Keywords: framed buildings, energy dissipation, damped braces, seismic design, nonlinear analysis, seismic analysis, reinforced concrete frames, framed structures, damped braces, hysteresis, earthquakes, seismic retrofitting, framed buildings, modelling, friction, metallic yielding, viscoelastic dampers, viscous dampers, stiffness, strength, dissipative braces, dynamic behaviour, ground motion
Nonlinear seismic analysis of RC framed structures equipped with hysteretic damped braces
The insertion of damped braces proves to be very effective for the seismic retrofitting of framed buildings. In the last few decades several applications have been used in many countries, adopting damping systems with different characteristics, depending on both the arrangement of the damped braces and kind of damping device. However, for a widespread application of this technique, practical design procedures and simple numerical models are needed. In this paper, attention is focused on the modelling and nonlinear seismic analysis of framed structures equipped with friction, metallic yielding, viscoelastic and viscous dampers. A design procedure is proposed for proportioning damped braces in order to attain, for a specific level of seismic intensity, a designated performance level of the structure. A six–storey reinforced concrete (RC) framed building, designed in a medium–risk seismic region, is supposed to be retrofitted as in a high–risk seismic region. Two different criteria are followed for distributing the stiffness and strength properties of dissipative braces, over the whole of each storey and among the single braces. A numerical investigation is carried to study the nonlinear dynamic behaviour of the designed structures under real and artificially generated ground motions. The results show that the proposed design procedure is effective and reliable.