scholarly journals Capacity-Demand-Diagram Methods Based on Inelastic Design Spectrum

1999 ◽  
Vol 15 (4) ◽  
pp. 637-656 ◽  
Author(s):  
Anil K. Chopra ◽  
Rakesh K. Goel
Keyword(s):  
Reduction Factor ◽  
Improved Method ◽  
Strength Reduction Factor ◽  
Diagram Method ◽  
Ductility Demand ◽  
Design Spectrum ◽  
Important Sense ◽  
Nonlinear Static Procedure ◽  
Nonlinear Static ◽  
Inelastic Design

An improved capacity-demand-diagram method that uses the well-known constant-ductility design spectrum for the demand diagram is developed and illustrated by examples. This method estimates the deformation of inelastic SDF systems consistent with the selected inelastic design spectrum, while retaining the attraction of graphical implementation of the ATC-40 Nonlinear Static Procedure. One version of the improved method is graphically similar to ATC-40 Procedure A whereas the second version is graphically similar to ATC-40 Procedure B. However, the improved procedures differ from ATC-40 procedures in one important sense. The demand diagram used is different: the constant-ductility demand diagram for inelastic systems in the improved procedure versus the elastic demand diagram in ATC-40 for equivalent linear systems. The improved method can be conveniently implemented numerically if its graphical features are not important to the user. Such a procedure, based on equations relating the yield strength reduction factor, Ry, and ductility factor, μ, for different period, Tn, ranges, has been presented, and illustrated by examples using three different Ry - μ - Tn relations.

Influence of Post-Yield Stiffness on Inelastic Seismic Response: A Stochastic Analysis

2017 ◽  
Vol 17 (02) ◽  
pp. 1750028 ◽  
Author(s):  
Rita Greco ◽  
Giorgio Monti ◽  
Giuseppe Carlo Marano
Keyword(s):  
Response Spectra ◽  
Reduction Factor ◽  
Seismic Action ◽  
Strength Reduction Factor ◽  
Response Modification Factor ◽  
Inelastic Response ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Constant Displacement ◽  
Inelastic Displacement Ratio

The main objective of this study is to evaluate inelastic response spectra conditioned on constant displacement ductility demand for a single degree of freedom system, which has positive post-yield stiffness. To develop this analysis, the nonlinear Bouc–Wen model is used and it is subject to a seismic action modeled by a nonstationary stochastic process. The study utilises stochastic linearisation technique and peak theory to obtain inelastic response spectra. More in detail, inelastic acceleration spectra, response modification factor spectra, strength reduction factor spectra, yield strength spectra, and inelastic displacement ratio spectra are obtained for constant displacement ductility demand. The novelty of the present study with respect to the previous ones in this field is to obtain inelastic response spectra in stochastic terms, starting from a stochastic model of the seismic motion. Results suggest that the effect of post-yield stiffness must be considered when determining inelastic response.

Influence of Wear Properties on Fretting Fatigue Life of a CK45 Alloy and the Al7175 Alloy

2008 ◽  
Vol 587-588 ◽  
pp. 971-975 ◽  
Author(s):  
M. Buciumeanu ◽  
A.S. Miranda ◽  
F.S. Silva
Keyword(s):  
Wear Resistance ◽  
Fatigue Life ◽  
Material Properties ◽  
Fatigue Behavior ◽  
Synergetic Effect ◽  
Fretting Fatigue ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
Wear Properties

The main objective of this work was to study the influence of the wear properties of two commercial alloys (CK45 and Al7175) on their fretting fatigue behavior. It is verified the effect of material local degradation by wear on a fatigue strength reduction factor, namely the stress concentration factor, and on the overall fretting fatigue life of these materials. The fretting fatigue phenomenon is a synergetic effect between wear and fatigue. It is dependent on both the fatigue and the wear properties of the materials. Material properties promoting an increase in wear resistance should enhance fretting fatigue life.

