1.0 System Overview
The Central Stainless Steel Core forms the main structural backbone of the 900‑meter helical supertall tower. It carries gravity and lateral loads, stabilizes torsion, and houses all major vertical transport and service systems.
Functional Role
- Carries gravity and lateral loads
- Provides torsional stability
- Contains elevators, service shafts, and mechanical risers
- Direct connection to all major systems:
- Floor systems
- Outriggers
- Vertical transportation
1.1 Global Dimensions
| Total Height | 900.0 m |
|---|---|
| Exterior Diameter | 24.0 m |
| Internal Clear Diameter | 22.8 m |
| Floor-to-Floor Height | 4.5 m (typ.) |
| Outrigger Spacing | Every 20 floors (~90 m) |
1.2 Zoning & Wall Thickness Strategy
Zone A — Lower Core (0–200 m)
- Wall Thickness: 120 mm
- Handles maximum gravity and seismic loads
- Provides high buckling resistance
Zone B — Mid Core (200–600 m)
- Wall Thickness: 80 mm
- Reduced axial load zone
- Optimized material efficiency
Zone C — Upper Core (600–900 m)
- Wall Thickness: 50 mm
- Lightweight stabilization
- Reduced inertia at upper levels
Engineering Logic
- Tapered thickness provides optimized stress distribution
- Prevents overdesign at upper levels
- Reduces overturning moment
1.3 Core Component Breakdown
1. Outer Tube (Core Shell)
- Material: Duplex Stainless Steel (EN 1.4462)
- Continuous cylindrical shell
- Full penetration welded construction
2. Ring Diaphragms
- Thickness: 60 mm
- Outer Diameter: 23.4 m
- Inner Diameter: 21.0 m
- Spacing: Every floor (4.5 m)
- Function: Prevent ovalization and transfer loads between core shell and floor system
3. Vertical Stiffeners
- Plate Thickness: 20 mm
- Depth: 400 mm
- Radial grid spacing
- Function: Increase buckling resistance and axial capacity
4. Radial Floor Connections
- Tube Diameter: 508 mm
- Wall Thickness: 20 mm
- Function: Connect floor framing to core and distribute loads radially
5. Outrigger Connections
- Tube Diameter: 914 mm
- Wall Thickness: 25 mm
- Function: Transfer lateral loads to mega‑columns and external frame
6. Service & Elevator Shafts
- Integrated within the core
- Symmetrical layout reduces eccentricity
7. Base Flange Connection
- Flange Thickness: 120 mm
- Bolt Size: M64 (Grade 8.8)
- Quantity: 32 bolts
- Function: Transfers loads to foundation and provides moment fixity
1.4 Core Cross Section
The core is a circular structural tube with an external diameter of 24.0 m and an internal clear diameter of 22.8 m. Internal stiffeners and shaft partitions are arranged symmetrically to prevent torsional imbalance.
1.5 Typical Floor Connection System
- Ring diaphragm installed at every floor
- Radial trusses connect floor deck to core
- Circumferential ring beams support secondary framing
Load Flow
Floor → Radial Beam → Ring Diaphragm → Core Shell → Foundation
1.6 Material Properties (EN 1.4462 Duplex Stainless Steel)
| Yield Strength | 450 MPa |
|---|---|
| Tensile Strength | 650 MPa |
| Elastic Modulus | 200 GPa |
| Shear Modulus | 77 GPa |
| Density | 7850 kg/m³ |
| Poisson Ratio | 0.30 |
| Thermal Expansion | 13.5 × 10⁻⁶ /°C |
| Fire Resistance | > 2.5 hours |
| Corrosion Resistance | Marine Grade (Excellent) |
1.7 Design Loads Applied to Core
- Dead Load
- Live Load
- Wind Load
- Seismic Load
- Torsional Load
- Outrigger Load
- Foundation Reaction
1.8 Structural Engineering Logic
Primary Load Spine
The core carries 60–70% of lateral loads and the majority of vertical loads.
Buckling Control
Achieved through ring diaphragms and vertical stiffeners.
Torsional Stability
Circular geometry minimizes stress concentrations and suits helical tower design.
Outrigger Interaction
Outriggers every ~90 m engage the perimeter structure and reduce drift.
Fabrication Logic
- Fully welded shell
- High‑strength bolted base
- Modular ring assembly
1.9 Tolerances & Construction Notes
- Fabrication tolerance: ±5 mm
- Installation tolerance: ±10 mm
- All welds: full penetration groove welds
- No construction joints (continuous core)
- Connections: welded or high‑strength bolted
1.10 Performance Summary
- High wind stability
- Excellent seismic resistance
- Balanced stress distribution
- High manufacturability
- Long service life due to corrosion‑resistant steel
What This Section Enables
The Central Stainless Steel Core is the structural brain and spine of the tower. It anchors all 20 major structural and mechanical sections, enabling stability, constructability, and long‑term performance.
