Scope of the Project
Seismic Hazards
Seismic hazard is the hazard associated with potential earthquakes in a region, and a seismic hazard map shows the relative hazards in different areas. Seismic hazards can be primary, such as liquefaction, ground shaking, and ground rupture, or secondary, such as tsunami or fire.
Several factors affect the level of seismic risk at a certain site, including frequency of seismic activity in the area, soil quality, and the type and characteristics of structure being erected at the site.Â
Seismic hazards are documented by the United States Geologic Survey and the Applied Technology Council. Calculation of seismic effect on structures is done according to rules set out in Minimum Design Loads for Buildings and Other Structures, published by the American Society of Civil Engineers and referred to as ASCE 7.
Building Code Design
Building Code design is a primarily strength-based paradigm with a successful design being one where capacity of the structure exceeds demands, as well as satisfying other serviceability requirements such as deflection and vibration limits. Separate documents are responsible for calculating capacity and demand; for example, demand is calculated through provisions in a document called Minimum Design Loads for Buildings and Other Structures, as published by the American Society of Civil Engineers.
Performance-based Earthquake Engineering
Performance-based earthquake engineering (PBEE) focuses on performance, rather than strength, as the ultimate criterion for producing a successful design. Performance is measured in terms of quantifiable damage done to the structure due to seismic hazards. This project focused on PBEE, as it is the most developed branch of performance-based engineering. The Structural Engineering Institute is in the process of developing performance-based methodologies and reference material for other hazards.
Potential Misunderstandings
There are three main areas of misunderstanding that are explored in this fellowship. The first involves the expected performance of a code-designed building when subjected to a major event, the second concerns the collapse risk of code-designed buildings, and the third deals with the expected performance of a code-designed building when subjected to minor events.