Thomaz Eduardo Teixeira Buttignol

Hydrodynamic cavitation erosion remains a critical durability problem for hydraulic concrete structures, yet its resistance is still often inferred from test methods that do not fully represent flow-driven damage. This study evaluates the cavitation-erosion performance of conventional concrete (CC), ultra-high-performance concrete (UHPC), and ultra-high-performance fiber-reinforced concrete (UHPFRC) using a calibrated cavitation-jet apparatus designed to provide repeatable, flow-representative loading. Erosion was quantified through cumulative mass loss and maximum cavitation erosion depth, and damage evolution was analyzed using replicate-level time series, Weibull growth models, and mixed-effects regression.The results reveal a distinct performance hierarchy. CC exhibited the fastest damage growth and the largest characteristic damage magnitudes, with mean mass loss and erosion depth of 60.1 g and 22.3 mm, respectively, whereas UHPC and UHPFRC remained within 21-39 g and 10.8-16.1 mm. The Weibull time-scale parameter was consistently larger for UHPC and UHPFRC, indicating slower damage onset, while the shape parameter remained above unity in most mixtures, confirming accelerating erosion with exposure time. Among the investigated mixtures, the most resistant systems were the dense UHPC mixes and the best-performing fiber-reinforced mixtures; however, no single fiber family dominated both mass-loss and penetration-depth metrics, so the preferred mixture depends on the target damage indicator.The statistical analysis indicates a weak, mixture-specific association between compressive strength and cumulative mass loss under the tested loading condition, but it does not show a reliable link between bulk strength and maximum erosion depth. Overall, the cavitation-jet apparatus provides a repeatable basis for comparing mixtures under the present hydraulic condition. Within this dataset, the dense UHPC mixtures and the better-performing fiber-reinforced mixes showed the highest cavitation resistance, but the ranking should be interpreted as specific to the tested materials and loading history. The results therefore support a controlled laboratory comparison rather than a universal ranking of all cementitious systems.

This article examines the behavior of reinforced‐concrete pile caps on two piles under concentric and eccentric loading, with emphasis on the influence of horizontal and vertical supplementary reinforcement on load‐carrying capacity. Although the Strut‐and‐Tie method does not include this reinforcement in the internal equilibrium, it was found to play an important role in crack control and ductility. The study comprised two stages: calibration of three‐dimensional nonlinear numerical models using experimental tests, and a parametric analysis varying the amount and spacing of supplementary reinforcement. The results show that increasing this reinforcement enhanced strength, reduced crack widths, and improved overall structural performance. Eccentric loading decreased load capacity, but the additional reinforcement mitigated this loss, leading to better performance under different loading conditions.

This paper investigates the shear behavior of steel fiber-reinforced concrete (SFRC) beams made of conventional concrete (CC) with natural aggregate and with 50% replacement using coarse recycled aggregate concrete (RAC). The experimental program comprised 12 simply-supported beams without transverse reinforcement, with depths of 300, 400, and 500 mm, tested under four-point bending and designed to failure in shear. For each beam height, two nominally identical beams were tested, considering both conventional and recycled aggregates. The material characterization showed that both mixtures met the performance requirements of ABNT NBR 16940:2021. Although the RAC mixture exhibited a greater dispersion of results during the characterization tests, the beam’s load-bearing capacity was not affected. Experimental tests confirmed that the RAC beams achieved ultimate shear capacities comparable to or higher than those of the CC beams for all depths investigated. Moreover, the beams became increasingly fragile with increasing height. The experimental shear strengths were compared with the predictions from the SFRC shear model recommended in ABNT NBR 16935:2021. For both concretes, code-based shear resistances accounted for only about 30-45% of the mean experimental capacities, indicating markedly conservative estimates. The results demonstrate that partial replacement of natural coarse aggregates with recycled aggregates does not affect the shear performance of SFRC beams and can be safely combined for sustainable structural applications.

The structural design of prestressed concrete girders in beam bridges is performed by coupling 3D parametric modeling, optimization, and statistical techniques, structural analysis, and design. The objective is to explore the potential and advantages of advanced design methodologies based on intelligent design. The full 3D parametric beam bridge is modeled in the software Rhinoceros (computer‐aided design)/Grasshooper (algorithm‐aided design). An optimization procedure using a genetic algorithm is adopted to find the minimum number of supports. With the 3D bridge configuration, static and modal finite element analyses are performed using the Karamba3D plugin to extract the internal forces of the prestressed girders. After that, the Ultimate and Serviceability Limit States are checked by plugging the non‐linear design equilibrium equations in a Python script directly into Grasshopper. The Simplex method is used to determine the feasible domain (space of solutions) allowing the choice of the most appropriate pair of girder height and prestressing force.

In this research we use topology optimisation to design statically determinate rectangular beams with different heights. For the sake of simplification, the constitutive material is assumed to be homogeneous. The aim is to verify the efficiency level that topology optimisation procedure has in removing material from the structural member still preserving the bending strength capacity. Topology optimisation is based on the Bi-directional Evolutionary Structural Optimisation (BESO) and Solid Isotropic Material with Penalisation (SIMP) methods. To use the SIMP method, a 3D parametric model of the beams was implemented in the Rhinoceros3D (Computer-Aided Design) software with the aid of the Grasshopper (Algorithm-Aided Design) plugin. The optimization was performed using the tOpos plugin. For the BESO method, the BESO 2D code developed in RMIT Univervity was used. The output for both codes are compared, highlighting the coherence of the results based on computational time efficiency and physically plausible generated shapes. After Topology Optimization, the structural behaviour was investigated using Karamba3D plugin. To obtain the maximum load for the beams with different heights and their final volume coming from topology optimisation, an additional optimisation method based on genetic algorithms was adopted to maximise an objective function based on deformation. This analysis was performed for local maximum displacement respecting limiting state serviceability criteria considering increasing distributed load and different volume fractions. In all the cases analysed, the width and span are fixed. The results of the optimisation procedure for beams with different heights are compared based on economic-sustainability criteria (volume of material) and load-bearing capacity (maximum bearing moment).

The scientific goal of this study was to investigate the effects of various parameters on cavitation-induced erosion, with the aim to enhance the understanding and assessment of cavitation resistance in hydraulic systems. Cavitation erosion poses significant challenges to the durability and efficiency of hydraulic components, such as those found in hydropower plants and pumping stations. Prompted by the need to improve the reliability of cavitation testing and material assessment, this research conducted a comprehensive sensitivity analysis of a cavitation jet apparatus (CJA). This study employed an experimental platform that consisted of a vertical cylindrical test tank, a submerged nozzle, and an aluminum sample. By examining a range of orifice diameters, this research identified that smaller diameters led to increased erosion intensity, with the most pronounced effects observed at a diameter of 2 mm. Furthermore, various standoff distances (SoDs) were tested, which revealed that shorter distances resulted in greater erosion, with the highest impact noted at an SoD of 5 cm. This study also evaluated different nozzle geometries, where it was found that a 132° conical sharped edges nozzle, combined with an orifice diameter of 2 mm and an SoD of 5 cm, produced the most severe erosion. Conversely, chamfered edges nozzles and a commercial nozzle (MEG2510) with an SoD of 10 cm or greater showed reduced erosion. These results highlight that by standardizing the testing duration to 1200 s, the CJA could reliably assess the cavitation resistance of materials. This study established a clear relationship between increased pressure and higher impact forces, which led to more severe erosion. The findings underscore the effectiveness of the CJA in evaluating material resistance under various cavitation conditions, thus addressing a critical need for reliable cavitation testing tools.