SEISMIC RETROFIT OF HISTORIC BUILDING STRUCTURES

Buildings with historic values are regional cultural assets worth preserving. The design technologies and building materials and methods that went into the original construction of these buildings are often drastically different from their contemporary counterparts, their structural renovation or retrofit brings forth many technical challenges to the design professional. This paper provides a general survey of the technical issues pertaining to the seismic retrofit of historic buildings, and explores various design procedures and construction methods for that purpose, including innovative technologies such as post tensioning, seismic isolation, composite wraps, etc. Special attention is given to the typical structural attributes of historic structures in terms of their structural stiffness, strength and ductility, how these parameters changed over the years, reliable methodologies for evaluating these primary structural attributes, and associated design implications for structural retrofit or hazard mitigations. Much of the discussion is based on a combination of the perspective provisions in building codes and alternative performance based approaches to meet the equilibrium, strain compatibility, and energy dissipation criteria, while a considerable weight is given to factors that influence preserving non-structural elements of historic value. A brief summary on cost implications is also provided. Overview Buildings with historic value are regional cultural assets worth preserving. At times, they also represent a potential source of revenue and stimulus for the economical revitalization of their neighborhoods. The factors used to classify a building as historic may vary in different countries and cultures, so obviously not every aged building falls into historical or monumental category. In United States, a building is historic if it is at least 50 years old, and is listed in or potentially eligible for the National Register of Historic Places and/or a state or local register as an individual structure, or as a contributing structure in a district. In prevailing practice, older structures are demolished and replaced by modern buildings due to economical and performance reasons, unless they can be claimed historic.