Executive Summary : | Secondary systems are components and systems attached to a primary structure that contribute to the functionality of the structure. They include architectural, electrical, mechanical, and building contents. The cost of secondary systems can vary between 75-90% of the total building cost. Modern code-designed primary structures can limit structural damage during severe earthquakes, but damage to secondary systems can be extensive, costly, and life-threatening. Seismic safety of secondary systems is crucial as they play a vital role in post-earthquake relief operations. Seismic design provisions for secondary systems must consider both the dynamic characteristics of the secondary system and the characteristics of the primary structure. Many buildings in the Indian subcontinent and other parts of the world are designed with various plan and elevation irregularities, which can arise due to irregular placement of lateral-load resisting elements, terrain constraints, and architectural constraints. These irregularities significantly modify the floor acceleration demands and the response of the secondary systems. None of the seismic design provisions for secondary systems worldwide account for these building irregularities. To ensure seismic safety of secondary systems in plan or elevation irregular primary structures, adequate seismic design provisions need to be developed and incorporated in building codes. |