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This paper presents a novel statistical analysis-based approach to non-parametric damage detection in truss bridges. The method utilizes the normalized acceleration response time histories (NARTHs) of a bridge under random excitation. The coefficients of variation matrices are calculated using NARTHs for the truss bridge in both its baseline and damaged states. The results are shown as the difference in covariance matrices (DCMs) between the two conditions (pristine and damaged). The row or column-wise summation of the DCM matrix yields a summation of the difference in covariance matrix (SDCM) bar plot having one distinct peak for the damaged member. The location and relative severity of the damage can be determined by examining the DCM matrix and the SDCM bar plot. The variation in magnitude of the coefficients demonstrates the relative severity of damage. Experimental investigation of the proposed method for detecting damage on the truss bridge shows promising results. The approach is then numerically validated using a finite element model of a truss bridge. The proposed method effectively identified, located, and evaluated damage, even when the acceleration time histories are contaminated with noise. The case of multiple-member damage detection in the truss structure is further investigated in the study. The early detection of damage and monitoring of its progression through this method can assist in creating efficient maintenance strategies for truss bridge infrastructure. [ABSTRACT FROM AUTHOR]

The combined use of finite element modeling and structural health monitoring is becoming increasingly relevant in bridge maintenance. A growing number of new and old structures is instrumented with different kinds of sensors driven by dedicated hardware and software, while numerical models are used to simulate the response of the structures under various scenarios. This paper presents the monitoring of the Smithfield Street Bridge, one of the oldest and most iconic bridges in the city of Pittsburgh (Pennsylvania, USA). The bridge was instrumented by an independent party, not involved with the research presented here, with strain, displacement, and rotation wireless sensors. A detailed finite element model of one of the spans of the bridge was developed to calculate the strains induced by standardized trucks under pristine and simulated damage conditions. In addition, the model enabled to determine the sensitivity necessary to detect relevant structural changes in the bridge. The results of the numerical analyses were then compared with the results of a test in which a truck of known weight crossed the bridge multiple times. Finally, the data relative to 3 years of uninterrupted monitoring were processed and analyzed to identify eventual anomalies. [ABSTRACT FROM AUTHOR]

Highlights The low resistance of bolted joints in pultruded unidirectional (UD) fiber‐reinforced polymer (FRP) profiles limits the load grade of truss bridges due to shear damage along UD fibers. To address this issue, this study proposes multi‐directional (MD) fiber architecture in FRP profiles to improve the ultimate bearing strength of bolted joints. The digital image correlation shows that the addition of off‐axis fibers in MD FRP profiles prevents shear failure in the UD FRP profile. As a result, the ultimate bearing strengths of MD FRP profiles are enhanced attributed to “off‐axis fiber tie action”. Micro‐computed tomography shows that fiber damage in MD FRP profiles emerged from outer plies, including fiber breakage in 90° and ±45° fibers and fiber kinking in 0° and ±45° fibers. The off‐axis fibers break due to tension when resisting the bearing load in MD FRP profiles. The fiber kinking indicated strength contribution from 0° to ±45° fibers. The fiber breakage and fiber kinking in each ply are dominant in bearing failure instead of delamination, which increases the bearing strength of the pultruded MD FRP profiles. These findings facilitate controlling damage evolution in the pultruded MD FRP profiles and designing high‐resistance bolted joints. Multi‐directional fibers improved bearing strengths of FRP profiles by 28.5%–33%. Off‐axis fibers bent under pin‐bearing, forming a tie action until breakage. Fiber breakage and kinking in each ply contributed to the bearing failure. Strain localization and redistribution were observed using DIC. [ABSTRACT FROM AUTHOR]

Due to the lack of connecting facilities, residents in the Gampong Blang Mirou and Kumba Kec. Bandar Dua have to travel via another route. Although proposals to the district government are submitted every year, a response was received in 2018. In 2018, the construction of the Blang Mirou--Kumba steel truss bridge was carried out using the DAK budget, the tender process for this development package used a budget of 14 billion Rupiah. The purpose of this research is to determine and analyze the increase in social interaction and economic growth as a result of the construction of the bridge connecting Gampong Blang Mirou - Kumba District. Bandar Dua Kab. Pidie Jaya. The method used is descriptive qualitative. The data sources used are primary data and secondary data. The research uses data obtained through interviews, observation, and documentation. Based on the results of the research and findings in the field, the conclusion is that the implementation of this policy can provide practical implications for the people of Pidie Jaya Regency, especially the people of Gampong Blang Mirou and Gampong Kumba as well as the Pidie Jaya Regency Government so that social interaction between the regions and the regional economy both increases. An interesting finding was that when the road was widened to build a connecting bridge, the community gave their land for free without having to be compensated by the government. [ABSTRACT FROM AUTHOR]

The document discusses the importance of structural health monitoring and performance evaluation for bridges and critical infrastructure. It highlights the need for innovative methods to assess the condition of existing structures and prioritize maintenance programs. The text covers various approaches, including sensor-based monitoring, non-destructive evaluation methods, and data processing techniques for damage detection and performance evaluation. The document also presents research articles on topics such as vibration-based damage detection, corrosion identification, and seismic impact studies, showcasing global efforts to enhance infrastructure resilience and safety. [Extracted from the article]

Steel truss bridges are especially vulnerable in the event of a sudden loss of a load-carrying element, which can trigger a chain of failures. This paper describes a unique case study of a steel truss bridge under construction subjected to sudden member breakages with an extensive monitoring system. The failures occurred during the dismantlement of temporary members that had been used to transform a three-span simply supported steel truss bridge into a three-span continuous structure during incremental launching. These temporary members needed to be removed once the bridge reached its final position. The robustness of the bridge was assessed using computer simulations of various failure scenarios to evaluate its capacity to effectively activate alternative load paths (ALPs). The results demonstrated the structural redundancy of the steel truss bridge. However, the dynamic response resulting from the failure of the temporary upper chord, due to the initially high tension in the rods, should not be overlooked. To mitigate this issue, a structural retrofitting method was proposed, involving jacking the truss girder above the side pier to reduce the tension in the temporary upper chord above the middle pier. The effectiveness of this method was demonstrated through both simulated and formal experimental tests. [ABSTRACT FROM AUTHOR]

