Masonry Arches – Name of the inclined surface on an abutment that receives the arch In arch construction terminology, what is the inclined bearing surface prepared on the abutment or pier to receive the arch barrel and transmit thrust into the support called?

Introduction / Context:
Each part of a masonry arch has a distinct name because loads and construction steps are specialized. Correct terminology helps communicate how thrust is transferred and where reinforcement or thickening is needed. This question focuses on the abutment interface that anchors the arch.

Given Data / Assumptions:

• Masonry or concrete arch built on abutments/piers.
• Inclined surface cut or cast to seat the first arch stones/bricks (voussoirs).
• Standard architectural/structural terminology applies.

Concept / Approach:

The inclined seating surface on the abutment that receives the arch ring is called the skewback. It aligns with the thrust line orientation so that compressive forces are transmitted safely into the support. Related parts include the soffit (intrados surface of the arch), spandrel (masonry above the extrados), haunch (portion near the springing), and crown (topmost region).

Step-by-Step Solution:

Verification / Alternative check:

Standard building construction texts and detailing drawings label the abutment bearing as skewback; setting-out shows skewback angle relative to horizontal.

Why Other Options Are Wrong:

Soffit, spandrel, haunch, and crown joint refer to different parts and not the abutment bearing interface.

Common Pitfalls:

Confusing soffit (surface of the arch) with the abutment seat; calling any inclined masonry “haunch” regardless of location.

Final Answer:

Skewback