Reliable Design Method Research Articles

Direct analysis method for noncompact and slender concrete-filled steel tube members

The concrete-filled steel tube (CFT) members made of noncompact/slender sections, experiencing complex behaviors such as local buckling, concrete confinement and slippage between the components, have been increasingly used in the practical engineering structures. However, few reliable design methods were available until the latest AISC 360-16, in which two types of methods are firstly provided. The first one uses P-M interaction curves with reduced or effective stiffness method while the second adopts effective stress-strain relationships based on the fiber section approach. The beneficial effects due to the restraint of steel tube have been implicitly considered in both of them. The first method approximately accounts for the member stiffness and employs the effective length method for stability design while the second method does not fully fulfill the requirements of direct analysis specified in AISC 360-16 as lack of consideration of slenderness effects and initial geometrical imperfections. This paper proposes a flexibility-based beam-column with member imperfections and incorporates the effective stress-strain models into the fiber section for direct analysis of noncompact/slender CFT members. The gradual change of member stiffness and the actual section capacity can be accurately reflected in the analysis process and as a result, the traditional effective length method is no longer required in the proposed direct analysis. It is also found that the initial imperfection of L/1000 is insufficient for CFT members. Some useful recommendations in line with AISC 360-16 are provided for practical design. Several experimental tests demonstrate the accuracy and robustness of the proposed method.

Probabilistic sensitivity analysis for the frame structure of missiles

In this study, the high-performance and high-reliability of missiles were achieved under the background of the probabilistic analysis for frame structure of missiles. On the basis of deep investigation of the artificial neural network method and mathematical model of multiorder moment method, artificial neural network based higher order moment approach was proposed for the probabilistic analysis of complex structure. As illustrated in frame structure probabilistic analysis with multiphysics fields based on artificial neural network based higher order moment, the reliability and failure probability of frame structure were studied. Furthermore, it was shown that the radial concentrated force P and the outer radius of the frame R2 are the most important factors, and the inside radius of the frame R1 and the ultimate tensile strength of materials σ b also have an important influence on the frame structure. Through comparison with Monte Carlo simulation, second-order fourth-moment approach and the artificial neural network based first-order second-moment approach, it was demonstrated that artificial neural network based higher order moment reshapes the possibility of complex aero-missile probabilistic analysis and improves computing efficiency while preserving the accuracy. Artificial neural network based higher order moment offers a useful insight for missile reliability design and optimization with multi-discipline. The efforts of this study also enrich the theory and method of mechanical reliability design.

Evaluation of floor vibration properties using measurements and calculations

Timber floor constructions are very common in the Nordic countries, for instance in single- and multifamily buildings. But building with wood is increasing in popularity for other building categories and there is wider interest in increasing the span width of wooden joist floors. Static and vibrational performance become crucial for serviceability of timber floors and often limit the design; however, constructors and designers want to increase the floor span width. To meet these challenges, reliable design methods are required and have therefore become a focus in many countries.This paper presents results from a number of measurements of different joist floor constructions. Parameters measured have also been calculated according to given equations and relevant methods. Both calculations and measurements include 17 laboratory objects and four field objects. The objects represent a huge variety of solutions and therefore a large spread of results. The main reason for the selection of floor solutions was to expand the possibilities and test the methods more than tuning current solutions into satisfactory floor vibration perception.The data and resulting analysis in this paper highlight benefits and limitations concerning relevant parameters for evaluation of floor vibration perception. According to this work, it is not possible to verify the Eurocode method with respect to accuracy, and the link to perception of floor vibrations is rather low. Another method should be used or developed for the future. Results presented in this paper show that sufficient accuracy may be achieved using parameters from the Hu and Chui (2004) method. Experiences from Norway over the last five years are also promising regarding evaluation of floor vibration perception using this method. However, attention should be given to floors with significantly lower damping properties and/or significantly higher (modal) masses. Damping properties or an alternative parameter taking a longer time interval of the vibrations into account should be considered.

