Structural Design of 3 Storey Building

Beta Scope

•  Structural design of the super-structure for the 3-storey building with more than 8000 sq ft of floor space

Background

Beta Design Consultants scope was the full civil and structural engineering design including:

• The structural design of the steel structure with a mix of pre-cast and cast in situ concrete floorings, spiral concrete stairs and a curved RC wall.The sub-structure was individual pad foundations.
• The design of all steel connections and the preparation of the fabrication drawings.
• The detailing of all cast-in-situ concrete members including the rebar bending schedules for the spiral stairs, the curved wall and the ring beams around the atrium large opening.
• The drainage design including the adoption of a network of perforated pipes discharging into a sump to get rid of the high level of ground water below the building footprint.

Beta Solution

Our Structural Engineers carried out the detailed structural analysis using Scia Engineer. The steel structure and the concrete floors and walls were all modelled together to allow accurate representation of the impact of the floor and walls on structure stability. This also allowed accurate transfer of loads from floors to the structure.

Idea Statica was used to design all steel to steel connections and achieve maximum standardisation possible to reduce cost of fabrication and time of installation.

Tekla Structures was used to model all the steel structure as well as to model the rebar of the curved RC members (Ring beams around openings, Spiral Stairs, RC Wall).

Practical Details

Large Atrium Opening

The building featured a 3.6m opening in the centre of the cast-in-situ slab. Spiral stairs lead to a landing on each floor that overlooked this atrium. It was an architectural requirement that the slab has no downstand or upstand around the opening or at the support points of the stairs.

Beta Design Consultants designed hidden reinforced concrete beams to support the slab around the openings and pick up the loading of the stairs.

Spiral Stairs

The spiral staircase was designed manually. The loads from the stairs, calculated using Reynolds method, were then applied at support points in SCIA.

To produce the rebar bending schedule, Tekla Structure 3D modelling of the rebar was used to work out the length of each bar in the spiral stairs (as they vary depending on distance from atrium centre).