Modal combination rules in response spectrum analysis: Early history

2020 ◽  
Author(s):  
Anil K. Chopra
Keyword(s):  
Spectrum Analysis ◽  
Response Spectrum ◽  
Early History ◽  
Response Spectrum Analysis ◽  
Combination Rules

Torsional Displacements in Base-Isolated Buildings

2000 ◽  
Vol 16 (2) ◽  
pp. 443-454 ◽  
Author(s):  
R. S. Jangid ◽  
J. M. Kelly
Keyword(s):  
Spectrum Analysis ◽  
Analytical Study ◽  
Response Spectrum ◽  
Equations Of Motion ◽  
Governing Equations ◽  
Response Spectrum Analysis ◽  
Combination Rules ◽  
Torsional Response ◽  
Torsional Coupling ◽  
Torsional Frequency

An analytical study of the effects of torsional coupling on the seismic response of a base-isolated building is presented. The isolated structure is modeled as a rigid deck supported on axially inextensible bearings. The governing equations of motion for the coupled lateral-torsional response of the system are derived. The eccentricity in the system is that specified by the Uniform Building Code (UBC). The displacement response of the isolated system with different combinations of building configuration, isolation damping, and the ratio of uncoupled torsional to lateral frequency of the system is investigated. The response of the isolated structure under a variety of near-fault and other earthquake ground motions is compared to that obtained by use of response spectrum analysis. In the response spectrum analysis the accuracy of several modal combination rules is evaluated. It is shown that torsional coupling can influence the response of the isolated structure, but if the layout of the isolation bearings is such that the torsional frequency is larger than the lateral frequency, the effect is reduced and the usual modal combination rules work well. It is also shown that in this case, the UBC static formula for the additional isolator displacements due to torsion is conservative.

Modal Combination in Response Spectrum Analysis of Piping Systems

1986 ◽  
Vol 108 (1) ◽  
pp. 73-77 ◽  
Author(s):  
A. K. Gupta ◽  
J.-W. Jaw
Keyword(s):  
Spectrum Analysis ◽  
Response Spectrum ◽  
Direct Integration ◽  
Response Spectrum Analysis ◽  
Combination Rules ◽  
Combination Methods ◽  
Modal Response ◽  
Piping Systems ◽  
Higher Modes Effect ◽  
Integration Analysis

Modal combination methods in the response spectrum analysis of piping systems have been investiaged. Two particular effects are identified, viz, (i) the residual rigid response, also known as the higher modes effect (HME); (ii) the correlation between the modal response and the rigid response. Gupta’s method accounts for both these effects. It is shown that Gupta’s method gives results which are much closer to the direct integration analysis results than are the results obtained from any other modal combination rules which ignore either one or both of the foregoing effects.

Comparison of eigenanalysis and Ritz vector approaches for response spectrum analysis of soil-pile-bridge systems

2021 ◽  
Vol 17 (3-4) ◽  
pp. 89-100
Author(s):  
M. Davidson ◽  
A. Patil ◽  
S.A. Rosenfeld ◽  
Z. Zhu
Keyword(s):  
Spectrum Analysis ◽  
Soil Structure ◽  
Response Spectrum ◽  
Active Regions ◽  
Ritz Vector ◽  
Response Spectrum Analysis ◽  
Fixed Base ◽  
Potential Benefits ◽  
Eigenvectors And Eigenvalues ◽  
Vector Approach

Frequency-based analysis techniques such as response spectrum analysis (RSA) are widely used for designing bridges in seismically active regions. Two well-known analysis procedures that underlie RSA are the solution of the eigenproblem and the approximation of the solution to the eigenproblem (i.e., approximation of eigenvectors and eigenvalues) through use of force-dependent Ritz vectors. While frequency-based methods have achieved widespread adoption in practice, certain simplifications remain common, such as neglecting soil-structure interaction (SSI) due to a fixed-base assumption. In the present study, frequency-based techniques packaged within a research version of a design-oriented computational tool are employed to analyze, assess, and compare results obtained from RSA with use of the eigenanalysis, and separately, Ritz vector approaches. Importantly, for the bridge configurations analyzed, SSI is taken into account. As outcomes, the potential benefits of the Ritz vector approach (as well as modeling strategies) are demonstrated. The study outcomes are intended to aid practicing engineers when the need to account for SSI is recognized as pertinent to a given bridge seismic design application.

scholarly journals A Literature Review on Seismic Response of Floating Column Building

2021 ◽  
Vol 9 (12) ◽  
pp. 68-72
Author(s):  
Deepak Jain
Keyword(s):  
Literature Review ◽  
Seismic Response ◽  
Spectrum Analysis ◽  
Response Spectrum ◽  
Seismic Loads ◽  
Seismic Zone ◽  
Response Spectrum Analysis ◽  
Promising Solution ◽  
Story Building ◽  
Shape And Size

Abstract: Floating column building is a new fascination for engineers. As floating column buildings provides more space and good aesthetics to the building. But have high structural challenges, when a floating column is provided in a multi-story building in a high seismic zone. This paper reviews several studies conducted on the floating column building and its behavior under seismic loads. This paper studies that floating column building are vulnerable to the high seismic zones. The risk of damage also depends on the shape and size of the buildings.The ductile detailing of the joints is the promising solution for immediate failure of such buildings. Keywords: Floating Column, Response spectrum analysis. Vulnerable, damage, multi-story

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