Assessment of ductility demand and reliability of bilinear single-degree-of-freedom systems under earthquake loading

2007 ◽  
Vol 34 (12) ◽  
pp. 1606-1615 ◽  
Author(s):  
H. P. Hong ◽  
P. Hong
Keyword(s):  
Coefficient Of Variation ◽  
Degree Of Freedom ◽  
Initial Stiffness ◽  
Single Degree Of Freedom ◽  
Ductility Demand ◽  
Single Degree ◽  
Code Calibration ◽  
Probabilistic Characterization ◽  
The Mean ◽  
Ground Motion Records

Probabilistic assessments of the ductility demand and reliability analysis were carried out for hysteretic bilinear single-degree-of-freedom (SDOF) systems. The assessment considered a set of strong ground motion records, and focused on evaluating the mean and coefficient of variation of the ductility demand for a given normalized yield strength. Results indicated that the ductility demand could be modeled as a Frechet (extreme value type II) variate. Based on the obtained results, empirical equations were provided to predict the mean ductility demand for hysteretic bilinear SDOF systems considering different natural vibration periods, damping ratios, and post-yield stiffness to initial stiffness ratios. Numerical results showed that the coefficient of variation of the ductility demand can go as high as one, depending on the characteristics of the structure. Also, a simple approach was given to estimate the probabilities of incipient damage and incipient collapse using the developed probabilistic characterization of the ductility demand. This approach, which could be suitable for design code calibration analysis, is illustrated numerically in this study.

Effect of the orientation of records on displacement ductility demand

2012 ◽  
Vol 39 (4) ◽  
pp. 362-373 ◽  
Author(s):  
A.D. García-Soto ◽  
H.P. Hong ◽  
R. Gómez
Keyword(s):  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Single Degree ◽  
Perfectly Plastic ◽  
Principal Axes ◽  
Hazard And Risk ◽  
Elastic Perfectly Plastic ◽  
Pseudo Spectral

Effects of the ground motion record orientation on the estimated pseudo-spectral acceleration (PSA) have been investigated and reported in the literature; the statistics of the PSA along the major and minor principal axes differ from that for a random orientation. This is true for California as well as for Mexican records. However, a statistical assessment of the effect of record orientation on the displacement ductility demand is lacking. Such an assessment could be important for gaining confidence in and understanding of using the ductility demand rules for seismic hazard and risk evaluations. The statistical analyses of the effect of orientation on the estimated displacement ductility demand for elastic-perfectly-plastic and bilinear hysteretic (single degree of freedom) systems is carried out in the present study using sets of records from Mexican inslab and interplate earthquakes, and California earthquakes. Based on the obtained statistics, it is suggested that the consideration that the ductility demand is independent of the orientation of the records can be adequate, especially for Tn greater than 0.3 s and elastic-perfectly-plastic hysteretic single degree of freedom systems.

Kinematic comparison of single degree-of-freedom robotic gait trainers

2021 ◽  
Vol 159 ◽  
pp. 104258
Author(s):  
Jeonghwan Lee ◽  
Lailu Li ◽  
Sung Yul Shin ◽  
Ashish D. Deshpande ◽  
James Sulzer
Keyword(s):  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Robotic Gait

Single-Degree-of-Freedom Based Pressure-Impulse Diagrams for Blast Damage Assessment

2014 ◽  
Vol 567 ◽  
pp. 499-504 ◽  
Author(s):  
Zubair Imam Syed ◽  
Mohd Shahir Liew ◽  
Muhammad Hasibul Hasan ◽  
Srikanth Venkatesan
Keyword(s):  
Damage Assessment ◽  
Structural Response ◽  
Blast Loading ◽  
Computational Effort ◽  
Degree Of Freedom ◽  
Negative Phase ◽  
Single Degree Of Freedom ◽  
Pressure Impulse ◽  
Single Degree ◽  
Structural Resistance

Pressure-impulse (P-I) diagrams, which relates damage with both impulse and pressure, are widely used in the design and damage assessment of structural elements under blast loading. Among many methods of deriving P-I diagrams, single degree of freedom (SDOF) models are widely used to develop P-I diagrams for damage assessment of structural members exposed to blast loading. The popularity of the SDOF method in structural response calculation in its simplicity and cost-effective approach that requires limited input data and less computational effort. The SDOF model gives reasonably good results if the response mode shape is representative of the real behaviour. Pressure-impulse diagrams based on SDOF models are derived based on idealised structural resistance functions and the effect of few of the parameters related to structural response and blast loading are ignored. Effects of idealisation of resistance function, inclusion of damping and load rise time on P-I diagrams constructed from SDOF models have been investigated in this study. In idealisation of load, the negative phase of the blast pressure pulse is ignored in SDOF analysis. The effect of this simplification has also been explored. Matrix Laboratory (MATLAB) codes were developed for response calculation of the SDOF system and for repeated analyses of the SDOF models to construct the P-I diagrams. Resistance functions were found to have significant effect on the P-I diagrams were observed. Inclusion of negative phase was found to have notable impact of the shape of P-I diagrams in the dynamic zone.

Sign in / Sign up

Export Citation Format

Share Document