Transactions of Nanjing University of Aeronautics & Astronautics
Mechanical Analysis and Numerical Simulation for New Type of Dynamic Control Devices
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Abstract:
The conventional dynamic control devices， such as fluid viscous damper （VFD） and isolating bearings， are unsuitable for the double-deck cable-stayed bridge due to a lack of sustainability， so it is necessary to introduce some high-tech dynamic control devices to reduce dynamic response for double-deck cable-stayed bridges under earthquakes. A （90+128） m-span double-deck cable-stayed bridge with a steel truss beam is taken as the prototype bridge. A 3D finite element model is built to conduct the nonlinear time-history analysis of different site categories in fortification intensity Ⅸ （0.40 g） degree area. Two new types of dynamic control devices-cable sliding friction aseismic bearings （CSFABs） and elasticity fluid viscous dampers composite devices （EVFDs） are introduced to reduce the dynamic responses of double-deck cable-stayed bridges with steel truss beam. The parametric optimization design for the damping coefficient C and the elastic stiffness of spring K of EVFDs is conducted. The following conclusions are drawn：（1） The hybrid support system by EVFDs and CSFABs play a good function under both seismic and regular work， especially in eliminating the expansion joints damage； （2） The hybrid support system can reduce the beam-end displacement by 75% and the tower-bottom bending moment by 60% under the longitudinal seismic excitation. In addition， it can reduce the pier-bottom bending moment by at least 45% under transverse seismic and control the relative displacement between the pier and beam within 0.3 m. （3） Assuming the velocity index α=0.3， the parametric optimization suggests the damping coefficient C as 2 000 kN·s·m-1 in site Ⅰ0， 4 000 kN·s·m-1 in site Ⅱ， 6 000 kN·s·m-1 in site Ⅳ， and the elastic stiffness of spring K as 10 000 kN/m in site Ⅰ0， 50 000 kN/m in site Ⅱ， and 100 000 kN/m in site Ⅳ.
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Clc Number:
TU318
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