عنوان مقاله [English]
Diagrid structural system is an efficient lateral load-resisting systems. Diagrid system contains diagonal truss elements through the height of the structure. Since lateral resisting elements is located in perimeter of the structure, this system acts as tubular system. The stability and shear rigidity of diagrid system is due to axial performance of diagonal elements. Recent studies have showed that tube increases lateral stiffness of the structure in tube systems. The purpose of this paper is to investigate the combined behavior of outer diagrid tube and inner core tube under lateral seismic loading. In this paper, twelve 36-story diagrid structures with inner core with different arrangements of incline angles for perimeter braces were designed. Composite structural systems were investigated in the form of a diagrid tube with an inner steel moment frame core and a diagrid tube with an inner concentrically-braced core. The combined behavior of these structures was evaluated under lateral seismic loading. A linear dynamic response analysis was used to obtain the interaction behavior of diagrid tube with internal core. The performance of the diagrid structures with inner cores indicates that most of the transferring lateral force in all stories is tolerated by the diagrid system; only in the last story was the shear absorbed by the internal core. Analytical results show that the effect of higher mode shapes of the structure in tall buildings causes the reduction of the shear stiffness of the diagrid at the building top. The analysis results show that diagrid system carried the significant lateral loads. Shear rigidity of diagrid systems increased when the angles of diagonal elements were reduced and the maximum shear rigidity was obtained for angle of 50.19 degree. Composite diagrid structural system with different arrangements of incline angles for perimeter braces is modeled in SAP2000 and analyzed for combined performance.