In the structural health monitoring of vibration systems, varying excitation always affects the accuracy of damage identification. The proposed symbolic three-order square matrix damage detection method with the matrix norm as a damage indicator can solve the difficult problem of damage identification under ambient excitation. The new sampling pattern extracts data from signals in the time domain at specific intervals based on the structural properties with the help of the autocorrelation coefficient. Then, the data extracted are converted into symbols and arranged into a three-order square matrix, and the Frobenius norm of the matrix is used for structural damage identification as a reliable damage indicator. In this process, the transmissibility function is employed to eliminate the effects of varying excitation. First, the method was verified by a cracked simply supported beam—a simulated Abaqus model. Then, a wooden truss bridge in the laboratory and an actual engineering scenario under ambient excitation together demonstrated the effectiveness and accuracy of the damage identification method and proved the proposed method to be robust to different types of damage under ambient excitation. Compared with other related methods, this method is more intuitive and efficient. [ABSTRACT FROM AUTHOR]

This study introduces the constraint‐aware optimization model (CAOM), a novel optimization framework designed to optimize the size, shape, and topology of plane truss structures simultaneously. Unlike traditional optimization models, which rely on gradient descent and frequently struggle with managing various constraints due to their dependence on a single optimization agent, CAOM effectively addresses this challenge. It does so by incorporating a variety of assistant modules along with the Adam optimizer, a variant of the gradient descent method. Uniquely, CAOM employs the leaky rectified linear unit (ReLU) activation function beyond its conventional use in neural networks, applying it as a mechanism to integrate constraints and losses seamlessly. The model's effectiveness was validated through two numerical examples and a practical application, demonstrating that CAOM can reduce structural weight by up to 84% compared to unoptimized designs while fully adhering to structural, dimensional, and moveable constraints. Furthermore, the study found that while shape optimization plays a key role for stiffness‐governed structures, size optimization is crucial for strength‐governed structures. Optimizing size, shape, and topology together consistently leads to the most weight‐efficient designs. This emphasizes the significance of a holistic approach in the optimization processes. [ABSTRACT FROM AUTHOR]

Steel bridge, as one of the main structural types in bridge design, has been widely used in rail transit. However, the train-induced vibro-acoustic problem of the bridge has become increasingly prominent. The vibration and noise characteristics must be more significant and complex than steel truss bridge because of too many components. Viscoelastic damping materials (VDMs) have the characteristics of both viscous liquid and elastic solid, and have better damping performance than other damping materials. Therefore, VDM plays an important role in vibration and noise reduction technology. In applications, VDM is usually combined with constraining materials to form composite viscoelastic damping materials (CVDM). In this paper, based on the dynamic receptance method and superposition principle, the coupling model of vehicle–track–bridge in the frequency domain is first established, and then the vibration and noise prediction model of a steel truss bridge with CVDM is established based on RUK theory and statistical energy analysis (SEA) method. Based on the prediction model, the natural dynamic characteristics of typical components of steel truss bridges with CVDM were investigated, and the control mechanism and influence rule of CVDM on train-induced vibration and noise of steel bridges were revealed. [ABSTRACT FROM AUTHOR]

The Friesen bridge near Weener – Europes largest lift‐swing‐bridge In December 2015, the historic railway bridge over the Ems River near Weener was destroyed by a ship collision. The movable bridge part of the Friesen bridge, a rolling bascule bridge (Scherzer bridge) was so severely damaged that it could not be repaired. After an intensive political discourse, it was decided to rebuild the bridge. A feasibility study determined that, considering all conditions, the reconstruction of the Friesenbrücke as a lift‐swing bridge is the preferred option. The bridge structure of the Friesenbrücke has a total length of 337 m, with the centerpiece being the approx. 145 m long movable truss section of the lift‐swing bridge. The new Friesenbrücke provides a clear width of 56.60 m for shipping and meets the safety and ease‐of‐navigation requirements for all affected traffic routes. The new Friesenbrücke in the northwest of Lower Saxony is a major project that is unique in its structural dimensions and logistical conditions. It will become the largest lift‐swing bridge for railway traffic in Europe. [ABSTRACT FROM AUTHOR]

Shui Su Ravine Bridge is built in Bai Shui County in Shaanxi Province, which is a part of the highway linking Heyang and Tongchuan. The bridge has been designed as a composite steel‐concrete truss bridge with 3 spans in total of 240 meters and a deck of 4 lanes. To meet the harsh environmental demand and lessen the future maintenance, the solution adopts the weathering steel Q420qENH similar strength as S420NL in European code. The bridge is erected by incremental launching and post‐installation of the pre‐cast concrete slab. Since the truss segment is all welded, two‐step models have been developed to evaluate the fatigue performance of the steel truss joint. In the simplified two‐dimensional model, Phase‐Field (PF) approach has been implemented to make a full fatigue evaluation of crack propagation in the truss. [ABSTRACT FROM AUTHOR]

The paper describes design and construction process of the unique reconstruction of the historical stone bridge at the lower head of the listed Hořín lock chamber at the confluence of the Vltava and Elbe rivers near Mělník. The original stone arch bridge from 1905 at the outlet of the lock had to be carefully dismantled and rebuilt into a lifting bridge with a vertical lift of 5 m. The goal was to preserve bridges original listed and preserved appearance and enable larger ships to pass under it. The design of reconstruction consisted of proposal of new substructure, new hidden steel superstructure, new hydraulic and mechanical parts and electronical controling system. The original appearence of the stone cladding had to be preserved, so new hidden truss steel kernel was inserted to form the support for the original stone cladding and concrete coupling shell. The stroke of the bridge is controlled electronically by hydraulic cylinders and a system of guides and restraints. The reconstruction of this unique bridge had been carrefully performed under surveilance of National Heritage Office. The project recieved the Czech Construction of the Year 2022 award. [ABSTRACT FROM AUTHOR]

