Analytical Study on the Behavior of Seismically Strengthened Concrete Frames Using External Shear Wall Curtains

Abstract

This research presents an analytical study on the behavior of concrete frames after being strengthened using an external shear wall curtain. The study is

based on an experimental investigation conducted by Saleh et al. The static study demonstrated a clear consistency between the analytical and experimental findings, leading to a dynamic subsequent survey of the same model, albeit through analytical methods only. The dynamic study revealed several phenomena accompanying the interaction between the external shear wall curtain and the existing building structure. One of these phenomena was that the shear behavior of the external shear wall curtain initially attracted a significant portion of the total base shear (approximately 50%) at the beginning of seismic excitation. However, as the PGA of the seismic record was reached, the curtain wall's base shear contribution began to diminish due to the yielding of the effective anchors. This highlights the important role of anchor configuration between the frame and the curtain wall and the prescribed section of these anchors to maintain a relatively constant rate of seismic energy dissipation during an event of a damaging earthquake. In addition, the analytical results indicated that numerically modeling an anchor as a truss element yields better results than an element with beam cross-section behavior. This raises questions about the anchor’s ability to dissipate energy in tension and not compression. The anchor's behavior may not be optimal under compression, suggesting the need for further research to achieve a balanced state of energy dissipation under both tension and compression.