The beams supporting the stair steps are generally known as
🔬 Understanding the Structural Support of Stairs
This question is about identifying the specific structural component that forms the backbone of a staircase. The steps (treads and risers) need to be supported by a larger element that transfers the load to the building's main structure (floors and landings).
Stringer (or Stringer Beam): A stringer is the inclined structural member that runs along the side of a flight of stairs, providing support for the treads and risers. In most conventional stair designs, there are two stringers, one on each side of the steps.
Essentially, the stringer is to a staircase what a joist is to a floor – it's the primary load-bearing element that carries the weight of the steps and the people using them.
⚖️ Detailed Analysis of the Options
Let's examine the function of each structural term to determine the correct answer.
(c) Stringers
Why it's correct: As defined, stringers are the beams specifically designed to support the stair steps. The treads and risers are fixed directly to them. This is the correct technical term.
(a) Headers and (b) Trimmers
Why they're incorrect: Headers and trimmers are framing members used to create an opening in a floor, known as a stairwell. Joists that are cut short to make way for the opening are supported by these framing members. While they are essential for the staircase opening, they support the landing and the ends of the stringers, not the individual steps along the incline of the flight.
(d) Spandrel beam
Why it's incorrect: A spandrel beam is typically located on the exterior perimeter of a building, spanning between columns and supporting the edge of a floor slab. While a staircase landing might be supported by a spandrel beam in some designs, this beam does not support the actual stair steps themselves.
📋 Key Takeaway: Distinguishing Between Stair Components
It's crucial to differentiate between the components that support the steps and the components that frame the opening for the stairs.
- Stringers: Support the inclined flight of steps.
- Headers/Trimmers: Frame the horizontal opening in the floor (the stairwell).
- Function: Without stringers, the steps would have no support and would collapse. They are the fundamental structural element of the stair flight itself.