Seismic performance assessment of tubular diagrid structures with varying angles in tall steel buildings

Diagrid system has emerged as an innovative structural system with an aesthetic view in the design of tall buildings. In this study, seismic performance of 36-story diagrid structures with varying angles are evaluated using pushover and nonlinear time history analysis. Furthermore, in order to evaluate the effect of diagrid core on behavior of structures, interior gravity frames are replaced with diagrid frames. The results of pushover analyses demonstrate that diagrid core can enhance the hardening behavior of structures when the angles of perimeter panels are lower or equal than those of the core compared to the conventional diagrids. In addition, core diagrids provide safe margins between the damage states under lateral loading. Nonlinear time history analyses are then performed to assess inter story drift ratio, residual drift, energy dissipation and hinges distribution of structures. It is observed that most of the models perform well under rare ground motions and hinges are well spread throughout the height among different elements and diagrid structures are capable of undergoing large deformations under rare earthquakes Large portion of input energy are dissipated by diagonal members and as the slope of exterior diagonals exceed that of perimeter tube, diagrid core efficiently participates in dissipating energy.