Nonlinear elastic dynamic analysis of space steel frames with semi-rigid connections

This paper presents a simple effective numerical procedure based on the beam–column method for nonlinear elastic dynamic analysis of three-dimensional semi-rigid steel frames. The geometric nonlinearity is considered by using stability functions and geometric stiffness matrix. An independent zero-length connection element comprising six translational and rotational springs is used to simulate the steel beam-to-column connection. The dynamic behavior of rotational springs is captured through the independent hardening model. The Newmark numerical integration method combined with the Newton–Raphson iterative algorithm is adopted to solve the nonlinear equations. The nonlinear elastic dynamic analysis results are compared with those of previous studies and commercial SAP2000 software to verify the accuracy and efficiency of the proposed analysis.

• An efficient analysis procedure of space semi-rigid steel frames is proposed.
• Stability functions are employed for modeling nonlinear geometry effects.
• Semi-rigid connections are modeled by zero-length nonlinear springs.
• Cyclic behavior of connections is captured by the independent hardening model.
• Proposed procedure proves to be a reliable tool for daily use in practical design.