Design Checking Research Articles

Structural reliability analysis of a seafastening structure for sea transport of heavy objects

This paper addresses the safety of marine operations related to a seafastening system for large-object transport. The aim is to present a structural reliability approach to accommodate the uncertainties affecting design checks. The probability of structural failure by use of design standards for assessing marine operations is studied using structural reliability analyses to shed light on the implicit reliability levels of such standards. A structural reliability model that includes the effect of uncertainty in weather forecasts is established. The reliability analyses show that the method to account for forecast uncertainty as defined in the standards compensates well for that uncertainty, and the failure probabilities in the case studies are between 10−4 and 10−3 per operation. A reliability model that includes the long-term statistical distribution of the environmental conditions is also established. This model is applicable for operations with a duration longer than three days and is used to study seasonal variations and the failure probability as a function of the duration of operations. The failure probability is calculated for execution in several months, showing the dependency on the time of the year and the duration of the operations. The failure probabilities are on the order of 10−4 per operation.

Develop an Activation Pressure Measurement Method of the Safety Vent and Investigate the Relationship between Cell Safety Devices' Activation Pressure and LIB Cell Safety

The current interrupt device (CID) and vent mechanism in the Cylindrical cells are a fuse-type safety device that permanently disconnects the cell's electrical circuit and releases internal pressure when triggered by excessive cell pressure by abnormal conditions to keeps the cell safe from the thermal runaway risks. Compared to the importance of the safety devices' activation pressure, the test method and apply the techniques to the cell characterization was not defined adequately.This research developed the test methods, procedures, and equipment to measure the activation pressure accurately of both the CID and vent mechanism simultaneously. We select four different cell markers' commercial 18650 cell models with about 3.5 Ah nominal capacity to evaluate the cell model's safety level and to identify the relationship between the activation pressure level and the safety test item: electrical, mechanical, environmental (Thermal) abnormal impacts.To investigate the relationship between cell safety devices' activation pressure and the cell model's safety, we performed some cell safety tests and cell model design checks. The cell alignment check with the electrode gap measurement, including some electrical tests, checks the test samples' quality status. Cell safety tests include thermal safety, external short circuit, nail penetration, impact, and crush test. Each safety test item's test condition and procedure are referenced from widely accepted cell safety standards and battery industrial best practices for the lithium-ion battery.The activation pressure of the CID and vent mechanism was measured simultaneously by detecting the cell voltage changes and applied pressure to vent, respectively. All four cell models have shown that the CID was always activated earlier at a lower pressure than the vent mechanism. The activation pressure of the CID and the vent mechanism of the four cell models were different by manufacturers. The tolerance and the activation pressure gap between CID and the vent mechanism of each cell model were different among the four cell models.The cell safety test items can be classified by 1) thermal and electric abuse test and 2) mechanical abuse test. We used the EUCAR Hazard Level to evaluate the safety level of each test item items. The table explains each test item's safety level of the four cell models according to the EUCAR Hazard Level criteria. The cell hazard levels of the thermal and electric abuse test items (thermal safety and external short circuit test) are strongly affected by the activation pressure level of the CID and vent mechanisms. The detailed investigation concluded that the CID's activation pressure level affects more than that of the vent mechanism to the thermal and electric abuse test items' hazard level. These results are derived from the fact that the safety device activates in advance at a lower pressure than the cell enclosure's opening.Meanwhile, the cell hazard levels of the mechanical abuse test items (nail penetration, impact, and crush test) were not affected by the safety devices' activation pressure level. Because the mechanical abuse test items always opened the cell enclosure in advance compared to the safety device activation.This research proposes to add the activation pressure level of the cell safety devices to the EUCAR Hazard Level criterion to enhance the efficiency of evaluating the cell models' hazard level. That can provide more worthy criteria for the cell selection and cell safety evaluation process for the multi-cell battery system design. Figure 1

