An Efficient Computational Method for Semi-rigid Steel Frame with Elements of Internal Plastic Hinge

Abstract

This paper proposes an efficient computational method for semi-rigid steel frame with elements of internal plastic hinge. The yield function of I or H section is derived by using section assemblage concept, and residual stress is considered in the initial yield function. Element with springs-in-series at each end is presented to consider the effect of semi-rigid connections and material nonlinearity. Based on the proposed method, it is demonstrated that internal plastic hinge can be well predicted by only using one element for the members subjected to distributed loads. The proposed element has the same nodal degrees of freedom as conventional element by condensing the non-nodal degrees of freedom introduced in the derivation. Other factors influencing the capacity of steel frames, such as shear deformation, geometric nonlinearity and initial imperfection, are explicated. Using FORTRAN, an improved nonlinear analysis program of semi-rigid steel frame is compiled. Numerical analysis shows that the proposed method has high efficiency and accuracy.