Seismic response analysis of a cable-stayed bridge with shape memory alloy seismic mitigation systems
Shape memory alloys(SMA)have the characteristic of superelasticity and shape memory property,and are increasingly applied to civil engineering.A novel SMA-based device is proposed,which has the seismic mitigation and displacement limiting capacities.The device connects with the superstructure and substructure of the bridge through axis pins.The novel device not only can restrain the bridge in a safe range,but also can dissipate the seismic energy,and protect the bridge from earthquake damage.This study comments with pseudo-static tests on a single SMA cable specimen and the novel device.The constitutive models of the SMA cable and the novice device are proposed based the test results.A finite element model of a cable-stayed bridge with a main span of 360 meters was established in OpenSeesPy software for investigation.Seven far-field and seven near-field earthquake records were selected to study the seismic responses of the cable-stayed bridge with the novel device equipping 0,5,10,15,20,30,40,50 SMA cables.The study results indicate that the maximum longitudinal displacement of the girder decreased significantly with the number of SMA cables increased.However,this reduction was accompanied by a slight increase in the average maximum curvature at the base of the main tower.For example,the seismic mitigation device with 10 SMA cables reduced the average maximum displacement of the girder by 51.8%and 36.8%under seven far-field and seven near-field earthquakes,respectively.However,the corresponding average maximum curvature at the tower base increased by 5.1%and 16.0%,respectively.Consequently,the proposed SMA-based seismic mitigation device can effectively reduce the displacement of the girder at the cost of a small curvature increment at the tower base.
seismic prevention of bridgedynamic analysisshape memory alloyseismic mitigation and displacement restraining device
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