Constant Sag Control for Long-Span Cable Bridges by Variable Cable Tension: Oversized Deck, Articulated Pylon and Hydraulic Pressure Accumulato

This document establishes prior art for a novel sag control system for long-span cable-stayed bridges combining three elements: (1) an oversized deck (factor 1.6), (2) a base-articulated outer pylon connected to a hydraulic jack, and (3) a hydraulic pressure accumulator providing passive and instantaneous cable tension increase upon live load application. The system achieves near-zero sag variation by actively varying the main cable tension as a function of live load, without any mid-span anchor block in the river. Load detection, elastic elongation compensation and thermal compensation are achieved through a single hydraulic pressure signal. The system operates on the positive safety principle. Applied to the new Francis Scott Key Bridge (Baltimore, 507 m main span), the system reduces pier protection costs by approximately USD 960 million compared to the planned rigid fender system. A timestamped proof of priority is established by this Zenodo deposit.