New 2B+GF+5storeys composite steel residential building

Structural discipline completed

Total Built up Area: 1875m2
Vertical Structural system: Steel structure, composite beams, composite & steel columns (SHS filled/not filled with concrete).
Horizontal Structural system: Moment resisting frames & Concentrically bracings.
Slab thickness: 80mm
Cantilevers length: 3.20m
Total height above Ground: 18.00m
Max excavation depth: 5.00m
Structural Materials: Concrete C45/55, Steel S355

Design Basis.
The design has been done according to the Eurocodes (EC-1,EC-2,EC-3,EC-4,EC-8)
Loading
Self-weight, according to materials
Additional Dead Load, 1,50kN/m2
Live Load, 5,00kN/m2
Seismic design
The seismic base shear of the building is calculated to:
-Acc. to the lateral force method: 3712 kN
-Acc. to the response spectrum analysis: 2048kN
According to the EC8, there is no requirement to scale the base shear derived from the RSA to the 85% of the one from the LFM.
This is a typical example where the lateral force method, fails to describe the distribution of the seismic force induced to the structure.
Max horizontal displacement on top δmax=33mm
Wind design
Wind forces have been considered acting to the center of each diaphragm.
Basic wind speed v_b,0=30,00m/s
The total wind base shear has been calculated as follows:
Wx=
Wy=

Slabs & Vertical forces transfer
Due to the limited available height, there was a special requirement regarding the total slab+beam height. In combination with the long cantilevers in the front elevation (l=3.20m), composite beams with shear studs and a solid slab of 80mm thickness have been chosen.
Structural modeling
Shell & frame elements have been used to analyze the structure. All vertical members have been considered fixed to the foundation level.
Special consideration has been given to the pools on the 2nd and the 5th floor of the building. Below is shown the effect that the concrete walls to the perimeter of the pool has to the column bending moments due to horizontal forces (earthquake and wind).