Evaluation of the Plastic Deformation Capacity of Composite Beams Through the Connection Coefficient

For safer structural design, a simple index that describes the plastic deformation capacity of composite beams is needed, similar to the connection coefficient in the case of strength. In this study, the relationships between the plastic deformation capacity and strength under varying material properties and geometric shapes of concrete and steel members were considered through finite element analyses. Based on the obtained results, the plastic deformation factor was defined as the ratio of two rotation angles. The minimum value of the connection coefficient in composite beams corresponding to the ductility factor under severe earthquakes was determined because the plastic deformation factor can be used similar to the ductility factor. In addition, the minimum value of the connection coefficient in bare steel beams that will be safe even if a concrete slab is added was determined; therefore, the design of bare steel beams and composite beams are connected by the connection coefficient.