section ,and the residual stress is considered for the section.(Section Fiber 1300):

section Fiber 1300 {
# Top flange
patch quad ...
}
# Bottom flange
patch quad ...
}
# web
patch quad ...
}

I want to add plates to the existing section which has the different section tag, (e.g., section Fiber 1400). The existing and new sections have the following differences:

1. Different thicknesses and widths
2. Different yield stress
3. The residual stress is not considered for the plates

Is it possible to create two fiber sections with different tag sections, apply the gravity load to the existing section (section Fiber 1300); then, replace the existing section(section Fiber 1300) by the new section (section Fiber 1400) , and proceed the analysis with another load pattern?

[mhscott]

You could define the plates too, but set their stiffness to zero (or something relatively small) initially, then update parameter E when you are ready to do the second stage of analysis.

Use the material tag of the plate material, say 3, when defining the parameter

parameter 1 element 5 material 3 E

updateParameter 1 0.0

do analysis

updateParameter 2 30000.0

analyze again

[ybala]

Thanks so much.

When I use the Parameter Command, this error is appeared:
Parameter:: Parameter 1 -- error encountered while attempting to identify parameter material 3 E

Would you please let me know how I can solve this error?

Thanks.

[mhscott]

The 3 refers to the tag of the material that has parameters you want to update

[ybala]

Exactly. In this example, the material tag is 100. The parameter command has been written for element 111; but, it does not work, and I received the error that I mentioned in the previous post.

uniaxialMaterial Steel02 100 $Fy $E [expr (0.1 * $Fy / 0.04) / $E] 30 0.925 0.15 0.4 22 0.4 22 ;

patch quad 100 20 1 [expr -$hc/ 2. - $Plate_t ] [expr -$Plate_b / 2.] [expr -$hc / 2.] [expr -$Plate_b / 2.] [expr -$hc / 2.] [expr $Plate_b / 2.] [expr -$hc / 2. - $Plate_t] [expr $Plate_b / 2.]

for {set i 111} {$i <= [expr $NELEMCOL + 110 - 1 ]} {incr i 1} {
element nonlinearBeamColumn $i ......;
}

parameter 1 element 111 material 100 E

updateParameter 1 0.0

Do analysis

updateParameter 1 200.0

Do other analysis

Would you please let me know which part is incorrect that the Parameter Command does not work?

Thanks.

[mhscott]

The parameter commands are not currently enabled for Steel02. You should try Steel01 for now to see if your approach is working.

[ybala]

Thanks so much.

[ybala]

I checked the section with Steel 01, and it does not work, either. Here is the error:
Parameter::addComponent 1 -- no objects were able to identify parameter material 100 E

What is the problem to receive this error?
Should I write the "Parameter command" after introducing the material, section and element of the member?

[mhscott]

Yes

[ybala]

But I still have this error. How should I solve it?

[mhscott]

Can you post your Tcl script, or atleast the relevant portions?