Nonprobabilistic Reliable LQR Design Method for Active Vibration Control of Structures with Uncertainties

The linear quadratic regulator (LQR), which allows a natural consideration of the constraints on state variables and control effort, is widely used in modern control theory for the active control of structural vibration. However, uncertainties are unavoidable in the design of active control systems. Thus, in the design process of an LQR controller, it is important to deal with these uncertainties, which are always bounded and have a great influence on the final performance of the closed-loop system. In this paper, the nonprobabilistic reliability concept is extended to the selection of weighting matrices for determining the LQR controller. First, a new uncertainty propagation analysis method for an active control system is presented. To adapt to the special problem of controller design, a novel nonprobabilistic reliability index is proposed. The reliability and safety margin of the closed-loop system can be continuously characterized by this modified nonprobabilistic reliability index. The weighing matrices used to design the LQR controller via the Riccati equation are finally determined by solving a reliability-based optimization problem. The proposed method preserves the excellent characteristics of LQR control theory and provides a quantitative method for selecting the weight matrices for LQR controller design in consideration of the inherent uncertainties. Two numerical examples are presented to demonstrate the effectiveness and feasibility of the proposed method. The results from these examples reveal that the uncertainties in active control system design can be addressed from a reliability perspective.

A reliability design method for a lithium-ion battery pack considering the thermal disequilibrium in electric vehicles

With the rapid development of lithium-ion battery technology in the electric vehicle (EV) industry, the lifetime of the battery cell increases substantially; however, the reliability of the battery pack is still inadequate. Because of the complexity of the battery pack, a reliability design method for a lithium-ion battery pack considering the thermal disequilibrium is proposed in this paper based on cell redundancy. Based on this method, a three-dimensional electric-thermal-flow-coupled model, a stochastic degradation model of cells under field dynamic conditions and a multi-state system reliability model of a battery pack are established. The relationships between the multi-physics coupling model, the degradation model and the system reliability model are first constructed to analyze the reliability of the battery pack and followed by analysis examples with different redundancy strategies. By comparing the reliability of battery packs of different redundant cell numbers and configurations, several conclusions for the redundancy strategy are obtained. More notably, the reliability does not monotonically increase with the number of redundant cells for the thermal disequilibrium effects. In this work, the reliability of a 6 × 5 parallel-series configuration is the optimal system structure. In addition, the effect of the cell arrangement and cooling conditions are investigated.

Numerical calculation model investigation on response for connector assembly of a free-standing hybrid riser with experimental validation

In order to provide efficient and reliable method for structural design and optimization of upper assembly and lower assembly of a free standing hybrid riser, a numerical calculation model and model test device for the upper assembly and lower assembly of a free-standing hybrid riser were established independently based on similarity criterion and correlative elastic-plastic mechanics theories and methods. The static and dynamic numerical calculations and corresponding tests for the upper assembly and lower assembly of a free-standing hybrid riser were carried out. The results show that the deviation between numerical simulation results and experimental results is less than 6.83%, and the dynamic test results coincide with the dynamic results of numerical simulation. The results of the above study demonstrate that the accuracy and reliability of numerical results for static and dynamic responses of the upper assembly and lower assembly and suggestions on further optimization for upper assembly and lower assembly of a free standing hybrid riser are given based on numerical simulation and test results. These results provide guidance for structural optimization of the upper assembly and lower assembly of a free-standing hybrid riser.

A Reliability-Based Multidisciplinary Design Optimization Method with Evidence Theory and Probability Theory

Uncertainties, including aleatory and epistemic uncertainties, always exist in multidisciplinary system. Due to the discontinuous nature of epistemic uncertainty and the complex coupled relation among subsystems, the computational efficiency of reliability-based multidisciplinary design optimization (RBMDO) with mixed aleatory and epistemic uncertainties is extremely low. A novel RBMDO procedure is presented in this paper based on combined probability theory and evidence theory (ET) to deal with hybrid-uncertainties and improve the computational efficiency. Firstly, based on Bayes method, a novel method to define the probability density function of the aleatory variables is proposed. Secondly, the conventional equivalent normal method (J-C method) is modified to reliability analysis with hybrid-uncertainties. Finally, a novel RBMDO procedure is suggested by integrating the modified J-C method into the frame of sequence optimization and reliability analysis (SORA). Numerical examples and engineering example are applied to demonstrate the performance of the proposed method. The examples show the excellence of the RBMDO method both in computational efficiency and accuracy. The proposed method provides a practical and effective reliability design method for multidisciplinary system.

