The aim of this study is to assess the performance objectives defined in the Iraqi Seismic Code (ISC) in order to make a realistic evaluation related to Performance-Based Seismic Design (PBSD) of multi-story reinforced concrete buildings and also to compare and evaluate structural response demands obtained from nonlinear static analysis procedures according to two versions of the capacity spectrum method (CSM) which are recommended in ATC 40 and ATC 55. Two groups of three-dimensional RC buildings with different heights, designed according to Iraqi Building Code Requirements for Reinforced Concrete (IBC), are investigated. Pushover analyses are carried out to determine the nonlinear behavior of the buildings under three different seismic hazard levels, for two Iraqi seismic zones, of earthquake loads. In order to determine performance levels of the buildings, maximum inter-story drift demands and plasticizing sequence are determined and compared with the related limits using the CSM recommended in ATC 40 and ATC 55. From the results of this research, it can be concluded that RC buildings designed according to the Iraqi codes sufficiently provide the performance objectives stipulated in the ISC. Comparing structural response quantities obtained from the two versions of CSM, effects on performance evaluations of the buildings are investigated comparatively, as well.

In this paper, nonlinear response of reinforced concrete circular tunnels subjected to seismic loads in clayey soil is presented. A series of two dimensional finite element models were adopted to investigate the dynamic behavior of tunnel soil system. The influence of several parameters including ground motion intensity, soil type, tunnel depth and tunnel diameter on the tunnel response was computed. Firstly, 1D equivalent-linear viscoelastic analysis was conducted in the frequency domain to evaluate the profile of Rayleigh damping coefficients. Hence, these profiles were used in order to simulate the 2D fully coupled finite element adopting visco-elasto-plastic effective stress models for the soil. The dynamic behaviour of tunnel was presented in terms of internal forces induced in tunnel lining. The analyses indicated that in case of the stiff clay, the results of closed form solution were close enough to the 2D analysis and the earthquake effects are considerable when the tunnel is close to the bed rock. In case of medium clay deposits, the effects vary according to the tunnel dimensions. Furthermore, Soft clay soil yielded when it exposed to earthquakes of greater than 0.5g magnitude. Earthquakes of 0.25g magnitude have a slight effect on the circular tunnels located at any depth in clayey deposit, but if another time domain are used with the same beak ground acceleration value, different effects might appear.