TO REPLACE OR NOT REPLACE: WHEN REPAIR IS THE RIGHT ANSWER

The Shenzhen Western Corridor is a 3.5-mile-long viaduct that comprises 12 segmental bridges and a cable-stay bridge. The bridge opened in 2007, providing a vital link between Hong Kong and mainland China. The bridge superstructure contains approximately 200 external post-tensioned (PT) tendons totaling  21 miles of PT tendons.

During routine inspections in 2019 and 2020,  the local inspectors found two ruptured tendons, exposing a potentially systemic problem. Subsequent investigations identified widespread issues with incomplete grouting in the tendons. This has resulted in varying degrees of corrosion in the PT tendons throughout the bridge. Based on these findings and the systemic nature of the issue, the Owner proposed complete removal and replacement of the 200 PT tendons (or 20 miles)  in the bridge.

Pivot was retained as an independent expert to examine the necessity of a full replacement. Our team conducted a detailed engineering assessment of all reports, borescope videos, material testing, and structural analyses.

Based on this detailed assessment, Pivot concluded that the complete replacement of the tendons is not unnecessary. Instead, Pivot recommended regrouting all existing air voids in the PT ducts, a proven technique used successfully for decades on major infrastructure projects. Filling voids with cementitious grout creates an alkaline environment that passivates the strands, providing consistent protection along their entire length and effectively stopping further corrosion, ensuring the long-term service life of the bridge.

Pivot also recommended replacing two PT tendons with significant corrosion damage and long-term monitoring of critical tendons using acoustic emissions. This comprehensive remediation plan will ensure the adequate and lasting performance of the bridge without the extensive disruption and expense of replacing all tendons.

PROJECT SERVICES:

Failure Investigation

Structural Repair Design

Corrosion Testing

Construction Litigation Support