Akkineni, Sneha (2018-07). Implementation of Simple Adaptive Control as a Hybrid Control Strategy for a Seismically Active Cable-Stayed Bridge. Master's Thesis. Thesis uri icon

abstract

  • The motion of structural systems is a major challenge faced in the field of structural engineering. Certain measures such as the application of passive, active and semi-active control devices as a solution to overcome the motion of seismically critical structures has been the most preferred solution in recent times in the field of earthquake engineering. The advantages offered by control devices in terms of reliability, serviceability and reduced long-term costs has led to their popularity. The current work presents the study of the performance of Quincy Bayview Bridge, a cable-stayed bridge located in Illinois. For a cable-stayed bridge, the deck-tower connections and abutments form the essential locations for assessment on the onset of a seismic activity. Therefore, the 3-span long continuous bridge consists of High Damping Rubber Bearing (HDRB) isolators and Magnetorheological Dampers (MR Dampers) located at the transverse and longitudinal directions to link the deck with towers and abutments. Simple Adaptive Control (SAC) is implemented into the MR Dampers as the control algorithm. The primary objective is to evaluate the performance of an uncontrolled cable-stayed bridge system with a bridge system integrated with passive hybrid (Linear Viscous Dampers and HDRB) and semi-active hybrid control (MR Dampers and HDRB). The uncontrolled and controlled bridge is analyzed for two historic seismic excitations - the 1940 El Centro Earthquake and the 1994 Northridge Earthquake. The work also focuses on analyzing and comparing the results of the hybrid control system to the system controlled solely by passive and semi-active devices. An additional passive strategy (passive-on and passive-off) is implemented to evaluate and compare the performance of an MR Damper with hybrid control. Moreover, to lessen the computational efforts, a reduced finite element model is created to capture the modal behavior of the complete structure and is investigated further to capture its dynamic performance. The response reduction with the hybrid control strategies was found on par with the passive and semi-active devices that validates the efficiency of hybrid control. A similar response of the MR Damper controlled with SAC and passive-on is observed as the former delivers performance with its highest capacity. The difference in peak response percentage reduction between the full and reduced model validates that the reduced model cannot be substituted for the complete model due to its inefficiency to capture the geometric and material non-linearity in addition to its complete dynamic behavior.

publication date

  • July 2018