Shaking table investigation of unbonded post-tensioned concrete rocking walls

This paper presents a shaking table investigation of three 5/18 scaled single rocking wall (SRW) systems with varied initial prestressing levels and cross-sectional areas of post-tensioned (PT) strands, thus extensively evaluating the seismic performance including the damage patterns, dynamic properties, displacement, and acceleration time history responses, stress of PT strands, and gap opening under multiple intensities of scaled ground motions. All three specimens exhibited a better self-centering capacity with fewer residual drifts than previous cyclic loading tests due to the shake-down phase following the dynamic response. With an increase in the peak ground acceleration (PGA), the fundamental frequencies and stiffness of the three models decreased to varying degrees. The dynamic comprehensive energy dissipation mechanism of multiple damping of the SRWs was analyzed and quantified. The measured inherent damping from the white noise tests was about 3.5%. In addition, the experimental results indicated that the energy dissipated by impact damping exhibits discreteness under different seismic wave excitations, varying in the range of 8.1 to 27.8%. A numerical model with multiple axial compressed springs as a key component was developed and accurately predict the dynamic response of SRWs. Moreover, a parameter analysis was conducted using the numerical model. The analysis revealed that The increase in initial prestressing levels and eccentricities of PT strands decrease the maximum displacement responses and residual drifts and slightly increase the maximum acceleration response of SRWs; The displacement response shows a nonlinear increase with aspect ratio and increase in aspect ratio significantly decrease the base shear response but improve the self-centering capacity of SRWs.