Peak ground acceleration

United States (equation 5.1-4), where /, is the site intensity in MM units and / is the ep ntral intensity in MM units. The site intensity is converted to the instmmental peak ground acceleration using an equation like equation 5.1-5. 

Failure frequencies of structures, equipment, and piping are related to their acceleration which is related to the ground-motion of the plant s foundation (e.g., the peak ground acceleration). For PSA, it is useful to present the seismic hazard at the site as a family of hazard curves with different nonexceedence-probability levels (Figure 5.1-3). By selecting various values of the peak ground acceleration, the acceleration and forces on the plant components may be obtained as described in the following. 

Murphy, J. R. and L, J. O Brien, 1977, The Correlation of Peak Ground Acceleration Amplitude with Seismic Intensity and Other Physical Parameters, Bull. Seismol. Soc. Am. 62 p 877. 

Under the same conditions, analysis of the reinforced concrete vaults housing the storage tanks showed that a peak ground acceleration of 0.5 g... 

An earthquake producing a 0.33-g peak ground acceleration at ICPP is considered a purely hypothetical upper-limit event which has not been exceeded in magnitude by any earthquake in recent geological times. The Arco fault has not been seismically active in historic time. 

Figure 6.9 summarizes the result of Equation (6.87) for site class A. The six curves (from top to bottom) show the log o PGA versus the magnitude of earthquake M for six levels of distance, namely 10, 50, 100, 250, 500 and 1000 km. This chart can be used for prediction of peak ground acceleration in the design process. One first estimates the closest fault from the site so the corresponding curve can be selected. This curve shows the estimated peak ground acceleration under different levels of earthquake, which may be estimated by neural networks [194]. 

Evaluation of Peak Ground Acceleration and Response Spectra Considering the Local Site Effects ... 

The local site effects play an important role in the evaluation of seismic hazard. The proper evaluation of the local site effects will help in evaluating the amplification factors for different locations. This article deals with the evaluation of peak ground acceleration and response spectra based on the local site effects for the study area. The seismic hazard analysis was done based on a probabilistic logic tree approach and the peak horizontal acceleration (PHA) values at the bed rock level were evaluated. Different methods of site classification have been reviewed in the present work. The surface level peak ground acceleration (PGA) values were evaluatedfor the entire study area for four different site classes based on NEHRP site classification. The uniform hazard response spectrum (UHRS) has been developed for the city of Bangalore and the details are presented in this work. 

Vipin, K. S., Anbazhagan, R, Sitharam, T. G. (2009). Estimation of peak ground acceleration and spectral acceleration for South India with local site effects probabilistic approach. Natural Hazards and Earth System Sciences, 9,865-878. 

The surface acceleration time history obtained from the ground response analysis for two typical sites C class site and B class site are presented in Figures llaand 1 lb respectively. It can be noticed from Figure 11 that the surface peak ground acceleration for C class and B class site is 0.53 g and 0.3 Ig respectively. It is evident that the C class site amplifies the ground motion in comparison to the input ground motion with PGA of 0.3 g. However the B class site does not amplify the input motion due to the presence of a thick hard sandy clay deposits characterized by very high shear wave velocity. 

For the deterministic scenarios, we considered three simulated artificial earthquakes with different Peak Ground Accelerations. Based on different levels of the PGA, we can make different seismic scenarios regarding the degree of damage of the buildings in a selected area of the city, presented in Fig. 5.1. 

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