In the PA video under Section 4.6, “Structural Systems in PA,” specifically for site-cast concrete spans table, what is the difference between a one-way solid slab and a one-way Beam & Slab system?
I was reviewing The Architect’s Studio Companion and noticed that both systems can include drop beams, which made the distinction unclear to me. How do these 2 systems differ, and does the One-way Beam & Slab system allow for longer spans compared to a one-way solid slab?
Great question @elie! The key distinction isn’t whether beams exist, but what’s doing the primary spanning.
One-way solid slab is the broader category, while one-way beam & slab is often treated as a subtype/configuration (basically a one-way solid slab supported by a regular beam framing system).
One-way solid slab: the slab itself is the main spanning element. You may have beams or thickened bands at supports, but the slab is still doing most of the spanning work between major supports.
One-way beam & slab: the beams are the primary spanning members, and the slab mainly acts as a deck spanning between beams (load path: slab → beams → girders/columns). It’s often listed separately because the behavior and sizing logic are more beam-dominant.
Because beams are deeper and more efficient in bending than a slab alone, one-way beam & slab systems generally allow longer spans (and better deflection control) than a slab spanning directly between supports.
Hope this helps!
Kiara Galicinao, AIA, NCARB
Product Coordinator
Black Spectacles