Structural Engineering

This study aims to optimize reinforced concrete (RC) bridge decks using the Leonhardt and Makowski method. A MATLAB based GUI for live load distribution analysis was developed, allowing users to observe the impact of varying design parameters like span, slab thickness, and deck width. The analysis will follow BS5400 provisions, focusing on HA and HB loading combination. The methodology involved creating a MATLAB program that integrates the Leonhardt method into an interactive GUI and MATLAB scripts to run batch inputs. This tool validates user inputs, apply load cases (UDL, KEL, HB vehicle loads), compute section properties, and generate both tabular and graphical outputs (e.g., bending moment diagrams). To verify accuracy, results from manual calculations for bridge of span 25m, deck width of 11m and slab thickness 230mm was compared. The MATLAB tool is showed strong agreement with both manual calculations with 0.002% difference while the percentage difference compared to the STAAD.Pro analysis was 2.97% when computing the maximum longitudinal bending moments. The parametric study showed that the maximum moments appeared on the first support. The tool created will be able to provide engineers and students a flexible environment to explore design alternatives and understand how the inputs influence bridge behavior. Although the MATLAB GUI developed in this study performed excellently when compared to manual calculation, more comparative testing with other load distribution methods and with finite element based tool to further test the accuracy of the study.

This study examines how curing reinforced concrete in a urea-salt solution, which simulates urine, affects its compressive strength and durability. This is compared to concrete cured in fresh water. The research addresses concerns about the decline of concrete structures in environments that are biologically or chemically harsh, such as areas often contaminated by urine. Understanding the impact of such exposure on concrete performance is important for improving the design and maintenance of durable structures under these conditions. The experimental work involved casting twenty concrete cubes, each measuring 100 × 100 × 100 mm, using a mix ratio of 1:2:4 and a water-cement ratio of 0.5. Ten cubes were cured in fresh water, while the other ten were cured in a urea-salt solution made with 10 g of urea and 2 g of sodium chloride (NaCl) per liter of water. The cubes were tested for compressive strength after 14 and 28 days of curing using a compression testing machine. The data gathered were analyzed and compared to evaluate the impact of the urea-salt solution on concrete performance. The average compressive strengths were 18.81 N/mm² and 23.17 N/mm² for the 14- and 28- day fresh-water samples, and 18.15 N/mm² and 17.81 N/mm² for the urea-salt-cured samples which indicates that concrete cured in fresh water showed normal strength growth with age. In contrast, the concrete cured in the urea-salt solution had a slight decrease in compressive strength over time. It was concluded that exposure to the urea-salt solution restricts full hydration and weakens concrete durability with extended contact. It is advised that structures in areas prone to urine contamination be shielded from direct exposure.