For some long span cable supported bridges, the longitudinal diaphragms in main girder are designed as steel truss to reduce structural self-weight. However, unanticipated fatigue cracking in critical details of longitudinal steel truss diaphragm may occur after only a few years of service, resulting in stiffness weakening and stress redistribution. Based on an actual cable-stayed bridge, this paper presents a fatigue analysis of longitudinal steel truss diaphragms and provide an effective strengthening measure to elongate the fatigue life. Using traffic information from bridge toll station, the fatigue vehicle models were established. Then, a multi-scale finite element (FE) model was developed to help determining critical details of potential cracking and calculating the vehicle induced stress. After obtaining the required parameters, fatigue life of the specific critical detail was estimated base on damage accumulation law. The result agrees well with field observation. To ensure the performance of steel girder, the strengthening measure that replace diagonal tubes in longitudinal steel truss diaphragm with bolted channel steels was proposed and then applied. The assessment result indicated that the provided strengthening measure achieves satisfactory effects. It can also provide experience and partial reference for maintenance of similar structures. [ABSTRACT FROM AUTHOR]

In Structural Health Monitoring (SHM) of bridges, accurately assessing damage is critical to maintaining the safety and integrity of a structure. One of the primary challenges in damage assessment is the precise localization and quantification of defects, which is essential for making timely maintenance decisions and reducing the risk of structural failures. This paper introduces a novel damage detection method for SHM of a truss bridge by coupling a Deep Neural Network (DNN) model with an evolved Artificial Rabbit Optimization (EVARO) algorithm. The integration of DNN with the stochastic search capability of the EVARO algorithm helps to avoid local minima, thereby ensuring more accurate and reliable results. Additionally, the optimization algorithm's effectiveness is further enhanced by incorporating evolving predator features and the Cauchy motion search mechanism. The proposed method is first validated using various data benchmark problems, demonstrating its effectiveness compared to other well-known algorithms. Secondly, a case study involving the Chuong Duong truss bridge under different simulated damage scenarios further confirms the superiority of the proposed method in both localizing and quantifying damages. [ABSTRACT FROM AUTHOR]

Structural Health Monitoring (SHM) system uses sensors to collect information and evaluate the structure, aiming for early damage detection. For many reasons, data from sensors can be corrupted, affecting the assessment results. Reconstructing lost or corrupted data helps complete it, improves structural assessments, and ensures structural safety. Artificial Intelligence (AI) has emerged in recent years as a solution to data problems. This study proposes the use of a One-Dimensional Convolutional Neural Network (1DCNN) to reconstruct lost vibration data during SHM. A complete dataset was used to train the 1DCNN network. After completing the training, the 1DCNN network received incomplete data to return erroneous data. The results of the study show that the proposed method is able to reconstruct vibration sensor data. [ABSTRACT FROM AUTHOR]

A servicing spacecraft motion control approach for the problem of on-orbit truss structure assembly is developed in this paper. It is considered that a cargo container with a rod set and servicing spacecraft are in orbit initially. The assembly procedure is based on spacecraft free-flight motion between the structure's specified points. The spacecraft is equipped with two robotic manipulators capable of attaching to the structure and holding rods. In addition, the spacecraft can repulse from the structure with a given relative velocity using a manipulator, so the spacecraft and the structure receive impulses. The repulsion velocity vector is calculated in order to reach the structure target point to deliver and install the rod into the truss structure, or to reach the cargo container and take a rod. The problem of searching the repulsion velocity is formulated as an optimization problem with constraints, taking into account the limited value of the repulsion velocity, collision avoidance with structure, restrictions on the angular velocity and translational motion of the structure in the orbital reference frame. This problem is solved numerically with an initial guess vector obtained analytically for simplified motion cases. The application of the proposed control scheme to the assembly of a truss-based antenna is demonstrated. It is shown that the servicing spacecraft is successfully transferred between the structure points by means of manipulator repulsion. Main features and limitations of the assembly problem using a spacecraft with two manipulators are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a demonstrative application of a forward model-driven approach to structural health monitoring (SHM), incorporating hierarchical validation methods. A key tenet of the approach is that an SHM system can be constructed that is capable of diagnosing damage at the full system level, without full system damage-state data having been used in its development; achieving this would be highly impactful as the system-level damage state data is generally not feasible to acquire (previous SHM methods such as data-driven SHM have been hindered by their dependence on these data). This is achieved by carrying out validation activities on the damage model at the subassembly level of the structure. The particular focus of the present paper is on damage detection and assessment, although the approach offers a natural basis for extension to other damage identification activities such as damage location and prognosis. The present study focuses on two of the key elements of the model-driven approach: validation of the predictive substructure models and their application in the assembled model. The ideas discussed are demonstrated in a case study based on a laboratory-scale truss bridge structure. [ABSTRACT FROM AUTHOR]

Form-finding is an essential task in the design of efficient lightweight structures. It is based on the crucial assumption of one single shape-determining load case, usually represented by self-weight. Adaptive components integrated into the structure open a way to even more efficient lightweight designs, as such structures can adapt their shapes to varying external loads and redistribute internal forces. This article presents a method for form-finding of adaptive truss structures subject to multiple, independently acting load cases, also incorporating possible design constraints. To ensure the consistency of the manufacturing lengths of passive elements in all load cases, special constraints are considered. The method enables to reduce sensitivity of the structural shape with respect to various different loads by means of actuation to meet design and serviceability requirements with a lower structural mass compared to conventional design strategies. This is demonstrated within a replaced real-world-like setting of an adaptive suspension truss bridge. [ABSTRACT FROM AUTHOR]

Although some researchers indicated that the rotation response of the structure is a proper index to identify the damage location, Wavelet Transform (WT) of rotation response of the bridge is not yet used to detect the damage location in the previous studies. In this regard, a numerical model of a truss bridge was developed using finite element method. The static response of the model under one point-load and a six-axle locomotive was calculated. The response obtained from the model was compared with that of the literature to investigate the validity of the model developed in this study. The WT coefficients of horizontal, vertical and rotation responses of each member of the bridge were obtained based on the Gaus2 wavelet basis function. Several damage scenarios were considered for the bridge to investigate the effectiveness of WT of rotation response of the bridge to detect the damage location. The obtained results show that the WT of horizontal displacement is not a proper index to detect the damage in the bridge members. A Comparison between WT coefficients of vertical displacement and rotation for all members indicates that the rotation response is a proper index to identify the damage and loading locations. In some cases, while the damage causes a significant jump on the WT coefficients of rotations of the members, the WT coefficients of vertical displacement of these members are not influenced by the damage. [ABSTRACT FROM AUTHOR]

