Finite element analysis is used to examine the buckling properties of rectangular plates with full and partial longitudinal and transverse stiffeners under in-plane uniaxial edge loadings. Various edge-loading scenarios have been examined, and whenever feasible, comparisons with previously published findings have been made. When calculating the initial stresses, pre-buckling conditions are considered. For varying plate aspect ratios, edge circumstances, and partial stiffener arrangements, buckling load parameters are calculated. The proposed analysis establishes the load parameter throughout the region for various loading and edge circumstances, as well as the position, configurations, and combinations of stiffeners. The plate and the stiffeners are regarded as distinct pieces in the structural modelling, and their integration is preserved. The results are contrasted with those found in the literature, and the buckling parameter is addressed. Stiffeners help the plate stay stable and avoid buckling for different stiffener case positions and arrangements in different mode shapes, according to the results of the buckling parameters.
This study investigates the applicability of the miniature compression test (MCT) for evaluating the yield strength of existing steel bridges. Preliminary tests were conducted to compare standard tensile tests with MCTs, confirming that the latter can reproduce the characteristic yield behavior, including upper and lower yield points. Material tests using MCT specimens extracted from existing bridges revealed that the measured yield strength was approximately 1.1–1.2 times higher than the specified minimum yield strength. Based on these results, a preliminary empirical correction factor of 1.084 was derived for the investigated material to convert the MCT results into equivalent tensile yield strength. Furthermore, structural performance was evaluated by applying the corrected yield strength to load-carrying capacity calculations. The results indicate that the influence of yield strength on load-carrying capacity differs between positive and negative bending regions, with a more pronounced effect observed in the negative bending region. These findings demonstrate that the MCT provides a practical and reliable method for strength evaluation of existing steel bridges.
Different software platforms may influence the surrogate model’s comparison and evaluation results. To overcome this challenge, this paper develops a unified surrogate modeling framework to predict the structural responses of a steel box girder bridge under moving-load analysis, ensuring consistency in both data generation and model assessment. Numerical simulations are conducted in MIDAS Civil to generate datasets of bridge’s deflection and combined stresses under variations in uniformly distributed and concentrated loads, as well as their simultaneous changes. Based on identical datasets, deep neural network, polynomial chaos expansion, and Gaussian process, are constructed and implemented within COMSOL for a consistent comparison. The models’ performance is quantified using the mean absolute error, root mean square error, and coefficient of determination. Bridge structural responses under moving-load analysis are effectively captured by all three surrogate models. The Gaussian process model performs best for single-parameter variations, while the polynomial chaos expansion model is more robust for multi-parameter cases. Stress responses are more sensitive to prediction errors than deflection. The proposed framework serves as a valuable benchmark for surrogate modeling-based prediction of bridge structural responses.
Many cast-in-place reinforced concrete box culverts in Louisiana were built using outdated standard plans originated from the 1940s and updated in the 1970s. These culverts often yield low load rating factors when evaluated using current AASHTO procedures. Despite this, they performed satisfactorily overtime with minimal signs of distress. Simple 2D frame element models are commonly used for structural analysis of typical box culverts due to their ease and speed. However, they tend to produce more conservative load rating results compared to complex modeling techniques like 3D plate element models. A parametric study was conducted using 120 3D finite element culvert models in various configurations, along with corresponding 2D frame element models. Correction factors were developed to correlate moment values from 3D and 2D analyses. Field testing of representative culverts was also performed to validate the analytical models. The study considered two types of wall-slab connections: pinned and moment connections. The results indicate that using moment connections, an at-rest lateral earth pressure coefficient, k o of 0.50, and the 3D-2D correction factor, yields more realistic load rating values that reflect field conditions. The study’s findings were used to develop guidelines for load rating reinforced concrete box culverts in Louisiana, which can also be applied to similar culverts elsewhere.
The utilization of intermediate diaphragms (IDs) in precast concrete (PC) I-girder bridges has been a topic of debate among researchers for decades, with its effectiveness remaining a subject of controversy. Nevertheless, the consideration of IDs is an essential aspect of engineering practice, making it crucial to explore their role in live load moment distribution. This study delves into the application of concrete IDs, examining the impact of various finite element modeling practices and key parameters on their effectiveness. A sensitivity study was conducted to compare the efficacy of grillage, planar, and solid models in determining the suitable modeling approach for straight, skewed, and curved deck bridges equipped with IDs. To optimize modeling practices, a further investigation was undertaken to evaluate the influence of different parameters on the role of IDs, including the presence of IDs, the rigidity of connections between IDs and girders, and several geometric parameters related to the bridge span layout. The live load moment envelope of girders was chosen as the response indicator to evaluate the role of IDs. The findings of the parametric study revealed that the removal of IDs leads to an increase in the midspan moment of the interior girders, while the midspan moment of the exterior girders decreases. Furthermore, it was found that the rigidity of connections between IDs and girders, girder spacing, and span length significantly influence the role of IDs in PC I-girder bridges.
