Optimal seismic response control of a long span cable-stayed bridge for a benchmark problem

Abstract

Structural Control has been growing in a fast pace as a subject contributing with means to alleviate the effects of harming loads. Correlated with other domains of human activity (electronics, automatic control, computer science, robotics, new materials, etc) important changes in philosophy and practice are recorded in Civil
Engineering.
Because Structural Control is still an expensive approach to protect structures, in the views are structures as long cable-supported bridges and tall buildings that are vital for people and social activities, especially during and after strong winds or earthquakes.
This paper is showing a developing procedure of the classical method of optimal control. A first step into this development was previously done when the first author was showing that it is possible to lower the degree of arbitrariness for the coefficients in the weighting matrices based on energy considerations.
In this work the method is further developed when the attention is given to using reduced state models, which is a more realistic approach than using the full-state method as in previous works.
For the FEM model of the cable-stayed bridge given by an international
benchmark, simulations have been performed using the method described above.
External actions are three important strong earthquake acceleration records. The discrete time approach time and time-delay existing between the calculation and application of the control forces are taken into consideration. Also the process noise and measurements are considered. A simple predictive procedure is proposed.
Results of the application are showing that the time-response and also frequency responses are considerably reduced: stresses, bending moments, forces, displacements, velocities, and accelerations are kept into allowable limits. Based on the benchmark performance indexes the controlled system is very competitive.