The "321" prefabricated highway steel truss bridge is widely used for highway rescue, disaster relief, and emergency traffic. This paper uses a 33 m double-row monolayer "321" prefabricated highway steel truss bridge to analyze its mechanical properties and component stability. The actual traffic flow capacity of a total weight of 53.32 tons is used in this study. The results show that the maximum internal force in the truss chord (including the stiffening chord) occurs in the middle span section when a centrally distributed load is applied. Meanwhile, the maximum internal force of truss diagonal members and truss vertical bars appears at the fulcrum section. Under the eccentrically distributed load, the maximum internal forces of truss chords (including stiffening chords) appear in the middle span section, which is closest to the vehicle load, while the maximum internal forces of truss diagonal members and truss vertical bars appear in the fulcrum section, which is closest to the vehicle load. While the maximum internal forces under the eccentrically distributed load are greater than the maximum internal forces under the centered-layout load, under the vehicle load, truss chords (including stiffening chords) are prone to buckling instability, and the buckling mode is mainly reverse out-of-plane buckling. The inclined members of the truss are prone to buckling instability, and the buckling mode is mainly the combination of out-of-plane bending and two-way out-of-plane bending. Truss vertical bars have good stability and are not easy to buckle. The main conclusions of this paper can provide references for the optimal design and operation safety of prefabricated highway steel truss bridges. [ABSTRACT FROM AUTHOR]

Bridges are vital for community development, and wood is a primary material due to its environmental benefits. However, wood’s moisture absorption can cause swelling and shrinkage, and low-density wood tends to have lower strength. The moment of inertia of a box beam is related to wall thickness and stiffness. Insufficient wall thickness can lead to plastic retention before peak load, reducing structural integrity. Thin walls can cause buckling under compressive loads, leading to failure. Truss bridge failures can also result from design errors. This study aims to analyze the effect of box beam wall thickness on the stiffness of camphor wood timber bridge trusses. Camphor wood with a cross-sectional area of 1,600 mm2 was used, with box beams of dimensions 45×45 mm (12 mm wall), 50×50 mm (10 mm wall), 58×58 mm (8 mm wall), and a solid beam of 40×40 mm (20 mm wall). Physical tests showed the wood’s specific gravity at 0.506 g/cm3 and moisture content at 12.47 %. The highest peak load was 19.613 kN for the BB.58.58.8 variation, which also had the greatest stiffness at 3.502 kN/mm. The BB.58.58.5 variation had the largest moment of inertia at 683,733 mm4 compared to the solid beam SB.40.40.20 at 213,333 mm4. The BB.45.45.12 sample had a t/D ratio 1.93 times larger than BB.58.58.8, indicating a more flexible structure with lower stiffness. This is confirmed by experimental results, showing that BB.45.45.12 had a stiffness 1.73 times lower than BB.58.58.8. Theoretical calculations also showed that BB.45.45.12 had a stiffness 2.03 times smaller than BB.58.58.8. Thus, the t/D ratio is inversely proportional to stiffness. This research contributes valuable insights for developing engineered wood products in construction and bridge design, particularly for village bridges in Indonesia. [ABSTRACT FROM AUTHOR]

The field load test is a direct and effective method for evaluating the performance of bridge structures. However, the existing bridge static load tests on site are costly, inefficient, and obstruct traffic; moreover, improper loading may also cause some damage to the bridge structure. This paper proposes a random model update method based on bridge dynamic load tests and the Bayesian inference as an alternative to the static load test. The Gaussian process model was used instead of the finite element model to reduce the cost of model calculation. Furthermore, choose the Markov Chain Monte Carlo (MCMC) method based on delay rejection adaptive Metropolis algorithm for Bayesian inference to improve the speed of the Bayesian method inferring the posterior probability density of updated parameters. First, the parameters to be updated for the bridge structure analysis model were determined based on the global sensitivity analysis method. Second, a uniform design sampling method was used to establish the Gaussian process optimization model to update the random model of the bridge structure. Finally, a reinforced concrete truss arch bridge was used to verify the correctness of the static load results of the bridge predicted by the random model update method based on dynamic load testing and Bayesian inference. The results show that the predicted results of the bridge static load test based on the dynamic load test and Bayesian reasoning method have an excellent agreement with the measured results, and this method can effectively overcome the adverse effects of the existing bridge static load test. [ABSTRACT FROM AUTHOR]

One of the most widely used linear techniques for solving damage identification problems and prediction of the system dynamic behavior is modal testing and analysis. However, most of real structures exhibit nonlinear behavior during their lifetime caused by a number of various reasons. The presence of nonlinearity in a structural system changes its dynamic characteristics; hence, the use of linear techniques is improper for prediction of the system behavior. In this paper, a vibration-based nonlinearity identification technique was proposed to identify early changes in a dynamic system prior to significant damages. This technique combines the time series Autoregressive Moving Average with Exogenous Inputs (ARMAX) modelling, probability theory, and Fuzzy C-Means (FCM) clustering algorithm to categorize the linear and nonlinear dynamic behaviors of a dynamic system. The technique aims to categorize the linear and nonlinear behaviors of a structure, when it is subjected to various levels of excitation source. To show the validity of the proposed method, a series of shake table tests was performed on a six-span steel truss bridge model. The bridge model was excited using different amplitudes of ground motion to control the nonlinearity degree of rubber-based supports. It can be concluded from the analysis results that the new vibration-based nonlinearity identification technique was able to identify nonlinear behavior of the bridge model once it was subjected to different levels of earthquake excitations. This algorithm was able to categorize the linear and nonlinear behaviors of the bridge model and define a specific threshold for different excitation sources. [ABSTRACT FROM AUTHOR]

