Thesis Defense - Osman Oğuzcan (MSCE)

Osman Oğuzcan – M.Sc. Civil Engineering

Asst. Prof. Dr. Bülent Erkmen– Advisor

Date: 25.05.2022

Time: 13:30

Location: AB1 246

EFFECTS OF UNBONDED MILD STEEL ON SEISMIC PERFORMANCE OF UNBONDED POST-TENSIONED

PRECAST CONCRETE SHEAR WALLS

Thesis Committee:

Asst. Prof. Dr. Bülent Erkmen, Özyeğin University

Asst. Prof. Dr. Taner Yılmaz, Özyeğin University

Assoc. Prof. Dr. Ali Sarı, İstanbul Technical University

Abstract:

Seismic energy dissipation of precast concrete lateral force-resisting systems constructed based on non-emulative or jointed connections is very limited since these systems experience little to no damage during seismic events. One additional seismic energy dissipation mechanism for unbonded post-tensioned precast concrete shear walls is using unbonded mild steel reinforcement over the wall joints, where joint gap opening occurs under lateral loads. Effects of unbonded mild steel bars on the system energy dissipation capacity and permanent drifts are not documented comprehensively for non-emulative precast concrete lateral force resisting systems. The main objective of this study is to investigate the effects of the mild steel design parameters on the seismic behavior of non-emulative unbonded post-tensioned precast concrete shear wall systems. In this study, a developed numerical finite element (FE) model is verified with experimental data. The experimentally verified modeling approach is used to develop FE models for several 5-story unbonded post-tensioned shear walls to investigate the effects of unbonded mild steel design parameters such as steel amount, location along the joint, and unbonded length on wall lateral behavior including its self-centering, energy dissipation capacity, and permanent prestress force losses for the unbonded tendons. The nonlinear structural behavior of the walls was determined by performing monotonic and cyclic pushover analyses, and nonlinear time history analysis with the OpenSees software. The finding of this study provides new and valuable contributions to the existing literature to further improve the seismic design of non-emulative precast lateral force resisting systems and provide a better understanding of the influence of unbonded mild steel on the seismic performance of jointed precast concrete walls.

Bio: 

Osman Oğuzcan graduated from the Civil Engineering Department of Gaziantep Zirve University in 2015. He started working as a research assistant and site control engineer in the following years. He completed his military service as a reserve officer civil engineer in the Ministry of National Defence, Ankara in 2018. He started his master's education at Özyeğin University in 2019 and worked as a teaching assistant in the meantime. His research interests are precast reinforced concrete systems, post-tensioned shear walls, and earthquake engineering. In the thesis study, he focused on the effect of mild steel design parameters on the seismic behavior of non-emulative precast concrete shear wall systems.