Steel Sitemas & Glued Laminated Timber: Benefits & Properties

Posted on Mar 21, 2025 in Geology

Steel Sitemas: Pros and Cons

Pros: Simple concept using tubes and spheres, economical for covering large spans, lightweight, rigid, and highly resistant. They are statically very resistant, require few elements, and steel allows great freedom in design. They can eliminate structural side mount elements, allowing easy and quick workforce reduction, and allow positioning of auxiliary elements and passage facilities.

Cons: Difficulties in realizing and calculating these structures. For large dimensions, it’s necessary to include thermal stress calculations. They can be damaged during transport, installation, and commissioning, requiring careful attention. Precision is needed in the redesign and execution. Special care is required regarding fire resistance and corrosion.

Glued Laminated Timber: Benefits of Lamination

The nodes are removed, resin nodes are eliminated, drying cracks do not appear, opening up more sections.

Types of Boards with Structural Use

  1. Particle Boards: Made from wood chips glued with thermosetting synthetic resins and polymerized by high pressure and temperature. Types: homogeneous, layers A3, waterproofing, and flame retardant. Density: light, medium duty, and heavy.
  2. Oriented Strand Board (OSB): Made from splintered wood fibers, flat and broad, compressed and arranged in different layers, oriented longitudinally.
  3. Board Tables: For flooring, tongued and grooved boards made with lambetadas or singing, can also be glued.
  4. Plywood: Very thin veneer foil (1mm or <5mm) obtained from a trunk that rotates at high speed. Veneers are glued with alternating fibers to dimension fibers perpendicularly. The panel is then pressed with controlled temperature for correct tail setting.

    Characteristics of Plywood: Resistance in two directions, uniform properties, low weight, very resistant relative to its weight, permits easy bending. When using phenolic resins in manufacturing, it offers structural use, great durability, and moisture resistance for formwork.

  5. Laminated Boards.
  6. Sandwich Panels: A sandwich panel composed of an inner core with adequate stiffness and exterior plywood boards.

Advantages of Using Panels

Speed of execution of assembly and structures, energy efficiency, competitive cost (expensive span), and design flexibility.

Properties of Glued Laminated Timber (GLT)

  1. Stability to Aggressive Agents: Only necessary to protect from mushroom and insect attacks and ensure ventilation in hidden or difficult access areas. For humidity > 20%, special protection is needed.
  2. Improved Mechanical and Structural Homogeneity: GLT offers better behavior and qualities compared to laminated timber.
  3. Durability: Stainless and considerable due to stable aging.
  4. Biological Material: Requires care and protection.
  5. Fire Resistance: Wood is not a fuel in GLT fabrication processes. The wood is not a heat conductor.

Timber During Fire

During a fire, timber burns with flames, charring the surface, preventing O2 from passing inside, halting the fire’s advance. The exterior layer acts as insulation, allowing the section to be designed with a sacrificial fire section.