Eurocode 2 Structural Design: Slender Precast Helical Stair (Segmented 2–3 Units)

We require a qualified structural engineer experienced in precast reinforced concrete helical stairs to carry out the architectural geometric setting out and full structural design to Eurocode 2. 1. Geometry & Aesthetic •Shaft Opening: 3,100 mm × 4,100 mm. •Floor-to-Floor Height: 3,400 mm. •Aesthetic Intent: We want to move away from a standard U-shape footprint toward an elegant, sculptural profile (such as a flowing teardrop or continuous elliptical ribbon with a flared transition), while strictly maintaining compliant risers, treads, and required headroom clearances. 2. Non-Negotiable Fabrication Constraints (Precast Yard Limits) •Segmented Construction: The stair cannot be cast or installed in one single piece. It must be designed as a 2-piece or 3-piece assembly with concealed, buildable structural connections (e.g., recessed bolted steel angle splices / shear pins). •Slender Profile: Target waist / throat thickness is 200 mm (slender aesthetic). Bulky 300 mm+ profiles are rejected. •Rebar Limit: Maximum bar diameter is 10 mm (hand-bent by precast manufacturer). Proposals relying on 12 mm or heavier main reinforcement will not be accepted. •Support Conditions: Intermediate retractable wall supports / steel wall brackets into the adjacent structure can be incorporated along straight or landing sections to control moments and joint stresses. 3. Required Deliverables 1.Geometric Setting Out & Headroom Check: 3D/2D layout of the teardrop/elliptical ribbon geometry showing compliance with UK/Eurocode building standards. 2.Structural Calculation Pack (Eurocode 2): Complete calculations modeling the stair in its segmented configuration, including load takedown, 3D torsional/shear analysis, deflection, and detailed design of the internal joint connections and anchorages. 3.CAD Drawings (AutoCAD .DWG & PDF): GA, setting-out, reinforcement layouts, and exact fabrication detailing of the mid-span connection/joint assembly. 4.Bar Bending Schedule (BBS): Fully detailing all bars (strictly $\le 10\text{ mm}$) and couplers/splice components. 4. How to Bid (Please Read Carefully)Do not submit generic copy-paste bids. In your proposal, explicitly state: 1.Your experience with segmented precast curved/helical stairs along with evidence. 2.How you intend to resolve the mid-span joint connection within a 200 mm section and 10 mm bar constraint (e.g., steel splice plate, wall supports, coupling system). 3.Confirm you can deliver within the stated 200 mm / 10 mm limits.