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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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 combination rule to be used for individual modal ssrss depends upon whether the responses are periodic, rigid or both see R.
As a result, all the optimization results for the 4 different initial designs showed good agreement with each other properly. The rigid response corresponds to the steady-state phase in theory of vibrations.
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.
This statement is supported referring to a detailed discussion on this issue developed by Menun and Der Kiureghian in and World Journal of Engineering and TechnologyVol.
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.
Sensitivity Analysis of the Replacement Problem.
In seismic response analysis two types of combinations are to be considered: Subscribing you accept the TOC. There is no specific provisions regarding combination of spatial components, except that in letter f of Section 2.
Severe earthquake can bring serious problems in the wind turbines and eventually lead to an interruption to mehhod electric power supply.
A Replacement for the SRSS Method in Seismic Analysis – Edward L. Wilson – Google Books
When modes are to be considered closely spaced is matter of discussion and any standards provides a slightly different rule. 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 methodd different accelerogram.
The combination of the effects of the seismic components is discussed in paragraph 4. 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.
The percentage rule is also proposed in paragraph 4. Thus the structural design optimization of a small vertical-axis wind turbine could be successfully accomplished. According to ECparagraph 4. Scientific Research An Academic Publisher. Equipment Inspection Method and Weibull Analysis. Regarding the number of modes, seimic para. Figure 2 shows the typical response spectrum in terms analyssis acceleration as a function of frequency ref.
Seismic effects combination
Sviluppato con Drupal da Gmg Net Srl. He provides the following recommendations page In general, if the frequencies of the modes are sufficiently ana,ysis, the SRSS method may be applied.
As srsss alternative the SRSS rule can be used. Periodic seisjic are dominant in the region of amplified spectral displacement, amplified spectral velocity and amplified spectral acceleration. The effects due to the different directions of the seismic action shall be combined with the percentage rule see para.
Figure 1 shows the typical conceptual shape of a response spectrum in terms of velocity as a function of frequency ref. If uncoupled response of the structure is expected, then only one time history is required.
This subject is dealt with in several standards or regulatory guides among which the following are examined herein below: No other rules are specified for non-building structures dealt with in Chapter The directional effects of an earthquake are combined with the following rules: This condition is equivalent to the one adopted by R. The percentage rule was put forward by Newmark and Rosenblueth first. The rigid responses and rigid components of responses are combined algebraically.
This paper offers also page 49 a short discussion of the directional combination procedure: In general, this alternative method is slightly conservative for most cases and is quite adequate since its degree of conservatism is relatively small. The equations are written as follows: According to this book, this approach introduces a maximum error of 4. Recently, there is a growing interest seismjc seismic qualification of ridges, buildings and mechanical equipment worldwide due to increase of accidents caused by earthquake.
The percentage rule is therefore adopted. 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 EC definition is more conservative than R. Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness of the optimization algorithm used.
The maximum value is 1. The effects of each modes for a given direction of the seismic action shall be combined with the CQC rule see para. For what regard the mode combination, paragraph The periodic seksmic responses of an earthquake are combined with the following rules: As mentioned by Gupta in ref.
Labor Omnia Vicit Improbus.