Evaluation of Strength Reduction Factors for Earthquake-Resistant Design

1994 ◽  
Vol 10 (2) ◽  
pp. 357-379 ◽  
Author(s):  
Eduardo Miranda ◽  
Vitelmo V. Bertero
Keyword(s):  
Strength Reduction ◽  
Soil Conditions ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Design Spectra ◽  
Earthquake Resistant Design ◽  
Earthquake Resistant ◽  
Influencing Parameters ◽  
Inelastic Design ◽  
Reduction Factors

Strength reduction factors which permit estimation of inelastic strength demands from elastic strength demands are evaluated. Results from various investigations of strength reduction factors carried out over the last 30 years are reviewed, and their results are presented in a common format which facilitates their comparison. The main parameters that affect the magnitude of strength reductions are discussed. The evaluation of the results indicates that strength reductions are primarily influenced by the maximum tolerable displacement ductility demand, the period of the system and the soil conditions at the site. Simplified expressions of strength reduction factors to estimate inelastic design spectra as functions of these primary-influencing parameters are presented.

Which Earthquakes are Expected to Exceed the Design Spectra?

2019 ◽  
Vol 35 (3) ◽  
pp. 1465-1483 ◽  
Author(s):  
Iunio Iervolino ◽  
Massimiliano Giorgio ◽  
Pasquale Cito
Keyword(s):  
State Of The Art ◽  
National Level ◽  
Seismic Events ◽  
Maximum Magnitude ◽  
Probabilistic Measure ◽  
Design Spectra ◽  
Earthquake Resistant Design ◽  
Safety Margins ◽  
Earthquake Resistant ◽  
Elastic Design

Extended recording coverage of contemporary seismic events allows a comparison of observed seismic actions with their counterparts used for design. Said comparison shows actions systematically exceeding design spectra. This paper discusses: (1) that considered exceedances can be anticipated by the probabilistic seismic hazard on the basis of which design actions are determined, (2) exceedances of elastic design actions are expected for earthquakes occurring close to the site even if their magnitude is far from the maximum magnitude considered in the hazard assessment, and (3) design spectra are likely to be exceeded in epicentral areas of earthquakes that occur frequently in the region where the code is enforced, but rarely occur close to the site under consideration. In fact, code-mandated protection against these earthquakes is factually warranted by the rarity with which they are expected to occur near the structure and other safety margins implicit to earthquake-resistant design. All these issues, addressed with reference to Italy, are discussed with the intent not to criticize the way spectra are determined, but rather to raise awareness and give a probabilistic measure about what to factually expect from state-of-the-art design at a national level.

scholarly journals Inelastic Analysis of Mdof Systems Damaged by Earthquakes, Posteriorly Subjected to Wind Load

2021 ◽  
Vol 7 (3) ◽  
pp. 575-593
Author(s):  
Oualid Badla ◽  
T. Bouzid ◽  
P. Martinez Vazquez
Keyword(s):  
Systems Engineering ◽  
Structural Reliability ◽  
Strength Reduction ◽  
Wind Loading ◽  
Ductility Demand ◽  
Inelastic Analysis ◽  
Control Systems Engineering ◽  
Mdof Systems ◽  
Wind Actions ◽  
Reduction Factors

This paper deals with the analysis of the inelastic response of buildings originally damaged by earthquakes and subjected to earthquake aftershock and wind loading. The overall aim is to establish the effect of wind actions on structural stability. To that end, one four-story bare frame benchmarked by the European Laboratory for Structural Assessment, is subject to various levels of winds and earthquake joint load while monitoring changes on the ductility demand. In this paper is shown that the combined action of strong winds and earthquakes, however its low probability of occurrence, would cause a decrease of strength reduction factors and considerably increase the ductility demand of damaged infrastructure hence inducing additional risks that would otherwise remain unquantified. The paper examines the non-linear performance of Multi-degree of freedom systems subject to various levels of winds and earthquake load and deals with the estimation of strength reduction factors. This is a relatively unexplored area of research which builds on past developments whereby inelastic performance of buildings has been discussed. It also links to various other paths of development such as structural reliability, forensic and control systems engineering. Doi: 10.28991/cej-2021-03091675 Full Text: PDF

scholarly journals Ductility and Strength Reduction Factors for Degrading Structures Considering Cumulative Damage

