THE EFFECTS OF ROTATIONAL COMPONENT OF RAYLEIGH WAVES ON TALL BUILDINGS

Mahir Çetin

(Thesis Supervisors: Prof. Eser Çaktı & Co- Supervisor: Prof. Erdal Şafak)

ABSTRACT

For a long time, seismic engineering only considered the translational components of seismic ground motion, ignoring the rotations. However, recent research in structural health monitoring has revealed that rotational components of seismic ground motion, particularly those of Rayleigh waves passing under a structure, can significantly increase displacement demands on buildings, especially those located in sedimentary basins. The behavior of buildings to rotational ground motion has not been extensively studied due to a lack of rotational records. Recently, effective methods have been developed to extract the rotational component of motion from the translational ones, and instruments capable of recording them have emerged. This allows us to study the behavior of structures to rotational ground motion. This thesis investigates the impact of rotational Rayleigh waves on tall building response by applying the rotational ground motion to single and multi-degree of freedom systems. The rotational motion is first formalized in the equation of motion for both linear and nonlinear single degree of freedom systems (SDOF). Then, earthquake ground motion records rich in surface wave content that are recorded in sedimentary basins are compiled, and their rotational components are extracted using the Normalized Inner Product (NIP) method, a recently developed method. Those extracted rotational records belonging to Rayleigh waves are applied to a set of linear and nonlinear SDOF systems to observe their effect on response spectra and inelastic deformation. Finally, the effect on the response of a representative tall building is studied by applying the extracted rotational records to it. The response is compared with and without the presence of rotational Rayleigh waves.