Modular construction has been in the news in the Big Apple recently, on the plans to construct a 34 story modular apartment building at the Atlantic Yards development in the Bronx Borough of New York City. Capsys Corporation has been selected to build the project designed by the engineering firm of Ove Arup & Partners. Much has been made in the press regarding the impact to the city’s construction unions and how these same unions initially offered support to the project as a means of generating construction jobs in a flat jobs market. Although the politics on something like this are always interesting, the technical challenges faced by the developer, designers, and builders make for fascinating reading on an ambitious project like this.
Architectural / Codes – Per the IBC, an R-2 occupancy of this size and geometry will have to be of Type IA construction; which is to say non-combustible (steel and concrete) as well as fire protected. 34 floors will require 3 hour protection for the structure and bearing walls, 2 hour protection for floor structures and 1-1/2 hour protection for the roof structure. Maintaining continuity in that protection across 900 individual modules, 34 floors high will be difficult at best.
Structural – A gravity resisting system designed to accommodate the cumulative dead-loads alone will be immense. More compact steel shapes normally used in commercial modular construction cannot handle these forces. It is apparent technologies beyond those of conventional multi-story modular construction are being applied. A similar challenge will be found with the lateral resisting system. The accumulating lateral forces will require elements of considerable strength and stiffness to resist the wind forces and control vertical drift.
Construction – The progressive accumulation of horizontal displacement if not tightly controlled can pose a huge problem as the individual modules are set atop one another. This will demand incredibly tight tolerances in the field as well as the manufacturing facility. Small misalignments in the lower portion of the building will be become significant when magnified by the height of 34 levels.
While permanent modular construction has made tremendous strides over the past several years, we still have yet to achieve widespread acceptance as an alternative form of construction that is equal in every way to site-built. This could very well be the project that turns enough heads to modify that thinking.