In recent years, researchers have taken advantage of the nonlinear characteristics of the underlying soil to mitigate the excessive seismic force demands on the superstructure under earthquake excitation. For this purpose, the conventionally designed foundation can be replaced with rocking foundation. This is achieved by under proportioning the shallow foundation. Although the mechanism of rocking foundations has been well documented, there remains a gap in developing a methodology for reduction of foundation sizes in multi storey Reinforced Concrete (RC) shear wall framed structure. Therefore, this study focuses on the seismic responses of a shallow foundations supporting a multistorey RC shear wall framed structure. The foundation for RC shear wall is proportioned by gradually reducing the earthquake load considered for the foundations to enhance the increased rocking effect and to mitigate seismic force demands. Thereafter, key parameters responsible for seismic behavior of sub-structure are being compared with conventionally designed foundation with increasing foundation rocking, by varying type of underlying soil and with increasing height. Seismic behavior obtained by implementing a series of nonlinear time history analyses indicates that the foundation rocking greatly influences the dynamic properties. With increasing degree of foundation rocking, natural fundamental period of the overall structure gets lengthened, with decreasing peak roof acceleration, thereby mitigating the peak base moment and base shear experienced at the shear wall compared to conventionally designed foundation. On the other hand, it is observed that there is an increase in roof displacement and shear wall settlement at the foundation level. It is found that the foundation of shear wall can be designed by considering 40%, 60% of earthquake loads for zone V and zone II structural designs, respectively without encountering excessive settlements. From the sensitivity analysis it is highlighted that the foundation size and design seismicity impact the base shear contribution ratios between shear wall and column members, fundamental natural period and foundation settlement.

This paper examines the effects of near-field pulse-like earthquake ground motions (GMs) on the seismic resilience, repair cost and time, and structural collapse risk of low-to-high-rise selected multi-story RC structures with special moment-resisting frames (SMRFs) and shear walls. Selected 5-, 10-, and 15-story structures are designed based on a seismically active region where pulse-like GMs are more likely to occur. Two different sets of near-field GMs are chosen based on the recommendations of FEMA P-695 to conduct nonlinear dynamic analyses. Subsequently, the methodology provided in FEMA P-58 is adopted to perform a comprehensive seismic performance assessment at various hazard levels. It is shown that the consideration of the effects of near-field pulse-like GMs can considerably increase the risk of structural collapse in RC shear wall systems, based on the ratio of the pulse period of ground motion records to the elastic first mode period, in comparison to the near-field GMs without a pulse. It is concluded that the stated ratio is a crucial parameter to assess the risk to the life safety (LS) of low-to-high-rise RC buildings. For frequently occurring seismic intensities, repairable damage to nonstructural elements is the main factor contributing to the total expected economic loss in the studied buildings, irrespective of the selected GM set and the number of stories. In addition, the contribution of collapse and demolition due to residual drift in the estimation of repair time is significant for pulse-like GMs.

This study investigates the seismic response of two 20-story adjacent reinforced concrete structures with differing lateral load-bearing systems, emphasizing the influence of soil-structure interaction. In total, 72 numerical models explored the combined effects of 9 earthquake motions, 4 soil types, and 2 structural designs. Analytical fragility curves revealed superior seismic resilience for the structure with shear walls compared to the bare frame structure. Shear walls increased the capacity to withstand earthquakes by up to 56% for each damage level. Soil behavior analysis investigated the effect of soil properties. Softer soil exhibited larger deformations and settlements compared to stiffer soil, highlighting soil ductility's role in the system's response. The study further assessed potential pounding between structures. The connection between structural stiffness and soil deformability significantly affected pounding risk. The provided gap (350 mm) proved insufficient to prevent pounding under various earthquake scenarios and soil types, leading to damage to RC components. These findings emphasize the crucial need to consider both structural systems and soil properties in seismic assessments.