ASSESSMENT OF NONLINEAR DYNAMIC RESPONSE OF DIAGRID STRUCTURES EXPOSED TO VARIATION OF INCIDENCE ANGLE OF PULSE TYPE GROUND MOTIONS

In recent years, diagrid structures have received increasing attention for aesthetically pleasing and structurally efficient system. As is common in these structures, the diagrid frames form the perimeter of the building (Adeli & Asadi, 2017; Sadeghi & Rofoii, 2018). In this research, three 20-story diagrid structures which have different façade pattern were selected and designed. Three skeletal configurations with diagonal angle of approximately 56o, 64o, 76o respect to horizontal axis have been considered. Furthermore, another bundled tube structure with the same sizes and skeletal configuration was also designed as the basic model for analytical comparison purposes subjected to near-field earthquakes. The façade pattern of the studied models with various criterion angles are shown in Figure 1. All of these four studied models are loaded and designed according to the Iranian seismic code 2800 and the Iranian national building code (issues 6 and 10).In almost all structural design codes, the direction of ground motion incidence is usually considered the same as main skeletal axis. The purposed simultaneous effect is also considered by superposition of 100% of earthquake lateral forcesimposed in the direction of a unique main axis which interacts with 30% of the aforementioned forces that applied in the direction of the other transverse main axis. Meanwhile in reality, there are many possible incident angles that would lead to non-uniform increases of dynamic response parameters (Hernandez & Lopez, 2002). In this paper, a set of values from 0 to 45 degrees with an increment of 15o has been applied for definition of incident angles related to earthquake excitations (Figure 2).

کلیدواژه ها:

Diagrid structure ، Directivity process ، Incident angle ، Velocity pulse ، Nonlinear dynamics