Abstract:
As highlighted by the 2010 Darfield earthquake, many older buildings, particularly those constructed from unreinforced masonry (URM), now require seismic improvement in order to withstand earthquake forces. There are many approaches and techniques to seismic improvement, the most common of which are outlined below and analysed in terms of the impact of each on the heritage and architectural value of the building. This review is intended as a continuation of an earlier article (Goodwin et al. 2009) which gave background information to furnish designers with information prior to considering seismic retrofit. This information included a simple process for determining the basic heritage value of a building and some guidelines for good building conservation practice. A heritage building is more than simply a collection of building materials. As buildings age, they become more permanent parts of local culture. They become associated with notable people; with the memories of the public; and places where important historic events occurred. They become unique, as buildings are simply no longer made the same way, and time provides them with characteristics that could never be designed into a new building1. Old buildings can become ‘heritage’, where they become important to the public rather than just to the owner and occupants; a recent example of this is the birdcage hotel in Figure 1. There is no line on one side of which lies ‘heritage’, and on the other ‘not heritage’; all old buildings will have some heritage value. The difficulty is in determining the degree of heritage value, and what is important and what is less important about a building.