block2d

[ali2012]

hello to all

suppose we want define a plate and mesh that.in the block2d command should we define coordinates of node 1 to 4 for the 4 nodes of the plate? i mean that, should i enter the coordinates of the 4 node of the plate in the node 1 to 4 in the block2d?

another question:i want to define a plate and mesh that.then i want to place 4 springs in the buttom of the 4 nodes of the plate.so i shoud define 8 nodes in the 4 node of the plate and then use zeroelement for define the spring.

program runs from first to the block2d very good. but when reach at the block2d command, give error:
Domain: : addNode - node with tag 1 already exists in model
WARNING failed to add node to the domain
node : 1

while executing
"block2D 10 10 1 1 shellMITC4 "2" {
1 1 0 0
2 -1 0 0
3 -1 0 2
4 1 0 2
}"

even i changed the nodetags that i defined in the first of the program, but yet i get that error, but in this way in the last:warning, node: 10
whats the problem
what can i do??

code:

wipe
wipeAnalysis
model basic -ndm 3 -ndf 6
puts "ndm=3, ndf=6"

node 10 1.0 0.0 0.0
node 11 -1.0 0.0 0.0
node 12 -1.0 0.0 2.0
node 13 1.0 0.0 2.0
node 14 1.0 0.0 0.0
node 15 -1.0 0.0 0.0
node 16 -1.0 0.0 2.0
node 17 1.0 0.0 2.0
puts "Node definition"

uniaxialMaterial Elastic 1 200000
puts "uniaxial material definition"

section ElasticMembranePlateSection 2 200000000000 .25 .02 7800
puts "section definition"

fix 14 1 1 1 1 1 1
fix 15 1 1 1 1 1 1
fix 16 1 1 1 1 1 1
fix 17 1 1 1 1 1 1
puts "constraints definition"

element zeroLength 1 10 14 -mat 1 -dir 2
element zeroLength 2 11 15 -mat 1 -dir 2
element zeroLength 3 12 16 -mat 1 -dir 2
element zeroLength 4 13 17 -mat 1 -dir 2
puts "zero elements definition"

block2D 10 10 1 1 shellMITC4 "2" {
1 1 0 0
2 -1 0 0
3 -1 0 2
4 1 0 2
}
puts "block2d definition"

set bamaccel "Series -dt .005 -filepath bamaccel"
puts "bamaccel definition"

pattern UniformExcitation 1 2 -accel $bamaccel
#start of the Transient Analisys
puts "uniform excitation definition"

test EnergyIncr 1e-10 100 2
algorithm Newton
numberer RCM
constraints Plain
system SparseGeneral -piv

integrator Newmark 0.5 0.25
analysis Transient

analyze 13312 0.005
puts "done!"

[vesna]

block2D command creates nodes tags for you. Check this example to see how it does: http://opensees.berkeley.edu/wiki/index ... d_elements

[ali2012]

hello
thanks a lot vesna
i understood that but what about nodes for defining springs. for defining springs i shoud define zerolengthelements. in my plate, instead of support, 4 springs exist in the buttom of the plate. block2d or block3d define nodes for plate or shell but what about 4 nodes with same coordinate with 4 nodes of plate.i want use uniaxialmaterial for the zerolength elements.
please help me.

[ali2012]

hello to all
my previous question solved.

another questiojn: how we can input distributed uniform load on the surface of the plate with unit of N/(m^2)???
i think eleload is not a suitable command. what command we should use to define uniform distributed load for static analysis(for the plate and shell)???

[vesna]

As of now there is no way to specify distributed uniform load on the plate element.