Research of Parameters of Electric Power Systems Affecting Core Saturation of Current Transformers with a Closed Magnetic Circuit in Transitional Short Circuit Modes

The relevance of the study is due to the excess of the permissible errors of current transformers in transient short-circuit modes associated with saturation of the cores of current transformers. The latter leads to improper operation of relay protection devices, which can negatively affect the stability of electric power systems and the efficiency of industrial enterprises with a continuous technological cycle, the power failure of which leads to significant economic damage. The aim of this work is to study the parameters of electric power systems that affect the saturation of the cores of current transformers with a closed magnetic circuit in transient short-circuit modes. The object of research is electromagnetic current transformers of accuracy class 10P in electric power systems. The study was carried out using numerical methods for solving algebraic and differential equations, methods of computer modeling of electromagnetic transient processes and functional programming. As a result, the main parameters influencing the nature and intensity of electromagnetic transients in current transformers during a short circuit are noted; it is shown that in transient short-circuit modes, significant errors in the operation of current transformers associated with core saturation are possible; recommended for assessing the compliance of current transformers of accuracy classes 5P, 10P with the conditions for the correct functioning of relay protection devices in transient short-circuit modes, to calculate the time to saturation of current transformers, taking into account the real parameters of the electric power system at the place where current transformers are installed, in addition to the traditional design checking of current transformers by permissible er-rors for the steady state short circuit.

Influence of SLS design requirements on the material consumption and self-weight of web-core sandwich panel FRP composite footbridges

This paper reports a parametric study on the influence of the serviceability limit state design requirements on the material consumption and self-weight of web-core sandwich panel FRP composite footbridges. It describes the initial design process of a typical FRP web-core sandwich panel footbridge, focussing on the relevance of the various design checks on the overall material consumption at a given slenderness. It is clear that over a wide range of input parameters, only the SLS requirements are relevant for the design of this bridge type. Consequently, the final material consumption and achievable slenderness strongly depend on the code requirements. These requirements are non-uniform over various international codes, but are shown to have a huge influence on the material consumption. The final results heavily depend on the input value of the damping factor. In addition, human induced damping is not included in current design procedures, which may lead to a significant underestimation of the effective damping and consequently to over-design. The results contribute to understanding the mechanical behaviour of this promising bridge type, point to the relevance of the choice of SLS requirements in codes and to the lack of fully understanding the vibrational behaviour currently adopted in calculation models.

Optimization of Object-oriented 3D CAD Pre-processing System for Steel Structure of High-rise Buildings

In this paper, the object-oriented method is used to study the pre-processing system of 3D high-rise building steel structure CAD. For the high-rise building steel structure design optimization system, users mainly contact with the functions of modeling, analysis, design checking and drawing. In fact, all these functions are carried out around the data stored behind. Three-dimensional high-rise building steel structure CAD pre-processing subsystem mainly integrates three-dimensional entity construction module, node design and editing module, construction drawing, processing drawing and CNC data output module. In this paper, the wall element is used to simulate the shear wall element, and the wall element can be automatically refined into a shell element composed of quadrilateral membrane element with rotational degree of freedom and generalized conforming bending plate element for thick and thin plate, which improves the speed and accuracy of analysis and calculation of shear wall. Various loads of high-rise building are calculated, especially the wind load of space action. It provides a new idea for wind load calculation of high-rise buildings. It is better to put forward a practical system optimization model, which can deal with the objective function, variables and constraints in a large number of engineering processing, and consider the actual constraints as fully as possible, which has strong practicability.

Use of Spectrum-matched versus Scaled Records to Evaluate Seismic Responses of a Latticed Shell

ABSTRACT Analysis of alatticed spherical shell is carried out by using the scaled and spectrum-matched records. The seed records for scaling and spectrum matching are selected, so their ground motion intensity measures are consistent with chosen targets. The analysis results indicate that the use of the spectrum-matched records leads to the coefficient of variation (COV) values of the load effects to be similar or smaller than the lowest COV values obtained by using the records scaled to the target ground motion intensity measure. Use of the spectrum-matched records for this structural type is preferred for some design checking situations.

