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Structural engineers design the frame that carries the building: foundations, columns, beams, slabs and load-bearing walls. Their decisions are backed by calculations, which is why their elements are the hardest to move and the most expensive to change late.
Loads (people, furniture, plant, snow, wind) travel from slabs to beams, to columns, to foundations. Change a load, or cut a hole in a member, and the engineer may need to re-check the members below it. That's why they ask about weights, openings and positions.
What structural engineers need from you
| Need | Why |
|---|---|
| Builders' work holes (size, position, purpose) early | Each one is checked and may need a detail or reinforcement |
| Plant and equipment weights and locations | Loads drive slab and beam design |
| Agreed grids and levels | The frame is set out from them |
| Coordination on the physical model | Their analytical model isn't for clashes |
The MEP subcontractor's coordinator resolves 120 duct-beam clashes by adding holes through the beams in the federated model and closing the issues. On site, the concrete contractor casts the beams without the openings, which were never in the structural drawings; coring them later needs the engineer's approval, a crane-hire week and two days of delay per floor.
The clashes are grouped into a builders' work schedule (size, position, purpose) and sent to the structural engineer as a formal request. The engineer approves 95, rejects 25 (too close to supports, so the ducts are rerouted), and issues a detail for sleeves cast in during the pour.
You have three penetrations from the latest federated model: a 300 mm duct through beam B12 at mid-span, a 150 mm pipe through a slab next to column C4, and a 600 × 400 mm duct through a core wall. List what you'd send the structural engineer for each, and which one you'd flag as most likely to be rejected.
Key takeaways
- The structural engineer owns the frame: foundations, columns, beams, slabs, walls that carry load, and their connections.
- Structure is the hardest thing to move late: changes need calculations, and sometimes ripple down to the foundations.
- Openings, penetrations and heavy equipment loads must be agreed with them, with sizes and positions.
- Their analysis model and their physical (BIM) model are different things; coordinate with the physical one.