The fatigue phenomenon has a significant effect on the joints of steel truss bridges, causing the formation of plastic hinges leading to potential collapse configurations. For this reason, in the last few years, the development of new methods to effectively strengthen such joints has gained attention. In this article, a mechanism for the improvement of the resistance to fatigue of these types of connections is proposed, by employing composite joints and post-tensioned metal straps (PTMSs). Following this approach, first the overstressed connections of the structure have been identified during the inspection phase, and subsequently, they have been encased in a concrete casting with a proper level of strength. To analyze the behavior of the steel–concrete mixed solution, a finite element model has been realized in ABAQUS (rel. 2022.0) and it has been validated based on comparison between the numerical results and the experimental ones obtained by laboratory tests. Then, a parametric analysis was performed to investigate the effect of the concrete type employed in the connection behavior. In the second stage of the research, based on the first cracks configuration obtained numerically and observed experimentally, PTMSs have been used to control the cracks and strengthen the joint. The strains and stresses on the concrete and steel parts of the connection were measured before and after the insertion of the PTMSs and compared with the outputs of the model. Additionally, a parametric analysis was carried out to assess the optimal number of straps. The effect of this solution on the resistance of the joint and on the behavior of concrete was analyzed and the effectiveness of the strengthening technique was assessed. [ABSTRACT FROM AUTHOR]

New or in-service truss bridges, with or without upper bracing systems, may display instability phenomena such as general lateral torsional buckling of the upper chord. The buckling of structural elements, particularly in the case of steel bridges, can be associated with the risk of collapse or temporary/permanent withdrawal from service. Such incidents have occurred in the case of several bridges in different countries: the collapse of the Dee bridge with truss girders in 1847 in Cheshire, England; the collapse of the semi-parabolic truss girder bridge near Ljubičevo over the Morava River in Serbia in 1892; the collapse of the Dysart bridge in Cambria County, Pennsylvania in 2007; the collapse of the Chauras bridge in Uttarakhand, India in 2012; and the collapse of a bridge in Nova Scotia, Canada (2020), and such examples may continue. Buckling poses a significant danger as it often occurs at lower load values compared to those considered during the design phase. Additionally, this phenomenon can manifest suddenly, without prior warning, rendering intervention for its prevention impossible or futile. In contemporary times, most research and design calculation software offer the capability to establish preliminary values for buckling loads, even for highly intricate structures. This is typically achieved through linear eigenvalue buckling analyses, often followed by significantly more complex large displacement nonlinear analyses. However, interpreting the results for complex bridge structures can be challenging, and their accuracy is difficult to ascertain. Consequently, this paper aims to introduce an original method for a more straightforward estimation of the buckling load of the upper chord in steel truss bridges. This method utilizes the theory of beams on discrete elastic supports. The buckling load of the upper chord was determined using both the finite element method and the proposed methodology, yielding highly consistent results. [ABSTRACT FROM AUTHOR]

In this paper, given the shortcomings of jellyfish search algorithm with low search ability in the early stage and easy to fall into local optimal solution, this paper introduces adaptive weight function and elite strategy, improving the global search scope in the early stage and the ability to refine the local development in the later stage. In the numerical study, the benchmark problem of dimensional optimization with a 10-bar truss structure and simultaneous dimensional shape optimization with a 15-bar truss structure is adopted, and the corresponding penalty method is used for constraint treatment. The test results show that the improved jellyfish search algorithm can provide better truss sections as well as weights. Because when the steel main truss of the large-span covered bridge is lifted, the site is limited and the large lifting equipment cannot enter the site, and the original structure does not meet the problem of stress concentration and large deformation of the bolt group, so the spreader is used to lift, and the improved jellyfish search algorithm is introduced into the design optimization of the spreader. The results show that the improved jellyfish algorithm can efficiently and accurately find out the optimal shape and weight of the spreader, and through Midas Civil simulation, the spreader used can meet the requirements of weight and safety. [ABSTRACT FROM AUTHOR]

The Cincin Lama bridge is a crucial component of a major road in Java Island, Indonesia. It comprises six spans of the Callender Hamilton-type truss bridge, with each span measuring 50 meters. Tragically, one of its six spans collapsed during operation on April 17th, 2018. To understand the cause behind this incident and extract valuable lessons from it, an investigation utilizing finite element analysis was initiated. The primary objective of this investigation was to pinpoint the root cause that precipitated the collapse of the bridge. To achieve this critical goal, the investigation commenced with a thorough examination of the site investigation reports, coupled with an assessment of the bridge's adherence to the Indonesian design code applicable during its construction. Subsequently, the bridge underwent analysis based on the most recent Indonesian codes, taking into account the estimated ultimate load experienced at the time of the accident. To consider the possibility of preexisting defects that may have contributed to the collapse, a fatigue analysis was also conducted. To ensure a precise estimation of the traffic load, weight in motion (WIM) data was utilized in the fatigue analysis. Through this detailed examination, it was revealed that the collapse was most likely triggered by a combination of an overloaded truckload and accumulated fatigue damage prior to the accident. The knowledge gained from this investigation will undoubtedly contribute to the improvement of safety measures and engineering practices in the construction of bridges, ensuring a more secure infrastructure for Indonesia's transportation network. [ABSTRACT FROM AUTHOR]

The object of research is a civil mainline aircraft with a transonic truss-braced wing. The problem of designing an aircraft of this scheme at the preliminary design stage is being solved in the work. The results of the work include the concept of designing aircraft with a transonic truss-braced wing, the main advantages of such a scheme, the process of determining the geometric parameters of the truss-braced, features of the preliminary design of an aircraft with an extremely high aspect ratio truss-braced wing, possible approaches to the arrangement of units and their mutual arrangement. The results are explained by the difference in the design model (the cantilever beam is replaced by a beam on two supports) in mass analysis and the increased wing aspect ratio in aerodynamic calculation. The final data are based on a statistical study to determine the basic geometric parameters of assemblies of modern mainline passenger aircraft, synthesis of parameters of analog aircraft. For example, an aircraft capable of carrying 250 passengers over a distance of 13.000 km is considered. In the design process, values of aspect ratio, taper ratio, wing area, vertical tail and horizontal tail area ratio, and fuselage dimensions are accepted. Drawings of the general appearance of the aircraft have been developed and, based on it, a master geometry of the theoretical contour has been constructed. Graphs of first-order polar and maximum lift-to-drag ratio have been plotted, the reduction of aerodynamic drag in percentage terms has been determined, and the increase in aerodynamic lift-todrag ratio in percentage terms for an aircraft with an extremely high aspect ratio truss-braced wing compared to similar characteristics of an aircraft with a conventional non-braced wing has been calculated. The approximate mass savings when using a truss-braced wing on the aircraft are determined in percentage terms. The expediency of using wings of greater aspect ratio, than modern aircraft currently have, has been justified. The expediency of using a brace for the aircraft with an extremely high aspect ratio wing has been justified. The obtained results can be used in practice in the process of developing the preliminary design of an aircraft with a truss-braced wing or in the modifications of existing aircraft to increase their fuel efficiency or increase the durability of wing elements due to reduced loads acting on them. [ABSTRACT FROM AUTHOR]

