Track 2: DESIGN - PLANNING THE CONSERVATION OF HISTORIC PLACES / Volet 2 : Conception - Planifier la conservation de lieux historiques

New Light on Baltimore’s Cathedral of Books – Part 2: Reversible Strengthening and Designing for Construction

Friday, October 13
10:30 AM - 12:15 PM

The George Peabody Library of Johns Hopkins University opened in 1878 and has continuously served the public as a premier research library for the University and City of Baltimore. The main stack room’s five tiers of ornamental cast iron balconies are fed light from the atrium lay light, above which a parallel history of building technology is embodied in the spectacular Phoenix Iron trusses that span the atrium. The owners sought to replace a failing skylight with new panels that, in addition to creating a waterproof exterior envelope, would provide improved insulation and light transmission properties. Another goal was to create improved access above the lay light for various maintenance functions. The changes resulted in an increase in load on the historic structure that was found to require strengthening (presented at the 2014 APT conference in Quebec). 2017 marked the culmination of a collaborative effort which included the development of retrofit strengthening designs by1200AE, skylight design by Ziger/Snead Architects from Baltimore, and construction by Grunley from Rockville, MD.

1200AE developed a retrofit strengthening system that minimized damage to the historic truss members while accommodating the very challenging requirements of construction above the library space.
The reinforcement employs an innovative approach of “reversible” detailing, where connections between new and old are implemented without drilled holes for bolts or welding between steel and iron. Working with the complex, historic geometries and connections required adjustability to be a fundamental principle of the strengthening details. The reinforcement components are short-length, steel members to facilitate access and lifting requirements. A range of construction-specific load cases was evaluated to maximize the strength of the iron trusses as the contractor aimed to install a work platform, supported by the bottom chord of the trusses, as early in construction as possible. This would serve the dual purpose of allowing safe access to install the truss reinforcement, but also provide protection for the lay light. However, having a full work platform over the lay light with construction loadings was found to be among the highest load scenarios the structure would be subjected to, and beyond the unreinforced truss capacity. The solution hinged on the installation of the permanent catwalks and their support of the work platform. Graphical representation, from concept sketch to precise detailing, were fundamental to collaborative design and construction.

Normal operations of the library were ongoing throughout construction. The work produced a new, more thermal-efficient skylight with transmittance appropriate to the historic space, a high-capacity, hybrid iron and steel roof truss assembly, and an accessible attic space allowing for MEP maintenance and preservation of the historic lay light. 1200AE is currently providing structural integration of a new fire suppression system within the main atrium.

Learning Objectives:

John A. Matteo

1200 Architectural Engineers, PLLC

Founding Principal at 1200 Architectural Engineers, John Matteo has a Masters in Civil Engineering from Princeton University and studied as Fulbright Scholar in Lausanne, Switzerland. Mr. Matteo served in the adjunct faculty at Columbia University, the University of Virginia, and currently serves as Director of Design in Civil Engineering at Johns Hopkins University. He was awarded the 2007 Kress Mid-Career Grant by the James Marston Fitch Foundation and the 2011 National Endowment for the Arts Fellow in Historic Preservation and Conservation at the American Academy in Rome. He is a registered Professional Engineer.


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Nicole Ferran, P.E.

Nicole Ferran has been at 1200 Architectural Engineers since 2013, after 16 years of experience at two other engineering firms. She has a Masters in Structural Engineering from the University of California at Berkeley, a Bachelors in Civil Engineering from the University of Maryland at College Park, and a Bachelors in Chemistry and Asian Studies from Williams College. She is a registered Professional Engineer in the states of California and Maryland.


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Send Email for John Cooke


New Light on Baltimore’s Cathedral of Books – Part 2: Reversible Strengthening and Designing for Construction

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