JC Method Research Articles

Performance Evaluation of Existing Reinforced Concrete Bridge Based on Reliability Analysis

Considering the resisting force variation with time, JC method was adopted to calculate the reliable indicator of the reinforced concrete bridge with simply supported beams based on the field test data. Combined with the classification of security evaluation, the bridge is evaluated as type 5 and rebuild measure was suggested.

The Application of MATLAB-Based Monte Carlo Method in Hydraulic Structures Reliability

Since the application restrictions of JC method for hydraulic structures reliability, and the drawbacks of Monte Carlo method for large and complex hydraulic structures, this paper combines MATLAB with Monte Carlo method to analysis and calculate hydraulic structures reliability. Also, this paper puts forward the grading standards for hydraulic structures reliability. Taking a masonry gravity dam for example, using the Monte Carlo method and MATLAB programming to analysis the dam's sliding and strength failure risk, and then grading the dam. The results show that the application of MATLAB-based Monte Carlo method in hydraulic structures reliability is simple and quick, with good usability and operability.

Reliability Analysis of the Vertical Bearing Capacity of Prestressed Pipe Pile Foundations

The paper introduces the basic principles of vertical bearing capacity of the pile by using static load test, establish the random site theory model of the bearing capacity of prestressed pipe pile foundations calculation, calculates and statistics the try count ratio of vertical bearing capacity of 144 prestressed pipe pile in Tianjin, work out calculation procedures of JC method, calculate reliability index of vertical bearing capacity and analyze calculation results. In the last, we build a model using the finite element software, analysis the displacement of pile top under earthquake, evaluates the horizontal bearing capacity of prestressed pipe pile.

Reliability of Gravity Foundation in Coral Sands Subject to Dynamic Wind Load

Taking circular gravity foundation of high-rise structure in coral sands as research object, on the basis of mechanical analysis of foundation during inclination, the inclination vibration equation was established. The amplitude of foundation inclination was calculated. The inclination performance function of foundation was established. JC method is used to calculate the reliability index of foundation. Calculation shows that the amplitude of wind velocity has great influence on the reliability index of foundation when the frequency of sinusoidal wind pressure equals the natural frequency of foundation in inclination vibration. In the design of foundation, the natural frequency of foundation in inclination vibration should be made as far away from the frequency of fluctuating wind pressure as possible.

Spoke Model for Calculating Reliability Index and Safety Factor of Slopes

Considering the disadvantages of the slice method commonly employed in reliability analysis of slopes, a novel method (Spoke model) was proposed for reliability analysis and safety factor calculation of slopes in this work based on geometrical relationship among slices. The safety factor and the coefficients of limit state function of slopes could be achieved with the Gaussian integral method. The minimum safety factor and the minimum reliability index, as well as their corresponding coordinates on the slip surface, can be calculated with the improved JC method and the searching method. A novel and practical method for reliability analysis of slopes has been achieved. With this method the slice process could be avoided, which helps to eliminate some calculation errors caused by oversimplified assumption. Moreover, the explicit expression of safety factor in this method requires no repeated iterative solution, which is employed in traditional slice methods, as well as can be developed into a limit state function required by calculation of the reliability index. It is demonstrated that this method works efficiently and succinctly in evaluation of reliability index and safety factor for soil slopes.

Queries for the Calculations of the Shear Wall Stability

The relevant specifications in China make the relevant regulations to guarantee the stability of the shear wall and provide the check formula. This paper discusses the rationality of the calculations on the shear wall stability from the perspective of the reliability index, and calculates the reliability index in the state of the shear wall’s instability limit by means of JC method, the result shows: the current regulations can not guarantee the requirement that the reliability index of the shear wall is not less than the target reliability index. Based on the target reliability index, load partial coefficient and load, geometric dimension probability statistical parameter, this paper uses JC method to make inverse operation, calculates the shear wall stable resistance force partial coefficient under four types of load effect combinations, and analyzes the influence of load effect ratio, thus getting the shear wall stable utmost limit load best resistance partial coefficient.

