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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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. 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. This paper offers also page 49 a short discussion of the directional combination procedure: The directional effects of an earthquake are combined with the following rules: According to ECparagraph 4.
According to this book, this approach introduces a maximum error of 4.
This condition is equivalent to the one adopted by R. The rigid responses and rigid components of responses are combined algebraically. 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.
When modes are to be considered closely spaced is matter of discussion and any standards provides a slightly different rule. The percentage rule analhsis therefore adopted.
For what regard the mode combination, paragraph Equipment Inspection Method and Weibull Analysis. This statement is supported referring to a detailed discussion on w issue developed by Menun and Der Kiureghian in and In general, if the frequencies of the modes are sufficiently separated, the SRSS method may be applied.
The equations are written as follows: The EC definition is more conservative than R. No other rules are specified for non-building structures dealt with in Chapter Severe earthquake can bring serious problems in the wind turbines and eventually lead to an interruption to their electric power supply.
The combination mmethod to be used for individual modal responses depends upon whether the responses are periodic, rigid or both see R. The maximum value is 1.
Seismic effects combination | Studio Alicino
SRSS3 method rwplacement have a rather large error if vor natural periods of the structure are close to each other, namely modal correlation coefficients of structure are large. There is no specific requirement. Figure 2 shows the typical response spectrum in terms of acceleration as a function of frequency ref.
This subject is dealt with in several standards or regulatory guides among which the following are examined herein below: Figure 1 shows the typical conceptual shape of a response spectrum in terms of velocity as a function of frequency ref. World Journal of Engineering and TechnologyVol.
Seismic effects combination
Periodic responses are dominant in the region of amplified spectral displacement, amplified spectral velocity and amplified spectral acceleration. In general, this alternative method is slightly conservative for most cases and is quite adequate since its degree of conservatism is relatively small.
Regarding the number of modes, in para. The combination of the effects of the seismic components is discussed in paragraph 4. The percentage rule was put forward by Newmark and Rosenblueth first. The periodic response corresponds to the transient phase in theory of vibrations.
Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness zrss the optimization algorithm used. The percentage rule is also proposed in paragraph 4.
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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 srsss with coefficients C i that have different values for different modes but can be approximated by the value 0. Sensitivity Analysis of the Replacement Problem.
As an alternative the SRSS rule can be used. For response spectrum RS analysis, the R.