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 directional effects of an earthquake are combined with the following rules: This statement is supported referring to a detailed discussion on this issue developed by Menun and Der Kiureghian in and Sensitivity Analysis of the Replacement Problem.
As mentioned by Gupta in ref. This subject is dealt with in several replscement or regulatory guides among which the following are examined herein below: In seismic response analysis two types of combinations are to be considered: Figure 2 shows the typical response spectrum in terms of acceleration as a function of frequency ref.
Sviluppato con Drupal da Gmg Net Srl. The periodic response corresponds to the transient phase in theory of vibrations. Recently, there is a growing interest in seismic qualification of ridges, buildings and mechanical equipment worldwide due to increase of accidents caused by earthquake.
Abalysis 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 srsd such as the maximum stress limit, maximum deformation limit, and seismic acceleration gain limit.
The rigid responses and rigid components of responses are combined algebraically. The percentage rule is also proposed in paragraph 4.
The percentage rule was put forward by Newmark and Rosenblueth first. If uncoupled response of the structure is expected, then only one time history is required. According to ECparagraph 4.
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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 provisions regarding combination of spatial components, except that in letter f of Section 2. The EC definition is more conservative than R. Periodic responses are dominant in the region of amplified spectral displacement, amplified spectral velocity and amplified spectral acceleration. The rigid response corresponds to the steady-state phase in theory of vibrations. As an alternative the SRSS replacsment can be used.
Analysid shifting the starting time of a given accelerogram does not constitute the establishment of a different accelerogram. No other rules are specified for non-building structures dealt with in Chapter He provides the following recommendations page This paper offers also page 49 a short discussion of the directional replacfment procedure: For response spectrum RS analysis, the R.
A Replacement for the SRSS Method in Seismic Analysis – Edward L. Wilson – Google Books
As a result, all the optimization results for the 4 different initial designs showed good agreement with each other properly. According to this book, this approach introduces a maximum error of 4. Also, the methor design optimizations were conducted for the four different initial design variable sets to confirm robustness of the optimization algorithm used.
The combination rule to be used for individual modal responses depends eeplacement whether the responses are periodic, rigid or both see R. The effects of each modes for a given direction of the seismic action shall be combined with the CQC rule tthe para.
The dotted lines refer to the case of multiple narrow-banded response spectrum with two or more peaks of acceleration. This condition is equivalent to the one adopted by R.
The equations are written as follows: The percentage method is never explicitly cited, but the theoretical bases for analysks are provided in Chapter 4, where the superposition dor 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. Severe earthquake can bring serious problems in the wind turbines and eventually lead to an interruption to their electric power supply.
Seismic effects combination
Scientific Research An Academic Publisher. For what regard the mode combination, paragraph Both periodic and rigid responses occur in the intermediate region between amplified spectral acceleration and high-frequency region DE in Figure analywis and Figure 2.
When modes are to be considered closely spaced is matter of discussion and any standards provides a slightly different rule. Thus the structural design optimization of a small vertical-axis wind turbine could be successfully accomplished.
In general, if the frequencies of the modes are sufficiently separated, the SRSS method may be applied. In general, this alternative method is slightly conservative for most cases and is quite adequate since its degree of conservatism is relatively small. Equipment Inspection Method and Weibull Analysis.
There is no specific requirement. Labor Omnia Vicit Improbus. Figure 1 shows the typical conceptual shape of a response spectrum in terms of velocity as a function of frequency ref.
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.