Marine Engine Room Alarm Monitoring System

Alarms affect operations in most part of the ship. Their impact on modern Engine Control Room operations is no less significant. The state of an alarm system serves as an indication of the extent to which the ship’s operations are under management control. Thus, the design of efficient and reliable alarm monitoring system is vital for safe and sound operations. Although several design techniques have been proposed, all the proposed design methods employ sophisticated and expensive approaches in resolving alarm issues. In this paper, a cheap, yet reliable and efficient alarm design method for engine room device monitoring is presented. The design method employs PLCs and SCADA-based system and adopts certain basic design requirements of alarm monitoring system presented in literary works. Reasons for such a design method are highlighted, and the programming platforms for the design are given. The strengths and weaknesses of some design methods presented in some published works are reported and solutions to such problems are proposed. The proposed design technique, including fault diagnostic algorithm, have been subjected to real-time online testing at the shipyard, specifically ChangjiangWaterway Bureau, China (ship name–Ning Dao 501). The testing results proved that this design technique is reliable, efficient and effective for online engine control room device monitoring.

Constitutive model for full-range cyclic behavior of high strength steels without yield plateau

In order to characterize static and cyclic behavior of high strength structural steels, coupons made of two typical kinds of such steels in China, i.e. Q550 and Q690 steels with nominal yield strength of 550 MPa and 690 MPa respectively, were designed and tested under monotonic tension and a variety of cyclic loading protocols. Uniaxial stress-strain curves from the test show that for both steels no obvious yield plateau was observed, and short-range isotropic softening occurred right after initial yielding, while the subsequent strain hardening was contributed by both kinematic hardening and long-range isotropic hardening. Based on these phenomena, a constitutive model was developed specifically for those high strength steels and implemented in numerical analysis through user-defined subroutines. Calibration method for material parameters in this constitutive model was also established that mainly depends on tension coupon test result. After that, simulation was conducted by using the developed model with its stress-strain curves compared with those from cyclic loading test. Good agreement was obtained. Therefore, the constitutive model and its calibration method can be used for further seismic or dynamic nonlinear analysis of high strength steel structures and will help to develop reasonable and reliable ductile design method of those structures.

Improved analytical solution of vertical pressure on top of induced trench rigid culverts

Induced Trench Installation (ITI) is a viable option to reduce the load on rigid culverts buried under high embankments. However, reliable design methods are limited, which restricts further applications of this technology. Based on Marston's formula, a modified analytical solution is proposed, in which the vertical stress across the width of the soil column immediately above the compressible layer is assumed to be distributed in a parabolic shape, and the effects of the geometry and stiffness of the soft layer on load reduction are considered explicitly. Comprehensive comparisons are made between field monitored results and the calculations from different design methods. Parametric studies are subsequently conducted to investigate the influence of different distribution patterns of vertical stress and the properties of the soft layer. It is found that compared to Marston's theory, the proposed method yields a closer estimation to the field measured data. Finally, a simplified design chart is introduced, which can facilitate use of the proposed method.

Patch loading resistance of slender plate girders with longitudinal stiffeners

It is commonly known that the patch loading resistance model of the EN1993-1-5 has a relative large scatter, and it can lead to significant underestimation of the patch loading resistance in case of slender plate girders with longitudinal stiffeners. Large number of previous investigations studied the structural behavior of the stiffened girders subjected to concentrated transverse force. Although a reliable and simple design method is not available in the international literature. The main part of these investigations focus on girders with one longitudinal stiffener, however in the bridge design praxis, usually more stiffeners are applied on the web. For these structures the applicability of the improved design methods is not proved. It is also known, that the current design method of the EN1993-1-5 does not consider the location of the longitudinal stiffener properly. The focus of the current paper is on the investigation of the patch loading resistance of longitudinally stiffened slender web girders and an enhanced design method development. Based on a large number of numerical simulations the structural behavior is studied and failure modes are classified. The effect of each geometrical parameter on the patch loading resistance is investigated and an improved design method is developed, which is consistent with the design philosophy and safety requirements of the EN1993-1-5 standard.

