DYNAMIC ANALYSIS OF STEEL FRAMES WITH SEMI-RIGID CONNECTIONS

Mass matrix and stiffness matrix of semi-rigid frames for dynamic finite element analysis are deduced . Multistory frames with semi-rigid connections of different initial stiffness are constructed together with the corresponding rigid frame. Finite element analysis software ANSYS is used to perform the numerical analysis. The influence of connection stiffness on natural frequencies of structures is analyzed. The response of different frames according to harmonic loading with different frequencies is studied. Further, by adopting a time-dependent method, structures under excitation of seismic waves are analyzed. Analysis results show that the connection flexibility has a great effect on structure's natural frequencies. The natural frequency decreases with the increase of connection flexibility. It is necessary to consider the connection flexibility in the seismic design of steel structures. Time curves of top point lateral displacement and column base shearing force of semi-rigid frames behave stably during the excitation time. Flexible connections can be used instead of rigid connections in seismic design of steel frames.