TY - GEN
T1 - Seismic resistance of natural and artificial variable stiffness reinforced concrete buildings
AU - Iskhakov, I.
AU - Ribakov, Y.
PY - 2005
Y1 - 2005
N2 - An influence of variable stiffness on seismic response of RC structures is discussed. A fully braced six-story RC frame is analyzed. First, an effect of concrete braces as a self-variable system is studied. It is shown that up to some limit the frame itself controls its behavior by adapting its dynamic characteristics during a current earthquake. It is achieved by autonomous disengagement of the frame concrete braces under tension and their further non-linear action under compression. The system has several levels of seismic adaptation and selects one for optimal response to a given earthquake. After reaching the limit optimal state, further self adaptation of the frame is impossible. In this case, increasing of the seismic affect may lead to disengagement of concrete braces under compression yielding a worse structural response. In order to avoid it, a system of artificial stiffness control is proposed. Using the controlled variable damping prevents collapse of braces under compression, and in this case the structure remains in its optimal state. The damping forces in the friction devices are regulated according to a displacement and velocity feedback optimal control theory. Changing the friction level at each time step of a current earthquake yields additional improvement of structural seismic behavior and avoids further need of retrofitting in order to prepare the structure to the next earthquakes.
AB - An influence of variable stiffness on seismic response of RC structures is discussed. A fully braced six-story RC frame is analyzed. First, an effect of concrete braces as a self-variable system is studied. It is shown that up to some limit the frame itself controls its behavior by adapting its dynamic characteristics during a current earthquake. It is achieved by autonomous disengagement of the frame concrete braces under tension and their further non-linear action under compression. The system has several levels of seismic adaptation and selects one for optimal response to a given earthquake. After reaching the limit optimal state, further self adaptation of the frame is impossible. In this case, increasing of the seismic affect may lead to disengagement of concrete braces under compression yielding a worse structural response. In order to avoid it, a system of artificial stiffness control is proposed. Using the controlled variable damping prevents collapse of braces under compression, and in this case the structure remains in its optimal state. The damping forces in the friction devices are regulated according to a displacement and velocity feedback optimal control theory. Changing the friction level at each time step of a current earthquake yields additional improvement of structural seismic behavior and avoids further need of retrofitting in order to prepare the structure to the next earthquakes.
KW - Active variable damping
KW - Optimal control
KW - RC structures
KW - Seismic design
KW - Self-variable stiffness
UR - http://www.scopus.com/inward/record.url?scp=80053411619&partnerID=8YFLogxK
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AN - SCOPUS:80053411619
SN - 1905088000
SN - 9781905088003
T3 - Proceedings of the 10th International Conference on Civil, Structural and Environmental Engineering Computing, Civil-Comp 2005
BT - Proceedings of the 10th International Conference on Civil, Structural and Environmental Engineering Computing, Civil-Comp 2005
T2 - 10th International Conference on Civil, Structural and Environmental Engineering Computing, Civil-Comp 2005
Y2 - 30 August 2005 through 2 September 2005
ER -