IEEE 344-2013 pdf free download – IEEE Standard for Seismic Qualification of Equipment for Nuclear Power Generating Stations.
4.5.2 Time history
A time history displays the earthquake-induced motion (usually in terms of acceleration) as a function of time. The simulated motion is derived from existing or artificially generated earthquake records. For application at any floor, the time history record generated includes the dynamic filtering and amplification effects of the building and other intervening support structures.
4.5.3 PSD function
The mean squared amplitude per unit frequency of the vibratory motion is characterized in terms of the PSD as a function of frequency. NOTE—Although the response spectrum and the PSD function do not define the exact waveform or duration of the excitation, they are valuable tools. They enable significant frequency-dependent properties of the motion to be seen at a glance from one curve. The PSD provides information regarding the excitation directly without including the effects on an array of SDOF oscillators as is done for the response spectrum. As a result, the PSD allows application of relationships between excitation and response by way of the transfer functions for linear systems.
4.6 Support structure and interactions
Seismic qualification of equipment requires consideration of installation features, such as (a) the seismic adequacy of the supporting structure (support assembly, structure, anchorage, floors, walls, or foundation), and (b) the potential for adverse seismic interactions (such as falling of overhead components, proximity impacts, differential displacements, spray, flood, or fire).
5. Seismic qualification approach The seismic qualification of Seismic Category I equipment shall demonstrate an equipment’s ability to perform its required safety function(s) during and/or after the time it is subjected to the forces resulting from a safe shutdown earthquake (SSE). For equipment being qualified by test and having more than one safety function, more than one SSE may be required to demonstrate satisfactory performance of all the safety functions. In addition, the equipment shall withstand the effects of a number of operating basis earthquakes (OBEs) [see 7.5, 8.1.5.2, item b) in 10.2.3.1, and 10.3] prior to the application of an SSE. The most commonly used methods for seismic qualification are contained in this standard. The methods are grouped into four general categories that
a) Predict the equipment’s performance by analysis.
b) Test the equipment under simulated seismic conditions. c) Qualify the equipment by a combination of test and analysis. d) Qualify the equipment through the use of experience data. Each of the preceding methods, or other justifiable methods, may be adequate to verify the ability of the equipment to meet the seismic qualification requirements. The choice should be based on the practicality of the method for the type, size, shape, and complexity of the equipment configuration, whether the safety function can be assessed in terms of operability or structural integrity alone, and the reliability of the conclusions. Seismic Category I equipment being qualified shall demonstrate that it can perform its safety function during and/or after an earthquake. The required safety function depends not only on the equipment itself but also on the system and plant in which it is to function. IEEE 344 pdf download.