PSEUDO NEGATIVE STIFFNESS DAMPERS FOR EARTHQUAKERESPONSE CONTROL OF CABLE-STAYED BRIDGES

摘要

Seismic response control of cable-stayed bridge discussed herein is to provide special bearings at thedeck-tower connections to reduce the seismic induced force and displacement. Elastic bearings plusspecial dampers are employed as the control devices.The dampers are the newly proposed pseudo-negative-stiffness-controlled damper. Practical advantage isthat control algorithm is simple and sensors are required only at the damper to measure relativedisplacement and velocity. The system has been verified experimentally in the laboratory.The control algorithm commands the variable damper to produce pseudo negative stiffness hystereticloop. That is, unlike linear viscous damper that produces elliptical shape hysteretic loop, the controlledvariable damper produces hysteretic loop that represent combination of negative stiffness and viscousdamping.The point is that the combination of pseudo negative stiffness hysteretic loop plus elastic bearing stiffnessproduces artificial hysteretic loop that approaches rigid-perfectly plastic force-deformation characteristicswhich has large damping ratio.In order to study the effectiveness of this damper for seismic response control of cable-stayed bridges,application of pseudo negative stiffness damper and linear viscous damper to a typical cable-stayed bridgein Japan and to the benchmark cable-stayed bridge in the US was carried out using numerical simulationsunder several earthquake excitations. The results show that the pseudo negative stiffness damper reducesseismic responses better than those by passively viscous damper.