MasudaNaoyaYour Design Journal entries this week should highlight your design thinking that influenced your decisions about:
- your overall strategy and the features of the structural system
- the material and framing system selected
- the locations of structural columns and major framing elements
- any special structural challenges
Structural System Strategy
Concept: A Fusion of Modern High-Rise and Traditional Japanese Architecture
My structural strategy aims to create a modern high-rise building while integrating the aesthetics and craftsmanship of traditional Japanese architecture. This approach balances structural efficiency, material innovation, and spatial flexibility, ensuring both performance and design integrity.
- Overall Structural Strategy & System Features
To achieve larger internal spaces and flexible layouts, we selected a structural system that allows for expansive interior spaces while maintaining the visual essence of wood construction.
Key Structural Features:
- Hybrid Timber-Steel Structure:
- While using a steel frame for structural efficiency and large spans, I will wrap the columns in wood to evoke traditional aesthetics.
- This ensures fire resistance, strength, and a warm wooden finish.
- Exposed Wood Elements for Architectural Identity:
- Traditional Japanese joinery-inspired detailing for exposed wood components.
- Ceiling beams and wall finishes will integrate CLT (Cross-Laminated Timber) panels where possible.
- Open Floor Plan in Exhibition Areas:
- Utilizing long-span steel beams to reduce interior columns.
- Braced frames strategically placed in service cores to maintain openness.
- Material and Framing System Selection
A hybrid structural system was chosen based on both performance and aesthetic goals.
Primary Structural System: Steel Frame with Wood Finishes
- Steel Columns & Beams:
- Provides high strength for a 7-story structure while allowing for long-span open areas.
- Columns will be wrapped in wood (e.g., engineered timber panels) to create a traditional Japanese appearance.
- CLT & Glulam Elements:
- CLT floor panels for specific areas (especially exhibition spaces) to introduce warmth and sustainability.
- Glulam beams in interior spaces to enhance the wooden aesthetic.
- Lateral Stability:
- Steel braced frames hidden in core areas (staircases & mechanical shafts) to resist seismic and wind loads.
- CLT shear walls in selected locations to contribute to lateral stability while maintaining a wooden interior.
- Structural Column & Major Framing Element Locations
The placement of columns and major beams follows a modular grid system optimized for both structural efficiency and design flexibility.
Structural Grid System:
- Primary Column Spacing: 9m × 9m (30ft × 30ft) grid for efficiency.
- Strategic Column Placement:
- Office areas: Regular column grids with steel columns clad in wood.
- Exhibition spaces: Fewer columns with long-span beams (W18×55 to W21×73) to create wide, open interiors.
- Framing System:
- Steel beams & CLT floor panels in office areas.
- Glulam beams for ceiling structures, exposed to highlight traditional craftsmanship.
- Bracing Locations:
- Placed in vertical cores (stairs/elevators) to maintain openness.
- Some CLT shear walls used for added stiffness.
- Structural Member Sizing
To ensure structural efficiency while maintaining large open spaces, the following member sizes have been selected based on assumed loading conditions and span requirements.
Primary Beams
For the primary beams, which support the main structural loads and contribute to the long-span open spaces in the exhibition areas, W21×73 beams are used. These beams provide sufficient strength to accommodate the wide spans while maintaining structural integrity.
Secondary Beams
To efficiently support the floor loads while maintaining an optimal beam depth, W14×38 beams are utilized for secondary framing. These beams are spaced at regular intervals to support the composite deck system effectively.
Columns
The primary structural columns, which serve as the main vertical load-bearing elements, are designed using W14×99 steel sections for the lower floors, ensuring adequate capacity for the accumulated axial loads. For the upper floors, where the loads are reduced, W12×53 columns are used to optimize material efficiency while maintaining structural stability. All columns are clad in engineered wood to achieve the desired aesthetic of traditional Japanese architecture.
Bracing System
To provide lateral stability against wind and seismic forces, braced frames are integrated within the core areas. HSS 8×8×1/2 hollow structural sections are used for the bracing elements, ensuring adequate stiffness and strength without compromising the architectural openness of the space.
Deck Slab
The floor system consists of a composite steel deck with a 3-inch metal deck topped with 3.5 inches of reinforced concrete, resulting in a total floor thickness of 6.5 inches. This system provides an optimal balance of strength, fire resistance, and vibration control while allowing for an efficient construction process.
This structural sizing strategy ensures that the building meets performance requirements while maintaining the aesthetic and functional goals of the design. The integration of steel framing with wood finishes and CLT elements allows for a structurally robust yet visually warm and inviting architectural space.
- Special Structural Challenges & Solutions
Challenge 1: Balancing Large Interior Spaces with Structural Efficiency
- Solution:
- Using long-span steel beams in exhibition areas while maintaining wood-clad columns.
- Mixing CLT in select areas for warmth while keeping steel for primary strength.
Challenge 2: Achieving a Traditional Wood Aesthetic in a High-Rise Steel Structure
- Solution:
- Steel columns wrapped in engineered wood panels.
- Exposed Glulam beams and CLT elements in public spaces to reinforce the Japanese architectural theme.
Challenge 3: Seismic Performance
- Solution:
- Steel braced frames in core areas for lateral stability.
- CLT shear walls in select areas to contribute to damping and rigidity.