seismic analysis as a tool for checking the structural system

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3125 3200 3250 5500 5500 5500 5500 5500 5500 5500 5500 Fig.1 Longitudinal section Fig.2 Transversal section The columns are 450x450mm reinforced with 12φ25 bars. The corner columns are 500x500mm reinforced with 16φ25 bars. The reinforcing bars are distributed uniformly along the perimeter of the cross-section. Ground-floor Thickness of the ground-floor slab is 200mm. The columns are 450x450mm reinforced with 12φ25 bars. The corner columns are 500x500mm reinforced with 16φ25 bars. Beams are 400x650mm (450mm+200mm slab), reinforced by 12φ25 bars uniformly distributed along the perimeter of the cross-section. First-floor Thickness of the first-floor slab is 200mm. The columns are 450x450mm reinforced with 12φ25 bars. The corner columns are 500x500mm reinforced with 16φ25 bars. Beams are 400x650mm (450mm+200mm slab). Roof The roof is located over one part of the building, 3x5.5m spans in longitudinal direction and 3x5.5m in transversal direction, with a 1200mm overhang along the perimeter. The thickness of the roof slab is 200mm. On the roof is an additional 150mm thick concrete covering slab. Beams are 400x650mm (450mm+200mm slab). Structural model The building was modelled as a 3D system consisting of beams, columns, slabs and walls (Fig.3 and Fig.4). The material concrete C35/45 with characteristic compression strength 35MPa and reinforcing steel S220 are used. In order to provide sufficient seismic resistance R/C shear walls of 200mm thickness are arranged in both X and Z horizontal directions (Fig.4).The walls and floors were modelled with shell elements, the columns and beams as beam elements. The elastic foundation stiffness (EFS), defined as the pressure producing a unit normal deflection of the foundation, is considered. The elastic foundation capability is assumed for foundation slab (EFS=50MPa/m) as well as for walls under the ground level (EFS=25MPa/m). ANSYS konference 2008 16. ANSYS FEM Users‘ Meeting & 14. ANSYS CFD Users’ Meeting Luhačovice 5. - 7. listopadu 2008 - 2 -
Fig.3 Structural 3D model Fig.4 R/C shear walls Static Loads Basement Dead load Self-weight of foundation slab 500 mm 12.5 kN/m 2 Self-weight of concrete wall 300mm 19.5 kN/m Ground-floor Dead load Self-weight of slab 200 mm 5 kN/m 2 Additional self-weight 2.5 kN/m 2 Self-weight of masonry partition walls 5.6 kN/m 2 First-floor Dead load Self-weight of slab 200 mm 5 kN/m 2 Additional self-weight 2.5 kN/m 2 Self-weight of masonry partition walls 4.9 kN/m 2 Roof Dead load Self-weight of slab 200 mm 5 kN/m 2 Additional self-weight of concrete cover 3.75 kN/m 2 Seismic load The site ground acceleration is quite high reaching the value of a g =3.2ms -2 . The soil parameters are similar to the soil class B (ENV1998). It is assumed a „Low“-ductile structure and then the calculation of behaviour factor is taken according to (ENV 1998-1-3). Choice of a „Low“-ductile structure is due to the fact, that the cross-sectional reinforcement does not allow adequate rotational capacity. q 0 =5 for R/C frame structure, k D =0.5 - ductility class factor (DC „L“), k R =0.8 - structural irregularity factor, q=q 0 k D k R =2. Because ductility class “L” was chosen, the masonry walls (thickness 400mm) are not taken into account as structural elements. In spite of this, the masonry walls should be furnished with a provision to protect them against falling out of the R/C frame during seismic design situation. The inelastic (q=2) design response spectrum, shown on Fig.5, is assumed. ANSYS konference 2008 16. ANSYS FEM Users‘ Meeting & 14. ANSYS CFD Users’ Meeting Luhačovice 5. - 7. listopadu 2008 - 3 -
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