Dr. Debra F. Laefer
Department of Civil Engineering
North Carolina State University
Campus Box 7908
Raleigh, NC 27695-7908
(919) 515-7631
dflaefer@unity.ncsu.edu

Since 1988 Dr. Debra F. Laefer has dedicated her career to the preservation, protection, and repair of historic and heritage structures.

Historic preservation should be considered as the ultimate challenge for civil engineers. The topic requires the most creative application and thorough understanding of structural engineering, material science, hydrology, and geotechnical engineering. The joy and satisfaction of working with such beautiful and important structures is only rivaled by the key technical skills and clever innovations demanded for successful interventions.

Earthquakes, terrorism, age-based deterioration, settlement, erosion, changes in the ground water table, and adjacent construction work including excavations, tunneling, pile driving, and blasting all pose acute threats to the stability and long term viability of historic structures. Appropriate interventions and treatments can range from traditional underpinning and mechanical bracing schemes to compensation grouting, jet grouting, micropiles, structural doweling, vibration and settlement monitoring, and alternatives to blasting, just to name a few.

Heritage projects are of unusual complexity, because they employ building materials and structural systems that often possess minimal tensile capacity -- load bearing masonry of brick, stone, terracotta, hollow clay tile, or frame structures of cast-iron or wrought iron. These materials are generally no longer employed as structural elements, and many are no longer used in any capacity. Because of the age of the structures, the original anticipated performance levels are often unknown and the impact of weather or age related deterioration further obfuscates reliable prediction. Because of changes in manufacturing processes, damaged units may not be replaceable without excess cost.

Developing good intervention schemes is often complicated by unknown load takedowns, which further complicate foundation and other subsurface related issues. The foundations can in and of themselves be problematic as they are often unknown or mixed quality. They may be simple unattached granite slabs, deteriorated piles, or of insufficient capacity for current loading conditions.

Join me on following pages to learn more about historic preservation from a civil engineering perspective.

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Department of Civil Engineering

The Civil Engineering Department at NCSU offers several degree programs concerned with the improvement and care of the built and natural environments and dealing with planning, design, construction, operation and maintenance of buildings, dams, bridges, power facilities, pollution control facilities, water supply, and transportation systems. Please visit Civil Engineering for more information.