It is well-known that the application of the Square-Root-of-Sum-of-Squares ( SRSS) method in seismic analysis for combining modal maxima can cause. A replacement for the SRSS method in seismic analysis [Edward L Wilson] on *FREE* shipping on qualifying offers. A Replacement for the SRSS Method in Seismic Analysis. Front Cover. Edward L. Wilson. Wiley, – Structural analysis (Engineering).

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Labor Omnia Vicit Improbus. When modes are to be considered closely spaced is matter of discussion and any standards provides a slightly different rule. As a result, all the optimization results for the 4 different initial designs showed good agreement with each other properly.

The rigid responses and rigid components of responses are combined algebraically. The effects due to the different directions of the seismic action shall be combined with the percentage rule see para. For what regard the mode combination, paragraph In general, this alternative method is slightly conservative for most cases and is quite adequate since its replacsment of conservatism is relatively small.

The percentage rule was put forward by Newmark anaalysis Rosenblueth first. This statement is supported referring to a detailed discussion on this issue developed by Menun and Der Kiureghian in and The periodic response corresponds to the transient phase in theory of vibrations.

Figure 1 shows the typical conceptual shape of a response spectrum in terms of velocity as a function of frequency ref.

## Seismic effects combination

teplacement Sviluppato con Drupal da Gmg Net Srl. Simply shifting the starting time of a given accelerogram does not constitute the establishment of a different accelerogram. The percentage rule is therefore adopted. This condition is equivalent to the one adopted by R. There is no specific provisions regarding combination of spatial components, except that in letter f of Section 2.

The combination of the effects of the seismic components is discussed in paragraph 4. SRSS3 method would have a rather large error if the natural periods of the structure are close to each other, namely modal correlation coefficients of structure are large.

There is no specific requirement. Equipment Inspection Method and Weibull Analysis. This subject is dealt with in several standards or regulatory guides among which the following are examined herein below: The rigid response corresponds to the steady-state phase in theory of vibrations.

## J-GLOBAL – Japan Science and Technology Agency

Recently, there is a growing interest in seismic qualification of ridges, buildings and mechanical equipment worldwide due to increase of accidents caused by earthquake. World Journal of Engineering and TechnologyVol. As an alternative the SRSS rule can be used. The EC definition is more conservative than R.

The directional effects of an earthquake are combined with the following rules: This paper offers also page 49 a short discussion of the directional combination procedure: Sensitivity Analysis of the Replacement Problem.

Periodic responses are dominant in the region of amplified spectral displacement, amplified spectral velocity and amplified spectral acceleration. Severe earthquake can bring serious problems in the wind turbines and eventually lead to an interruption to their electric power supply.

The effects of each modes for a given direction of the seismic action shall be combined with the CQC rule see para. The dotted lines refer to the case of multiple narrow-banded response spectrum with two or more seiwmic of acceleration.

Subscribing you accept the TOC. The combination rule to be used for individual modal responses depends upon whether the responses are periodic, rigid or both see R.

The maximum value is 1. If uncoupled response of the structure is expected, then only one time history is required.

Scientific Research An Academic Publisher. The percentage rule is also proposed in paragraph 4. Regarding the number of modes, in para. In seismic response analysis two types of combinations are to be considered: Then, the seismic analysis for each direction can be performed separately and then combined by the square root of the sum of the squares SRSS.

The periodic modal responses of an earthquake are combined with the following rules: According to this book, this approach introduces a maximum error of 4. The equations are written as follows: Both periodic and rigid responses occur in the intermediate region between amplified spectral acceleration and high-frequency region DE in Figure 1 and Figure 2.

For response spectrum RS analysis, the R.

### A Replacement for the SRSS Method in Seismic Analysis – Edward L. Wilson – Google Books

To overcome and prevent these undesirable problems, structural design optimization of a small vertical axis wind turbine has performed, in this study, for seismic qualification and lightweight by using a Genetic Algorithm GA subject to some design constraints such as the maximum stress limit, maximum deformation limit, and seismic acceleration gain limit.

The percentage method is never explicitly cited, but the theoretical bases for it are provided in Chapter 4, where the superposition of the i-modes is provided as linear combination with coefficients C i that have different values for different modes but can be approximated by the value 0.

Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness of the optimization algorithm metgod. No other rules are specified for non-building structures dealt with in Chapter