Seismic Response Analysis And Vulnerability Research Of Gantry Crane Under Near-fault Seismic Exciations

The frequent happening of violent earthquakes around the world proves that the Earth has entered an active seismic period,indicating the great urgency of aseismic structures requirement of human-being.As a key equipment of bulk cargo transferring,the gantry crane are getting bigger and bigger in structure scale.However,all types of large-scale structures can be significantly affected by earthquakes.Therefore,it is necessary to carry out deeper aseismic research on the gantry crane structure.Near-fault ground motion is a typical kind of strong seismic ground motion.It has become an indispensable factor to be studied in aseismic structures research has due to its significant influence to the structures.The seismic vulnerability research has a good effect on assessing the aseismic performance of structures.Therefore,in order to study the aseismic performance of the gantry crane structure more deeply,the seismic response analysis and vulnerability research of gantry crane structures under near-fault seismic excitation were carried out in this paper.The research contents of the paper include the following aspects:1.Research on the characteristics of near-fault seismic ground motion.Based on the in-depth study of the representation form and the formation mechanism of the basic characteristics of the near-fault seismic ground motion,the seismic ground motion selection principle was established to select the ground motion,and the basic dynamic characteristics of the near-fault seismic ground motion were studied from the two aspects of amplitude and spectrum characteristics.The results show that: the near-fault seismic ground motion would cause more serious damage to the structure,and it needs to pay great attention to the impact of near-fault seismic ground motion in the structural aseismic research.2.Gantry crane structure modeling and fundamental research.On the basis of rationally simplifying the structure of the gantry crane,a finite element model of a certain gantry crane structure was established by ANSYS software.The fundamental research of the gantry crane structure were carried out by Static mechanical analysis and modal analysis to verify and calibrate the strength,stiffness and dynamic stiffness of gantry crane structure,and preliminarily anslyze the basic dynamic characteristics of the gantry crane structure.3.The time-histories analysis method was applied to analyze the seismic response of the gantry crane structure under the excitation of near-fault seismic ground motion,during which,the impacts of velocity pulse effect,directional effect,sliding effect,vertical effect and spectral characteristic parameter PGV/PGA of near-fault ground motion on the seismic response of the gantry crane structure were respectively studied.And the result show that: all the characteristics of the near-fault seismic ground motion have certain increase effect on the seismic response of the gantry crane structure.The comparative analysis of the seismic response of the gantry crane structure under the excitation of the near-fault seismic ground motion,the mid-field seismic ground motion and the far-field seismic ground motion show that the seismic response of the gantry crane structure varies a lot under the ground motion excitation of different fault intervals,and it is necessary to independently perform the aseismic analysis of the gantry crane structure according to seismic ground motion distinguish by different fault interval.4.Research on seismic vulnerability of gantry crane structure.The damage index of the gantry crane structure is established according to the deformation failure criterion and the first-excursion failure criterion,based on which,the vulnerability calculation method based on the incremental dynamic analysis method was applied to obtain the seismic vulnerability function and curve of the gantry crane under the excitation of near-fault seismic ground motion,the mid-field seismic ground motion and the far-field seismic ground motion,thus to predict the threats of potential earthquakes to the gantry crane structure and assess the damage situation of the gantry crane structure after the happening of the earthquake.According to the results of seismic vulnerability analysis,the damage probability of the gantry crane structure in different seismic fortification intensity areas is calculated to assess the aseismic performance of the structure.The aseismic performance of the gantry crane structure in the area with 6/7/8-degree seismic fortification intensity meets the “three-level” seismic fortification requirements of China.But under the action of the 9-degree rare earthquake,the gantry crane structure may possibly be destroyed totally.If necessary,the aseismic design needs to be increased.