Analysis and Design of ANSS for Seismic Protection of RCC Plane and Space Frame Structure.

Abstract

Seismic forces and displacements in existing structures can be reduced effectively in an approach where the structure is intentionally weakened and damping is added. Intentionally weakened means the strength and stiffness are reduced. The above approach does ensure the safety of lives in case the design earthquake event occurs, and the prevention of collapse in case of a maximum earthquake event. However, the approach also results in permanent deformations and inelastic movements of the structural system during a seismic event. The weakening and the additional damping approach can be modified and improved if the apparent weakening of the structure is achieved. This can be done with the help of a system known as adaptive negative stiffness system (ANSS). ANSS consists of a combination of a damper and negative stiffness device. Parametric study is done on plane frame and space frame structure with and without ANSS so as to highlight the effectiveness of ANSS in the seismic protection of structures. A plane frame and space frame of G+5 story is modeled in SAP 2000 software by incorporating negative stiffness device and viscous dampers for comparing it with frames without negative stiffness device and dampers. The parameters for the design of NSD for G+5 plane and space frame structure are calculated. The results of plane frame structure with and without ANSS are compared to convey the effectiveness of ANSS in the seismic protection of structures.