Node Coords & Mass

# import OpenSeesPy and demo modElement
import openseespy.opensees as ops
from opsparser import OpenSeesParser
from ArchBridge2 import ArchBridge2

# first hook all commands before your opensees code
parser = OpenSeesParser(ops)
parser.hook_all()

# some Elementse may have provided some code
ArchBridge2()

Challenge: Determining appropriate new tag values for modElement components

• when you want to add some code after existing code, you may find it difficult to know which new tag to use

• sometimes during parametric studies, change of Elementesize(occupying more tags) becomes problematic due to cascade effect

Common approaches:

1. Using large numbers (e.g., 10001, 20001) to avoid conflicts

2. Configure another way to allocate tags with a little time(but annoying)

Solution: Using automated tag management

We provide two methods for this purpose:

• newtag property: Returns a single new unused tag

• newtag_upper property: Returns a single new unused tag that is max of all tags + 1

• get_new_tags(num:int, start:int = 1): Returns a list of ‘num’ new unused tags

from opsparser import OpenSeesCommand as Command
# Example of adding a new node:
Node = Command.NODE.instance
print(Node.newtag)        # in this case 242
print(Node.newtag_upper)  # in this case also 242

# but what will happen after adding a new node?
ops.node(Node.newtag+10, *[-1,-1,-1])

print(Node.newtag)        # This value remains unchanged until you actually use ops.node(Node.newtag, *coords)
print(Node.newtag_upper)  # in this case not 242

242
242
242
253

# and you can also get a list to build your modElement if you want, like:
print("5 newtag list:")
for tag in Node.get_new_tags(5):
    # ops.node(tag,*coords)
    print(tag, end=" ")

print("\n15 newtag list:")
# if it exceeds 11(252 is already used), it will start from 253
for tag in Node.get_new_tags(15):
    # ops.node(tag,*coords)
    print(tag, end=" ")

# you can also put a large number before it(but your code should be more robust)
print("\n10 newtag list:")
for tag in Node.get_new_tags(10,start = 5000):
    # ops.node(tag,*coords)
    print(tag, end=" ")

5 newtag list:
242 243 244 245 246
15 newtag list:
253 254 255 256 257 258 259 260 261 262 263 264 265 266 267
10 newtag list:
5000 5001 5002 5003 5004 5005 5006 5007 5008 5009

# similarliy, we have these property & method for Elementements and materials and so on
Element = Command.ELEMENT.instance
print(Element.newtag)
print(Element.newtag_upper)
print(Element.get_new_tags(5))

Material = Command.MATERIAL.instance
print(Material.newtag)
print(Material.newtag_upper)
print(Material.get_new_tags(5))

440
440
[440, 441, 442, 443, 444]
5
602
[5, 6, 7, 8, 9]