Abstract: Taking a certain luffing jib tower crane as the research object,it used finite element analysis software ANSYS to obtain the dynamic response under seismic excitation.Choosing El-Centro as the input,it obtained response curve of four characteristic nodes,which showed the variation trend between node displacement amplitude and jib elevation angle under seismic excitation.According to the severity rating table of reliability designed a sensitive reference table,it expressed the relationship between displacement amplitude and jib elevation angle.The higher the sensitivity,the faster the change of node displacement amplitude along with the elevation angle changes under seismic load.Calculation results show that the X-direction displacement of tower crane rapidly grows with the elevation angle increases,the difference between the maximum value and the minimum value is 14 times,thus it belongs to high sensitivity that X-direction displacement is the main displacement of tower crane.Therefore,jib elevation angle should be in low-angle state to relieve seismic influence when the tower crane is non-working state.

Key words: luffing jib tower crane, seismic excitation, time-history analysis, sensitivity