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This paper presents an in-depth analysis of the mechanical behavior and joint shear capacity optimization of segmental U-shaped bridges, with a focus on the application of precast segmental techniques in the construction of U-beam bridges widely used in urban rail transit networks. This study further explores the roles of key position distribution and size in the overall stability and service behavior of such structures. Considering the critical case study of the Colombia Bogotá Metro Line 1 project, finite element modeling was carried out using ABAQUS 6.14 to simulate concrete material behaviors and to evaluate the stress–strain relationship in accordance with the concrete plastic damage model and existing standards. This research identifies the significant contribution of keys in minimizing deformation and enhancing shear capacity, demonstrating the pivotal influence of shear key design on the mechanical behavior of segmental bridges. By calculating the shear capacity under different cases, this study provides recommendations on key distributions and dimensions that optimize joint shear capacities, indicating that augmenting key size within the web plate section decisively reinforces the bridge’s mechanical resilience.

This study investigates the mechanical performance of resistance spot-welded titanium lap joints made of Grade 1 and Grade 5 alloys. Experimental tests were combined with artificial neural network modeling to predict joint load-bearing capacity based on welding current and welding time. Three models were developed for Grade 1/Grade 1, Grade 1/Grade 5, and Grade 5/Grade 5 joints. The mixed Grade 1/Grade 5 joint achieved the highest predictive accuracy, with an R2 value of 0.9289. Statistical evaluation confirmed high model reliability, with mean relative errors between four and six percent. The most accurate model was optimized using a genetic algorithm. The algorithm identified an optimal parameter set consisting of a welding current of 2.89 kA and a welding time of five pulses. This configuration produced a predicted load-bearing capacity of 3.2 kN, which meets the required threshold of three kilonewtons. Contour maps showed that the optimal point lies near the boundary of the high-strength region and corresponds to the lowest welding current and shortest welding time that still ensure sufficient joint quality. The results demonstrate that combining neural network modeling with evolutionary optimization is an effective approach for designing efficient welding processes for dissimilar titanium joints.

This study explores the tensile performance of blind rivet joints in galvanized steel sheets, focusing on their behavior under shear and normal load conditions. Blind rivets are frequently used in structural applications due to their ease of installation and ability to be applied from one side, making them highly effective in industries like aerospace and automotive. Two types of DIN 7337—4.8 × 8 blind rivets—galvanized steel St/St and stainless steel A2/A2—paired with galvanized steel sheets DX51D + Z275, were experimentally tested to assess how their material properties affect their joint strength, deformation patterns, and failure modes. Single-lap shear, double-lap shear, and pure normal load tests were conducted in multiple configurations to evaluate joint performance under varying loading conditions, simulating real-world stresses. Using custom-built equipment, controlled forces were applied perpendicular to the rivet joints to replicate practical loading conditions. The results revealed distinct differences in the load-bearing capacities of the two materials, offering valuable insights for applications where corrosion resistance and structural integrity are critical. Finite element analysis (FEA) was then used to simulate the behavior of the joints, with the results validated against experimental data. To enhance the reliability of numerical simulations in optimizing the design of rivet joints, a methodology was proposed to calibrate non-linear FEA models to experimental results, and a substantial agreement of 92.53% was achieved via optimization in ANSYS OptiSLang. This research contributes to our broader understanding of riveted connections, providing practical recommendations for assessing the performance of such joints in various engineering fields.

