Interactive analysis and design of flexibly connected frames

Abstract Analysis and design of steel frames is usually conducted under the assumption that beam-to-column connections are either fixed or pinned. In reality, most connections are semirigid and possess a certain rotational stiffness. This study investigates the nonlinear connection behavior and geometric nonlinearity of the frame members in conjunction with the Load and Resistance Factor Design (LRFD) specification of the American Institute of Steel Construction (AISC). An integrated analysis and design computer program which applies to the partially restrained type of construction has been developed. The program is a nonlinear, iterative and interactive-aided analysis and design tool based on the stiffness method and polynomial connection model. The stiffness coefficients of the frame members, the secant stiffness of the beam-to-column connections and the geometric stiffness coefficients are combined to form the overall nonlinear stiffness for the frame member. The iterative solution procedure is implemented on the incremental stiffness equation of the structure to the point where convergence occurs. The members of the frame are checked for limit states of strength and a re-analysis/design can be made if necessary.