IEEE 344:2013 pdf free download – IEEE Standard for Seismic Qualification of Equipment for Nuclear Power Generating Stations
electrical device may be required to have no spurious operations during the earthquake or to perform anactive function both during andor after the earthquake,or it may be required to survive during theearthquake and perform an active function after the earthquake,or any combinations of these.Anotherdevice may only be required to maintain structural integrity during andor after the earthquake. Throughoutthis standard, it is assumed that the requirements given here are understood and that the definition of thesafety function is provided as part of the equipment qualification specification. It is the responsibility of theuser to verify that the qualification approach selected complies with the requirements.
When the safety function of equipment requires a demonstration of operability during the earthquake,itshall be demonstrated during the strong motion portion of the qualification simulation.
The seismic testing，when part of an overall qualification program，shall be performed in its propersequence as indicated in IEEE Std 323, and care should be taken to identify and account for significantaging mechanisms with test margins as discussed therein.° Within these guidelines it shall be demonstratedthat the equipment is capable of performing its safety function throughout its qualified life,including itsfunctional operability during and/or after an SSE at the end of that qualified life.
Earthquake experience data will result in seismic capacities that are significantly less than those obtainedfrom seismic testing.This is because earthquake ground motions,which form the basis for establishingcapacities in 10.2, are significantly less than the seismic accelerations typically obtained during shake-tabletesting.
Non-safety-related equipment whose continued function is not required but whose failure or interactioncould reduce the functioning of safety-related equipment in proximity to an unacceptable level shall becapable of maintaining structural integrity so that seismic events up to and including the SSE would notcause such a failure. The seismic qualification approach for this non-safety-related equipment is the sameas for safety-related equipment, except that demonstration of operability may not be required. Non-safety-related equipment in proximity to safety-related equipment is typically referred to as Seismic Category llequipment.
6.1 Introduction
Damping is the generic name ascribed to the numerous energy dissipation mechanisms in a system. Inpractice, damping depends on many parameters,such as the structural system, mode of vibration, strain,normal force,velocity, materials, joint, and slippage. In linear vibration theory, the simplifying assumptionis made that damping is purely viscous or proportional to the relative velocity of moving parts. Therefore,when a value of damping is associated with a practical system, it is usually assumed to be equivalent toviscous or linear.This is a convenient simplification relating real-world hardware behavior, which may benonlinear to some degree, with theoretical concepts that normally utilize linear methods of analysis.
For equipment composed of an assembly of components，there is usually no single value of damping.Damping is associated with every part of the equipment, ranging from bolted or welded construction touniform material. The value of damping may vary from place to place, depending on numerous factors.Therefore,when a value of damping is ascribed to equipment, it is common to give a range of typicalvalues. Since each mode of vibration of a structure can， and most often does,have a different value ofdamping, a useful practice in analysis is to associate a value of damping to each mode of vibration of theequipment that is in the frequency range of interest.