Guidelines for Building and Structure Relocation

Guest author:  Todd Holbert | BAE/MAE |Architectural Engineering, Penn State, May  2015

As engineers navigate the design process of buildings and other structures, there is a factor that is rarely, if ever, accounted for: relocation. As a result, the relocation of buildings and other structures is a specialized facet of the industry. Relocations can occur for a number of reasons, including historic preservation, construction purposes, and fixing errors. Since relocations have been occurring for hundreds of years, there are a number of standard practices that have developed, which have since been enhanced by the development of modern technology and engineering practices. The knowledge and hands-on experience of building relocation companies in conjunction with the technical expertise of structural engineers is critical for a successful relocation.

General Overview

The relocation process involves shoring and supporting the structure on steel framing in addition to properly bracing it inside and out to preserve its current state. The steel frame consists of “mains” which support the cross beams and rest on the roll beams. Bracing can consist of numerous combinations of interior bracing, such as shear walls and diagonal bracing, and exterior bracing, such as tension cables. A series of hydraulic leveling jacks, located between the “mains” and the roll beams, are utilized to keep the structure level throughout the relocation, which is an intensive process. The jacks are controlled by a Unified Jacking Machine, which enables to structure to be lifted uniformly regardless of pressure or load. Meanwhile, the structure is shifted by either using push-jacks to slide the “mains” along the roll beams or moving the roll beams on a set of dollies in unison towards the desired location. Careful calculations and preparation are necessary not only to properly determine the loads when designing the steel frame and bracing, but also to create an appropriate zoning configuration for the leveling jacks. In the event that the structure needs to be transported along a roadway, further attention has to be paid to ensure that size and weight limitations are met and that the intended relocation method is acceptable.

Cape Hatteras Lighthouse

In addition to the more common occurrence of moving houses and small commercial structures, it is sometimes necessary to move much larger and complex structures. One such case is that of the Cape Hatteras Lighthouse. Harrowing and daunting in its nature, the relocation of the Cape Hatteras Lighthouse was essential for the preservation of the historic beacon situated in the Outer Banks of North Carolina. Initially completed in 1870, the lighthouse sat 1,500 feet from the coast, where it remained until 1999 when it was moved 2,900 feet inland to its current location (AACE 2000) due to its threatened status. Perpetual erosion of the shoreline resulted in only 120 feet separating the lighthouse from the waters of the Atlantic Ocean by 1970, threatening the tallest brick lighthouse in the United States (NPS 2001). After numerous attempts to preserve the lighthouse in its original location, the National Park Service began planning and fundraising to move the Cape Hatteras Lighthouse, ultimately receiving funding from Congress in 1998. Relocation efforts involved not only the lighthouse itself, but also the set of accompanying historic structures, resulting in an $11,800,000 overall budget (Schierhorn 1999). Funding was provided in two separate fiscal years, 1998 and 1999, causing the design to be completed a year prior to construction. International Chimney Corporation worked in conjunction with Expert House Movers to design and execute the relocation of the Cape Hatteras Lighthouse. The National Park Service also hired Wiss, Janney, Elstner Associates (WJE) as a consultant to aid in the preservation of the lighthouse during the relocation by monitoring cracks and stresses, conducting tests on materials, supervising the construction of the new lighthouse base, and executing final condition surveys (WJE). The Cape Hatteras Lighthouse Relocation Team was rounded out by Masonry Building Corporation, a historic architect and masonry consultant, which was responsible for the erection of the masonry foundation at the lighthouse’s final location (Scheirhorn 1999).

The Cape Hatteras Lighthouse Relocation began with the lengthy process of excavating and shoring the structure in place so the steel framing grid could be constructed. Once completed, the load was progressively transferred from the shoring structure to the steel framing through the use of the hydraulic jacks. Once everything was set, push-jacks were used to move the lighthouse five feet at a time. On June 17, the Cape Hatteras Lighthouse began its twenty-three day journey to its new location. Once in place, the load was transferred from the steel frame to another set of shoring structures, which allowed the roll beams, “mains”, and cross beams to be removed and the construction of the new brick foundation on top of a concrete pad. The selection of a brick foundation was made based in part for efficiency and economy, but also because it enabled the lighthouse to be supported continuously throughout its footprint. After a lengthy and tedious relocation process, the Cape Hatteras Lighthouse was operational again in November 1999.

More Information and Case Studies

For additional discussion on Building Relocation, including more case studies and references (as well as the citations noted in this post), please follow the link to the full article: Guidelines for Building & Structure Relocation available on the Failures Wiki.
Photo Credit: Building Relocation in Washington, DC, Todd Holbert.

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