Observations from hydrodynamic testing of a flexible, large-diameter monopile in irregular waves

As the offshore wind industry moves toward larger wind turbines and deeper water, wave-induced loads on large-diameter monopiles are of increasing importance for ultimate limit state design checks. The combination of a relatively large diameter with steep waves in intermediate water depth presents challenges for numerical methods, and small-scale hydrodynamic testing of monopiles is therefore a necessary step in reducing the uncertainties in numerical analyses. Here, we aim to summarize the experimental observations in a new set of tests carried out with a flexible monopile wind turbine, and to understand the similarities and differences between these results and previous studies. Compared to previous studies, the present tests consider a larger monopile diameter and hub height, and include a larger number of realizations and repetitions. The distribution of extreme values and the contributions from different structural modes are studied. These experimental results provide insight into the physical effects which must be accurately captured by numerical tools that are used in design.

VALUATION OF DURABILITY OF ROD PILLARS OF THE SLOPY RESCUING DEVICE

The need for special saving devices arises during emergency response. Such situations are connected with rescuing of people or animals from deep narrow holes or even from under blockages of constructions. By using the saving devices the cargo raising on a certain height is possible if other ways of delivery are absent. Main structural elements of saving devices are three rod pillars. Top ends of rods are connected in a mounting knot. Often the saving device is equipped with the winch. The winch could be fasten to one of the rod pillars or have individual placing. Rescuing devices differ in a type of a rod design (straight or a slopy plane), loading capacity, rods production material, type of rods connection, a possibility of using on slopes with pillars location in the different planes, modifications of winches, compactness during transportation. There is a big variety of rescuing devices, however in the market of Ukraine offer mostly straight rod rescuing devices. Therefore there is a need for creation of design and durability checking of the slopy rod rescuing device which could be applied to carrying out rescue operations from bridges, buildings and other constructions. In this work it is performed an estimation of durability of a design of the slopy rod rescuing device. It is considered three cases of the support pillars placement. The first case is when pillars of the slopy rescuing device are placed in one horizontal plane. The second case - the longest rod pillar is placed on a ledge. The third case - two shorter rod pillars are placed on a ledge. For each of these cases it is established a type of deformation of rods of the saving device. Construction rods are stretching or compression during work are and loaded with longitudinal forces. From the stretching durability condition the cross section of steel rods is picked up.

On Short-Term Fatigue Analysis for Wind Turbine Tower of Two Semi-Submersible Wind Turbines Including Effect of Startup and Shutdown Processes

AbstractFatigue limit state design check for offshore wind turbines is based on SN curves and the Palmgren–Miner rule approach and focuses normally on stationary processes for which startup and/or shutdown operations induced transient load processes are normally not accounted for. However, large databases of real-time measurements show that the shutdown and startup operations may appear in any operational conditions and the frequency of such operations could be considerable. Although design standards require fatigue design checks for the transient load processes induced by startup and shutdown operations, relevant publications addressing this issue are very limited in particular for floating wind turbines. This paper focuses on analyzing the importance of startup and shutdown induced transient load processes on fatigue damage in the tower of two MW-level horizontal axis semi-submersible wind turbines. The analysis is carried on by comparing short-term fatigue damage in several environmental conditions with and without the startup and shutdown induced transient load processes. It is found that, in many environmental conditions, startup and/or shutdown operations may make an increase in short-term fatigue damage by 10% to 100%, while in some situations, the fatigue damage may be increased by up to 200%. The importance of the transient load processes on long-term fatigue damage is related to the occurrence frequency of startup and shutdown events. Publicly available data indicate that the average time between two consecutive shutdown events might be less than 39 h. However, more data and analysis are needed regarding these issues.

