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Sensor-based monitoring of bridges has the potential to be an important tool to supplement visual inspection. Monitoring can provide quantitative data to evaluate the condition of bridge components (e.g. bearings and expansion joints) and to inform operation and maintenance decisions. However, the use of sensor systems to monitor bridges is often limited by cost. This paper presents the design, development, and field implementation of a low-cost micro-electromechanical systems (MEMS) and Internet of things (IoT)-based system to measure bridge bearing movement. The developed system uses accelerometers and converts changes in gravitational acceleration to longitudinal bearing displacement. The monitoring system uses a hybrid wired/wireless approach, in which the sensing nodes are wired to a gateway node from which data is transmitted to the cloud. Power is provided by means of a single battery that is charged using a solar panel. To evaluate the system performance in the field, it was installed on the Waaban Crossing in Kingston, Canada. Results of the study showed that the proposed system was capable of measuring movement of the bridge at a cost that was significantly less than a commercial monitoring system. Limitations of the system, cost of installation, and calibration of the sensors are also discussed. [ABSTRACT FROM AUTHOR]

In the Structural Health Monitoring (SHM) framework, model updating procedure is an iterative or cyclical process which gives numerical model of structure having modal behaviour close to the dynamic behaviour of real structure. Normally for structures with or without any expansion joints typical model updating procedure is used. But the typical procedure may not be applicable for long uniform buildings having expansion joints since the individual blocks in structure connected with expansion joints tend to vibrate in coherence. This behaviour is confirmed by observing the identicalness of modal frequencies of individual blocks in long uniform buildings. This phenomenon was observed in three selected long uniform buildings. When structures connected with expansion joints vibrate in coherence or when the modal frequency of the connected structures are identical, the numerical models of these structures cannot be updated using typical procedure for the following reasons: (1) Modal parameters from Modal identification of structure doesn't represent the actual parameters of the individual block since the ambient vibration is not independent and is influenced by interaction between blocks. (2) Modal analysis of analytical model of individual structural blocks gives dynamic parameters which are true to the model. And these two sets of parameters can't be compared for convergence in model updating procedure. Therefore, to update a numerical model of long uniform buildings with expansion joints having the coherence phenomenon among its individual blocks, a different is needed. Hence, a new approach is proposed where instead of using modal parameters from analytical analysis, the parameters obtained for the structure from modelled floor responses to weak earthquake using Frequency Domain Decomposition (FDD) algorithm are used for checking convergence in model updating procedure. To demonstrate the proposed procedure, two long uniform buildings in which the coherence phenomenon was observed were updated by applying the proposed procedure and results are discussed. Here for the selected buildings, only modal frequencies were used for checking convergence, since mode shapes obtained were not reliable as floor vibration data of intermediate floors were not available. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive probabilistic framework is proposed and adopted to perform seismic reliability and risk analysis of existing link slab (LS) bridges, representing a widely diffused structural typology within the infrastructural networks of many countries worldwide. Unlike classic risk analysis methods, innovative fragility functions are used in this work to retrieve more specific and detailed information on the possible failure modes, without limiting the analysis to the global failure conditions but also considering several intermediate damage scenarios (including one or more damage mechanisms), and providing insights on the numerosity of elements involved within a given damage scenario. Reliability analyses are performed on a set of LS bridges with different geometries (total lengths and pier heights) designed according to the Italian codes enforced in the 1970s. Accurate numerical models are developed in OpenSees and Multiple-Stripe nonlinear time–history analyses are carried out to build proper demand models, from which fragility functions are determined according to two limit states: damage onset and near-collapse. Mean annual rates of exceeding are thus estimated through the convolution between the hazard and the fragility. The results shed light on the main failure mechanisms characterizing this bridge typology, highlighting how different levels of risk (hence safety margins) can be associated with failure scenarios that differ in terms of elements/mechanisms involved and damage extension. Such a higher level of detail in the risk analysis may be useful to better quantify post-earthquake consequences (e.g., costs and losses) and define more tailored retrofit interventions. A comparison of the reliability levels associated with bridges of the same class with different geometries is finally presented. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the impact that certain types of expansion joints have on noise levels produced by regular traffic on the streets of Cluj-Napoca. The study was carried out on three distinct locations, all three road bridges had steel expansion joints, the first one had asphalt covering the joints, the second one was in excellent condition, as it was a newly refurbished bridge and the last one with visible signs of degradations.