Steel truss girder suspension bridges are gradually applied to long-span railway bridges. The fatigue damage correction factor is an important parameter for fatigue calculation, however the research on the coefficient is limited to small-span bridges. This paper analyzes force characteristics of main truss members, calculates the fatigue damage correction coefficient of truss members, and studies the influences of train loading length, annual traffic level of fatigue damage correction coefficient. The main conclusions are as follows: (1) The influence line and fatigue stress characteristics of the main truss members were studied; the stress range of members under tension or mainly under tension is analyzed, and the stress ranges and ratios between dead and live loads in main truss members are investigated. The results show that the maximum stress range of the bottom chord is 182 MPa, the ratios of dead to live loads of about 90 % of bottom chords and diagonal web members exceed the current specifications, and stress ratios of about 10 % of bottom chords and diagonal web members exceed the current specifications. (2) The fatigue damage correction coefficients of main truss members under different train loading lengths and annual traffic levels are calculated and recommended. The research results provide a basis for updating and supplementing the railway steel bridge code. [ABSTRACT FROM AUTHOR]

Continuous Warren truss steel railway bridges are one of the main forms of railway bridges. Due to the deterioration of materials and the long-term effect of loads, the bridges will inevitably experience performance degradation, which may lead to the failure of the bridge structure to continue to operate. In order to study the mechanical properties of steel structure bridges after material deterioration and long-term loads, a continuous Warren truss steel railway bridge that has been in operation for nearly 30 years (built in 1996) is used as the research object, and a combination of field tests and finite element (FE) simulations are used to carry out research on its mechanical properties under different loads. The research results show that after nearly 30 years of operation, the steel structure bridge has local damage, but the bearing capacity still meets the requirements of heavy-duty traffic. At this stage, the corrosion of the steel structure and the damage of the bearing should be repaired in time to prevent the damage from expanding. [ABSTRACT FROM AUTHOR]

Temperature-induced bridge responses are highly sensitive to changes in bridge properties. Thus, the relationship between temperature and associated responses can be used as a surrogate to assess the health of bridges. However, the relationship between temperature and temperature-induced displacement is influenced significantly by bridge bearing properties. The temperature variation cannot cause longitudinal displacements until the longitudinal restraint of bearings is overcome. Additionally, the temperature-induced strains highly depend on spatial temperature distributions in bridges. The developed mappings seldom consider the aforementioned issues, resulting in errors that can conceal the variation produced by the changes in bridge conditions. Focusing on long-span steel truss arch bridges with spherical bearings, this study seeks to accurately map the temperature-induced responses considering the bearing properties and spatial temperature distributions. The relationship between temperature variation and temperature-induced responses is explored initially using the elastic beam theory. Subsequently, the mapped relationship is validated using field monitoring data. Results show that the relationship produces unique flat planes in 3 D space; the plane parameters, including the orientation and boundary, are determined by the structural parameters, especially the bridge cross-section properties and bearing properties. Accordingly, the 3 D baseline can provide a feasible signature for bridge conditions. [ABSTRACT FROM AUTHOR]

Integral truss arch bridge over the A3 at the Fürth/Erlangen motorway junction – sustainability and efficiency achieved by combining traditional structural systems The widening of the A3 between the Fürth/Erlangen and Biebelried motorway junctions to six lanes prompted the construction of a 70 m flyover structure without any intermediate supports. From the submissions to a design competition, an integral truss arch bridge design was chosen for the structure. The innovative combination of arch and truss resulted in a highly efficient and robust structure and an extremely flat bridge spanning the motorway. All sustainability aspects were considered in the design – economic efficiency, durability, environmental friendliness and aesthetics. Innovative details such as linear drainage and an exceptional soffit with a special design of haunched precast elements resulted in maximum functionality and durability in addition to the beautiful design of the bridge. Due to its novel shape, which contributes to the variety in today's bridge construction, the structure was awarded the Deutscher Ingenieurpreis Straße und Verkehr in the category Baukultur. [ABSTRACT FROM AUTHOR]

The European railway network includes many steel truss girder bridges, often dating back to the end of the nineteenth century. Assessment by the partial factor method according to Eurocodes often reveals insufficient reliability of these bridges. In particular, they fail to satisfy the equilibrium limit state when a strong wind occurs simultaneously with an unloaded train crossing the bridge. To avoid unnecessary structural interventions and expensive traffic restrictions, representative types of these bridges are tested in a wind tunnel to refine the force coefficients of wind pressure for the specific shape of the bridge and selected types of lightweight train. The values of force coefficients based on wind tunnel tests correspond to 70–80% of those provided in EN 1991–1–4. Traffic flow records for the railway line under consideration are then utilised to obtain distributions of weights and heights of lightweight trains. Detailed probabilistic analysis focused on a long-span truss bridge with an intermediate bridge deck demonstrates that the reliability of this bridge is close to the target reliability level when wind tunnel force coefficients are considered along with site-specific free-field wind and railway traffic records. [ABSTRACT FROM AUTHOR]

