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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Regarding the number of modes, in para. In seismic response analysis two types of combinations are to be considered: World Journal of Engineering and TechnologyVol. No other rules are specified for non-building structures dealt with in Chapter The periodic response corresponds to the transient phase in theory of vibrations.

Simply shifting the starting time of a given accelerogram does not constitute the establishment of a different accelerogram. Sviluppato con Drupal da Gmg Net Srl. This subject is dealt with in several standards or regulatory guides among which the following are examined herein below: If uncoupled response of the structure is expected, then only one time history is required.

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. The dotted lines refer to the case of multiple narrow-banded response spectrum with two or more peaks of acceleration.

Sensitivity Analysis of the Replacement Problem. In general, if the frequencies of the modes are sufficiently separated, the SRSS method may be applied. Periodic responses are dominant in the region of amplified spectral displacement, amplified spectral velocity and amplified spectral acceleration. The combination of the effects of the seismic components is discussed in paragraph 4.

The maximum value is 1. The effects due to the different directions of the seismic action shall be combined with the percentage rule see para.

Scientific Research An Academic Publisher. As a result, all the optimization results for the 4 different initial designs showed good agreement with each other properly.

## Seismic effects combination

The percentage rule was put forward by Newmark and Rosenblueth first. According to ECparagraph 4. The rigid response corresponds to the steady-state phase in theory of vibrations. As an alternative the SRSS rule can be used.

### Seismic effects combination | Studio Alicino

There is no specific provisions regarding combination of spatial components, except that in letter f of Section 2.

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 percentage rule is also proposed in paragraph 4.

In general, this alternative method is slightly conservative for most cases and is quite adequate since its degree of conservatism is relatively small. Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness of analysiss optimization algorithm used. Subscribing you accept the TOC. The seissmic rule to be used for individual modal responses depends upon whether the responses are periodic, rigid or both see R.

As mentioned by Gupta in ref. This condition is equivalent to the one adopted by R. 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.

According to this book, this approach introduces a maximum error of 4. Labor Omnia Vicit Improbus. Equipment Inspection Method and Weibull Analysis. The rigid analysia and rigid components of responses are combined algebraically.

This statement is supported referring to a detailed discussion on this issue developed by Menun and Der Kiureghian in and Replacementt paper offers also methoe 49 a short discussion of the directional combination procedure: Thus the structural design optimization of a small vertical-axis wind turbine could be successfully accomplished.

For what regard the mode combination, paragraph Figure 1 shows the typical conceptual shape analysks a response spectrum in terms of velocity as a function of frequency ref.

Recently, there is a growing interest in seismic qualification of ridges, buildings and mechanical equipment worldwide due to increase of accidents caused by earthquake. The effects of each modes for a given direction of the seismic action shall be combined with the CQC rule see para.

For response spectrum RS analysis, the R. He provides the following recommendations page Aanalysis periodic modal responses of an earthquake are combined with the following rules: When modes are to be considered closely spaced is matter of discussion and any standards provides a kn different rule. Severe earthquake analyss bring serious problems in the wind turbines and eventually lead to an interruption to their electric power supply.

The directional effects of an earthquake are combined with the following rules: 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.

The equations are written as follows: The percentage rule is therefore adopted.

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 Z subject to some design constraints such as the maximum stress limit, maximum deformation limit, and seismic acceleration gain limit. There is no specific requirement. Figure 2 shows the typical response spectrum in terms of acceleration as a function of frequency ref.