Flag

Symmetric/Asymmetric Flag

Some self-centering and rocking systems show flag shaped hysteresis behavior. The Flag01 model defines a symmetric flag shaped hysteresis rule. The Flag02 model is an extension of the Flag01 model and defines an asymmetric flag shaped hysteresis rule.

More flexible flag shaped hysteresis behavior can be achieved by combining multilinear elastic model with for example bilinear hardening model.

Syntax

material Flag01 (1) (2) (3) (4) (5)
# (1) int, unique material tag
# (2) double, elastic modulus
# (3) double, yield stress, positive
# (4) double, residual stress, can be either positive or negative
# (5) double, hardening ratio

material Flag02 (1) (2) (3) (4) (5) (6) (7) (8)
# (1) int, unique material tag
# (2) double, elastic modulus
# (3) double, tension yield stress, positive
# (4) double, tension residual stress, can be either positive or negative
# (5) double, tension hardening ratio
# (6) double, compression yield stress, negative
# (7) double, compression residual stress, can be either positive or negative
# (8) double, compression hardening ratio

History Variable Layout

location	value
initial_history(0)	tension_reverse_strain
initial_history(1)	tension_reverse_low_strain
initial_history(2)	compression_reverse_strain
initial_history(3)	compression_reverse_low_strain

Remarks

1. Flag01 is a wrapper of Flag02.

2. If Flag01 is used, the compression yield stress and residual stress would be -(3) and -(4) so that the response would be symmetric.

Usage

material Flag01 1 1000 10 3 .1
materialTest1D 1 1E-3 20 2 7 5 10 20 10 50 10 5 20 10 12 25 40
exit

example one

material Flag02 1 1000 10 3 .1 -20 -5 -.1
materialTest1D 1 1E-3 20 2 7 5 10 20 10 50 10 5 20 10 12 25 40
exit

example two