en Structure-Concrete Structure- Concrete Technical Note Technical Note <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">In recent years, different damage indexes have been introduced in engineering literature. The most prominent one among other</font></font></i></p> <p align="LEFT"><font face="Times New Roman" size="2"><font face="Times New Roman" size="2"><i>counterparts is the 1985 Park and Ang&#39s damage index (DI</i></font></font><font face="Times New Roman" size="1"><font face="Times New Roman" size="1">PA</font></font><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">), which demonstrates well calibration against experimental</font></font></i></p> <p align="LEFT"><font face="Times New Roman" size="2"><font face="Times New Roman" size="2"><i>results. Hence, it has traditionally had broad application in the field of structural engineering. Commonly, in DI</i></font></font><font face="Times New Roman" size="1"><font face="Times New Roman" size="1">PA </font></font><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">relevant</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">parameters are assessed based on plastic-hinge approach, which is not well suited to consider the coupled response between</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">stress resultants (axial force and flexural moment) especially in grossly nonlinear domain. The reason is that named approach</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">is utilized constant shape plastic moment-curvature curve, which is not capable of varying the shape throughout loading history.</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">Another drawback of plastic-hinge method is the difficulty of representing precisely partial yielding of the cross-section. To</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">remedy the situation, the fiber discretization technique is used in this paper. Based on the fiber discretization strategy, not only</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">have the stiffness and strength degradation been characterized more accurately, but also the distribution of plasticity along the</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">plastic zone has been considered. Besides, the multi-directional effect of axial force and flexural moment is considered to assess</font></font></i></p> <p align="LEFT"><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">DI parameters. Additionally, this strategy directly incorporates the effect of transverse confinement into cross sectional</font></font></i></p> <p><i><font face="Times New Roman" size="2"><font face="Times New Roman" size="2">constitutive behaviour.</font></font></i></p> Damage index, Fiber discretization, Multi-directional effect, Transverse confinement 237 246 http://ijce.iust.ac.ir/browse.php?a_code=A-10-93-1&slc_lang=en&sid=1 Reza Abbasnia abbasnia@ IUST.ac.ir 1800319475328460010180 1800319475328460010180 Yes Iran University of Science and Technology Neda Mirzadeh 1800319475328460010181 1800319475328460010181 No Iran University of Science and Technology Kamyar Kildashti 1800319475328460010182 1800319475328460010182 No Iran University of Science and Technology