Whilst the research project OPUS investigated a wide array of structural typologies, the present contribution focuses on composite steel concrete frames with either steel columns or composite columns and subjected to low as well as high seismic actions. Accordingly four possible combinations are studied (see Table 2): composite frames with steel columns (low and high seismicity) and composite frames with composite columns (low and high seismicity). All frames have the same general typology. The structure is a 5-stories / 3 bays office building, with a height of 17.5m. An intermediate beam in Y-direction allows adopting a slab's thickness of 12 cm. The slabs are made of reinforced concrete and fully connected to the steel profile (full interaction). The surfaces of the slabs are 21m (3 bays in the X-direction) by 24m (4 bays in the Y-direction). The dimensions of the building are given in Figure and 3.
Figure . Plane view of the composite frames
Figure . Elevation of the composite frame.
Table . Definition of the moment resisting frames.
Persistent and transient design situations are defined according to EN 1991 values . The live load acting on the building is chosen for a use category "office" and the other variable actions are reported in Table .
Buildings are supposed to lie on a soil of type B. The importance factor I is set equal to 1. The reference peak ground acceleration (agR) is chosen equal to 0.25 g for high seismicity and 0.1g for low seismicity. The values of the parameters describing the recommended type 1 elastic response spectrum are reported in Table . The corresponding elastic response spectra are represented in Figure . Combinations for Service Limit State (SLS) and Ultimate Limit State (ULS) are summarized in Table .
Table : Type 1 elastic response spectrum parameters