Shear LimitCurve
This command is used to construct an axial limit curve object that is used to define the point of axial failure for a LimitStateMaterial object. Point of axial failure based on model from Chapter 3. After axial failure response of LimitStateMaterial is forced to follow axial limit curve.
| limitCurve Axial $curveTag $eleTag $Fsw $Kdeg $Fres $defType $forType <$ndI $ndJ $dof $perpDirn $delta> |
| $curveTag | unique LimitCurve tag |
| $eleTag | integer element tag for the associated beam-column element |
| $Fsw | floating point value describing the amount of transverse reinforcement <math>(F_{sw} = \frac{A_{st}f_{yt}d_c}{s})</math> |
| $Kdeg | floating point value for the slope of the third branch in the post-failure backbone, assumed to be negative (see Figure 4-6) |
| $Fres | floating point value for the residual force capacity of the post-failure backbone (see Figure 4-6) |
| $defType | integer flag for type of deformation defining the abscissa of the limit curve
1 = maximum beam-column chord rotations 2 = drift based on displacment of nodes ndI and ndJ |
| $forType | nteger flag for type of force defining the ordinate of the limit curve. See NOTES 1.
0 = force in associated limit state material 1 = shear in beam-column element 2 = axial load in beam-column element |
| $ndI | nteger node tag for the first associated node
(normally node I of $eleTag beam-column element) |
| $ndJ | integer node tag for the second associated node
(normally node J of $eleTag beam-column element) |
| $dof | nodal degree of freedom to monitor for drift. See NOTES 2 |
| $perpDirn | perpendicular global direction from which length is determined to compute drift. See Notes 2. |
| $delta | drift (floating point value) used to shift axial limit curve |
NOTES:
- Options 1 and 2 assume no member loads
- 1 = X, 2 = Y, 3 = Z
EXAMPLE:
DESCRIPTION:
Modeling Failures in Existing Reinforced Concrete Columns by Ken Elwood: File:ElwoodCJCE2004.pdf
REFERENCES:
Elwood, K.J and Moehle, J.P., "Shake Table Tests and Analystical Studies on the Gravity Load Collapse of Reinforced Concrete Frames", Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA. PEER 2003/01.
Code Developed by: Ken Elwood, University of British Columbia