http://hdl.handle.net/20.500.14044/33845 Mon, 20 Jul 2026 20:07:58 GMT 2026-07-20T20:07:58Z http://hdl.handle.net/20.500.14044/33782 Robust Optimization of the Steel Single Story Frame Zabojszcza, Paweł; Radoń, Urszula; Tauzowski, Piotr In contemporary design practices, building structures are expected to not only meet safety requirements but also be optimized. However, optimal designs can be highly sensitive to random variations in model parameters and external actions. Solutions that appear effective under nominal conditions may prove inadequate when parameter randomness is considered. To address this challenge, the concept of robust optimization has been introduced, which extends deterministic optimization formulations to incorporate the random variability of parameter values. In this study, we demonstrate the applicability of robust optimization in the design of building structures using a simple orthogonal frame as an example. The static-strength analysis is conducted based on the displacement method, utilizing second-order theory. To assess the safety level of the steel frame, a preliminary evaluation is performed by determining the reliability index and failure probability using the Monte Carlo Method. Robust optimization is then employed, leveraging the second-order response surface. Experimental designs are generated following an optimal Latin hypercube plan. The proposal of a mathematical-numerical algorithm for solving the optimization problem while considering the random nature of design parameters constitutes the innovative aspect of this research. Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/20.500.14044/33782 2024-01-01T00:00:00Z http://hdl.handle.net/20.500.14044/33781 Dynamic Analysis of Geosynthetic-reinforced Pile-supported Embankment for a High-Speed Rail Alsirawan, Rashad; Koch, Edina Geosynthetic-Reinforced-Pile-Supported (GRPS) embankments are a trustworthy option ideal to support the railways over soft soils. They are widely used for the time-bound infrastructure projects. The majority of earlier research concentrated on the analysis of the GRPS embankments under static loads while the studies on the behavior of these constructions under dynamic loads are scarce. The fundamental purpose of this study has been to better comprehend the dynamic behavior of GRPS embankments in terms of stresses and settlements distribution via 3D modeling employing the finite element method (FEM). The advanced constitutive model of Hardening soil with small-strain stiffness was utilized to simulate the behavior of the soils under dynamic loads and the train load was modeled according to the recommendations of LM71 Eurocode. The results indicate to the contribution of the piles and geosynthetic reinforcement in the decrease of the settlements. The behavior of settlements and stresses under static and dynamic loads is similar. The load efficiency of the piles decreases during the passage of the train remarkably. The train speed affects obviously on the behavior of the GRPS embankment. Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/20.500.14044/33781 2024-01-01T00:00:00Z http://hdl.handle.net/20.500.14044/33779 The Analysis of High-Speed Railway Seismic- induced Track Geometric Irregularity Li, Guolong; Yang, Fei; Gao, Mangmang; Sun, Wentao; Qu, Xiangyu The high-speed railway in China passes through various seismic zones. As the track geometric irregularity is a critical aspect impacting train operation safety and train- induced vibration, it is meaningful to investigate the influence of earthquakes on the seismic-induced track geometric irregularity of high-speed railways. To determine the impact of earthquakes on track conditions, a complete study was conducted using various earthquake magnitude levels (3.0 to 7.0), varied limiting train speeds, and different track structural types (ballasted and ballastless track). The track quality index, long-wave irregularities, 10 m chord measurement, and vehicle vibration are analysed to suggest the change of track geometric irregularity and its influence after the earthquake. At the same time, the vehicle-track analysis model is used to calculate the difference in vehicle vibration under different seismic-induced track conditions. The vehicle acceleration, the rate of wheel load reduction, derailment coefficient indicators are investigated. These results imply that earthquakes have an impact on high-speed railways, causing track geometric irregularities to shift, which may contribute to increased vibration while trains are running. Compared to the ballasted track, whose normal speed is 250 km/h, the ballastless track, whose nominal speed is 350 km/h, was affected by the earthquake less. According to data, earthquakes have an influence on long waves greater than 1 m. While small and moderate earthquakes have a minor effect on railway safety, they do have an effect on train operating comfort because vehicle vibration is amplified as a result of the seismic-induced track geometric irregularity being worse. Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/20.500.14044/33779 2024-01-01T00:00:00Z http://hdl.handle.net/20.500.14044/33778 Investigation of Rail Welded Joint Stresses, by using a Narrow Gap Welding Method, in Ballasted Railway Tracks Galdiani, Milad Alizadeh; Mosayebi, Seyed Ali; Mohit, Ali In the modern railway superstructure construction and maintenance, particularly where higher speeds are required, the rail sections may be welded together to form Continuous Welded Rail (CWR). There are various methods for welding the rails, such as thermite welding, flash-butt welding, gas-pressure welding, enclosed-arc welding, etc. Narrow Gap Welding is another way of welding the rail joints and because of the lower implementation costs, easier, quicker process and acceptable performance, it is usually used over other methods in maintenance operations. Since this method is newer than others, there is lack of knowledge concerning the standard process of narrow gap welding and the factors that affect the final quality. In the narrow gap welding, two different welding electrodes are used for the welding process. One electrode, with higher stiffness, is used for the rail head and the other electrode, with lower stiffness, is used for the rail web and foot. In this research, the relationship between these different welding electrodes and the amount of stress in rail joint was investigated via experiments and modeling, by a finite element method. The results indicate that the number of stresses, in the junction of rail head and web, was reduced by 37%, when the electrode with higher stiffness was used for the whole rail head, plus 1 cm of rail web. Field investigations demonstrated that the performance of rail welds was acceptable. Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/20.500.14044/33778 2024-01-01T00:00:00Z