Deflection Reliability Analysis of PSC Box-Girder Bridge under High-Speed Railway Loads

A high-speed railway (HSR) construction boom has been observed in China during the past few years, in which prestressed concrete (PSC) box-girders are widely used for HSR bridges. Concerns have been raised regarding the long-term deflection of girders under the combined actions of concrete creep, shrinkage, and tendon relaxation, since the time-variant deflection significantly undermines the safety of high-speed trains. This paper presents the time-variant deflection reliability analysis of an existing HSR PSC box-girder bridge, in which a hybrid method, consisting of the response surface (RS) method, the finite element (FE) method and the checking point method (i.e., the JC method), is used. The pre-and post-cracking behaviors of the thin-walled box girder are described by using composite degenerated shell elements with the smeared cracking model and the Hordijk's tension softening relation. In particular, the CEB-FIP model for creep and shrinkage is applied in the finite-element (FE) analyses. By using the probabilistic sensitivity analyses, random variables that significantly affect the time-variant deflection are selected for the reliability calculation. It is found that the deflection reliabilities are high in the early stage of bridge service but decrease rapidly during the first 10 to 20 service years. Higher speed limits result in a significant decrease in deflection reliability indices, which may fall below the target value prior to the expected service life. The proposed methodologies can be used in the design optimization, speed control and making rational maintenance or repair strategies for HSR PSC bridges.

Reliability Assessment under Combinations of Snow Load Effect: The Lightweight Steel Structures with Gabled Frames and Components Designs

Purpose: to assess reliability factor of Gable Framed Lightweight Steel Structural and Components, under combination of load effect of permanent loads and snow loads. Method: JC method is adopted in the calculations. From reliability of geometrical meaning, transform the solving of reliability problem into the finding of minimum constraints, and calculate reliability indicators by using a non-linear programming called ‘Lingo’ software. Results: based on dead load plus snow load, and combination of dead load plus snow load and wind load, to calculate reliability indicator of structural components under axial tension, axial compression, and eccentric compression. Conclusion: when combined with snow load, reliability indicator (of Gable Framed Lightweight Steel Structures and Components) is less than the standard permitted reliability indicator, which is beta=3.2.

Reliability Analysis on Shear Capacity of Broad-Limb Special-Shaped Columns

Abstract. The limit state equation of the shear capacity with earthquake action effect combination is presented, and the statistical parameters and probability distribution of the representative value of gravity load and earthquake action effects in the limit state equation are discussed, in which, the representative value of gravity load complies with normal distribution, while the earthquake action effect complies with extreme value type-I distribution. By statistics on the test results of broad-limb special-shaped columns under repetitive-loading, indefinite coefficient statistical value on calculation model of shear capacity formula of broad-limb special-shaped columns is obtained, and then JC method is adopted to make a reliability analysis on the calculation formula. It is shown from the results that the formula is safe enough in calculating shear capacity of broad-limb special-shaped columns.

Reliability Analysis of Subgrade Bearing Capacity of Gravity Foundation of Wind Turbine Based on JC Method

The design of foundation of wind turbine should meet the requirement of subgrade bearing capacity. In this paper, reliability method was used to analyze the bearing capacity of gravity foundation of wind turbine. The circular gravity foundation in coral sands is taken as research object. By deriving the expression of maximum pressure at the edge of foundation base under the action of overturning moment, the performance function of subgrade bearing capacity reliability analysis is established. JC method is used to calculate the subgrade bearing capacity reliability index. Effect of foundation size to reliability index is analyzed. Iterative calculation shows that the method proposed in this paper can calculate the reliability index of foundation quickly.

Resistance partial factor and reliability of cast ball-and-socket support joint

Considering the uncertainty of material performance, geometric characteristic and analysis method, the analysis of statistical parameters of the resistance of cast ball-and-socket support joints and the reliability analysis are carried out by JC method (improved first-order second-moment method) based on the relevant experimental data. Results show that the resistance partial factor of the joint increases with the increase of the reliability index. The resistance partial factors are suggested corresponding to the reliability index under different load combinations. Moreover, the suggested resistance partial factor is adopted in reliability design, and it is found that the reliability index of the joint is larger than the target reliability index. The optimal load combination is the one in which live load plays an important control role. Finally, based on the suggested resistance partial factors, the reliability analysis of cast ball-andsocket support joints of a project is conducted.

