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Efficient Load-Bearing Capacity Assessment of a Degraded Concrete Manhole Using Sectional Homogenization
This study addresses a practical and efficient approach to evaluating the load-bearing capacity of severely degraded concrete manholes. Concrete deterioration, often advanced and highly irregular, can be captured accurately through surface scanning to create a detailed model of the damaged structure and also to build a simplified modeling to enable rapid engineering-level assessment, filling a critical gap in infrastructure maintenance. The repair strategy involves applying an internal polyurea layer, a variable-thickness polyurethane foam layer depending on the degree of localized degradation, and an external polyurea layer to restore the original shape of the manhole. However, these repairs do not fully restore the manhole’s original load-bearing capacity. A full 3D model, encompassing millions of finite elements, would provide a detailed analysis of strength reductions but is impractical for engineering applications due to computational demands. An alternative approach utilizing sectional homogenization is proposed, where sectional properties are sequentially averaged to calculate effective parameters. This approach enables the use of only a few hundred shell elements, each representing thousands of elements from the detailed 3D model, thus providing a rapid, engineering-level assessment of load-bearing reductions in degraded manholes. The study finds that while the repair method restores up to 76% of bending stiffness in heavily corroded sections, it does not fully recover the original load-bearing capacity.
Optimal Design of Rectangular Tank Walls With Ribs Using Numerical Models and Global Optimization
This paper addresses the optimization of the cross-section in rectangular above-ground tank walls, incorporating vertical ribs and an optional top ring. The objective is to minimize the volume of concrete used, while maintaining key performance criteria such as keeping the maximum tensile stress below the material’s allowable limit and minimizing deflections. The analysis is performed using the finite element method (FEM), with the optimization handled through a local gradient-based algorithm (trust region method), supported by a multistart technique to navigate the complexity of the design space and avoid suboptimal solutions. The results demonstrate that this approach effectively reduces concrete consumption without exceeding the tensile stress limits or causing excessive deflection, offering more efficient and cost-effective designs for rectangular tanks used in water storage applications. This method provides valuable insights into the balance between material usage and performance constraints, contributing to sustainable engineering practices.