Fatigue is an important issue for the failure of steel railway bridges. It is very challenging for a railway industry to regularly monitor the fatigue safety of millions of steel railway bridges in a cost-effective and easy way requiring the least worker effort and software expertise. This case study presents the fatigue life assessment (FLA) of an existing railway bridge in a simple and easy way. Microsoft Excel (for calculation of limit states of failure and fatigue life) and STAAD.Pro or similar structural analysis software (for modeling of the bridge truss) was used. A total station was used to ascertain the actual behavior of the bridge and to derive a correction factor. The various limit states of normal and shear stresses and strains in truss members and pot–polytetrafluoroethylene (PTFE) bearing components are addressed in a single procedure. The accuracy of the method was validated using a case study of a failed railway bridge. LVDT-based deflection measurements showed the accuracy of the adopted total station instrument–based experimental program. To check the fatigue safety of the bearing components, available equations from the literature were used to make the procedure easy and quick. In addition, the accuracy of the equations was ensured through a detailed numerical modeling of pot-PTFE bearings using finite-element modeling in Ansys. The results show that among the various limit states of normal and shear stresses and strains in truss members and bearing components, the shearing strain limit state of the elastomeric pad of the pot-PTFE bearings governs the fatigue life, which often is disregarded in usual FLA. The results indicate that the adopted method is cost- and time-effective. This case study presents a fatigue life assessment procedure executed on a real-life steel railway bridge. The procedure is quick, easy to implement, requires less funding and human effort, and can be used for many bridges. The adopted procedure requires only structural analysis software such as STAAD.Pro, MS Excel, and a total station surveying instrument. The total station surveying instrument is used to arrive at a corrected factor from the measured deflection values, which validates the analytical model of the steel bridge with the real-time behavior of the bridge at site. Skilled specialist human effort or software personnel with expertise in Ansys fatigue workbench, Abaqus, and UMAT interfaces are not required. The total station surveying–based approach quite accurately captured the failure of another real-life railway bridge, which failed in fatigue. The procedure is generic in nature and can be applied to other types of railway bridges with different types of bearings. The method can investigate the failure of stress- and strain-based fatigue failure of different bearing components and various limit states of truss or frame members in a single procedure in a computationally efficient way. [ABSTRACT FROM AUTHOR]

Resin sleeper is an important method to improve the quality of open deck structure, but the composite forming process and material characteristics have a direct impact on the service performance of sleepers. According to the characteristics of the open deck structure of resin sleepers, macro and micro finite element models of resin sleepers are established respectively based on ABAQUS and other simulation platforms. From the perspective of multi-scale simulation, the effects of composite material density, fiber bundle diameter, orientation and distribution on the bearing capacity and deformation of sleepers are studied. The results show that: Increasing the fiber bundle diameter and fully dispersing the fiber bundle can reduce the sleeper stress by 10%~30%; Changing the fiber orientation has a significant effect on improving the bearing capacity of sleepers. Optimizing the fiber distribution orientation can reduce the stress on the surface of sleepers by 20% ~ 30%; On this basis, a fiber bundle layering structure of "45°/0°/45°" is proposed. With this structure, higher bearing capacity can be obtained under the same deformation control level, which is 30% ~ 50% higher than the full section longitudinal layering scheme. The research shows that the bearing capacity of resin sleepers can be improved by making use of the material characteristics and optimizing the manufacturing process. [ABSTRACT FROM AUTHOR]

Propped cantilever truss is not a common bridge construction technique. The performance of such bridges under operational and extreme loading is not reported in the literature either. In this paper, failure mechanisms in a propped cantilever truss bridge are reported using field investigation. The field observations are supplemented by numerical analysis to identify the causes of failure. A a systematic account of damage mechanisms in bridge components is also reported. The failure of the Lamgadi Bridge over the Seti River in Nepal is used as a case study example. The loading and construction protocols are detailed, and numerical analysis results are juxtaposed with the field observations to explain the failure mechanisms. Field observations and numerical results show that lack in adequate design is the most likely cause of the bridge collapse. Numerical results also indicate that the roller support at the propped end, unlike the hinged pot bearing used in the as constructed bridge would have been a safer choice. The failure could have been easily prevented with proper numerical simulation of the bridge response during the design phase. [ABSTRACT FROM AUTHOR]

This paper presents an enhanced version of the Artificial Rabbit Optimization (ARO) algorithm designed for identifying structural damage in bridge structures. The original ARO draws inspiration from survival observed in wild rabbits. However, it demands a substantial investment of computational time. Therefore, in this paper, the Improved ARO (IARO) algorithm incorporating elements of the Grey Wolf Optimizer (GWO) through hybridization, is employed to deal with optimization problems. The central concept of this approach involves infusing predator-hunting characteristics into the prey-rabbit during the hunting process, thereby enabling more effective predator evasion. The proposed method is evaluated through a series of simulations related to two real bridges: a simple supported beam structure and a steel truss bridge. The results show a significant improvement in accuracy and efficiency in determining structural damage while considering factors such as damage location, severity, and computation time. These findings underscore the potential of the proposed approach for real-world applications in structural health monitoring and damage detection. [ABSTRACT FROM AUTHOR]

This study introduces a Radial Basis Function-Genetic Algorithm-Back Propagation-Importance Sampling (RBF-GA-BP-IS) algorithm for the multi-scale reliability analysis of Fiber-Reinforced Polymer (FRP) composite structures. The proposed method integrates the computationally powerful RBF neural network with GA, BP neural network and IS to efficiently calculate inner and outer optimization problems for reliability analysis with hybrid random and interval uncertainties. The investigation profoundly delves into incorporating both random and interval parameters in the reliability appraisal of FRP constructs, ensuring fluctuating parameters within designated boundaries are meticulously accounted for, thus augmenting analytic exactness. In application, the algorithm was subjected to diverse structural evaluations, including a seven-bar planar truss, an architectural space dome truss, and an intricate nonlinear truss bridge. Results demonstrate the algorithm's exceptional performance in terms of model invocation counts and accurate failure probability estimation. Specifically, within the seven-bar planar truss evaluation, the algorithm exhibited a deviation of 0.08% from the established failure probability benchmark. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle (UAV) remote sensing technology is vigorously driving the development of digital cities. For experimental objects such as large, protruding, and structurally complex steel truss railway bridge structures, commonly used oblique photography and cross-circular photography techniques can lead to blurring, missing, or lower accuracy of fine texture in the models. Therefore, this paper proposes a real-scene three-dimensional modeling method that combines oblique photography with inclined photography and compares it with oblique photography and cross-circular photography techniques. Experimental results demonstrate that the model generated by combining oblique photography with inclined photography exhibits clearer textures, more complete lines, and higher accuracy, meeting the accuracy requirements of 1:500 topographic map control points. This method plays a beneficial auxiliary role in the inspection of ailments such as steel structure coating corrosion and high-strength bolt loss in steel truss railway arch bridges. [ABSTRACT FROM AUTHOR]