Design of Pressure Vessels for Low-Cycle Fatigue

1962 ◽  
Vol 84 (3) ◽  
pp. 389-399 ◽  
Author(s):  
B. F. Langer
Keyword(s):  
Fatigue Strength ◽  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
Fatigue Curve ◽  
Pressure Vessels ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
The Mean ◽  
Fatigue Evaluation

Methods are described for constructing a fatigue curve based on strain-fatigue data for use in pressure vessel design. When this curve is used, the same fatigue strength-reduction factor should be used for low-cycle as for high-cycle conditions. When evaluating the effects of combined mean and alternating stress, the fatigue strength-reduction factor should be applied to both the mean and the alternating component, but then account must be taken of the reduction in mean stress which can be produced by yielding. The complete fatigue evaluation of a pressure vessel can be a major task for the designer, but it can be omitted, or at least drastically reduced, if certain requirements can be met regarding design details, inspection, and magnitude of transients. Although the emphasis in this paper is on pressure vessel design, the same principles could be applied to any structure made of ductile metal and subjected to limited numbers of load cycles.

scholarly journals Calculation of Axial Compression Capacity for Square Columns Strengthened with HPFL and BSP

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Hua Huang ◽  
Kailin Xi ◽  
Yu Zhang ◽  
Jinghui Shi ◽  
Boquan Liu
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
High Performance ◽  
Reduction Factor ◽  
Steel Plates ◽  
Strength Reduction Factor ◽  
Compression Performance ◽  
Load Carrying ◽  
Calculation Results ◽  
Primary Damage

The load carrying capacity and failure mechanism of 8 square columns strengthened with high-performance ferrocement laminate (HPFL) and bonded steel plates (BSP) were analyzed on the basis of experiments on the axial compression performance of these columns. Results show that the reinforcing layer worked together with the original columns as a whole, and the load-bearing capacity significantly increased. When failure of the strengthened column occurred, the mortar and concrete were crushed and bulged outward in the middle of the columns, the angle bars and longitudinal steel bars buckled, and some stirrups were pulled out. The chamfering of angle bar momentously affected the primary damage of steel strand. The values of the strength reduction factor and pressure effective utilization coefficient of the mortar were suggested. Based on the experiments and existing tests of 35 columns strengthened with HPFL, equations for the axial compression bearing capacity were proposed and all calculation results agreed well with testing results. Therefore, the calculation method could be used in the capacity design of axial compression strengthened columns.

Strength reduction factor of self-centering structures under near-fault pulse-like ground motions

2020 ◽  
Vol 24 (1) ◽  
pp. 119-133
Author(s):  
Huihui Dong ◽  
Qiang Han ◽  
Xiuli Du ◽  
Canxing Qiu
Keyword(s):  
Ground Motions ◽  
Time History ◽  
Reduction Factor ◽  
Strength Reduction ◽  
The Self ◽  
Hysteretic Behavior ◽  
Hysteretic Model ◽  
Strength Reduction Factor ◽  
Vibration Period ◽  
Near Fault

Many studies on the strength reduction factor mainly focused on structures with the conventional hysteretic models. However, for the self-centering structure with the typical flag-shaped hysteretic behavior, the corresponding study is limited. The main purpose of this study is to investigate the strength reduction factor of the self-centering structure with flag-shaped hysteretic behavior subjected to near-fault pulse-like ground motions by the time history analysis. For this purpose, the smooth flag-shaped model based on Bouc-Wen model which can show flag-shaped hysteretic behavior is first described. The strength reduction factor spectra of the flag-shaped model are then calculated under 85 near-fault pulse-like ground motions. The influences of the ductility level, vibration period, site condition, hysteretic parameter, and hysteretic model are investigated statistically. For comparison, the strength reduction factors under ordinary ground motions are also analyzed. The results show that the strength reduction factor from near-fault pulse-like ground motions is smaller. Finally, a predictive model is proposed to estimate the strength reduction factor for the self-centering structure with the flag-shaped model under near-fault pulse-like ground motions.

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