6.0 Overall Structural System Overview
The 900‑meter helical supertall tower uses a hierarchical composite structural system integrating the central reinforced core, radial floor truss network, outrigger and belt truss system, helical exterior mega‑frame, and dome crown structure.
Primary Building Parameters
- Total Height: 900.0 m
- Total Stories: 200
- Typical Floor Height: 4.5 m
- Primary Structural Material: Duplex Stainless Steel EN 1.4462
- Secondary Material: Stainless Steel 316L
- Design Life: 150 years
- Fire Resistance: Passive protection system
6.1 Structural System — Exploded Hierarchy
Component stack from top to foundation:
- Helical Dome Structure
- Outrigger Truss Levels (every 20 stories)
- Belt Truss Levels (every 10 stories between outriggers)
- Radial Floor Trusses (every floor)
- Central Core (Duplex Stainless Steel)
- Vertical Core Columns
- Core Perimeter Walls
- Diagonal Bracing (X‑brace system)
- Foundation Connection Ring Beam
- Foundation Pile System
6.2 Vertical Structural Zoning
Outrigger Levels (Height Markers)
- Level 20 → 90.0 m
- Level 40 → 180.0 m
- Level 60 → 270.0 m
- Level 80 → 360.0 m
- Level 100 → 450.0 m
- Level 120 → 540.0 m
- Level 140 → 630.0 m
- Level 160 → 720.0 m
- Level 180 → 810.0 m
- Level 200 → ~900.0 m
Belt Truss Levels
- Occur every 10 stories
- Located between outrigger zones
- Provide circumferential stiffness
Radial Floor Trusses
- Installed every floor
- Vertical spacing: 4.5 m
6.3 Typical Floor Structural Module
Geometry
- Module Diameter: 220.0 m
- Central Core Diameter: Ø24.0 m
- Floor Plate Type: Composite deck system
Component Breakdown
1. Floor Deck
- Composite slab on steel deck
- Function: Load distribution + diaphragm action
2. Secondary Radial Members
- Material: Stainless Steel hollow section
- Diameter: Ø219 mm
- Wall Thickness: 12.5 mm
3. Primary Radial Trusses
- Hollow section chords
- Diameter: Ø508 mm
- Wall Thickness: 25 mm
4. Perimeter Ring Beam
- Diameter: Ø2323 mm
- Wall Thickness: 60 mm
5. Perimeter Connections
- Connect floor module to helical mega‑frame nodes
6.4 Outrigger Truss System (Typical Level)
Configuration
- Truss Type: Vierendeel
- Depth: 8000 mm
- Material: Duplex Stainless Steel
Components
- Outrigger truss arms
- Ring beam interface
- Connection nodes
- Exterior mega‑frame linkage
- Central core anchoring
Engineering Logic
- Transfers overturning moment from core to perimeter
- Increases global stiffness
- Reduces lateral drift
6.5 Belt Truss System (Typical Level)
Components
- Belt truss mega ring (Ø2200 mm)
- Radial diagonal members
- Vertical stiffeners
- Frame connections
- Core interface
Function
- Ties perimeter columns together
- Distributes lateral loads evenly
- Enhances torsional resistance
6.6 Diagonal Bracing System (X‑Brace)
Specifications
- Tube Diameter: Ø323 mm
- Wall Thickness: 20 mm
- Bracing Angle: 60° typical
- Material: Duplex Stainless Steel EN 1.4462
Components
- Diagonal tubes
- Node connectors
- Core column interface
- Floor‑level tie‑ins
Function
- Prevents buckling
- Provides shear resistance
- Stabilizes vertical columns
6.7 Structural Member Schedule
| Central Core Columns | Ø2400 mm × 80 mm — Duplex SS — 1 set |
|---|---|
| Core Perimeter Walls | 1200 mm height modules × 80 mm — Duplex SS — varies |
| Primary Radial Truss | Ø508 mm × 25 mm — Duplex SS — 24/floor |
| Secondary Radial Members | Ø219 mm × 12.5 mm — Hollow SS — 48/floor |
| Perimeter Ring Beam | Ø2323 mm × 60 mm — Duplex SS — 1/floor |
| Outrigger Truss | 8000 mm depth × 50 mm — Duplex SS — 4/level |
| Outrigger Ring Beam | Ø2400 mm × 60 mm — Duplex SS — 1/level |
| Belt Truss Mega Ring | Ø2200 mm × 50 mm — Duplex SS — 1/level |
| Belt Truss Diagonals | Ø508 mm × 20 mm — Hollow SS — 24/level |
| Diagonal Bracing | Ø323 mm × 20 mm — Duplex SS — varies |
| Connection Nodes | Cast/Fabricated — variable — varies |
6.8 Foundation Connection System
Ring Beam
- Diameter: Ø24.0 m
- Heavy structural ring
Pile System
- Pile Diameter: Ø1.5 m
- Number of Piles: 48
- Pile Spacing: 7.2 m centers
Components
- Base plate
- Anchor bolts (M64)
- Leveling nuts
- Welded connections
Function
- Transfers axial and lateral loads to ground
- Distributes load evenly across pile group
6.9 Foundation Layout Plan
- Circular pile arrangement
- Radial symmetry for uniform load transfer
- Core‑aligned centroid
6.10 Helical Frame Connection Detail
Members
- Exterior mega‑frame tubes: Ø508 mm
- Connection nodes: Cast steel
Connections
- Bolts: M64 (Grade 8.8 stainless steel)
- Welds: Full penetration groove welds
Function
- Transfers load between radial floors, helical exterior frame, and ring beams
6.11 Design Load Summary
| Dead Load | 5.0 kN/m² |
|---|---|
| Live Load (Office) | 3.0 kN/m² |
| Wind Load | Per Section 12 |
| Seismic Load | Per Section 12 |
| Total Design Load | 8.0 kN/m² + environmental |
6.12 Material Properties (Duplex SS EN 1.4462)
| Yield Strength | 450 MPa |
|---|---|
| Tensile Strength | 650 MPa |
| Elastic Modulus | 200 GPa |
| Shear Modulus | 77 GPa |
| Density | 7850 kg/m³ |
| Poisson’s Ratio | 0.30 |
| Corrosion Resistance | Excellent |
| Fire Resistance | > 2.5 hours |
6.13 Engineering Logic
Global Structural Strategy
- Core = primary vertical load carrier
- Outriggers = moment transfer system
- Belt trusses = perimeter stiffening
- Helical frame = torsional + wind resistance
Load Path
- Floor loads → radial trusses
- Radial trusses → core + perimeter ring
- Lateral loads → outriggers
- Outriggers → exterior mega‑frame
- Entire system → foundation ring → piles
Performance Behavior
- Wind: resisted via helical geometry + outriggers
- Seismic: distributed through ductile braced system
- Torsion: minimized via continuous ring structures
6.14 General Notes
- All welds: Full penetration groove welds unless noted
- All bolts: Stainless Steel M64 (Grade 8.8)
- Fabrication tolerance: ±5 mm
- Installation tolerance: ±10 mm
- All dimensions in millimeters unless stated
