Large displacement elastic analysis of planar steel frames with flexible beam-to-column connections under static loads by corotational beam-column element

This paper presents the elastic large-displacement analysis of planar steel frames with flexible connections under static loads. A corotational beam-column element is established to derive the element stiffness matrix considering the effects of axial force on bending moment (P-Δ effect), the additional axial strain caused by end rotations and the nonlinear moment – rotation relationship of beam-to-column connections. A structural nonlinear analysis program is developed by MATLAB programming language based on the modified spherical arc-length algorithm in combination with the sign of displacement internal product to automate the analysis process. The obtained numerical results are compared with those from previous studies to prove the effectiveness and reliability of the proposed element and program.