Abstract
A screw jack is a device which converts input torque into amplified axial force, capitalizing on the device’s gearbox mechanism. Traditionally used in auto repair shops, the screw jack has been studied for the first time for active structural control. The dynamic properties of the device were investigated using open loop control, and the screw jack was found to have a high delay between command and measured force. Numerical simulations and parametric studies of SDOF systems with an LQG-controlled screw jack showed improvements to structural performance at 4 different levels of control effort. Loop simulation method experiments were conducted under seven ground motion records – benefits to structural response were dependent on the type of earthquake, with greater benefits observed for records with greater low-frequency content. Future work should investigate the types of structures and earthquakes for which the screw jack is most impactful using real-time hybrid simulation.
Highlights
As civil engineering structures are large and costly projects, they should be designed to appropriately withstand forces which can be reasonably expected during their service life
Linear quadratic gaussian (LQG) controllers are often used in active control across different control applications (Gawronski, 2004)—they are concerned with linear systems subjected to gaussian noise, undergoing control with quadratic costs
This section of the paper discusses the results from the various types of tests which were performed on the device, including characterization tests, development of the system transfer function, numerical simulation tests and parametric investigations, and results from the loop simulation method tests
Summary
As civil engineering structures are large and costly projects, they should be designed to appropriately withstand forces which can be reasonably expected during their service life. This paper presents a study investigating a screw jack device, traditionally used in mechanical engineering applications, in a structural control application. This device presents an interesting opportunity in the field of structural control, as the screw jack is a low-cost, low-energy alternative to traditional hydraulic actuators (Society of Manufacturing Engineers, 1984). The objectives of this study are to investigate and characterize the device, both in static as well as dynamic environments, in order to understand its potential for mitigating structural vibrations and damage. This will be done by performing characterization tests and developing a robust system transfer function. The study aims to simulate the performance of the screw jack in a single-degree-offreedom structure, both numerically as well as using loop simulation method techniques
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