Fuzzy Logic reaches dizzying heights
Have you ever contemplated the frightening prospect of being caught in a high-rise building during an earthquake, regardless of the fact that it's unlikely to fall down?

Researchers in UTS:Engineering are developing a Fuzzy Logic controller to manage an active structural control system to minimise the sickening movement triggered in high-rise buildings by strong earthquakes and high winds.

Fuzzy logic is a method of dealing with mathematical concepts that have variables. It is most commonly used to make adjustments in household appliances. For example, in washing machines it is used to sense the size of the load and adjust the amount of water accordingly.

Team leader Professor Bijan Samali, who is an expert with 20 years experience in this field, says there is a growing need to verify the potential of Fuzzy Logic controllers, which were first proposed in the 1990s.

"Fuzzy Logic controllers can deal more easily with the uncertainties of input data from vibration sensors located in buildings, including uncertainties in structural properties. Current controllers neglect such changes in the structural properties, which could lead to less than optimal control.

"These controllers can also incorporate human experience about the system, and its performance, and can be easily implemented in a Fuzzy chip; which guarantees immediate reaction times and autonomous power supply."

The main objective of this research is to check the validity of a Fuzzy Logic controller to manage three proven active structural control mechanisms. The Active Mass Driver (AMD), for example, consists of a large block of concrete or steel that is installed on the top floor of the building to act as a pendulum. When the structure is excited by wind or earthquake, the AMD is pushed from side to side by an external hydraulic actuator system to stabilise the motion of the building.

Professor Samali is working on the project with Associate Professor Quang Ha, who is an expert in electronic control theory, "Quang is developing the fuzzy logic algorithm that will deliver the right amount of force at the right time. The objective is to apply the minimum force to the block to achieve the maximum control of the structure's motion.

"The concept is simple but there's a lot involved. In a nutshell if the building is swaying left we need to push the mass to the right as soon as we detect the motion. Timing is critical; a late reaction makes the situation worse, and it will require a lot of power to move the block, hence the need for optimum algorithms."

The team anticipates completing computer simulations to predict structural motion and estimate the parameters required to reduce it by the end of this year and to undertake final tests on scaled models on the UTS shake table in the New Year.

 

For further information, contact:

Bijan Samali

Group Head & Professor

Infrastructure and the Environment

UTS:Engineering

Ph: 9514 2023