scholarly journals Safety Criteria and Standards for Bearing Capacity of Foundation

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Yanlong Li ◽  
Wangtao Fan ◽  
Xuguang Chen ◽  
Yunhe Liu ◽  
Bo Chen
Keyword(s):  
Bearing Capacity ◽  
Safety Factor ◽  
Reliability Index ◽  
Factor Of Safety ◽  
Safety Margin ◽  
Engineering Structures ◽  
Evaluation Standards ◽  
Factor Method ◽  
Reliability Based Design ◽  
Target Reliability Index

This paper focuses on the evaluation standards of factor of safety for foundation stability analysis. The problem of foundation stability is analyzed via the methods of risk analysis of engineering structures and reliability-based design, and the factor of safety for foundation stability is determined by using bearing capacity safety-factor method (BSFM) and strength safety-factor method (SSFM). Based on a typical example, the admissible factors of safety were calibrated with a target reliability index specified in relevant standards. Two safety criteria and their standards of bearing capacity of foundation for these two methods (BSFM and SSFM) were established. The universality of the safety criteria and their standards for foundation reliability was verified based on the concept of the ratio of safety margin (RSM).

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.

Target Reliability Index for Load and Resistance Factor Design of Class 2 Carbon Steel Pipes

2017 ◽  
Author(s):  
Kleio Avrithi ◽  
Ramiro Mendoza
Keyword(s):  
Carbon Steel ◽  
Internal Pressure ◽  
Reliability Index ◽  
Safety Margin ◽  
Resistance Factor ◽  
Safety Factors ◽  
Target Reliability Index ◽  
Partial Safety Factors ◽  
Factor Design ◽  
Load And Resistance Factor

The use of the Load and Resistance Factor Design (LRFD) for Class 2 nuclear piping can be an alternative of the traditional Allowable Stress Design (ASD) method currently used in the ASME Boiler Pressure Vessel Code, Section III, Div. 1 providing the benefit of a known and consistent reliability for the designed piping. The design uncertainties and the necessary safety margin are evaluated for each equation for all service levels by considering the applied loads (e.g., earthquake, deadweight, internal pressure, etc.) and the resistance of steel, in the form of either the yield or ultimate strength, as separate variables described by their mean value, distribution, and coefficient of variation. The procedure yields different partial safety factors for each load and the resistance in opposition to the one safety factor used in each of the ASD equations of the Code. Although LRFD equations have been developed in the past, a range of possible partial safety factors were assigned to the variables, corresponding to different levels of reliability. This paper discusses the method used, namely calibration, for achieving same reliability as in the Code equations, and the progress made to assess a minimum target reliability index or else acceptable probability of failure for the LRFD equations that consider the earthquake load for pressurized pipes as well as the design for internal pressure for Class 2 nuclear pipes made of carbon steel.

Barrier Function Method in Reliability Based Design Optimization

2005 ◽  
Vol 297-300 ◽  
pp. 1882-1887
Author(s):  
Tae Hee Lee ◽  
Jung Hun Yoo
Keyword(s):  
Design Optimization ◽  
Barrier Function ◽  
Reliability Index ◽  
Feasible Solution ◽  
Reliability Based Design Optimization ◽  
User Requirement ◽  
Mean Values ◽  
Reliability Based Design ◽  
Design Variables ◽  
Reliability Method

In practical design applications, most design variables such as thickness, diameter and material properties are not deterministic but stochastic numbers that can be represented by their mean values with variances because of various uncertainties. When the uncertainties related with design variables and manufacturing process are considered in engineering design, the specified reliability of the design can be achieved by using the so-called reliability based design optimization. Reliability based design optimization takes into account the uncertainties in the design in order to meet the user requirement of the specified reliability while seeking optimal solution. Reliability based design optimization of a real system becomes now an emerging technique to achieve reliability, robustness and safety of the design. It is, however, well known that reliability based design optimization can often have so multiple local optima that it cannot converge into the specified reliability. To overcome this difficulty, barrier function approach in reliability based design optimization is proposed in this research and feasible solution with specified reliability index is always provided if a feasible solution is available. To illustrate the proposed formulation, reliability based design optimization of a bracket design is performed. Advanced mean value method and first order reliability method are employed for reliability analysis and their optimization results are compared with reliability index approach based on the accuracy and efficiency.

Problems of Cold-Bent Notched C-Shaped Profile Members

2014 ◽  
Vol 941-944 ◽  
pp. 1871-1875 ◽  
Author(s):  
Nikolay I. Vatin ◽  
Tatiana Nazmeeva ◽  
Roman Guslinscky
Keyword(s):  
Bearing Capacity ◽  
Cross Sections ◽  
Experimental Investigations ◽  
Heat Current ◽  
Thermal Profile ◽  
Engineering Structures ◽  
Normative Documents ◽  
Steel Members ◽  
Global Buckling ◽  
Stability Of Structures

Nowadays cold bent steel thermal сold-bent С-profile is widely used in building construction but we still have some little studied questions in the fields of thermal conductivity, air permeability, resistibility and corrosion behavior of the profile. Cold-bent notched С-profile is used for interior exterior panel members. Lengthwise notches made chequerwise in the profile walls increase the distance of heat flow and decrease heat conductivity and eliminate cold bridges that is why the profile is called “thermal profile”. Cold-bent profile made by cold bending requires alternate approach when engineering structures are designed and maintained. The approach means thin walls’ and the profile special form’ impact on the bearing capacity and stability of the structures should be taken into account. In spite of the wide use of cold-bent notched C-profile in building frameworks, we see lack of information on how the notches influence the bearing capacity and stability of structures. There are no official normative documents on calculation and designing of cold-bent notched profile structures. We carry out theoretical and experimental investigations on global buckling and bearing capacity of steel members of C-shaped notched profiles of different cross-sections area. We carry out theoretical and experimental investigations on heat current passing through the thermal profile structure is held with the use of testing bed.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

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