Abstract
A damage index for seismic performance of RC members is proposed on the basis of 3D multi-axial fiber analysis. The elasto-plastic and fracturing model for concrete compression is applied for estimation of the fracture parameter, which is defined as the reduced elastic stiffness for each micro-cell component of member cross sections. The averaged fracture parameter over the cross section is treated as the index of cross-sectional damage for the remaining axial force-carrying mechanism. This index provides an approximation of damage related to seismic performance level II (reparable after seismic actions) not only for one-directional but also multi-axial flexure. This method is also effective for RC members confined by lateral ties.
