Effect of Ground Motion Sequence on Response of Squat Reinforced Concrete Shear Walls

Most industrial and nuclear facilities rely on reinforced concrete structural walls as their primary seismic lateral-force-resisting components. In nuclear facility structures, squat walls commonly have an aspect ratio lower than 0.5 and are designed to be thick for radiation shielding and blast and fire protection. The combination of a squat and thick wall geometry causes very high wall stiffness and strength. However, there is significant uncertainty about expected strengths, deformation capacities, and failure modes of these walls in earthquake load sequences, such as main-shock/aftershock combinations. Hybrid simulation is an effective experimental method to examine these issues: it enables simulation of the seismic response of squat and thick shear walls without the need to recreate the often very large mass associated with the remainder of the prototype structure. A hybrid simulation program utilized two shear wall specimens to investigate the variations of squat wall responses caused by different earthquake magnitude sequences. The results of these simulations indicated that different earthquake magnitude sequences do not have a significant effect on the force-deformation response and failure mode sequence of squat reinforced concrete shear walls.