Basalt fiber-reinforced polymer (BFRP) composites are increasingly utilized in photovoltaic mounting systems due to their excellent mechanical properties and durability. Bolted connections, valued for their simplicity, ease of installation, and effective load transfer, are widely employed for joining composite components. An orthogonal experimental design was adopted to investigate the effects of key parameters—including bolt end distance, number of bolts, bolt material, bolt diameter, preload, and connection length—on the load-bearing performance of three bolted BFRP plate configurations: lap joint (DJ), single lap joint (DP), and double lap joint (SP). Test results showed that the DJ connection exhibited the highest average tensile load capacity, exceeding those of the SP and DP connections by 45.3% and 50.2%, respectively. This superiority is attributed to the DJ specimen’s longer effective shear length and greater number of load-bearing bolts. Conversely, the SP connection demonstrated the largest average peak displacement, with increases of 29.7% and 52.9% compared to the DP and DJ connections. The double-sided constraint in the SP configuration promotes more uniform preload distribution and enhances shear deformation capacity. Orthogonal sensitivity analysis further revealed that the number of bolts and preload magnitude significantly influenced the ultimate tensile load capacity across all connection types. Finally, a calculation model for the tensile load capacity of bolted BFRP connections was established, incorporating a friction decay coefficient (α) and shear strength (τ). This model yields calculated errors under 15% and is applicable to shear slip-dominated failure modes, thereby providing a parametric basis for optimizing the tensile design of bolted BFRP joints.

Testing shear-resisting plates in steel connections is one of the most challenging laboratory undertakings in steel construction, as the most common experimental layout design includes simulating the connection with its adjoining members. This significant hindrance gained particular magnitude as the need to test prototypes of topologically optimised shear cover plates became more pressing. Indeed, new code-compliant topology optimisation approaches for steel construction have recently been offered, and physically non-linear analyses have been demonstrated to be vital for assessing these elements. Hence, a rapid and reliable experimental process has become a fundamental necessity. To answer this need, a novel layout is herein proposed, in which topologically optimised and previously numerically examined bolted shear plates of a well-known steel joint were tested. The results allowed for the definition of the material trilinear model for use in subsequent numerical analysis, as well as the validation of the numerical simulation results. The discrepancy between the previously mathematically anticipated and empirically determined ultimate resistance did not exceed 1.7%.

This study presents a comprehensive design and calculation methodology for prefabricated expansion foundations of onshore wind turbines, addressing the critical need for modular construction while ensuring structural integrity. The proposed approach encompasses both overall structural performance verification and connection joint design, considering the stiffness reduction effects of modularization. A novel punching shear capacity checking method is developed specifically for assembled expansion foundations, incorporating joint weakening factors. The research establishes equilibrium equations and verification formulas for splice joints under different loading conditions, demonstrating that the shear amplification factor at joints varies with local compressive stress. The analytical results demonstrate several key findings: (1) the derived maximum joint shear formula shows excellent agreement with finite element results across various load conditions (R2 = 0.99906); (2) the optimized shear key configuration increases the joint’s load-bearing capacity by 35% compared to conventional designs; and (3) the developed Python-based calculation system reduces the design time by 60% while maintaining accuracy within 5% of detailed FEM analysis. These quantitative outcomes validate the effectiveness of the proposed methodology and provide practical guidelines for implementing modular construction in wind energy infrastructure.

Resistance spot welding (RSW) is one of the most relevant industrial processes in different sectors. Key issues in RSW are process control and ex-ante and ex-post evaluation of the quality level of RSW joints. Multiple-input–single-output methods are commonly used to create predictive models of the process from the welding parameters. However, until now, the choice of a particular model has typically involved a tradeoff between accuracy and interpretability. In this work, such dichotomy is overcome by using the explainable boosting machine algorithm, which obtains accuracy levels in both classification and prediction of the welded joint tensile shear load bearing capacity statistically as good or even better than the best algorithms in the literature, while maintaining high levels of interpretability. These characteristics allow (i) a simple diagnosis of the overall behavior of the process, and, for each individual prediction, (ii) the attribution to each of the control variables—and/or to their potential interactions—of the result obtained. These distinctive characteristics have important implications for the optimization and control of welding processes, establishing the explainable boosting machine as one of the reference algorithms for their modeling.