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Edén Bojórquez ◽  
Sonia E. Ruiz ◽  
Alfredo Reyes-Salazar ◽  
Juan Bojórquez
Keyword(s):  
Structural Properties ◽  
Seismic Design ◽  
Ground Motions ◽  
Strength Reduction ◽  
Cumulative Damage ◽  
Earthquake Resistant ◽  
Earthquake Resistant Structures ◽  
Simple Systems ◽  
Insight Into ◽  
Reduction Factors

The effect of cumulative damage on the strength requirements of degrading structures is assessed through the evaluation of the target ductility and corresponding strength reduction factors of simple degrading structures. While the reduction on ductility is established through the use of Park and Ang index, the suggestions given by Bojórquez and Rivera are used to model the degradation of the structural properties of the simple systems. Target ductilities and their corresponding reduced strength reduction factors are established for five sets of ground motions; most of them are recorded in California. The results given in this paper provide insight into all relevant parameters that should be considered during seismic design of earthquake-resistant structures. Finally, some recommendations to evaluate the effect of cumulative damage on seismic design are suggested.

Spectrum-compatible accelerograms for inelastic seismic analysis of short-period structures located in eastern Canada

1993 ◽  
Vol 20 (6) ◽  
pp. 951-968 ◽  
Author(s):  
P. Léger ◽  
A. K. Tayebi ◽  
P. Paultre
Keyword(s):  
Seismic Analysis ◽  
Historical Records ◽  
Eastern Canada ◽  
Ductility Demand ◽  
Inelastic Analysis ◽  
Earthquake Resistant Design ◽  
Acceleration Time Histories ◽  
Short Period ◽  
Earthquake Resistant ◽  
Smooth Design

Smooth design spectra are generally used to describe the seismic excitation provided by the maximum design earthquake for safety evaluation of critical facilities located in eastern Canada. However, a comprehensive study of the inelastic behaviour of critical structural systems requires a step-by-step inelastic analysis in the time domain. This paper presents a study of the inelastic seismic analysis of short-period structures subjected to ground motion acceleration time histories compatible with eastern Canadian conditions and defined (i) from historical records scaled to the smooth design spectrum intensity, (ii) from spectrum-compatible accelerograms generated by random vibration theory, and (iii) from the modification of the Fourier spectrum coefficients of historical records while preserving the original phase angles. The ductility demand, the input energy, the hysteretic energy, the number of yield events, and other performance indices are examined in parametric analyses to identify the type of earthquake motions that is critical for earthquake resistant design of short-period structures. Key words: earthquake resistant design, artificial accelerograms, eastern Canada.

scholarly journals FUNDAMENTAL STUDY ON EARTHQUAKE RESISTANT DESIGN OF FILL-TYPE DAMS

1983 ◽  
Vol 1983 (339) ◽  
pp. 127-136 ◽  
Author(s):  
Yoshio OHNE ◽  
Hidehiro TATEBE ◽  
Kunitomo NARITA ◽  
Tetsuo OKUMURA
Keyword(s):  
Fundamental Study ◽  
Earthquake Resistant Design ◽  
Earthquake Resistant

A NEURAL NETWORK-WAVELET MODEL FOR GENERATING ARTIFICIAL ACCELEROGRAMS

2004 ◽  
Vol 02 (03) ◽  
pp. 217-235 ◽  
Author(s):  
GENE F. SIRCA ◽  
HOJJAT ADELI
Keyword(s):  
Neural Network ◽  
Geographic Location ◽  
Training Data ◽  
Wavelet Network ◽  
Design Spectrum ◽  
Earthquake Resistant Design ◽  
Earthquake Resistant ◽  
Structural Configurations ◽  
Earthquake Accelerograms ◽  
Artificial Accelerograms

In earthquake-resistant design of structures, for certain structural configurations and conditions, it is necessary to use accelerograms for dynamic analysis. Accelerograms are also needed to simulate the effects of earthquakes on a building structure in the laboratory. A new method of generating artificial earthquake accelerograms is presented through adroit integration of neural networks and wavelets. A counterpropagation (CPN) neural network model is developed for generating artificial accelerograms from any given design spectrum such as the International Building Code (IBC) design spectrum. Using the IBC design spectrum as network input means an accelerogram may be generated for any geographic location regardless of whether earthquake records exist for that particular location or not. In order to improve the efficiency of the model, the CPN network is modified with the addition of the wavelet transform as a data compression tool to create a new CPN-wavelet network. The proposed CPN-wavelet model is trained using 20 sets of accelerograms and tested with additional five sets of accelerograms available from the U.S. Geological Survey. Given the limited set of training data, the result is quite remarkable.

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