Reliability Assessments of Concrete Filled FRP Tube Columns

2013 ◽  
Vol 405-408 ◽  
pp. 731-734
Author(s):  
Ying Wu Zhou ◽  
Feng Xing ◽  
Li Li Sui
Keyword(s):  
Safety Factor ◽  
Coefficient Of Variation ◽  
Reliability Index ◽  
Concrete Strength ◽  
Reliability Design ◽  
Partial Safety Factor ◽  
Highly Sensitive ◽  
Partial Safety Factors ◽  
Reliability Assessments ◽  
Frp Tube

This paper has investigated the reliability of concrete filled FRP tube columns using the FRP confined concrete theory developed recently by the authors. The reliability index of the column is assessed by Monte Carlo method. The importance of the use of partial safety factors of FRP and concrete in the reliability design of concrete filled FRP tube columns is studied. The results indicate that the reliability index of concrete filled FRP tube columns increases remarkably as the FRP partial safety factor increased. It is concluded that the FRP partial safety factor is independent on the coefficient of variation of FRP strength but is highly sensitive to the coefficient of variation of concrete strength especially in the case of low confinement ratio. Considering the actual situation in engineering applications, to reach a target reliability index of 3.5, a partial safety factor of 1.4 is finally recommend for both FRP and concrete.

Reliability-Based Derivation of Partial Safety Factor for Structural Integrity Assessment

2008 ◽  
Author(s):  
Shuo Pan ◽  
Jianping Zhao
Keyword(s):  
Safety Factor ◽  
Fracture Mode ◽  
Structural Integrity ◽  
Research Work ◽  
Random Variables ◽  
Assessment Procedure ◽  
Safety Factors ◽  
Integrity Assessment ◽  
Partial Safety Factor ◽  
Partial Safety Factors

When there are uncertainties in the input random variables, or scatter in the material properties, probabilistic assessment is a useful tool for decision making in the field of safety analysis. The partial safety factor (PSF) method was aimed on ensuring that the failure probability did not exceed a target value. In order to be conservative the input value for each random variable during the assessment procedure should be multiplied by the partial safety factors. So it is essentially a deterministic assessment using conservative values of the input random variables and a relatively simple and independent method of assessing failure probabilities using R6 failure assessment diagram. The application of partial safety factors is an important breakthrough of assessment in structures containing defects. In recent years, sets of PSFs for load, defect size, fracture toughness and yield stress had been given in two standards, BS7910 and API579. However, the recommended PSFs in both standards were larger than the original PSFs in PD6493 which was replaced by BS7910. It is therefore a new method of calculating PSFs should be found to prove which is more appropriate and convenient for engineering application. In the case of the partial safety factor method target reliabilities in the range from 0.001 to 0.00001 were considered and new series of PSFs were derived from the results of reliability analysis for the linear elastic fracture mode and elastic-plastic fracture mode. After comparing with the PSFs in BS7910 and API 579, it is concluded that the partial safety factors were generally conservative compared to our research work.

Partial safety factors for designing and assessing flexible pavement performance

2004 ◽  
Vol 31 (3) ◽  
pp. 397-406 ◽  
Author(s):  
S S Wang ◽  
H P Hong
Keyword(s):  
Safety Factor ◽  
Load Resistance ◽  
Flexible Pavement ◽  
Pavement Performance ◽  
Single Factor ◽  
Safety Factors ◽  
State Highway ◽  
Partial Safety Factor ◽  
Reliability Method ◽  
Partial Safety Factors

In designing and assessing pavement performance, the uncertainty in material properties and geometrical variables of pavement and in traffic and environmental actions should be considered. A single factor is employed to deal with these uncertainties in the current American Association of State Highway and Transportation Officials (AASHTO) guide for design of pavements. However, use of this single factor may not ensure reliability-consistent pavement design and assessment because different random variables that may have different degrees of uncertainty affect the safety and performance of pavement differently. Similar problems associated with structural design have been recognized by code writers and dealt with using partial safety factors or load resistance factors. The present study is focused on evaluating a set of partial safety factors to be used in conjunction with the flexible pavement deterioration model in the Ontario pavement analysis of cost and the model in the AASHTO guide for evaluating the flexible pavement performance or serviceability. Evaluation and probabilistic analyses are carried out using the first-order reliability method and simple simulation technique. The results of the analysis were used to suggest factors that could be used, in a partial safety factor format, for designing or assessing flexible pavement conditions to achieve a specified target safety level.Key words: deterioration, reliability, pavement, serviceability, stochastic process, performance, partial safety factor.

Reliability Studies on Concrete Filled FRP Tube Columns Using Different Design Code Models

2013 ◽  
Vol 405-408 ◽  
pp. 735-739
Author(s):  
Ying Wu Zhou ◽  
Li Li Sui ◽  
Feng Xing
Keyword(s):  
Tensile Strength ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Reliability Index ◽  
Concrete Strength ◽  
Design Codes ◽  
Design Code ◽  
Reliability Study ◽  
Simulation Results ◽  
Frp Tube

The paper presents an in-deep reliability study on concrete filled FRP tube columns using four well-known design codes which include the ACI 4402R-08, the CNR-DT200, UK code (TR55) , and the Chinese code. Monte Carlo method is utilized to calculate the reliability index of the column. The simulation results reveal that the reliability index depends heavily on the design code and the ACI 4402R-08 design code is found to be the most reliable one for the design of concrete filled FRP tube columns. The variation of the unconfined concrete strength has remarkable influences on the reliability of the column while the variation of the FRP tensile strength can hardly affect the reliability. Consequently, it is concluded that the partial safety factor for concrete or the FRP proposed in existing design codes may be suitably enhanced in order to make up the reliability loss due to the increment of the variation of concrete.

scholarly journals Efficient optimum safety factor approach for system reliability-based design optimization with application to composite yarns

2019 ◽  
Vol 19 (3) ◽  
pp. 221-230 ◽  
Author(s):  
Gh. Kharmanda ◽  
I. R. Antypas
Keyword(s):  
Design Optimization ◽  
Safety Factor ◽  
Reliability Index ◽  
Performance Measure ◽  
Alternative Methods ◽  
Reliability Based Design Optimization ◽  
Implementation Framework ◽  
Reliability Level ◽  
Reliability Based Design ◽  
Convergence Stability

Introduction. The integration of reliability and optimization concepts seeks to design structures that should be both economic and reliable. This model is called Reliability-Based Design Optimization (RBDO). In fact, the coupling between the mechanical modelling, the reliability analyses and the optimization methods leads to very high computational cost and weak convergence stability. Materials andMethods. Several methods have been developed to overcome these difficulties. The methods called Reliability Index Approach (RIA) and Performance Measure Approach (PMA) are two alternative methods. RIA describes the probabilistic constraint as a reliability index while PMA was proposed by converting the probability measure to a performance measure. An Optimum Safety Factor (OSF) method is proposed to compute safety factors satisfying a required reliability level without demanding additional computing cost for the reliability evaluation. The OSF equations are formulated considering RIA and PMA and extended to multiple failure case.Research Results. Several linear and nonlinear distribution laws are applied to composite yarns studies and then extended to multiple failure modes. It has been shown that the idea of the OSF method is to avoid the reliability constraint evaluation with a particular optimization process.Discussion and Conclusions. The simplified implementation framework of the OSF strategy consists of decoupling the optimization and the reliability analyses. It provides designers with efficient solutions that should be economic satisfying a required reliability level. It is demonstrated that the RBDO compared to OSF has several advantages: small number of optimization variables, good convergence stability, small computing time, satisfaction of the required reliability levels.

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