Seismic Performance of Cable-sliding Modular Expansion Joints Subject to Near-fault Ground Motion

Abstract

According to the research fruits of the diverse damages of bridge in the past, bearings' invalidation is the main reason of the damage of isolated bridges and causes oversized relative displacements between pier and girder. Eventually, it may lead to severe collision of superstructure. It is extremely dangerous when near-fault motion occurs, because it has obvious velocity pulse effect and increases the risk of colliding between girders.Aiming at this problem, this paper puts forward a device named cable-sliding modular expansion joints (CMEJs) that can control the relative displacement and avoid collision. The working principle and mechanical model are described, and then based on a triple continuous seismic isolation bridge which has different heights of piers, a 3D model with or without CMEJs is established. The responses of continuous beam bridges using the CMEJs are comprehensively inspected under the consideration of the velocity pulse effect, and then a real simulation of limit performance of CMEJs is made, focused on CMEJs' restraining effect.The calculation shows that velocity pulse effect would magnify the seismic response of isolation bridges. In addition, the device can well control the displacement and prevent collisions. And the isolation technology combined with CMEJs can be more effective to play their respective roles. The advantage in controlling displacement is obvious. Keywords near-fault ground motion, the effect in limiting relative displacement; cable-sliding modular expansion joints (CMEJs), seismic isolation bridge, velocity pulse effect

Seismic Evaluation of Horizontally Curved Bridges Subjected to Near-Field Ground Motions

“…Numerous researches have been conducted to control the pulse effects of near-fault ground motions on base isolated bridges. Gao et al (2015) proposed a cablesliding modular expansion joint which significantly decreased the relative peak displacement due to near-fault ground motions. Ghosh et al (2012) studied the types of seismic isolators in the response of continuously curved bridges in plan under the influence of the near-fault ground motion of Kobe and found that LRB, HDRB and FPB systems could reduce the response of pier displacement and force.…”