Buckling resistance of HSS box section columns Part II: Analytical study

The accurate and economical consideration of the flexural buckling resistance of high strength steel (HSS) structures is highly important in the design. According to the previous research results the flexural buckling behaviour of HSS and NSS columns can be significantly different, which differences are not considered in the current design rules. The aim of the current study is to obtain a reliable design method for the flexural buckling resistance of HSS welded box section columns. The buckling resistance is previously determined by the authors based on an experimental research program and based on stochastic numerical simulations . The current paper focuses on the investigation of the theoretical background of the flexural buckling phenomena and on the implementation of the specialties regarding HSS materials into the buckling curve formulation. The analytically derived Ayrton-Perry type formulation is studied and modified based on the theoretical and numerical investigations implementing the effect of residual stresses and geometrical imperfections into the design method. Using the revised buckling curve, the flexural buckling resistance of welded box columns can be predicted with larger accuracy for steel grades between S420 – S960.

Distributed collaborative probabilistic design of multi-failure structure with fluid-structure interaction using fuzzy neural network of regression

Abstract To improve the computing efficiency and precision of probabilistic design for multi-failure structure, a distributed collaborative probabilistic design method-based fuzzy neural network of regression (FR) (called as DCFRM) is proposed with the integration of distributed collaborative response surface method and fuzzy neural network regression model. The mathematical model of DCFRM is established and the probabilistic design idea with DCFRM is introduced. The probabilistic analysis of turbine blisk involving multi-failure modes (deformation failure, stress failure and strain failure) was investigated by considering fluid–structure interaction with the proposed method. The distribution characteristics, reliability degree, and sensitivity degree of each failure mode and overall failure mode on turbine blisk are obtained, which provides a useful reference for improving the performance and reliability of aeroengine. Through the comparison of methods shows that the DCFRM reshapes the probability of probabilistic analysis for multi-failure structure and improves the computing efficiency while keeping acceptable computational precision. Moreover, the proposed method offers a useful insight for reliability-based design optimization of multi-failure structure and thereby also enriches the theory and method of mechanical reliability design.

住宅用ダクト換気システム設計法の信頼性向上に関する研究 : 第1報-換気システム部材の風量-静圧特性試験方法の検討

住宅用ダクト換気システム設計法の信頼性向上に関する研究 : 第1報-換気システム部材の風量-静圧特性試験方法の検討

住宅用ダクト換気システム設計法の信頼性向上に関する研究 : 第2報-各種換気システム部材への風量-静圧特性試験方法の適用及び静圧損失計算に基づく換気システム設計法の検証

住宅用ダクト換気システム設計法の信頼性向上に関する研究 : 第2報-各種換気システム部材への風量-静圧特性試験方法の適用及び静圧損失計算に基づく換気システム設計法の検証

Aromaticity of graphene nanoflakes in a new way: fragment analysis by combination of the nucleus-independent chemical shifts and the anisotropy of current induced density.

A graphene nanoflake (GNF) is a polycyclic aromatic hydrocarbon (PAH) with a huge two-dimensional π-conjugated carbon material in which a central benzene ring is surrounded by identical benzene-type rings through infinite alternant method. In this paper, we explore the structure-aromaticity relationship of the GNFs and the GNFs with hollow sites (GNFHs) by combining the nucleus-independent chemical shifts (NICS) with the anisotropy of the current induced density (ACID). Firstly, the benzene is a typical aromatic molecule (NICS=-9.671ppm), GNFs 1-6 is darned with benzene and the corresponding GNFHs 1'-6'. Secondly, the NICS values of GNFs 1-6 alternately vary: -1.214 (1)>-13.847 (2)<-2.662 (3)>-14.530 (4)<-3.932 (5)>-13.978 (6) ppm, the GNFs (2, 4, 6) with even fragments of annulene have larger aromaticity than that of GNFs (1, 3, 5) with odd fragments of annulene. Significantly, the NICS values of GNFs 1-6 can also be fragment analyzed by the NICS values and ACID of benzene and corresponding GNFHs 1'-6'. The NICS values for GNFs (2, 4, 6) can be roughly estimated by the NICS value of benzene minus the NICS value of the GNFHs (2', 4', 6'), respectively. The NICS values for GNFs (1, 3, 5) can be roughly estimated by the NICS value of the GNFHs (1', 3', 5') minus the NICS value of benzene, respectively. We hope that the present work can provide a simple and reliable method for the rational design of the GNF with aromaticity, which may be used to understand the origin of the graphene nanoflake aromatic properties.