Movement joints are needed in bridges to accommodate longitudinal expansion and contraction. Enough joint width needs to be available to accommodate not only longitudinal expansion but also expected movements of joints during earthquakes. This may result in excessive joint openings. Devices that can dissipate energy have been suggested to reduce joint displacements. Shape memory alloy (SMA) is one of these energy dissipation devices, which is well known for its ability to return to its natural shape after being deformed. Several cases of bridges and different conditions of seismic events are modeled and tested using developed software programs in MATLAB to show the efficiency of using SMA inside bridge joint openings. These models include the case of two adjacent frames with SMA inside them (2�frames), the case of multi�frames with constant hysteretic SMAs between every two of them (N�frames), the case of multi�frames with constant hysteretic SMAs taking the delay of seismic forces between frames into consideration (delay), and the case of variable masses of bridge frames. Also, parametric studies are performed to show the impacts of all parameters of bridge frames and SMA retrofit devices on seismically joint openings. The results show that the superelastic SMA device plays a huge role in controlling bridge opening and enables limiting the joint width of all models during earthquakes with different values reaching 60% in some cases depending on bridge frame properties, ground motion characteristics, and the hysteretic properties of SMA devices.

Bottles of breathing apparatus can be filled with a compressor and directly connected to “air banks”. During the filling of the bottles of breathing apparatus with high–pressure compressors, or with the help of “air banks”, there is an increase in pressure in time and the amount of compressed medical air in the bottle. The consequence is an increase in tension in the bottle material, which is in direct connection with the specified parameters. The intensity of the stress and the influence of the increase in pressure over time on the stresses of steel and composite cylinders are also identified using strain gauges. With tensometric measuring tapes, dilatation measurements were performed on a steel and composite bottle/cylinder of breathing apparatus (SCBA – self– contained breathing apparatus) with a cold–water test. They are used to measure local deformations on real structures. The aim of the research is to define the gradient of bottle filling speed, which ensures safety, and reliability of this procedure and which is influenced by parameters such as: bottle material, bottle correctness, correct airflow valve, temperature rise, minimum bottle filling time, etc. [ABSTRACT FROM AUTHOR]

Movement joints are needed in bridges to accommodate longitudinal expansion and contraction. Enough joint width needs to be available to accommodate not only longitudinal expansion but also expected movements of joints during earthquakes. This may result in excessive joint openings. Devices that can dissipate energy have been suggested to reduce joint displacements. Shape memory alloy (SMA) is one of these energy dissipation devices, which is well known for its ability to return to its natural shape after being deformed. Several cases of bridges and different conditions of seismic events are modeled and tested using developed software programs in MATLAB to show the efficiency of using SMA inside bridge joint openings. These models include the case of two adjacent frames with SMA inside them (2--frames), the case of multi--frames with constant hysteretic SMAs between every two of them (N--frames), the case of multi--frames with constant hysteretic SMAs taking the delay of seismic forces between frames into consideration (delay), and the case of variable masses of bridge frames. Also, parametric studies are performed to show the impacts of all parameters of bridge frames and SMA retrofit devices on seismically joint openings. The results show that the superelastic SMA device plays a huge role in controlling bridge opening and enables limiting the joint width of all models during earthquakes with different values reaching 60% in some cases depending on bridge frame properties, ground motion characteristics, and the hysteretic properties of SMA devices. [ABSTRACT FROM AUTHOR]

Large floors of industrial enterprises, warehouses, stores, and shopping centres are quite heavily loaded with production technologies, transport mechanisms, stored material or shelf stackers. Regarding simple reinforcement and construction, industrial floors have been used in recent decades mainly reinforced with fibres from so-called fibre-reinforced concrete. Most slab failures are caused by extreme loads on the unbearable subsoil, a small amount of fibres, or by the shrinkage of concrete due to insufficient structural design of sliding, shrinking and expansion joints. Recently, however, in several constructions, structural failures have occurred caused by a volume-unstable subsoil in the form of a mixture of slag or metallurgical debris. The article deals with some failures of fibre concrete floors in practice, their methods of diagnostics and laboratory analysis of samples. The results are supplemented by practical examples of floor failures with respect to their origin. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive probabilistic framework is proposed and adopted to perform seismic reliability and risk analysis of existing link slab (LS) bridges, representing a widely diffused structural typology within the infrastructural networks of many countries worldwide. Unlike classic risk analysis methods, innovative fragility functions are used in this work to retrieve more specific and detailed information on the possible failure modes, without limiting the analysis to the global failure conditions but also considering several intermediate damage scenarios (including one or more damage mechanisms), and providing insights on the numerosity of elements involved within a given damage scenario. Reliability analyses are performed on a set of LS bridges with different geometries (total lengths and pier heights) designed according to the Italian codes enforced in the 1970s. Accurate numerical models are developed in OpenSees and Multiple-Stripe nonlinear time–history analyses are carried out to build proper demand models, from which fragility functions are determined according to two limit states: damage onset and near-collapse. Mean annual rates of exceeding are thus estimated through the convolution between the hazard and the fragility. The results shed light on the main failure mechanisms characterizing this bridge typology, highlighting how different levels of risk (hence safety margins) can be associated with failure scenarios that differ in terms of elements/mechanisms involved and damage extension. Such a higher level of detail in the risk analysis may be useful to better quantify post-earthquake consequences (e.g., costs and losses) and define more tailored retrofit interventions. A comparison of the reliability levels associated with bridges of the same class with different geometries is finally presented.

