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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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As mentioned by Gupta in ref. For what regard the mode combination, paragraph Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness of the optimization algorithm used.

There is no specific provisions regarding combination of spatial components, except that in letter f of Section 2. Figure 1 shows the typical conceptual shape of a response spectrum in terms of velocity as a function of frequency ref. For response spectrum RS analysis, the R. This subject is dealt with in several standards or regulatory guides among which the following are examined herein below: Simply shifting the starting time of a wnalysis accelerogram does not constitute the establishment of a different accelerogram.

This paper offers also page 49 mtehod 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.

Seismic effects combination | Studio Alicino

The equations are written as methid According to ECparagraph 4. Then, the seismic analysis for each direction can analyzis performed separately and then combined by the square root of the sum of the squares SRSS. Subscribing you accept the TOC.

The periodic modal responses 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.


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Sensitivity Analysis of the Replacement Problem. 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.

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 seiismic limit, maximum deformation limit, and seismic acceleration gain limit.

The directional effects of an earthquake are combined with the following sesimic There is no specific requirement. This condition is equivalent to the one adopted by R. According to this book, this approach introduces a maximum error of 4. As an alternative the SRSS rule can be used.

The maximum value is 1. In general, this alternative method is slightly conservative for most cases and is quite adequate since its degree of conservatism is relatively small. The combination rule to be used for individual modal responses depends upon whether the responses are periodic, rigid or both see R.

As a result, all erplacement optimization results for the 4 different initial designs showed good agreement with each other properly.

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

srsx No other rules are specified for non-building structures dealt with in Chapter Scientific Research An Academic Publisher. The percentage rule is also proposed in paragraph 4.

The effects of each modes for a given direction of the seismic action shall be combined with the CQC rule see para. Sviluppato con Drupal da Gmg Net Srl.

In general, if the frequencies of the modes are sufficiently separated, the SRSS replacemeny may be applied. 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 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.

Thus the ni design optimization of a small vertical-axis wind turbine could be successfully accomplished. Severe earthquake can bring serious problems in the wind turbines and eventually lead to an interruption to their electric power supply. The percentage rule is therefore adopted. Labor Omnia Vicit Improbus.

When modes are to be considered closely spaced is matter of discussion and any standards provides a slightly different te. The EC definition is more conservative than R.

The rigid responses and rigid components of responses are combined algebraically. The percentage rule anzlysis put forward by Newmark and Rosenblueth first.

Regarding the number of modes, in para. In seismic response analysis two types of combinations are to be considered: He provides the following recommendations page The rigid response corresponds to the steady-state phase in theory of vibrations.

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.

Equipment Inspection Method and Weibull Analysis. If uncoupled response of the structure is expected, then only one time history is required.