The Port Authority of New York and New Jersey's Bayonne Bridge crosses the entrance to the ports of Newark and Elizabeth, NJ, USA. The longest steel truss arch span in the world when it opened in 1931, the bridge was designed by Othmar Ammann. To maintain the economic vitality of the ports, the original 46 m navigational clearance needed to be raised to 65.5 m in order to accommodate mega container ships passing through the newly widened Panama Canal. Precast concrete segmental construction was used along with an innovative staged construction approach to avoid long-term bridge closures and to expedite the construction schedule. The new navigational clearance was attained in 2017 and project completion occurred in mid-2019. [ABSTRACT FROM AUTHOR]

To enhance the safety management of steel-truss-bridge construction, an evaluation method based on the improved DEMATEL–ISM was proposed to analyze the risk factors involved in such construction. Decision Making Trial and Evaluation Laboratory (DEMATEL) is a method for systematic factor analysis that utilizes graph-theory and -matrix tools, allowing for the assessment of the existence and strength of relationships between elements by analyzing the logical and direct impact relationships among various elements in a system. The distinctive feature of Interpretative Structural Modeling (ISM) is the decomposing of complex systems into several subsystems (elements) and constructing the system into a multi-level hierarchical structural model through algebraic operations. Specifically, triangular fuzzy numbers are introduced initially to improve the direct influence matrix in the DEMATEL method, thereby reducing the subjectivity of expert evaluations. The degree of influence, influenced degree, centrality degree, and causality degree of each influencing factor are determined and ranked based on the above analysis. In response to the characteristics of top-push construction, 20 key factors were selected from four aspects: "human, material, environment, and management". The top five identified influencing factors are displacement during pushing (X10), safety-management qualification (X18), local buckling (X14), overturning of steel beams (X13), and collision with bridge piers during guide beam installation (X7). Subsequently, corresponding solutions were proposed for different influencing factors. The results of the study offer targeted measures to enhance the safety management of steel truss bridge construction and provide a reference for accident prevention. [ABSTRACT FROM AUTHOR]

A diaphragm is an essential component of a T-girder bridge. Evaluating the influence of various truss diaphragms (TDs) on the structural behavior and load distribution factor of T-girder bridges assists in bridge design and strengthening. In this study, a series of experiments and simulations were conducted to investigate the strengthening effect of two types of TDs (i.e., triangle-TDs and K-TDs) based on a small-scale T-girder bridge model. Formulas for the flexural rigidity of the two types of TDs were proposed and verified by using rigid-joint girder methods, experiments, and simulations. Then, taking the K-TD as an example, the calculation method for the stiffness of the truss was analyzed and derived based on rigid-joint girder and graphic multiplication methods. The results showed that K-TDs had a better strengthening effect than triangle-TDs. The deflection and strain of the K-TD-strengthened T-girder bridge were reduced by 21% and 16%, respectively, compared with those of the triangle-TD-strengthened bridge. The formulas for flexural rigidity were proposed and used to calculate the load distribution factor. The maximum error of the calculated load distribution factor was 16% compared with the simulation and experimental results. Moreover, the calculation method for the stiffness of the K-TDs was analyzed and obtained. Deterioration of multigirder bridges is getting worse due to the increasing traffic load and insufficient maintenance. Adding diaphragms to the existing bridges can improve the load distribution of multigirder bridges and reduce the maximum load of the girders. This work evaluated the influence of two types of truss diaphragms (triangle truss diaphragm and K truss diaphragm) on the load distribution of a T-girder bridge, and the results showed that the two types of truss diaphragms can reduce the maximum deflection and strain in the T-girder bridge effectively. The flexural rigidity formulas for the two types of truss diaphragm were proposed and proved to be accurate by comparing with experiments and finite-element methods. Moreover, the truss stiffness of the K truss diaphragm was derived by a graphic multiplication method. These formulas can be used by bridge engineers for new bridge designing or existing bridge strengthening in practical engineering. [ABSTRACT FROM AUTHOR]

Complex grid-like structures such as steel truss bridges and steel truss roofs commonly exist in civil engineering applications. Since these structures are usually subject to dynamic operational forces, faults like chemical corrosion, fatigue crack, and bolt loosening arise, and seriously affect structural health. To consider some issues in existing frequency domain fault evaluation methods like applicability for complex structures, requirement of baseline data, neglect of nonlinear boundaries, and localization of local faults, a novel method using nonlinear vibration features and Euclidean distance measurement is presented in this paper. Firstly, complex grid-like structures are decomposed into a series of simple T-type substructures according to structural characteristics and load paths. Secondly, related T-type multi-degree-of-freedom model is built by simulating potential faults and nonlinear boundaries as related nonlinear damper-spring connections. Thirdly, exciting the model and extracting output responses only, novel and local fault features, which are functions of structural properties, nonlinear fault-induced loads and transmissibility functions, are defined. Then, utilizing defined features from the local substructure to be evaluated only, a novel fault index is defined with Euclidean distance measurement. Finally, corresponding evaluation method is developed, and its effectiveness and applicability are demonstrated by comparative studies on a lab bolted grid-like structure. [ABSTRACT FROM AUTHOR]

Convolutional neural networks (CNN) are widely used for structural damage identification. However, the presence of environmental disturbances introduces noise into the acquired acceleration response data, impairing the performance of CNN models. In this study, we apply empirical mode decomposition (EMD) and variational mode decomposition (VMD) to denoise the data from a steel truss bridge. By comparing the smoothness and convergence of the obtained modal functions (IMFs) using EMD and VMD, we confirm the effectiveness of VMD in smoothing and denoising the bridge structure signals. Additionally, we propose a convolutional self-attention neural network (CSANN) model to extract features and identify damage in the denoised data using VMD. Comparative analysis of the CNN, LSTM, and GRU models reveals that the VMD-CSANN model outperforms the others in terms of damage localization and identification accuracy. It also exhibits excellent performance when handling noise-contaminated data with a noise level of 10%. These findings demonstrate the efficacy of the proposed method for identifying internal damage in steel truss structures, while maintaining smoothness and robustness during processing. [ABSTRACT FROM AUTHOR]