Seismic Residual Displacement of Core-Outrigger Structure Under Resonant Ground Motions
Fei Fei Sun1, Zhi Bin Hu2, Lei Xiao2, Jie Huang2
1 State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University.
No. 1239 Siping Road, Shanghai, 200092, China
ffsun@tongji.edu.cn
2 College of Civil Engineering, Tongji University.
No. 1239 Siping Road, Shanghai, 200092, China
2012zbhu@tongji.edu.cn
200761300@163.com
sevender@163.com
Abstract. The residual displacement becomes an increasingly important performance indicator for performance based seismic design. Ground motions containing different energy components may cause significantly different responses of a structure. A 1/40 scaled planar test model of a 56-story core-outrigger structure was tested on shaking table considering two types of ground motions, i.e. non-resonant and resonant ground motions. Characteristics of residual displacement responses of the test model are analyzed and compared first. Then the accuracy of a finite element model and the approximate method proposed by the FEMA P-58 to estimate residual displacement demands is examined with reference to the test results. Main conclusions are as follows:
(1) With the same small PGA of 0.07g, no residual displacement occurred under the non-resonant ground motion while obvious residual displacements were caused by the resonant ground motions. The residual displacement in the first-period resonant ground motion case was larger than 2.1 times of that in the second-period resonant ground motion case.
(2) In the resonant ground motion cases, damage accumulative behavior of the test model under successive input of different ground motions should be considered in finite element analysis. The softening behavior of the columns on the 13th floor makes a major contribution to the residual displacement in the resonant ground motion cases.
(3) In the resonant ground motion cases, residual drifts predicted by FEMA P-58 have large discrepancy with the test results. The residual drift in the first-period resonant ground motion case is underestimated by 55%.
Keywords: Residual displacement, Resonant ground motion, Shaking table test, Finite element analysis.
