System Reliability Analysis of Deep Sliding Stability of Gravity Dams

2011 ◽  
Vol 243-249 ◽  
pp. 5641-5649
Author(s):  
Sheng Hua Jiang ◽  
Jian Guo Hou ◽  
Ying Ming He
Keyword(s):  
Reliability Analysis ◽  
Failure Mode ◽  
Safety Factor ◽  
Linear Method ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Safety Factors ◽  
Strength Reduction Factor ◽  
Gravity Dams ◽  
Sliding Stability

Various potential sliding paths and different failure modes should be considered in the stability of gravity dam against deep sliding when there are several faults. The safety factor of every fault is calculated with nonlinear finite element method, and the most possible sliding path is obtained by strength reduction method. The results indicate that the strength reduction factor is larger than the safety factors of all the faults. Based on the weighted regression response surface method, the reliability indices of the faults are computed and are compared with the safety factors, which shows there’s not an entire equity relationship between the reliability index and safety factor. Each failure mode of sliding path is a parallel system of several faults, and the final failure mode is the serial system composed of all sliding paths. The reliability of every sliding path and the final system are analyzed by means of the gradual equivalent linear method, and the results are consistent with the strength reduction factor. It’s recommended the reliability analysis be applied to the safety evaluation of deep sliding stability of gravity dams to make up the shortcomings of the safety factor method.

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.

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.

Study on Buckling Strength Reduction Factor for Vertical Vessel Skirts With Access Opening by Elastic-Plastic Analysis

2019 ◽  
Author(s):  
Takuma Takahashi ◽  
Shunji Kataoka ◽  
Yoshiaki Uno ◽  
Toshikazu Miyashita
Keyword(s):  
Reduction Factor ◽  
Strength Reduction ◽  
Geometric Feature ◽  
Strength Reduction Factor ◽  
Nonlinear Buckling ◽  
Design Factor ◽  
Buckling Strength ◽  
Elastic Plastic ◽  
Design Concepts ◽  
Practical Design

Abstract Access opening is a key geometric feature of vertical vessel skirts. To ensure the structural stability of skirts, buckling strength reduction caused by openings shall be numerically evaluated. In the previous study, Buckling Strength Reduction Factor (BSRF) was introduced as a design factor representing the effects of openings. However BSRF is based on the elastic bifurcation buckling under axial compressive load. The relations between BSRF and practical design conditions, such as bending moment, material plasticity, and local deformation, are not yet evaluated. The purpose of this paper is to develop the buckling design method for vertical vessel skirts with access opening by investigating the relation between BSRF in consideration of practical design conditions and conventional design concepts for straight cylinder. The finite element analyses of buckling strength were conducted for cylindrical shells with and without openings under bending moments. In addition, nonlinear buckling behaviors of skirts with opening were studied by elastic-plastic analyses and limit-load analyses. These studies revealed the relation between BSRF and conventional buckling design concepts. Based on these results, a new buckling design approach which includes the application BSRF was proposed. This proposed approach provides a practical guide for buckling design of vertical vessel skirts with access opening.

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