Movement joints are needed in bridges to accommodate longitudinal expansion and contraction. Enough joint width needs to be available to accommodate not only longitudinal expansion but also expected movements of joints during earthquakes. This may result in excessive joint openings. Devices that can dissipate energy have been suggested to reduce joint displacements. Shape memory alloy (SMA) is one of these energy dissipation devices, which is well known for its ability to return to its natural shape after being deformed. Several cases of bridges and different conditions of seismic events are modeled and tested using developed software programs in MATLAB to show the efficiency of using SMA inside bridge joint openings. These models include the case of two adjacent frames with SMA inside them (2–frames), the case of multi–frames with constant hysteretic SMAs between every two of them (N–frames), the case of multi–frames with constant hysteretic SMAs taking the delay of seismic forces between frames into consideration (delay), and the case of variable masses of bridge frames. Also, parametric studies are performed to show the impacts of all parameters of bridge frames and SMA retrofit devices on seismically joint openings. The results show that the superelastic SMA device plays a huge role in controlling bridge opening and enables limiting the joint width of all models during earthquakes with different values reaching 60% in some cases depending on bridge frame properties, ground motion characteristics, and the hysteretic properties of SMA devices.

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System identification proves in general to be very efficient in the extraction of modal parameters of a structure under ambient vibrations. However, great difficulties can arise in the case of structures composed of many connected bodies, whose mutual interaction may lead to a multitude of coupled modes. In the present work, a methodology to approach the identification of interconnected diaphragmatic structures, exploiting a simplified analytical model, is proposed. Specifically, a parametric analysis has been carried out on a numerical basis on the simplified model, i.e., a multiple spring–mass model. The results were then exploited to aid the identification of a significant case study, represented by the Pavilion V, designed by Riccardo Morandi as a hypogeum hall of the Turin Exhibition Center. The structure is indeed composed of three blocks separated by expansion joints, whose characteristics are unknown. As the main result, light was shed on the contribution of the stiffness of the joints to the global dynamic behavior of structures composed of interacting diaphragms, and, in particular, on the effectiveness of the joints of Pavilion V. [ABSTRACT FROM AUTHOR]

The pounding effect at the expansion joints on the seismic response of a long-span deep-water high pier bridge with multiple approach spans under earthquake is studied considering the fluid–structure interaction effect. The nonlinear fibre element is used to simulate the main piers and transition piers. The contact element is employed to consider the seismic pounding effect at the expansion joints. The hydrodynamic pressure is applied to the main piers and transition piers in the form of added mass of graded accumulation. Forty seismic records of different earthquakes are used as input to conduct the longitudinal time history analysis of the whole bridge. The seismic responses of bridge structure with and without pounding effect are compared to analyse the impact of pounding on the structure. The results show that considering the pounding effect at the expansion joints, the seismic response of the main pier under the fluid–structure interaction effect is reduced, which indicates that the pounding is beneficial to the main pier. Due to the out-of-phase vibration between the main bridge and the approach spans, the pounding force at the expansion joints on the left and right transition piers is the largest, and the pounding transmission effect is obvious. The transmission effect makes the positive displacement amplitude of the right bearings on the top of each pier of the right approach spans increase evidently. The increased amplitude of each pier is not synchronous, which will increase the possibility of unseating. [ABSTRACT FROM AUTHOR]

