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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The combination of the effects of the seismic components is discussed in paragraph 4.

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

This paper offers also page 49 a short discussion of the directional combination procedure: 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 Then, the seismic analysis for each direction can be performed separately and then combined by the square root cor the sum of the squares SRSS.

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.

Thus the structural design optimization of a small vertical-axis wind turbine could be successfully accomplished.

As an alternative the SRSS rule can be used. The combination rule to be used for individual modal responses depends upon whether the responses are periodic, rigid or both see R. This statement is supported referring to a detailed discussion on this issue developed by Menun and Der Kiureghian in and 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 rigid responses and rigid components of responses are combined algebraically. 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.

Figure 2 shows the typical response spectrum in terms of acceleration as a function of frequency ref. The periodic modal responses of an earthquake are combined with the following rules: Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness of the optimization algorithm used.

In general, this alternative method is slightly conservative for most cases and is quite adequate since its degree of conservatism is relatively small.

Seismic effects combination | Studio Alicino

The directional effects of an earthquake are combined with the following rules: Periodic responses are dominant in the region of amplified spectral displacement, amplified spectral velocity and amplified spectral acceleration. 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. Sensitivity Analysis of the Replacement Problem.

As a result, all the optimization results for the 4 different initial designs showed good agreement with each other properly. In seismic response analysis two types of combinations are to be considered: According to ECparagraph 4. The percentage rule is also proposed in paragraph 4. Subscribing you accept the TOC.

There is no specific provisions regarding combination of spatial components, except that in letter f of Section 2. Regarding the number of modes, in analyzis.

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When modes are to be considered closely spaced is matter of discussion and any standards provides a slightly different rule. The rigid response corresponds to the steady-state sres in theory of vibrations.


Equipment Inspection Method and Weibull Analysis. World Journal of Engineering and TechnologyVol. 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 EC definition is more conservative than R. No other rules are specified for aalysis structures dealt with in Chapter 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.

There is no specific requirement.

The percentage rule was put forward by Newmark and Rosenblueth first. For response spectrum RS analysis, the R. Scientific Research An Academic Publisher. As mentioned by Gupta in ref. The dotted lines refer to the case of multiple narrow-banded response spectrum with two or more peaks of acceleration.

The percentage method is never explicitly cited, but the theoretical bases for it are methhod 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.

Sviluppato con Drupal da Gmg Net Srl. Figure 1 shows the typical conceptual shape of a response spectrum in terms of velocity as a function of frequency ref.