What did Zhaozhou Bridge / Anji Bridge look like?

A single-span segmental stone arch bridge with a main arch span of 37.02m. On each side of the main arch are two smaller secondary arches (open spandrels), which both reduce dead weight and increase flood discharge capacity.

How did Zhaozhou Bridge / Anji Bridge work?

Stone arch ring under load → arch axis approximates the optimal thrust line → loads produce mainly compression with negligible bending moment → open-spandrel small arches reduce the weight of the fill above → during floods, small arches split and discharge the flow → reduce hydraulic impact on the bridge.

← DiscoveriesS-Tier · Foundational

赵州桥（安济桥）

Zhaozhou Bridge / Anji Bridge

The world's oldest surviving and best-preserved single-span open-spandrel segmental stone arch bridge. The open-spandrel design reduces the bridge's self-weight and allows flood discharge, reducing hydraulic impact.

赵州桥（

Scientific Principle

Arch structural mechanics: the optimal thrust line ensures the section experiences compression only, with no bending moment. Open-spandrel arch: the hollow-spandrel arch form reduces dead load → reduces abutment thrust.