Magnification factor for pile internal forces of pile-supported wharves under bi-directional ground motions

In order to determine the pile internal forces of wharf under simultaneous seismic excitation in orthogonal horizontal directions with ease, the total internal forces can be obtained by multiplying the pile forces of two-dimensional model under transverse earthquake loading with a magnification factor. The factors were computed from the seismic response of wharves having various aspect ratios (length to width) and eccentricity ratios when subjected to 30 pairs of bi-directional earthquake records. Mean magnification factors and their corresponding dispersion are presented for all ground motion ensembles. The influence of aspect ratio and eccentricity ratio is evaluated and discussed. It is concluded that the magnification factor can be expressed as the function of aspect ratio and eccentricity ratio, and follows lognormal distribution. The proposed equation of magnification factor can be an alternative for internal force analysis of wharves under bi-directional ground motion. The total internal forces of pile under bi-directional horizontal motions can be determined by multiplying the pile forces under transverse earthquake loading with a magnification factor based on two-dimension analysis. The magnification factor can be expressed as the function of aspect ratio and eccentricity ratio of wharf. The magnification factor follows lognormal distribution, which enables designers to compute factor with certain reliability. image