HRIL symposium examines innovative
conservation technologies, practices
Preservation scholars, students and practitioners gathered Feb. 28 in Bryan, Texas to discuss innovative conservation technologies and practices at the Fifth Annual Historic Preservation Symposium sponsored by the Historic Resources Imaging Laboratory and the Department of Civil Engineering at Texas A&M University.
The 2004 symposium challenged attendees to re-examine the nature of conservation and the significance of technology to practice.
“Conservation, the wise use of resources, is usually associated with images of the past, but the maintenance of the past for future use and enjoyment demands creativity and innovation,” said David G. Woodcock, professor of architecture and HRIL director. “The challenge is to preserve the historic fabric while maintaining active use, and that requires a deep knowledge of the technology of materials and assemblies of the past, as well as the latest techniques and methods, and a clear philosophy for putting them into practice.”
As with previous symposia, the 2004 event featured presentations from leaders in the historic preservation and conservation field. The morning sessions, which focused on conservation engineering, were followed by afternoon sessions examining current conservation practices in the design and construction industries. A panel discussion, chaired by Jim Singleton, a local architect and president of the Brazos Chapter of the American Institute of Architects, culminated the day’s events.
The symposium speakers, which included three engineers, a construction manager and an architect, prompted participants to consider conservation from a variety of perspectives while identifying goals common to each point of view.
SYMPOSIUM SPEAKER SUMMARY:
Preserving Scotland’s heritage
John Addison, a visiting European Union Scholar and conservation engineer with Peter Stephen and Partners in Edinburgh, Scotland, discussed the value of learning from the art and craft of historic structures. He illustrated his points with case studies of restorations of iron bridges and castles and the rescue of two ancient masonry arch bridges in the wilds of Scotland.
A passionate preservationist, Addison utilizes innovative and sometimes unconventional preservation techniques. He once successfully used sacks of concrete to infill an arch that had suffered major deterioration. He also advocates the use of hydraulic lime instead of cement. In May 2004 he made a presentation on the pitfalls and solutions in working with buildings 60 to 600 years old at the American Lime Conference at Sweet Briar College in Virginia.
To learn more about the use of lime-based materials for the conservation and repair of Scotland's traditional buildings, visit the Scottish Lime Centre Web site http://www.scotlime.org/.
Accessing building materials
Patrick Sparks, a structural engineer and president of Sparks, Larosche and Associates in Pflugerville, Texas, discussed innovation and judgment in the assessment and characterization of building materials, with the controversial theme “does strength matter?”
“In assessing an existing structure, we consider the original design, the condition of materials, the effects of age and past usage, and the requirements for continued service,” explained Sparks, who is a specialist in the evaluation and design of historic structures. To evaluate structures, Sparks combines on-site, non-destructive testing and visual assessment with his understanding of historic construction materials and techniques to achieve the best solution for each specific project.
For the benefit of symposium participants, the engineer outlined issues to consider when surveying structures made of wood, masonry and metal construction. He also shared the results of his firm’s research and tests of Texas' iron and steel bridges. His findings led to a debate, later in the day, about the virtues of using wrought iron instead of steel. Wrought iron, which has properties that resist rust, was used in many historic bridges as tie rods and as Phoenix columns — a unique design that used sections of iron flanges riveted together to increase compressive strength.
To read more about the services and innovative conservation practices utilized by Sparks, Larosche and Associates, visit the company Web site http://www.sparkslarosche.com/CompanyProfile/Sparks.html.
More information about historic bridges is available online at the Historic Bridge Foundation Web site www.historicbridgefoundation.com.
Peter Lee, senior structural engineer with Skidmore Owings & Merrill in San Francisco, examined conservation engineering for earthquake protection. While traditional earthquake design focuses on preventing major failures and loss of life, he said, new technologies have made it feasible to obtain higher seismic performance levels and even prevent damage altogether.
Over the last 15-20 years, seismic isolators have been in use. These are alternating layers of rubber and steel laminated together to produce a bearing that is rigid in the vertical direction, but flexible in the horizontal direction. Isolators reduce the vibration responses in structures and as a result, reduce earthquake damage. In recent years, fiber-reinforced elastomeric bearing systems have been developed to replace the steel and rubber isolators and greatly reduce the cost of such systems.
Another system for reducing potential earthquake damage to historic structures uses friction pendulum seismic isolation, also called a “sliding system.” These are structural supports that use an innovative way to achieve a pendulum motion of the supported structure. By placing these concave spherical bearings at each support point, the structure sways with a gentle pendulum motion during earthquake ground shaking. This allows the ground to shake without damaging the structure.
Fort Mackinac renovation
Ronald Staley, vice president of the Christman Company in Lansing, Michigan, used a recent preservation project at Fort Mackinac, Michigan to illustrate innovative construction management approaches to conservation.
The French erected Fort Mackinac in the mid-18th Century during the French and Indian War and British soldiers later occupied it during the American Revolution. The fort, which is located on Mackinac Island, off the northeast coast of Michigan, posed numerous logistics problems from the start. The site is a National Historic Landmark and a popular tourist destination. The park had to remain open throughout the project and, due to weather constraints, the project had to be completed during the tourist season. All materials had to be shipped to the island and, because cars are not allowed on the island, special permits were required for the use of motor vehicles. Also, archeologists were required to be involved throughout the process to ensure that no important artifacts were damaged during the renovation.
Restoring the exterior walls of the fort was the project’s first priority. This was difficult because the amount of deterioration within the walls could not be completely assessed until the restoration began and deteriorated stone and mortar could be removed. Using a design-build approach, the construction manager hired an architecture firm, the Smith Group from Detroit, and they worked as a team to define the scope of work and an action plan to stay within the $4 million budget. The original projections showed that the team would finish the project within budget and a year ahead of schedule.
Learn more about Fort Mackinac at the Mackinac State Historic Parks Web site http://www.mackinacparks.com/fortmackinac/.
Integrating new and historic design
Paul Spencer Byard, an architect and principal of Platt Byard Dovell White Architects in New York City, an attorney, and director of the Historic Preservation Program at Columbia University, discussed the interface between modern and historic architecture using examples of successful architectural additions by master architects.
Sir Christopher Wren, a 17th Century scholar, had to be creative in his design for the Royal Navy College http://www.greenwichfoundation.org.uk/ Hospital in Greenwich, so that the view of the Queen’s house would be preserved. The design of the New Studios Building http://www.cranbrookart.edu/new_studios_project/ at the Cranbrook Academy was a significant task for the Moneo Brock Studio. The building forms a courtyard with an historic Art Museum designed by Eliel Saarinen, the original architect for the campus.
Byard also presented his firm’s design for the New 42nd Street Studios http://studios.new42.org/about.cfm, a project in New York’s Time Square that won many awards including the 2002 AIA National Honor Award. The building responded to its environment with light and color — two important features of the surrounding area. Byard’s presentation prompted discussion about the affects modern design will have on future preservation considerations.
Images of the New 42nd Street Studio are available at the Platt Byard Dovell White Architects Web site http://www.pbdw.com/. More of Byard’s ideas about thoughtful design of additions to historic buildings are detailed in his 1998 book, “The Architecture of Additions.”