Multi-storey commercial building design
A multi-storey building stacks loads, stability and services into a structure that has to stand up in normal use and not collapse disproportionately if something goes wrong. We design multi-storey commercial and mixed-use buildings to do both, for developers across the UK.
What gives a multi-storey building its stability?
Usually reinforced concrete cores around the lifts and stairs, shear walls, or braced steel bays, which carry the wind load down to the foundations. We locate and size the stability system early because it shapes the efficiency of the whole frame.
Vertical load paths and the frame
In a multi-storey building every floor adds its load to the columns below, so the load accumulates towards the foundations and the lower columns carry the most. We design a continuous vertical load path from roof to foundation, sizing columns and transfer structures so the load travels cleanly downwards. Where the floor plate below differs from the floors above, for parking, a lobby or retail at street level, we design transfer beams or a transfer plate to carry the columns above across the changed grid below.
The frame is chosen for the building's height, use and programme. Steel frames with composite floors erect quickly and suit offices and mixed use, reinforced concrete frames give inherent fire resistance and mass, and hybrid schemes mix the two. We design the members to the relevant Eurocode, BS EN 1993 for steel or BS EN 1992 for concrete, and coordinate the grid with the cores, services and cladding so the building goes together as one system.
Stability and lateral loads
Standing a tall building up against wind is a whole design in itself. We provide lateral stability through reinforced concrete cores, braced steel bays or shear walls, positioned so they carry the wind load down to the foundations and resist the twisting a non-symmetric plan produces. Wind actions are taken from BS EN 1991-1-4 and its UK National Annex, and we check overall sway, inter-storey drift and, for slender buildings, the comfort of occupants under wind-induced movement.
The cores and shear walls do double duty, enclosing the lifts and stairs while acting as the stiff spine of the building. We design them for the combined wind and gravity load and for the large overturning forces that build up over the height, transferring those forces into foundations sized to resist uplift on the windward side. Getting the stability system located and sized early is what keeps the rest of the frame efficient.
Robustness, disproportionate collapse and foundations
Multi-storey buildings must be designed so that if one element is lost, the damage does not spread into a disproportionate collapse. We follow the requirements of Approved Document A and BS EN 1991-1-7, tying the structure together horizontally and vertically, checking key elements and designing so that the accidental removal of a column is bridged over rather than pulling the building down. The building's consequence class sets how far these checks have to go.
The foundations carry the accumulated load of the whole building plus the overturning from wind. We design piled foundations, rafts or a piled raft for the column and core loads, checking settlement as well as capacity so the frame is not distressed by differential movement. Where there is a basement, we design the retaining walls and the basement box for ground and water pressure and tie the whole substructure into the stability system above.
What we check.
The points our calculations resolve for a project like this.
- Continuous vertical load path with transfer structures at changed grids
- Frame material chosen for height, fire, programme and use
- Lateral stability by cores, shear walls or braced bays
- Wind sway, inter-storey drift and occupant comfort checks
- Robustness and disproportionate collapse to BS EN 1991-1-7
- Piled or raft foundations for accumulated load and wind overturning
From enquiry to sign-off.
Enquiry
Send drawings or describe the problem. We confirm the scope, the deliverables and a target timescale.
Information
We agree the survey, drawings or data we need and any site access required.
Engineering
Design, calculation or assessment to the relevant Eurocodes and UK National Annex.
Issue
A clear, defensible report or set of calculations, with assumptions and limitations stated.
Common questions
What gives a multi-storey building its stability?
Usually reinforced concrete cores around the lifts and stairs, shear walls, or braced steel bays, which carry the wind load down to the foundations. We locate and size the stability system early because it shapes the efficiency of the whole frame.
What is disproportionate collapse and do you design for it?
It is the risk that losing one element triggers a collapse far bigger than the initial damage. We design against it following Approved Document A and BS EN 1991-1-7, tying the structure together and checking that the loss of a column can be bridged over.
Can you handle a mixed-use building with parking or retail below?
Yes. Where the lower floors have a different grid, we design transfer beams or a transfer plate to carry the columns above across the changed layout below, and we tie the whole load path down to suitable foundations.
Do you design multi-storey schemes across the UK?
Yes. We work on multi-storey commercial and mixed-use buildings for developers across the UK, delivering calculations remotely and arranging site visits by region.
Related in commercial, industrial & agricultural structural engineering.
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