Abstract: The fiber beam-column model, which is an important milestone in the development of simulation technique for structural systems, has been widely used in recent years with its simplicity, efficiency and generality. However, the poor simulation results in many key issues of the structural system using the model cannot be avoided due to the limitation of the basic assumptions of the model. This paper thoroughly reviews the research group's 7-years' efforts and progress in improving the conventional fiber beam-column model to solve several critical problems in structural simulation. Firstly the conventional fiber beam-column model is developed on the platform of general finite element software MSC.Marc and further expanded to the simulation of steel-concrete composite frames. Then four new fiber beam-column models are proposed to give satisfactory prediction results to four key issues in structural simulation including the slab spatial composite effects in composite frames, the nonlinear shear and sliding effects of coupling beams, the rebar anchorage slip in the footings and the whole-process cracking behavior of RC beam and columns, respectively. These models are proved to completely keep the advantages of conventional fiber beam-column models and accurately consider the above complicated effects, according to the verifications by numerous test data and elaborate finite element analysis. Based on the proposed models, a nonlinear analysis program COMPONA-MARC is developed for commonly used structural systems such as RC, steel and steel-composite structures, which provides a powerful platform and tool for elaborate nonlinear structural simulations.