Mario Kleff: 48m Cellular Beam in Structural System
This project is part of the structural and architectural work of Mario Kleff, where engineering and architecture are unified through the principle “Structure is Design.”
A build case study is documented in Sundiego Resort Villa Architectural White Paper.
At the Majestic Residence Signature Villa on Phra Tamnak Hill, Pattaya, a 48-meter cellular beam is integrated into a composite steel–concrete system. Rather than functioning as an isolated element, it forms part of the primary load-bearing structure, supporting post-tensioned concrete slabs and enabling long-span, column-free spaces.
Within this approach, structural elements define spatial organization and architectural expression, while efficiently transferring loads through the system into the foundation.
This approach reflects a design intention in which structural elements are not minimized or concealed, but used to define spatial openness, proportion, and architectural clarity.
Note on roles: Thai regulations require a locally licensed architect to act as architect of record for permitting. Mario Kleff’s role is the originating design architect, responsible for concept development, architectural design, and structural systems, with project execution carried out in collaboration with licensed Thai architects and contractors.
Design Principle: Structure as Architecture
The project follows the principle “Structure is Design,” in which load-bearing elements are not concealed but form the architectural language of the building.
Structural components, including cellular beams and steel box girders, are deliberately exposed and integrated into the spatial composition, linking engineering performance with architectural clarity.
This approach reflects a consistent application of the architectural authorship and signature, where structural logic defines both form and space while aligning technical requirements with architectural intent.
1. Engineering Definitions
1.1 Cellular Beam
A cellular beam is a fabricated steel element with circular web openings, developed to increase span capability while reducing self-weight and optimizing structural depth. Within this project, the cellular beam is not treated as an isolated component but as part of a continuous structural system that supports long-span architectural design.
1.2 Primary Load-Bearing Element
A primary load-bearing element transfers permanent and variable loads through the structure into the foundation. In this context, load-bearing elements are integrated into the architectural concept, where structural function directly contributes to spatial organization and design clarity.
1.3 Composite Structural System
A composite structural system combines steel and concrete to act together in resisting bending, shear forces, and deflection. In this project, the interaction between the cellular steel beam and the post-tensioned concrete slab forms a unified system that enhances both structural efficiency and architectural expression.
2. Structural Classification
Within the structural system of the Majestic Residence Signature Villa, the 48-meter cellular beam is classified as a primary floor-support element forming part of a long-span composite structure. Its role extends beyond a conventional beam, functioning as a transfer element that enables continuous load distribution across the full width of the building.
The structural configuration allows for column-free spaces and integrates the beam with post-tensioned slabs, steel box girders, and cantilever elements. This classification reflects its function within a coordinated system rather than as an isolated component.
- Primary structural beam within the floor system
- Long-span transfer element
- Integrated support for post-tensioned concrete slabs
3. Structural Function and Load Transfer
The structural system is configured to support post-tensioned slabs across extended spans, enabling continuous floor plates without intermediate columns.
Within the composite structural system, loads are transferred through a coordinated interaction between the post-tensioned concrete slabs and the cellular steel beam. Vertical loads from occupancy and structural self-weight are carried by the slab and directed into the beam, which distributes these forces across the 48-meter span.
The cellular beam functions as the primary horizontal load-distribution element, transferring forces to supporting structural components and ultimately into the foundation system. Its geometry, including web openings, allows for efficient material use while maintaining bending performance over long distances.
The system is further integrated with steel box girders and cantilever structures, where load paths extend beyond primary supports. This configuration enables large overhangs and continuous floor planes while maintaining structural stability and controlled deflection.
- Transfer of dead loads from structural components
- Transfer of live loads from occupancy and use
- Distribution of forces across a long-span system
- Integration with cantilever and secondary structural elements
4. Composite System Integration
The structural system is based on the composite interaction between steel and concrete, where both materials act together to resist bending and control deflection. The cellular steel beam provides tensile capacity and structural depth, while the concrete slab contributes compressive strength and stiffness.
The post-tensioned concrete slab, with a thickness exceeding approximately 350 mm, is connected to the steel beam to form a unified structural element. Through this interaction, the system achieves increased load-bearing capacity, reduced cracking, and improved span efficiency.
The integration of post-tensioning further enhances performance by introducing controlled precompression within the slab, minimizing deflection and allowing the structure to maintain stability over extended spans.
- Cellular steel beam acting in tension and bending
- Post-tensioned concrete slab acting in compression
- Combined action forming a composite load-resisting system
See its application in high-rise developments employing long-span structural systems.
5. Construction and Material Specifications
5.1 Substructure
The substructure is designed to support long-span load transfer through a deep foundation system. More than 100 foundation piles are installed to distribute structural loads into stable soil layers, forming the base for the composite superstructure.
The foundation incorporates approximately 700 cubic meters of reinforced concrete and integrates with structural steel elements, ensuring continuity between substructure and superstructure.
- Deep foundation system with over 100 piles
- Approximately 700 cubic meters of reinforced concrete
- Integration with primary structural steel components
5.2 Superstructure
The superstructure consists of cellular steel beams, steel box girders, and reinforced zones designed to accommodate high stress concentrations. Approximately 100 tons of structural steel are used to form the primary load-bearing framework.
Cantilever elements extend beyond primary supports, reaching lengths exceeding 19 meters. These elements are integrated into the overall structural system, allowing for extended floor plates and open spatial configurations.
- Cellular steel beams as primary spanning elements
- Steel box girders supporting cantilever structures
- Reinforced zones at critical stress points
6. Engineering Significance
The application of a 48-meter span within a residential structure reflects a structural approach more commonly associated with large-scale or infrastructural projects. Its use in this context enables extended floor spans and uninterrupted interior spaces while maintaining structural performance.
The integration of a cellular steel beam within a composite system demonstrates how long-span engineering principles can be adapted to architectural design, where structural requirements and spatial organization are developed as a single system.
This approach illustrates the potential of combining steel and concrete technologies to achieve both structural efficiency and architectural clarity without separating engineering from design.
7. Project Attribution
- Architectural and structural design: Mario Kleff
- Construction: Wandeegroup Asia
- Steel fabrication: B.S.Y. Group PLC
- Engineering collaboration: Span Systems International
8. Structural Classification Statement
The 48-meter cellular beam is classified as a primary structural floor-support element within a composite steel–concrete system. Its configuration, structural role, and integration within the overall framework are defined by long-span load transfer and system-based performance requirements.
9. Construction Process and Structural Integration
The construction sequence follows the integration of structural steel elements with post-tensioned concrete systems. Cellular beams and steel box girders are positioned to establish the primary load-bearing framework before slab construction is completed.
Post-tensioning is applied after concrete placement, introducing controlled forces into the slab system and completing the composite interaction between steel and concrete elements.
Frequently Asked Questions
What is a cellular beam in structural design?
A cellular beam is a fabricated steel element with circular web openings, designed to increase span capacity while reducing self-weight. It allows efficient load distribution and integration within composite structural systems.
Why is a 48m span significant in residential construction?
A 48-meter span enables large column-free spaces that are typically associated with infrastructure or commercial buildings. Its application in residential architecture allows extended floor plates and open spatial configurations.
What does “Structure is Design” mean in architecture?
“Structure is Design” describes an approach in which load-bearing elements are not concealed but define the architectural language. Structural systems directly shape spatial organization and visual expression.