Strength Reliability Design of Pressure Shell Based on PDS

The shell of scroll compressor was subjected to internal gas pressure during operation. In order to ensure the safety of the pressure shell, the structure parameters of the shell were determined initially by pressure vessel design method, and the strength of the shell was checked by finite element method. Because of the uncertainty of structural parameters, the reliability of the shell of scroll compressor was analyzed by finite element method and probability design system (PDS), and the reliability and probabilistic sensitivity of the shell were obtained. The results showed that the material’s strength, working pressure, thickness of head wall, thickness of cylinder wall, radius of cylinder and radius of head were the main factors to affect the reliability of the shell, and the reliability design method was better economic than the conventional design method. The above conclusions provide a scientific basis for the further optimal design of scroll compressor’s shell.

Dynamic neural network method-based improved PSO and BR algorithms for transient probabilistic analysis of flexible mechanism

To improve the computing efficiency and precision of transient probabilistic analysis of flexible mechanism, dynamic neural network method (DNNM)-based improved particle swarm optimization (PSO)/Bayesian regularization (BR) (called as PSO/BR-DNNM) is proposed based on the developed DNNM with the integration of extremum response surface method (ERSM) and artificial neural network (ANN). The mathematical model of DNNM is established based on ANN on the foundation of investigating ERSM. Aiming at the high nonlinearity and strong coupling characteristics of limit state function of flexible mechanism, accurate weights and thresholds of PSO/BR-DNNM function are discussed by searching initial weights and thresholds based on the improved PSO and training final weights and thresholds by the BR-based training performance function. The probabilistic analysis of two-link flexible robot manipulator (TFRM) was investigated with the proposed method. Reliability degree, distribution characteristics and major factors (section sizes of link-2) of TFRM are obtained, which provides a useful reference for a more effective TFRM design. Through the comparison of three methods (Monte Carlo method, DNNM, PSO/BR-DNNM), it is demonstrated that PSO/BR-DNNM reshapes the probability of flexible mechanism probabilistic analysis and improves the computing efficiency while keeping acceptable computational precision. Moreover, the proposed method offers a useful insight for reliability-based design optimization of flexible mechanism and thereby also enriches the theory and method of mechanical reliability design.

A theoretical model for the rotational stiffness of storage rack beam-to-upright connections

Experiments are generally used to investigate connection behaviour of steel storage racks, but the procedures are expensive and time-consuming. Various connections with complicated geometrical details necessitate simple and reliable design methods. This paper presents a mechanical model based on the component method to predict the initial rotational stiffness of beam-to-upright connections in cold-formed steel storage racks. In the model, five basic deformable components contributing to the initial rotational stiffness of beam-to-upright connections, are involved, i.e. tab in bending, upright wall in bearing, and upright wall in bending, beam-end-connector in bending and shear, upright web in shear. The mechanical model is validated against experiments, and the results show that the initial rotational stiffness values obtained from the mechanical model have a satisfactory agreement with the experimental results. Finally, based on the proposed mechanical model, main components influencing the initial rotational stiffness of connections are analysed in this paper.

Instability analysis of reinforced concrete walls with various support conditions

SummaryAxially loaded reinforced concrete walls can be designed using simplified design methods given in codes such as the Australian Concrete Standard Code (AS3600‐09) and the American Concrete Institute Code (ACI318‐14). However, these practical equations are based on empirical models, and their scope of application is still limited. In particular, walls with the various support conditions, high slenderness, and aspect ratios have been given little treatment. Recent research has been undertaken on the applicability of more reliable and accurate wall design methods. This paper initially presents a derived numerical technique incorporated in a computer program (WASTABT), to implement the iterative analysis for concrete walls with various support conditions. The outputs from the WASTABT program are verified using the results obtained from previous experimental results. A parametric study is then conducted using the verified computer‐based numerical technique to analyse axially loaded reinforced concrete panels. The study focuses on the effect of varying panel properties such as slenderness ratios, aspect ratios, concrete strengths, eccentricities, and reinforcement ratios, along with varying support conditions.