Structural Reinforcement of Elevator Shafts

An unusual and highly complex application performed in New York finds in Ruregold reinforcement systems a functional, effective response capable of combining technical-performance objectives, ease of installation and durability.

In addition to the deterioration of their main structural elements, buildings are subject to deterioration over time which can also affect their plant equipment, and in particular the masonry envelopes in which they are contained. Among the most obvious of these is the case of lift shafts, whose construction characteristics can vary greatly both in terms of materials and executive techniques used according to the age of the building, and whose maintenance therefore requires a specific approach, different from that used for the restoration of ordinary masonry surfaces.

This is was the situation faced during the redevelopment works of the Thurgood Marshall Federal Courthouse in New York, a historic building located in the centre of Manhattan in which the Ruregold solutions for structural reinforcement based on FRCM composite materials were chosen and applied.

Completed in 1936, the Thurgood Marshall Federal Courthouse is a 33-story tower that, at the time of its construction, was the tallest public building in the United States. In 2021, the building underwent an extensive redevelopment plan which involved not only the granite facade elevations and the spectacular golden pyramidal roof but also all the fire and safety equipment, updated to the latest standards, the entrances , stairwells and elevator shafts. In fact, the latter showed degradation due to water infiltration and induced by operating vibrations.

The particular operating conditions dictated by the location, together with the need to limit plant downtimes to a minimum and ensure certain and contained execution times, led the construction management to choose the solution to reinforce the walls of the lift shafts based on the Ruregold systems with FRCM composite materials. In this specific case the choice fell on the system composed of the bidirectional carbon C-Mesh 84/84 (84+84 g/m2) in combination with the inorganic matrix MX-C 25 Muratura, integrated by the carbon fibre connector C-JOINT.

C-JOINT is a connection system for connecting existing masonry and reinforced concrete structures. This staple connector is made on site using a bundle of parallel and continuous yarns/strands, gathered inside a tubular elastic net made with polyester, polyamide and latex threads, which can be stretched both longitudinally and transversally and is removable. This beam becomes rigid only after being impregnated with the appropriate inorganic matrix MX-JOINT, and inserted inside the hole suitably made in the structural element.

Suitable for applications on masonry such as bindings or shear and flexural reinforcements thanks to the high weight of the carbon mesh and the high performance inorganic matrix, the system allows an increase in the resistant capacity of structural elements for in-plane and out-of-plane actions and an increase in the ductility of masonry buildings, guaranteeing high reliability thanks to the post-cracking behaviour in detachment conditions.

Also resistant to high temperatures and to freeze-thaw cycles and also applicable on damp substrates and without the use of special protections, this solution also offers a marked simplicity and reliability of application.