Seismic analysis of uplift-available gantry crane subjected to extreme earthquake loads

Abstract

This paper aims to investigate the uplift behavior coupled with the non-linearity both in material properties and in geometry deformations of a typical gantry crane under near-field ground motions. First, the highly nonlinear and time variable model considering the uplift-available boundary condition based on the theory of Mohr-Coulomb friction is established of the gantry crane using the OpenSees platform. Then, a series of time-history analyses on this model structure is performed under three near-field seismic loadings with different exceeding probabilities. Furthermore, the comparison between the uplift-available gantry crane and the fixed crane is also carried out to provide in-depth insight into the structural responses under different boundary conditions. Finally, coupling with the material and geometry inelastic behavior, the uplift response process is modeled in this paper and the seismic incident angle from 0 up to 360 degrees is also examined to quantitatively confirm the prioritization of uplift event and the other inelastic responses. And the new conception of uplift probability is first proposed herein to reveal the nature of uncertainty. It is found that uplift behavior plays an essential role in designing and evaluating the seismic performance of gantry cranes; further, the uplift response increases the seismic demand of the gantry crane structure and even causes collapse under strong ground motions.