Structural monitoring of the restoration of Titanic’s Dry Dock

Belfast landmarks inextricably linked to the story of the Titanic are now opening to the public. Thompson Dry Dock was built in 1905 especially for the final fit out of the Titanic and her sister ships and it is currently being restored as part of the ‘Thompson Titanic Trail’. The lock gate and dock were last used in 2001 and were deemed unsafe for use due to the corrosion that has occurred over the last 100 years in the steel that forms the lock gate structure. This has prohibited safe access to the floor of the dock. Restoration is underway to ensure that the dock can be opened safely as a tourist attraction in this the centennial year of the Titanic. This paper present some of the results of structural monitoring of the steel work which ensured the safe transfer of loading from the original lock gate to enable construction of a new bund. The real time monitoring during dewatering ensured the safety of staff working inside the cofferdam and integrity of the transfer structure through the highest loading conditions 1. Background to Thompson’s Dry Dock and Lockgate Thompson’s Dry Dock (Figure 1) provides a true reflection of the epic scale of the shipbuilding industry in Belfast and is a dominant feature in the Titanic Quarter. The dock was first opened by Belfast Harbour Commissioners in 1911 when the 259.1m (850 feet ) long Thompson Dry Dock was the largest in the world, taking ~500 men over more than five years to build, at an equivalent cost in today’s money of £50m. The dock was used to check and paint the Titanic’s hull, fit the propellers into position, install the boilers and to apply some of the final fixtures and fittings. Named after the BHC Chairman of the day, Robert Thompson, the dock could be drained of its 24 million imperial gallons of water in l00 minutes using the huge pumps in the adjacent Pump-House. Both the dock and pump house are masterpieces of Edwardian engineering and provide great inspiration for the Science Park’s hi-tech occupants who are reclaiming Queen’s Island’s as a centre for innovation. The lock gate was a travelling caisson and as it was constructed in the early 1900’s it coincided with the move from wrought and cast iron to steel after the advances in the Bessemer process for controlling the carbon content in iron. The steel used was the best material of the day but equivalent to low grade mild steel today. The gate is a hollow structure with internal spanning members and is divided into two internal horizontal compartments, the lower one being approximately three times the size of the upper. The frame of the gate is made of riveted steel plates (similar to those in the Titanic). Riveting was reaching the end of its life cycle; it had been common in wrought iron structures but has been replaced by welding and bolting Civil Structural Health Monitoring Workshop (CSHM-4) Lecture 05 Licence: http://creativecommons.org/licenses/by-nd/3.0 1