| A wharf of a port takes an important part of national economics and society development, port break may result in enormous economy loss and social influence. Poor performance of the pile-wharf during the earthquake was well documented by numerous seismic failures at worldwide ports. Sufficient earthquake resistant capacity should be needed by pile-supported wharf during design working life for reducing hazard of wharf structures collapse. The seismic damage of marginal pile supported wharf concentrate on the pile foundation mainly in which failure pattern include foundation bearing capacity shortage, soil structure interaction(sand liquefaction and excessive curvature of piles at the interface between soft and stiff soil layer), batter pile damage and slope deformation. Due to the significant importance of understanding the deterioration mechanism for different types of pile-wharf under seismic motion, the seismic performance analysis results of pile-wharf are as follows:(1) Nonlinear seismic response analysis of pile-supported wharf structure is performed using finite element software ABAQUS, including relative displacement, acceleration, shearing force and bending moment of wharf structure under the different acceleration of ground motion. On a basis of the occurring time and sequence of plastic hinges of piles defined in process, mechanism of yield, weak location and pattern of failure of the structure are distinguished.(2) In order to better understand influence of batter piles on seismic performance of wharf structure, elastic-plastic time history analysis are implemented for two cases using ABAQUS. The evaluation of model behavior are summarized that (a) horizontal displacements increased where batter piles were detached due to less stiffness; (b) significant increases in residual displacement were observed when the batter piles were attached; (c) the deformability of batter piles were weak, resulting in concrete cracks and bearing capacity loss.(3) Nonlinear seismic response analysis is performed for irregular wharf structure in order to evaluate the influence of irregular plane on lateral force, bending moment and torsion angle. A comparison between regular and irregular wharf structure on seismic response aspects is conducted. Calculated results demonstrates that there exists different level increase of lateral force, bending moment at pile head and torsional angle of entire irregular wharf structure as a result of irregular plane type. (4) Nonlinear static analysis (pushover analysis) is used and developed for seismic performance analysis of wharf structure. The general framework of nonlinear pushover analysis for wharf is presented. The relationship between effective damping and displacement ductility factor is deduced based on hysteretic characteristic of wharf under cyclic load. The procedure to locate the performance point on the envelop curve, which corresponds to the target displacement, is illustrated. To identify the validity of results from pushover analysis, time-history analysis is performed for the wharf under sixteen input motions. The displacement requirement obtained by pushover analysis is proved to be close to the average displacement calculated by time history analysis. So it’s concluded that pushover analysis is a powerful tool for seismic design and analysis of pile-wharf in practical engineering.(5) Nonlinear seismic time history analysis of wharf structure will result in unacceptable matrix sizes due to a large number of piles. As an alternative, the structural characteristics of a entire wharf structure may be modeled by using the SUPER-PILE model. Peak target displacement of the SUPER-PILE model is evaluated using elastic modal response spectra analysis and compared with simulated results from nonlinear time history analysis. The calculated case indicated that approximate solution of maximum displacement can be evaluated effectively using the SUPER-PILE simplified method, and computed amount is decreased simultaneously. |
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