Analysis and modelling of the seismic behaviour of high ... - Ingegneria
Analysis and modelling of the seismic behaviour of high ... - Ingegneria
Analysis and modelling of the seismic behaviour of high ... - Ingegneria
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2. DUCTILITY AND SEISMIC RESPONSE OF STRUCTURES<br />
2.3 The performance based <strong>seismic</strong> design<br />
During recent earthquakes, including those <strong>of</strong> California <strong>and</strong> Japan, structures in<br />
conformity with modern <strong>seismic</strong> codes performed as expected; <strong>and</strong>, as expected,<br />
<strong>the</strong> loss <strong>of</strong> lives was minimal. However, <strong>the</strong> economic loss due to sustained<br />
damage was substantial. Earthquakes in urban areas have demonstrated that <strong>the</strong><br />
economic impact <strong>of</strong> physical damage, loss <strong>of</strong> function <strong>and</strong> business interruption<br />
was huge <strong>and</strong> damage control must become a more explicit design consideration.<br />
A promising approach to such needed development is <strong>the</strong> performance-based<br />
engineering (PBE); its application to significant <strong>seismic</strong> hazards is commonly<br />
known as performance-based <strong>seismic</strong> engineering (PBSE). An important phase <strong>of</strong><br />
performance-based <strong>seismic</strong> engineering is <strong>the</strong> performance-based <strong>seismic</strong> design<br />
(PBSD), that is defined as “identification <strong>of</strong> <strong>seismic</strong> hazards, selection <strong>of</strong> <strong>the</strong><br />
performance levels <strong>and</strong> performance design objectives, determination <strong>of</strong> site<br />
suitability, conceptual design, numerical preliminary design, final design,<br />
acceptability checks during design, design review, specification <strong>of</strong> quality<br />
assurance during <strong>the</strong> construction <strong>and</strong> <strong>of</strong> monitoring <strong>of</strong> <strong>the</strong> maintenance <strong>and</strong><br />
occupancy (function) during <strong>the</strong> life <strong>of</strong> <strong>the</strong> building." (Bertero <strong>and</strong> Bertero, 2002).<br />
Therefore, a comprehensive performance based design involves several steps:<br />
14<br />
• selection <strong>of</strong> <strong>the</strong> performance objectives;<br />
• definition <strong>of</strong> multi-level design criteria;<br />
• specification <strong>of</strong> ground motion levels, corresponding to <strong>the</strong> different design<br />
criteria;<br />
• consideration <strong>of</strong> a conceptual overall <strong>seismic</strong> design;<br />
• options for a suitable structural analysis method;<br />
• carrying out comprehensive numerical checking.<br />
2.3.1 Performance objectives (POs)<br />
A conceptual framework for <strong>the</strong> performance base <strong>seismic</strong> design has been<br />
developed encompassing <strong>the</strong> full range <strong>of</strong> <strong>seismic</strong> engineering issues to be<br />
referred to design <strong>of</strong> structures for predictable <strong>and</strong> controlled <strong>seismic</strong> performance<br />
within established levels <strong>of</strong> risk. The first step is <strong>the</strong> selection <strong>of</strong> <strong>the</strong> performance<br />
design objectives (POs). These objectives are selected <strong>and</strong> expressed in terms <strong>of</strong><br />
expected levels <strong>of</strong> damage resulting from expected levels <strong>of</strong> earthquake ground<br />
motions (SEAOC, 1995). POs will range from code minimum requirements (usually<br />
based on fully operational under minor earthquake ground motions <strong>and</strong> on life