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In construction, “span” refers to the distance or length between two supports of a structural element, such as a beam, truss, or bridge. The span determines the load-bearing capacity and overall stability of the structure, influencing design considerations and material selection. Proper calculation and analysis of the span are essential for ensuring structural integrity and safety in construction projects.


The primary function of span in construction is to support loads and distribute weight between two supports. Key aspects of the function of span include:

  • Load Bearing: Spans bear the weight of the structure, including live loads (e.g., occupants, furniture) and dead loads (e.g., building materials, fixtures).
  • Structural Stability: Spans provide stability to the structure by transferring loads to the supporting elements, such as columns, walls, or foundations.
  • Clearance: Spans create open areas or clearances between supports, allowing for unobstructed movement, access, and use of the space below or between structural elements.

Types of Spans

There are several types of spans commonly used in construction:

  • Simple Span: A simple span is supported by two fixed supports, such as columns or walls, with no additional support points in between.
  • Continuous Span: A continuous span is supported by more than two supports, providing additional stability and load-bearing capacity.
  • Cantilever Span: A cantilever span is supported at one end and extends horizontally, with the opposite end unsupported or anchored to a fixed point.
  • Arch Span: An arch span is formed by a curved or arched structural element, such as an arch bridge, providing strength, stability, and aesthetic appeal.


Spans are used in a wide range of construction applications, including:

  • Roof Systems: Spans support the roof structure, allowing for open floor plans, large interior spaces, and architectural flexibility.
  • Bridge Design: Spans provide the structural framework for bridges, allowing for the spanning of rivers, valleys, and other obstacles.
  • Floor Systems: Spans support floor joists, beams, and slabs, providing stability and load-bearing capacity for residential, commercial, and industrial buildings.

Design Considerations

Proper design of spans is essential for ensuring structural integrity, safety, and efficiency. Key design considerations include:

  1. Load Requirements: Determine the expected loads, including dead loads, live loads, wind loads, and seismic loads, to calculate the required span capacity.
  2. Material Selection: Select appropriate materials, such as wood, steel, concrete, or composites, based on structural requirements, durability, and cost considerations.
  3. Support Configuration: Determine the optimal support configuration, considering factors such as span length, support spacing, and load distribution.
  4. Structural Analysis: Perform structural analysis, including calculations and simulations, to assess the strength, deflection, and stability of the spans under various loading conditions.


In construction, span refers to the distance or length between two supports of a structural element. By supporting loads, providing stability, and allowing for architectural flexibility, spans play a crucial role in the design, construction, and performance of residential, commercial, and industrial buildings, as well as bridges and other infrastructure projects.

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