Reliability Analysis on the Repaired Shaft Project Based on an Improved Response Surface Method

In order to analyze the reliability and failure probability of the repaired shaft engineering, this article makes fail-safe analysis and instability risk prediction of the shaft engineering. A reliability analysis method was applied combining the improved response surface method which has improved sample points’ selection based on the traditional response surface method to decreasing the number of the structural analysis under the premise of the accuracy of the calculated results with numerical simulation. The limit state whose failure criteria was safe factor was constructed to analyze the reliability of the repaired shaft engineering, the reliability index of the repaired shaft engineering was computed by JC method. The results show the reliability index value of the repaired shaft engineering is 3.1127 slight fewer than design objective value and it’s failure probability value is 0.0929%, which show that the repaired shaft is stable and it’s deformation should be monitored to ensure it is safety application because of it is reliability index value slight fewer than design objective value.

Reliability Analysis of Fatigue Crack Growth with JC Method Based on Scientific Materials

Since the fatigue crack propagation process from initial size till final fracture is affected by lots of random factors, it is difficult to evaluate the fatigue reliability. Based on reliability theory, the first order second moment method ( JC method) is adopted to analyze and compute the fatigue reliability. To account for the uncertainties of material resistance, the parameters in the deterministic fatigue crack growth rate equation and material fracture toughness are taken as random variables with Normal distribution or Log-Normal distribution. Consequently, the limit state equation of fatigue crack growth is derived. The fatigue reliability index at any moment is calculated iteratively through JC method. As a computation example, the curve of fatigue crack growth reliability index with time is presented.

Load and Resistance Factors for Progressive Collapse Resistance Design of Reinforced Concrete Building Structures

Due to the absence of provision for the load and resistance factors in design codes in China, designers often quote the provisions which are given in criterion or guidance of other countries such as USA. However, the partial safety factors of the load are various in different criterions. Based on the reliability theory, the load and resistance factors for progressive collapse resistance design of building structures were determined in this study. Firstly the simplified format of design expression in the ultimate state was obtained according to the expression in routine structural design. Then the failure probability of a structure during design reference period was taken as the sum of the probability of all incompatible failure events in this period, and the objective reliability index of the structure could be obtained. Finally using trial-and-error procedure and JC method, reliability analysis was performed for structural members to obtain the partial safety factors of load effects and resistance and the coefficient for combination value of load effects in design expression in the ultimate state. In this paper the load and resistance factors for progressive collapse resistance design of reinforced concrete structures subjected to blast was calculated as an example, and the recommendation values were given for the application at last.

The effects of stochastic characteristics of materials on the reliability of a composite ship hull

The effects of stochastic characteristics of materials on the reliability of ship hulls made of composite materials under longitudinal moment were extensively studied using reliability and sensitivity calculations of a composite ship hull which was sagging. The reliability indices and failure probabilities of the ship in three kinds of failure modes (buckling, material failure, and ultimate collapse) were calculated by the surface response method and JC method. The importance factors of random variables in stochastic models, such as the model errors in predicting the ultimate longitudinal strength of ship and the longitudinal bending moment that the ship withstands, as well as the stochastic characteristics of materials in the models used, were calculated. Then, the effects of these random variables, including the stochastic characteristics of materials on the reliability index and the failure probability of ships which were sagging, were discussed with their importance factors. The results show that the effects of stochastic characteristics of materials on the reliability of ship hulls made of composite materials should be considered during the reliability assessment of composite ships. Finally, some conclusions and recommendations were given for high-speed ship design and safety assessment.

Linearly Unbiased Estimation Combined with JC Method for the Carbonation Contamination of Some Concrete Bridges in Taipei

Linearly Unbiased Estimation Combined with JC Method for the Carbonation Contamination of Some Concrete Bridges in Taipei

Characterisation of toughened polymers using fracture mechanics

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