The present article deals with transient thermal stress calculation on a safety horizontal shell and tube condenser. This condenser is used in a power plant for cooling of hot steam diverted from the turbine in the case of its emergency shutdown. The standard stress calculation was provided according to the EN 13445 standard in steady regime. As consistent with this calculation, an expansion joint must be used on the shell. The main aim of this article is to describe a detailed calculation of the transient temperature field on the shell and tubes, using finite element method analysis, and longitudinal thermal stresses on the shell and tubes during the start‐up process. Transient analyses are useable for more accurate EN 13445 calculation and, furthermore, for fatigue calculation. [ABSTRACT FROM AUTHOR]

System identification proves in general to be very efficient in the extraction of modal parameters of a structure under ambient vibrations. However, great difficulties can arise in the case of structures composed of many connected bodies, whose mutual interaction may lead to a multitude of coupled modes. In the present work, a methodology to approach the identification of interconnected diaphragmatic structures, exploiting a simplified analytical model, is proposed. Specifically, a parametric analysis has been carried out on a numerical basis on the simplified model, i.e., a multiple spring–mass model. The results were then exploited to aid the identification of a significant case study, represented by the Pavilion V, designed by Riccardo Morandi as a hypogeum hall of the Turin Exhibition Center. The structure is indeed composed of three blocks separated by expansion joints, whose characteristics are unknown. As the main result, light was shed on the contribution of the stiffness of the joints to the global dynamic behavior of structures composed of interacting diaphragms, and, in particular, on the effectiveness of the joints of Pavilion V.

Abstract A light rail passenger transportation system is being built in Seattle, WA, USA, that traverses Lake Washington over an existing pontoon bridge. The water level in Lake Washington changes throughout the year. This causes rotations of the transition spans, which are needed at each end of the bridge to carry traffic between the fixed, land-based structure, and the floating structure. This paper explains a novel method, the Curved Element Supported Rail (CESuRa) system, that provides rails with the ability to undergo joint rotations at the ends of the transitions spans without risk of damage, while maintaining full vertical support of the track across the joint. The geometric characteristics on which it depends for proper operation, considerations that must be accounted for when using the system for other applications in the future, and an overview of the implementation of the system on the floating bridge are discussed.

Expansion joints and structural bearings developed on the basis of component testing Expansion joints and structural bearings are especially for bridges, as key elements of our infrastructure, of special importance. Since late 1950s IMB/MPA Karlsruhe assigns a unique role in the development and assessment of these complex construction products. In particular by harmonized European Standards and European Technical Assessments this role has gained further weight and influence. By means of various examples for component testing this paper will demonstrate, how by the support of IMB/MPA Karlsruhe high performance solutions for structural bearings and expansion joints have been developed and regarding the assessment new methods have been elaborated, as well as applied. Whereby it is possible to provide an outlook in the application of future European specifications and allow an insight to newest developments in the field of structural bearings and expansion joints. [ABSTRACT FROM AUTHOR]

Summary: Expansion joints of bridges are vulnerable to damage due to the thermal expansion and contraction, vehicle traffic, and so forth. Currently, the temperature–displacement relationship model may be the only qualitative method for condition evaluation of bridge expansion joints using the field monitoring data. The quantitative assessment based on the finite element model updating techniques is heavy computational burden and time consuming. Therefore, a Gaussian process (GP) metamodel‐based model updating method is proposed in this study and performed for the quantitative identification on the boundary condition of the expansion joints of Jiangyin Suspension Bridge using the long‐term displacement and temperature monitoring data. At first, the relationship between the longitudinal boundary stiffness (LBS) and structural temperature is formulated on the basis of thermal effects of the bridge deck. The range of LBS is approximately estimated by the regression coefficients from 1‐year monitoring data and is used as initial bounds for the subsequent model updating procedure. The GP metamodel is formulated to map the relationship between the LBS and the longitudinal displacements under the thermal effects. The LBS identification of the Jiangyin Suspension Bridge is performed within the fast‐running GP metamodel. The results show that the longitudinal displacements using the updated LBS are in good agreement with the measurements, which verifies the effectiveness of GP metamodel‐based model updating method in identifying the LBS of the long‐span suspension bridge. [ABSTRACT FROM AUTHOR]

In the paper are presented general rules of the assortment of expansion joints in bridges located in areas being under the mining impacts. The maintenance problems associated with ground deformations are also mentioned. The special attention is given to the noise emitted by expansion joint devices. A legal status in the protection from noise and factors affecting this noise are discussed.

