Structural Typology Issues and Existing Building Codes
Preservation and rehabilitation of existing buildings are stated objectives of the model Existing Building Code, but and only the Level 3 alteration triggers real rehabilitation measures. Because mandatory retrofits are difficult to legislate, the structural rehabilitation work described in appendices is voluntary. It is difficult to find statistics that list how many buildings have been actually rehabilitated (and how effective) since the introduction of an existing buildings codes. The engineering community in large municipalities, like New York City, is well aware of the typologies present in the local building stock and their potential structural limitations. For instance, the 20,000 urm extant buildings erected prior to 1900 form a typology due to commonalities of use, size, material and empirical methods of design and construction. Their past performance has revealed a potential instability weakness under service loads. In the upcoming NYC Existing Building Code provisions have been specifically dedicated to this typology. Using various NYC examples of building types with known structural issues, the presentation will demonstrate the value of an existing building code drafted by local engineers. The final section will discuss how WTC investigations led to specific features of the code intended to guide the design of a NYC typology - buildings exceeding 600 ft in height.
Upon completion the participants will be able to:
- Evaluate the advantages of using building typologies in drafting building codes.
- Estimate the legal and technical difficulties for legislating mandatory structural retrofit.
- Distinguish the major NYC typologies and understand the current efforts to include effective structural retrofit systems in NYC existing building code.