Rock the MIC: The Matrix of Implied Causation, a Tool for Experimental Design and Model Checking

Path modeling and the extended structural equation modeling framework are in increasingly common use for statistical analysis in modern behavioral science. Path modeling, including structural equation modeling, provides a flexible means of defining complex models in a way that allows them to be easily visualized, specified, and fitted to data. Although causality cannot be determined simply by fitting a path model, researchers often use such models as representations of underlying causal-process models. Indeed, causal implications are a vital characteristic of a model’s explanatory value, but these implications are rarely examined directly. When models are hypothesized to be causal, they can be differentiated from one another by examining their causal implications as defined by a combination of the model assumptions, data, and estimation procedure. However, the implied causal relationships may not be immediately obvious to researchers, especially for intricate or long-chain causal structures (as in longitudinal panel designs). We introduce the matrix of implied causation (MIC) as a tool for easily understanding and reporting a model’s implications for the causal influence of one variable on another. With examples from the literature, we illustrate the use of MICs in model checking and experimental design. We argue that MICs should become a routine element of interpretation when models with complex causal implications are examined, and that they may provide an additional tool for differentiating among models with otherwise similar fit.

Optimal Design of Block Quay Walls

Block walls, consisting of stacked unreinforced prefabricated concrete blocks, are commonly used for the construction of quay walls in the presence of rocky subgrades. A traditional design of block quay walls is based on manual design iterations, envisaging sufficient safety against ultimate limit states (ULS) such as sliding, overturning or loss of bearing capacity of the foundation soil. In addition, the designer should consider stability during the different construction stages of the block wall, referred to as buildability constraints. This design process can be laborious, while the resulting designs comprise a large volume of concrete. In order to optimize block quay walls, we developed an automated design procedure in the framework of gradient-based optimization, accounting for the various ULS and buildability constraints encountered in engineering practice. The design checks for a block quay wall are first explained in detail. This includes global ULS requirements that apply to the block wall as a whole, and internal ULS requirements to consider sliding and overturning of separate blocks. During construction, the block wall has to be stable during all construction stages, which imposes additional design constraints. Next, block walls consisting of rectangular blocks and chamfered blocks are optimized. The resulting designs obtained with the automated design procedure satisfy all design requirements, and have a realistic layout. Furthermore, the influence of the different construction stages is studied, demonstrating the practicality of the proposed automated design procedure.

Building Information Modelling, Artificial Intelligence and Construction Tech

Adoption of digital information tools in the construction sector provides fertile ground for the birth and growth of companies that specialize in applications of technologies to design and construction. While some of the technologies are new, many implement ideas proposed in construction research decades ago that were impractical without a sound digital building information foundation. Building Information Modelling (BIM) itself can be traced to a landmark paper from 1975; ideas for artificially intelligent design and code checking tools date from the mid-1980s; and construction robots have laboured in research labs for decades. Yet only within the past five years has venture capital actively sought startup companies in the ‘Construction Tech’ sector. Following a set of digital construction innovations through their known past and their uncertain present, we review their increasingly optimistic future, all through the lens of their dependence on digital information. The review identifies new challenges, yielding a set of research topics with the potential to unlock a range of future applications that apply artificial intelligence.

Design and model checking of timed automata oriented architecture for Internet of thing

The architecture model of the Internet of thing system is the primary foundation for the design and implementation of the Internet of thing system. This article discusses the method and practice of time automaton modeling and model checking for the architecture of the Internet of thing system from the state and time dimensions. This article introduces the theory and method of modeling using time automata. And then, combined with the actual need of the elderly health cabin Internet of thing system, a dynamic and fault-tolerant time automaton model is established through a relatively complete architecture modeling. The model checking method verifies that the designed Internet of thing system has no deadlock system activity, service correctness, and timeliness correctness. The results of modeling experiments and model validation show that the reference model of time automata Internet of thing architecture established in this article can better reflect the nature of interaction with the physical world, heterogeneity and large-scale, dynamic, and incompleteness of the Internet of thing system.