Metal Bellows finds wide application in expansion joints, which are used in aerospace, chemical plants, power system, heat exchangers, automotive vehicle parts, piping system, petrochemical plant, refineries, etc. During service they are subjected to various stresses and exposed to different environments, which leads to failure. Hence there is a need for proper design of metal bellow as per the application. The main objective of the paper is to evaluate the stresses generated in the metal bellow and the cycle life working at different working pressures. In this paper, the stresses are calculated using Expansion Joint Manufacturing Association (EJMA) standards and compared with the results obtained using ANYS software for two different materials namely Inconel 625 and Inconel 718 for the pressure values ranging from 20 to 40 bar.

Summary: Expansion joints are used as a special connection equipment between adjacent buildings to accommodate the relative motions generated by wind, thermal, or earthquake loads, but they often exhibit damage during severe earthquakes. The level of damage and safety factors required to avoid loss of function are not well considered in current design practices. The objective of this paper is to provide quantitative information on the seismic damage probability of common expansion joints and the associated repair costs. The designer and engineer can refer to this information as a basis for decision making in the selection of expansion joints. Four common types of expansion joints are considered: high‐ and standard‐performance floor and wall expansion joints, whose damage states have been evaluated recently by the authors through shaking table tests. First, the fragility functions of expansion joints for seven damage patterns are developed utilizing the test results. Next, the vulnerability of expansion joints installed between adjacent building models is assessed via incremental dynamic analysis. The recommended level of safety factor to ensure the function of expansion joints is discussed. Finally, a procedure for cost‐effective selection of expansion joints is introduced, where case studies are examined using buildings with different characteristics. The presented results are deemed to be beneficial for improving the design practice of expansion joints and for reducing future seismic loss. [ABSTRACT FROM AUTHOR]

This article aims to study the effects of pounding and fluid–structure interaction on a typical long-span deep-water bridge with high hollow piers. With potential-based fluid elements modeling fluid–structure interaction between hollow piers and water, and gap elements simulating pounding at gap locations, three-dimensional(3D) finite element models were built for the typical deep-water bridge. The longitudinal seismic responses of the bridge under the combination effects of pounding and fluid–structure interaction were studied from two cases where the hollow piers contact with outer water only and both outer water and inner water, respectively. For comparison, the individual effects of pounding or fluid–structure interaction were also analyzed. The results indicate that the fluid–structure interaction could be one of the critical factors which can result in pounding between adjacent segments of deep-water bridges, because the fluid–structure interaction can amplify the seismic relative displacement between adjacent spans of deep-water bridge. The combination effects of pounding and fluid–structure interaction are negligible on seismic responses of deep-water bridge piers compared with the individual effect of fluid–structure interaction; however, they can lead to further increase of deck displacement of approach span, no matter compared with the individual effect of fluid–structure interaction or pounding, which increases the possibility of approach span unseating. Whether pounding happens or not, the existence of the inner water in the hollow piers causes aggravated effect on seismic responses of deep-water bridge. [ABSTRACT FROM AUTHOR]

Abstract The duct system is one of the structures that most need a series of conditions that require the system to have a certain flexibility of movement due to thermal stresses, changes in the direction of the duct system and the unevenness on the ground. Metal bellows are designed to provide flexibility to the system, however, to guarantee the proper properties in service one should consider the material used in the component manufacturing as well as the manufacturing process itself. This research aimed to study a case of failure due to the stress corrosion of an austenitic stainless steel expansion joint. For the assessment of the main factors that led to the failure of the expansion joint, some analyses were employed: microstructural characterization by optical microscopy and scanning electron microscopy (SEM); X-ray diffraction; solution annealing heat treatments and microhardness. The results showed that the cleaning conditions allowed pits and cavities to form on the inner surface of the bellows while the forming processes used in the bellows manufacturing of the expansion joints were responsible for providing the necessary metallurgical conditions for the nucleation and propagation of cracks from pits and cavities. From the results it was possible to enumerate a series of recommendations that take into account an adequate cleaning of the component as well as the appropriate thermal treatments to optimize the service life of the studied component. Highlights • Corrosion resistance of expansion joint bellows • Stress corrosion cracking of stainless steel • Nucleation of cracks due to metallurgical conditions [ABSTRACT FROM AUTHOR]

