The lower half of the arch between the crown and skew back is called:
🏛️ Understanding the Sections of an Arch
An arch's curve is not just one uniform section; it's described by different terms for its various parts. This question asks you to identify the specific term for the lower portion of the arch's curve.
Defining the Boundaries
- Crown: This is the highest point of the arch, where the keystone is located.
- Skew back: This is the angled surface on the support (abutment) where the arch begins to curve upwards.
The question is asking for the name of the section of the arch that lies between these two points.
🧩 Identifying the Correct Term
(B) Haunch: The Lower Flank of the Arch
The Haunch is the correct answer. It refers to the lower half of the arch's curve, extending from the crown down to the skewback. This section is structurally critical because it is where the outward horizontal force (arch thrust) is at its maximum. Therefore, the strength of the haunch and the ability of the abutment to resist its thrust are vital for the arch's stability.
(A) Spandril: The Space Above
The Spandril is the triangular space that is *above* the arch, bounded by the arch's outer curve (extrados), a horizontal line from the crown, and the vertical support. It is not part of the arch's curve itself.
(C) Springer: The First Stone
The Springer is the very first wedge-shaped stone (voussoir) that rests on the skewback at the springing line. It is only the starting block of the curve, not the entire lower half.
(D) Voussoirs: The Building Blocks
Voussoirs is the general term for all the wedge-shaped stones used to construct the arch. It refers to the individual components, not a specific section of the arch's curve.
🖼️ Visual Diagram of Arch Components
This diagram clearly illustrates the location of the Haunch relative to the Crown, Skew back, and other parts of the arch.