Mortise-and-tenon (M–T) joint is a traditional joint type commonly used in wood constructions and wood products. Bending moment capacity (BMC) is a critical criterion to evaluate the strength of the M–T joint. In order to design the M–T joint structure more rationally, many researchers have been devoted to studying on this topic. However, the factors influencing the BMC are too many to conduct comprehensive studies using experimental tests, especially for tenon size. In this study, the BMC and bending stiffness of the M–T joint were studied using a combination of finite element method (FEM) and response surface method to optimize the tenon size of the M–T joint. The results showed that (1) the proposed finite element model was capable of predicting BMC of M–T joints with the ratios of FEM to observed, ranging from 0.852 to 1.072; (2) the BMC and stiffness were significantly affected by tenon size, and tenon length had a more significant effect on BMC than tenon width, while the tenon width affected the bending stiffness more significantly; (3) the response surface model proposed to predict and optimize the BMC of the M–T joint relating to tenon length and tenon width was capable of providing an optimal solution; (4) it was recommended to make the ratio of tenon length to tenon width higher than 1 to get higher BMC of M–T joints. In conclusion, this study will contribute to reducing the cost of a huge amount of experimental tests by applying FEM and the response surface method to design M–T joint wood products.

In view of the problems of traditional repair materials for anchorage concrete of expansion joints, such as ease of damage and long maintenance cycles, the design of polyurethane concrete was optimized in this article, which could be used for rapid repair of concrete in anchorage zone of expansion joints. A new type of carbon fiber grid–polyurethane concrete system was designed, which makes the carbon fiber grid have an excellent synergistic effect with the quick-hardening and high-strength polyurethane concrete, and improved the flexural bearing capacity of the polyurethane concrete. Through the four-point bending test, the influence of the parameters such as the number of grid layers, grid width, and grid density on the flexural bearing capacity of polyurethane concrete beams was tested. The optimum preparation process parameters of carbon fiber grid were obtained to improve the flexural performance of polyurethane concrete. Compared with the Normal specimen, C-80-1’s average flexural strength increased by 47.7%, the failure strain along the beam height increased by 431.1%, and the failure strain at the bottom of the beam increased by 68.9%. The best width of the carbon fiber grid was 80 mm, and the best number of reinforcement layers was one layer. The test results show that the carbon fiber grid could improve the flexural bearing capacity of polyurethane concrete. The carbon fiber grid–polyurethane concrete system provides a new idea for rapid repair of the anchorage zone of bridge expansion joints, and solves the problems such as ease of damage and long maintenance cycles of traditional repair materials, which can be widely used in the future.

The punching shear performance of reinforced concrete (RC) slab–column joints with shearhead reinforcement was investigated to optimize shearhead reinforcement design. Nine slab–column joint specimens were designed with different flange thicknesses, web thicknesses, cantilever lengths, and anchor stud sizes. The specimens were subjected to reversed static loading tests to investigate their failure history and failure modes; measure the load capacity, deformation, and strain of the joints; investigate the influence of different design combinations on the punching shear failure mode and load capacity of the joints; and elucidate their failure mechanisms. Test simulation analysis and numerical parametric analysis were conducted based on the test results. The results showed that the shearhead enhanced the punching shear performance of the slab–column joint and improved the brittleness of the punching shear failure. Installing steel section flanges and anchor studs enhanced the synergy among the longitudinal reinforcement, steel section, and concrete in the joint, and increasing the web thickness and installing flanges both improved the punching shear capacity and ductility of the joint. The installation of flanges on the web of the steel section increased the ultimate load capacity by more than 40% and increased the mid-span displacement at failure by more than twice that of the specimen without flanges and the specimen with studs. Adding anchor studs to the web of the steel section increased the ultimate punching shear capacity of the RC slab–column joint by 25%. Using anchor bolts instead of flanges improved the punching shear capacity of the joint but was not as effective in improving ductility. Increasing the flange thickness to increase the load capacity had a marginal effect; the ultimate load capacity increased by only 7% when the web area increased by 2/3, and the shearhead did not enhance punching shear capacity if the cantilever of the steel section was too short. Finally, based on the existing code, test results and numerical parametric analysis results, a method for calculating the punching shear capacity of RC slab–column joints with shearhead reinforcement was proposed.