The Economic Justification of Semi-Active Damping Systems for Civil Structures

2014 ◽  
Author(s):  
Steven Pritchett
Author(s):  
Austin Downey ◽  
MohammadKazem Sadoughi ◽  
Liang Cao ◽  
Simon Laflamme ◽  
Chao Hu

Structural control systems, including passive, semi-active and active damping systems, are used to increase structural resilience to multi-hazard excitations. While semi-active and active damping systems have been investigated for the mitigation of multi-hazard excitations, their requirement for real-time controllers and power availability limit their usefulness. This work proposes the use of a newly developed passive variable friction device for the mitigation of multi-hazard events. This passive variable friction device, when installed in a structure, is capable of mitigating different hazards from wind and ground motions. In wind events, the device ensures serviceability, while during earthquake events, the device reduces the building’s inter-story drift to maintain strength-based motion requirements. Results show that the passive variable friction device performs better than a traditional friction damper during a seismic event while not compromising any performance during wind events.


2013 ◽  
Author(s):  
Gabriele Cazzulani ◽  
Tullio Balduzzi ◽  
Francesco Ripamonti ◽  
Daniele Rocchi

Author(s):  
Juchirl Park ◽  
John A. Peterson

Reducing or eliminating seat noise and vibration are the main objectives of a semi-active damping system implemented in a commercial vehicle seat. The system must be developed such that control forces minimize seat motion. Abrupt motion with semi-active damping systems is typically called ‘dynamic jerk.’ Semi-active damping in a seat application places the control forces close to the seat occupant so there is less ‘filtering’ to protect the human from feeling dynamic jerk. Whereas in an automotive suspension there might be more tolerance for dynamic jerk because the comparatively heavy vehicle body acts to filter some of the dynamic jerk and the interaction of the tire and road input may also mask it. In this research, dynamic jerk has been addressed and studied for the advanced SEAT application. The seat has been tested with varying sine inputs at specific amplitudes. The response of the semi-active damping seat system has been analyzed to characterize dynamic jerk and a control algorithm has been developed to minimize this undesirable response. The conclusion is that dynamic jerk is dependent on the damper’s physical properties as well as the system’s sensors. A Design of Experiments statistical study was carried out to determine what are the most influencing factors. Limiting the range of damping force reduces the control authority; however, allowing full damping force may trigger dynamic jerk. Identifying the dynamic jerk plays an important role in order to have the indication of the properly tuned system. In this research, the identification strategy of the dynamic jerk is studied and developed.


Author(s):  
C. Brecher ◽  
S. Bäumler ◽  
B. Brockmann

The positioning accuracy of conventional servo hydraulic cylinders is limited by oil compressibility, leak oil, nonlinearities, hysteresis effects, etc. This affects the control quality of the actuator, which is essential for a use in high dynamic positioning tasks, such as applications in active damping systems for machine tools. The presented hydraulic actuator design is a new approach to extend those limitations by using membrane based piston guidance and casing of pressure chambers. The actuator design is based on a linear mathematical model and FE-Simulations. The developed linear actuator model is integrated into a coupled multi body simulation of an existing active damping system. As the results of the coupled multi body simulation were promising, the actuator was manufactured and put into operation. A first insight into the behavior of the actuator and the verification of the linear actuator model is provided.


Author(s):  
Jordan T. Camp

While many analysts have commented on the representation of 1968 campus events and antiwar demonstrations, less attention has been paid to the global significance of the dramatic struggles in industrial Detroit during the period. The meanings of events in the city were intensely fought over. As Stuart Hall, Chas Critcher, Tony Jefferson, John Clarke, and Brian Roberts observed, the events of 1968 were “an act of collective will, the breaks and ruptures stemming from the rapid expansion in the ideology, culture and civil structures of the new capitalism . . . in the form of a ‘crisis of authority.’” In Detroit the crisis of authority was expressed in the form of popular political struggles against racism, state violence, and the contradictions of life in the industrial capitalist city. This article asks and answers the following research questions about the struggle over the meaning of this decisive turning point in US history: What was the relationship between racial ordering, uneven capitalist development, and mass antiracist and class struggles? How did Black working-class organic intellectuals resist and alter hegemonic definitions of the situation? How are the dialectics of insurgency and counterinsurgency to be best theorized during this precise historical conjuncture? 


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