Summary: The performance of nonstructural components has attracted attention, and previous large earthquakes have resulted in widespread damage to expansion joints. In contrast to the main structural components, for which ductility beyond the design tolerance is ensured, the safety margin of nonstructural components classified as the product of mechanical engineering, such as expansion joints, is uncertain. This paper investigates the damage sequence and safety margin of expansion joints through shake table testing. The expansion joints were installed to connect 2 rigid steel frames with short and long natural periods. Four commonly used types, high‐performance and standard‐performance floor and wall expansion joints, were tested. Seven damage patterns of the 4 expansion joints were observed, and most of the damage patterns were considered displacement dependent. The damage mechanisms and relative displacements at the moment of damage were identified by using strain gauges attached near collision and damage locations. The high‐performance expansion joints showed only minor damage beyond the design motion range, whereas the standard‐performance expansion joints exhibited minor damage below the design motion range and failure at the design motion range or slightly beyond. For each damage state, repair information was obtained through a questionnaire to an expansion joint manufacturer, and the sum of the initial cost and repair cost for high‐performance and standard‐performance expansion joints was compared. The results will be useful for the selection of expansion joints in the design process. [ABSTRACT FROM AUTHOR]

A light rail passenger transportation system is being built in Seattle, WA, USA, that traverses Lake Washington over an existing pontoon bridge. The water level in Lake Washington changes throughout the year. This causes rotations of the transition spans, which are needed at each end of the bridge to carry traffic between the fixed, land-based structure, and the floating structure. This paper explains a novel method, the Curved Element Supported Rail (CESuRa) system, that provides rails with the ability to undergo joint rotations at the ends of the transitions spans without risk of damage, while maintaining full vertical support of the track across the joint. The geometric characteristics on which it depends for proper operation, considerations that must be accounted for when using the system for other applications in the future, and an overview of the implementation of the system on the floating bridge are discussed. [ABSTRACT FROM AUTHOR]

Over the past few years, longitudinal displacement has gained popularity as a means of evaluating the condition of long-span cable-supported bridge components, such as bearings. However, accurately predicting bearing displacement under varying load conditions is challenging due to the exposure of bridges to environmental and traffic loads. To address this issue, a hierarchical convolutional neural network (HCNN) model was developed in this paper for predicting bearing displacement using comprehensive loads as predictors. Structural health monitoring (SHM) systems of a cable-stayed bridge are utilized to provide one-month datasets for training and testing of the proposed method. Temperature, wind, and vehicle loads are adopted as input variables, and bearing displacement is the output. Results demonstrated the effectiveness of the proposed approach in predicting bearing displacement with an accuracy of over 95.6%, surpassing other models like traditional CNN, encoder-decoder, and U-Net in both accuracy and efficiency. Additionally, the contributions of different loads in predicting displacement are investigated, demonstrating the importance of traffic loads. Cumulative displacement can consequently be calculated for condition assessment of components such as bearings and expansion joints. A comparison with another cable-stayed bridge showed that the expansion joints in the current bridge were in satisfactory condition. Overall, the proposed approach can facilitate predictive maintenance in long-span bridges, helping to prevent premature failures. [ABSTRACT FROM AUTHOR]

W artykule przedstawiono konstytutywny model materiału podlegającemu przemianie fazowej wywołanej odkształceniami plastycznymi oraz rozwojowi uszkodzeń. Przemiana fazowa opisana jest modelem liniowym. Ponadto, w pracy uwzględniono izotropowy rozwój uszkodzeń. Opis konstytutywny został zaimplementowany w komercyjnym programie Abaqus/Explicit z wykorzystaniem zewnętrznej procedury użytkownika VUMAT. Dokonano symulacji testu jednoosiowego rozciągania w celu porównania wyników eksperymentalnych z numerycznymi. Jako przykład rzeczywistego elementu konstrukcyjnego, pracującego w warunkach temperatur kriogenicznych, dokonano symulacji pracy kompensatora.

Highlights • Pre-conceptual study of the DEMO upper port duct bellows. • Bellows geometry and interface identification based on 2015 DEMO CAD model. • Identification and verification of load cases through FE thermal expansion analysis. • Development of bellows optimization tool based on available analytical procedures. • FE simulations of simple and complex bellows. Abstract This paper describes the first study on the DEMO upper port duct bellows. It aims at establishing the basis for their pre-conceptual design through available standardized analytical procedures and identify the bellows features where the analytical procedures fail and the detailed finite element (FE) analyses are required. The available analytical procedures have been found insufficient for the specific bellows design, considering the rather challenging size, load cases and non-standard trapezoidal shape of the DEMO upper port duct bellows. Although a properly verified design of the bellows cannot be provided at this stage, the development of an optimization tool has been initiated to identify a valid range of bellows parameters that fulfill the design constraints while optimizing their mass or length. The preliminary design results are presented and the shortcomings of the analytical tool identified through FE analyses of bellows performed with the ABAQUS code. [ABSTRACT FROM AUTHOR]