Dynamic Analysis of Carrier Structure of a Marine Underwater Mechanical Arm

In this paper, the support structure of a certain type of marine underwater manipulator is taken as the object to carry out solid modeling and mechanical properties analysis. At sea level 5, the maximum stress and displacement of the carrier structure are obtained through static analysis, and the first six frequency modes, peak response frequency and amplitude of the carrier structure are obtained through modal analysis and harmonious response analysis. The results show that the safety can be guaranteed under 5-level sea conditions, and the influence of cyclic loads on the structure is significant. The influence of cyclic loads on the structure should be taken into account when analyzing the structure. The research results have engineering application value and guiding significance for optimum design and safety strength checking of underwater manipulator carrier structure.

Structural steel design using second-order inelastic analysis with strain limits

Steel framed structures are affected, to greater or lesser extent, by (i) geometrical nonlinearity associated with the change in geometry of the structure under load and (ii) material nonlinearity related to the onset and spread of plasticity. In traditional design approaches, the design forces and moments within structural members are usually determined from simplified structural analyses (e.g. first or second-order elastic analysis), after which member design checks are performed to assess the strength and stability of the individual members. The extent to which the strength and deformation capacity of cross-sections is affected by local buckling is typically assessed through the concept of cross-section classification. For example, only compact (Class 1) cross-sections are considered to possess sufficient rotation capacity for plastic hinges to develop and for inelastic analysis methods to be used. This approach results in step-wise capacity predictions and is considered to be overly simplistic. Since the structural analysis of steel framed structures is typically performed using beam finite elements, which are unable to explicitly capture local buckling, a more sophisticated treatment of the available deformation capacity is required if inelastic analysis methods are to be used for all cross-section classes. A novel method of design by advanced inelastic analysis has recently been developed (Gardner et al., 2019a; Fieber et al., 2019a, 2018a, 2018b [1–4]), in which strain limits are employed to represent the effects of local buckling in beam finite element models and thereby control the spread of plasticity and level of force/moment redistribution within a structure. It is thus possible to use a consistent advanced analysis framework to design structures composed of cross-sections of any class. In the present paper, application of the proposed design method to continuous beams and planar frames is illustrated and assessed. Ultimate load capacity predictions are compared against results obtained from benchmark shell finite element models that explicitly capture local buckling and to conventional steel design. It is found that the proposed method predicts safe-sided ultimate capacities that are consistently more accurate than current design methods, particularly for structures benefiting from strain hardening and for structures composed of non-compact cross-sections where inelastic redistribution is typically ignored.

Non-linear Impact of the Short Circuit Impedance Selection on the Cost Optimized Power Transformer Design

Since the electrical machine design is a complex task it can be divided into sub-problems, e.g. preliminary and final design processes and checking of the final design. This paper deals with the preliminary design process, which provides the key-design parameters of the electrical machine. Traditionally, these electrical machine models in preliminary design phase neglect or use oversimplified insulation system models and the tap changing selection is not involved during the calculation of key-design parameters. The aim of this study is to assess the effect of the insulation distance minimization and tap-changing on the key design parameters of a cost-optimized large power transformer. For this purpose, the paper shows some examples, where the cost optimal design — in contrast to the classical insulation design rule — contains larger insulation distances than the possible minimum values. The effect of tap-changing methods are also investigated. These cost optimization made by a verified, metaheuristic method-based transformer optimization algorithm. The results show involving the insulation design and tap-changing selection into the preliminary design process can provide more economical designs.

Bigraph specification of software architecture and evolution analysis in mobile computing environment

Software system evolution is an active and important research topic in software engineering. In guiding software system evolution, software architecture plays a critical role. In the traditional software architecture, only the link information of components is considered, while the place information of components is usually neglected. However, due to the emerging mobile computing, pervasive computing, and intelligent computing, the place information is as important as the link information in the software architecture. Especially in mobile computing environments, the place changes often lead to changes in software configuration and functionality. In this paper, we study the Bigraph specification of software architecture and use it to describe both link and place information in detail. Based on Bigraph specification, we investigate the structural characteristics in the software architecture, and design checking algorithms for the component’s link exceptions and place exceptions. Furthermore, we address the well-evolved software architecture from a new perspective, which includes three basic evolution operation rules and their well-evolved conditions. We discuss the overall software architecture evolution through strong and weak bi-simulation in terms of software functionality. Finally, two case studies about software system in the evolution operation are presented, which illustrate the effectiveness of our approach.

