This page contains brief descriptions and selected papers that document these efforts.

Coupled Building Control

Description: Connecting adjacent buildings for response reduction has been shown to be an effective method of structural control. As buildings are built taller and more flexible the resulting long periods become increasing more difficult to control using traditional methods of structural control (e.g. tuned and active mass dampers). Coupling adjacent buildings can provide the necessary level of safety and performance.

Active coupled building control was implemented in 2001 in the recently constructed Triton Square office complex in Tokyo, Japan. These 45-, 40- and 35-story office buildings are connected near the top floors with 35-ton actuators.

This research examines active coupled building control through analytical studies and conducting experimental tests to verify acceleration feedback control strategies, considered the affect of building configuration and damper location on passive and active control strategies, proposed semiactive coupled building control, and examining the ability to control dynamically similar structures.

Semiactive Control of Cable Vibration

Stay cables, such as are used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. Transversely-attached passive viscous dampers have been implemented in many bridges to dampen such vibration. However, only minimal damping can be added if the attachment point is close to the bridge deck. For longer bridge cables, the relative attachment point becomes increasingly smaller, and passive damping may become insufficient. 

In 2002, MR dampers were applied to 156 of the stay cables on the Dongting Lake Bridge in the Hunan Province of China for protection against rain-wind induced vibration. Currently the MR dampers on the Dongting Lake Bridge are operated in a passive mode with constant optimal voltage applied to the dampers during rain-wind conditions.

This research examines and demonstrates that "smart" semiactive cable damping employing feedback control can provide increased supplemental damping. The smart damping control strategy employs H₂/LQG clipped optimal control using only force and displacement measurements at the damper for an inclined flat-sag cable. Both analytical and experimental studies have been conducted. Cable response is seen to be substantially reduced by the smart damper.

Probabilistic Measure to Assess the Efficacy of Semiactive Control

Semiactive (smart) damping technology has been proposed to protect civil structures from dynamic loads. Each application of smart damping control provides varying levels of performance relative to active and passive control strategies. Currently, researchers compare the relative efficacy of smart damping control to active and passive strategies by running numerous simulations. These simulations can require significant computation time and resources. Because of this, it is desirable to develop an approach to asses the applicability of smart damping technology which requires less computation time.

This research identifies a control design method that utilizes a probabilistic approach to determine the efficacy of smart damping technology.

Nonlinear Test Structure for Structural Control Applications

Typically civil structures (e.g. buildings and bridges) are designed to survive large seismic events by allowing damage to the structural systems. This damage is observed as structural members yield and results in non-linear dynamic behavior (for buildings this is typically at the beam-to-column connections).

The nonlinear experimental test structure will incorporate controllable nonlinear connections to simulate structural yielding without actually damaging the test structure. Current test structures either behave linearly or receive actual damage while incorporating nonlinear material behavior. To verify the performance of proposed control strategies on nonlinear structures, as needed for performance-based engineering studies, a nonlinear experimental test structure that can endure numerous nonlinear tests is desired.