01054371

Component

Vent Building 3 (VB 3) of the new Central Artery Tunnel (CA/T), which is located at 500 Atlantic Avenue in Boston, Massachusetts is a heavy poured concrete structure with its roof situated about 3 feet below grade. The vent building contains twenty-three 100+ inch diameter double-width centrifugal fans that, for a number of reasons, are not vibration isolated. The fans exhaust into a cluster of reinforced concrete shafts that rise up to about 250 feet above grade. The land on which the vent building is situated is owned by Intell Management. The tall stacks are to be embedded in a luxury hotel/residential condominium complex that Intell is to construct. The new building is to be built atop the vent building and is also to be partially supported by the stacks. This paper summarizes the history of the work on the project, including vibration measurements and SEA modeling, and the strategy used to determine whether elastomeric vibration isolation elements should be incorporated into most structural connections with the vent building. The acoustical analysis for this project has been a joint effort of Cavanaugh Tocci Associates, Inc. (CTA) and R.H. Lyon Corp (RHL) as acoustical consultants to the Owner (Intell) and Wilson Ihrig & Associates, Inc. (WIA) as acoustical consultant to the Hotel Tenant (Six Continents Hotels). Because of the complexity of the building and the analysis, this paper focuses on a few specific areas. These are the structural connections between the stacks and floors of the hotel and residential floors, sound levels at 125 Hz, where the NC rating (by the tangency method) of fan noise in building spaces has been generally found to be dominant, and, finally, whether vibration isolated connections of the hotel floors with the vent building stacks are required. The work in this project intentionally excluded consideration of fan vibration source mechanisms and fan vibration isolation. The CA/T could not allow any changes to fan installations that such investigation might propose since, at the outset of the project, the installation of tunnel ventilation fans was the chief limitation in the timely opening of the northbound tunnel, which could not afford to be delayed.

01054353

English

pp 948-961

2004

Noise-Con 04. The 2004 National Conference on Noise Control Engineering

CD-ROM

Figures; Photos; Tables (1)

Case studies; Fans; Reinforced concrete; Tunnels; Ventilation systems; Vibration; Vibration isolation

Central Artery/Tunnel Project

Elastomeric isolation

Boston (Massachusetts)

Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls

TRIS, TRB

Jul 26 2007 2:35PM