Design and Performance Check of Gain-Scheduled Flight Controller Depending on Uncertain Scheduling Parameters for MuPAL-α

Design and Performance Check of Gain-Scheduled Flight Controller Depending on Uncertain Scheduling Parameters for MuPAL-α

Resonance Investigation and its Effects on Weight Optimization of Tubular Steel Wind Turbine Towers

The dynamic behavior of tubular steel wind turbine towers is investigated, with emphasis on discussing how the effort to avoid resonance of the soil-foundation-tower system, by keeping its eigenfrequencies outside specific ranges around the rotor (1P) and blade-passing (3P) frequencies, influences tower optimization. For modern, tall towers avoidance of resonance becomes critical compared to other structural design checks, such as buckling and fatigue. Considering that the rotor and blades have predefined mass and rotation frequencies, the tower’s fundamental frequencies should be controlled considering the cross-sectional properties of the tower as well as the flexibility of its foundation. The objective of the optimization problem formulated in this work is to reduce tower weight, while satisfying the resonance and buckling criteria and considering restrictions pertaining to fabrication, transportation and erection. The vibration modes and frequencies of a 120m tall tower are determined via detailed as well as simplified finite element models, with the latter proving to be sufficiently accurate. The dependence of the tower’s vibration frequencies on the soil and foundation is also investigated. The numerical models are introduced into the high performance optimization computing platform (HP-OCP), to obtain an optimum distribution of tower shell thickness over the height.

Quantitative Definition of Seismic Performance Levels for Precast Bridge Piers with Continuous Reinforcement

For construction sites within cities, which require fast construction because of restrictions in road occupation time, or for other occasions where construction period is an important factor because of similar reasons, application of a modular construction method using precast members is efficient in terms of shortening the construction period. The substructures of bridges are normally constructed using cast‐in‐place, which has been a major cause of delays in construction. Application of a modular construction method could decrease the occupation time in the sites. A prime example is the Accelerated Bridge Construction (ABC) by the Texas Department of Transportation (TDOT) and Federal Highway Administration (FHWA). Precast members are the key components of ABC. The main purpose of this paper is to provide clear seismic performance standards for precast bridge piers. Current seismic design codes require force‐based design checks and provide qualitative evaluation of the overall structure. They do not provide specific qualitative criteria for individual structures with particular types. Previous research has been focused on reinforced‐concrete bridge piers, while lacking on research towards prefabricated bridge piers with continuous reinforcements. In order to quantitatively evaluate the seismic performance level of prefabricated bridge piers, the seismic performance was quantitatively suggested in accordance with the classification of four which are operational, immediate occupancy, life safety, and collapse prevention. These criteria are cracking of cover concrete, crushing of cover concrete, yielding of axial steels, and fracture of axial steels. Based on the given seismic performance evaluation criteria, evaluation and verification were conducted on four prefabricated bridge piers with continuous reinforcement that have undergone quasistatic cyclic experiments. The moment‐curvature analysis model was constructed for the parametric study and verified through experimental results. Based on the developed M‐Phi model, prefabricated bridge piers with continuous reinforcement, which were designed force‐based using response correction factor, were evaluated. In addition, parametric study was also conducted focusing on concrete strength, magnitude of prestress, and transverse reinforcement. Depending on the level of individual performance produced by ranges of these variables within possible runs on actual piers, the impact of 3 variables was analyzed. Furthermore, in response to changes in each variable, the impact on the relevant seismic performance level was verified through response spectrum analysis.