Search Results (73)

This paper reports a statistical analysis of a database archiving information on the strengths of the materials in existing Italian bridges having pre- and post-tensioned concrete beams. Data were collected in anonymous form by analyzing a stock of about 170 bridges built between 1960 and 2000 and located in several Italian regions. To date, the database refers to steel reinforcing bars, concrete, and prestressing steel, whose strengths were gathered from design nominal values, acceptance certificates, and in situ test results, all derived by consulting the available documents for each examined bridge. At first, this paper describes how the available data were collected. Then, the results of a statistical analysis are presented and commented on. Moreover, goodness-of-fit tests are carried out to verify the assumption validity of a normal distribution for steel reinforcing bars and prestressing steel, and a log-normal distribution for concrete. The database represents a valuable resource for researchers and practitioners for the assessment of existing bridges. It may be applied for the use of prior knowledge within a framework where Bayesian methods are included for reducing uncertainties. The database provides essential information on the strengths of the materials to be used for a simulated design and/or for verification in the case of limited knowledge. Goodness-of-fit tests make the collected information very useful, even if probabilistic methods are applied. Full article

The seismic risk assessment of large building stocks is crucial for informed asset management in earthquake-prone regions, providing decision-support for retrofit intervention planning. Many existing methodologies focus on a single structural typology or asset class (e.g., ordinary buildings or industrial facilities), thus limiting their applicability to mixed portfolios. This study proposes a comprehensive and adaptable methodology for the seismic assessment of diverse building stocks—a cross-typology approach encompassing masonry, reinforced concrete (r.c.), precast r.c., and steel structures. The approach integrates deficiency-based qualitative evaluations with simplified mechanical models tailored for each building class. Where validated methodologies were unavailable, new assessment tools were developed. The proposed framework was applied to an industrial-oriented building stock comprising 79 structural units at regional scale, demonstrating its capability to identify priority structures for retrofitting interventions. By overcoming the constraints of typology- or asset-specific approaches, this methodology enables a more comprehensive and scalable assessment. This ultimately contributes to effective risk mitigation planning and seismic resilience enhancing. Full article

The building industry is a major consumer of resources and a significant contributor to environmental degradation, largely due to its reliance on energy-intensive materials and construction practices. In this context, the reuse of components from decommissioned structures offers a promising strategy for reducing the environmental impact of new constructions. Steel products are particularly suitable for reuse, as they retain their mechanical properties over time. However, the adoption of reused members requires a shift from conventional design approaches, which typically allow for free dimensioning of elements, toward strategies where components must be selected from available stocks and strategically integrated into new structures. This process demands a careful balance between geometric configuration, structural performance, and material availability. This paper presents a new design methodology for gridshells that integrates geometry and sizing optimization to maximize the use of reused members. The proposed approach was validated through application to a dome structure. The structural behavior was assessed through nonlinear buckling analyses, alongside a simplified evaluation of greenhouse gas emissions to quantify the environmental impact. The findings highlight the potential of reuse-based strategies to promote more sustainable structural designs. Full article

For over five decades, blending hydrogen into existing natural gas pipelines has been explored as a potential solution to reduce greenhouse gas emissions. Despite its promise, implementing this approach has been slow due to concerns about hydrogen embrittlement (HE) and its interactions with various metals. Stainless steel alloys like 316L are commonly used in hydrogen service due to their superior resistance to HE. However, the impact of additive manufacturing (AM) on 316L’s susceptibility to HE when subjected to gas charging has not been thoroughly investigated. To fill this knowledge gap, we created conventionally manufactured and AM 316L tensile bars and solubility specimens, which were then exposed to hydrogen-blended natural gas at 10 MPa with a 50% blend and 100% pure H₂. Both conventionally manufactured and additively manufactured specimens had as-received/printed samples that were used as controls. The samples underwent mechanical evaluation through tensile testing and hot chemical extraction to assess hydrogen solubility. Further analysis revealed significant changes in the microstructure near the fracture area of the soaked samples using scanning electron microscope fractography and metallography. These findings were compared with our previous work on traditionally produced 316L bar stock, which demonstrated that AM processing conditions can yield superior performance in terms of resistance to HE. Notably, this study provides valuable insights into the effects of AM on 316L’s susceptibility to HE when subjected to gas charging. The results have significant implications for the development and implementation of AM 316L for hydrogen/natural gas applications in pressure regulators when AM processing conditions are well-controlled. This article is a revised and expanded version of a paper entitled “Effect of Hydrogen-Blended Natural Gas on Additive Manufactured 316L Stainless Steel in Pressure Regulator Environments”, which was presented at TMS in Las Vegas, March 2025. Full article

With rapid urbanization and industrialization, steel in-use stocks (SIUS) have experienced significant growth, playing an important role in urban mining and future renewable resources. Although previous studies have quantified SIUS at the provincial level, a comprehensive understanding of its spatial distribution remains limited. This study uses Henan Province as a case to assess SIUS and its spatial distribution at the provincial level. A spatio-temporal characterization framework is developed to systematically analyze SIUS dynamics, integrating the bottom-up model, the spatial autocorrelation model, the Tapio–LMDI model, and the stock-driven model. The findings show that total SIUS has been continuously increasing, reaching 499.35 Mt in 2023, with the buildings sector being the largest contributor, accounting for 67%. However, due to its large population, per capita SIUS was 5.09 t/cap in 2023, lower than that of China. Spatial analysis reveals significant autocorrelation in per capita SIUS, with notable spatial heterogeneity in its density. Moreover, the average annual growth rate of SIUS is projected to decline from 10% in 2023 to 5% in 2060, suggesting that SIUS in Henan is approaching a saturation phase, consistent with theoretical expectations. Full article

Stone mastic asphalt (SMA) is the most widely adopted asphalt mixture on highway pavement in China. However, the cost of SMA is rising continually due to the increasing shortage of high-quality basalt aggregate. On the other hand, China’s steel slag and reclaimed asphalt pavement (RAP) stock is abundant, and steel slag has excellent strength and wear-resistant performance, which can fully or partially replace part of the basalt aggregate. The content of asphalt may be increased due to the porosity of the steel slag. If fine RAP rich in asphalt is also used for SMA, it can partially fill the voids of steel slag and reduce the amount of new asphalt and fine aggregate. For this objective, SMA 13 was designed with two particle sizes of coarse steel slag aggregate (5–10 mm, 10–15 mm) and one fine RAP (0–5 mm), named SR-SMA. The fundamental pavement performance of SR-SMA was evaluated through a wheel-tracking test, low-temperature beam bending test, freeze–thaw indirect tensile test, and four-point bending fatigue test. For comparison, the mix design and performance tests of two SMAs involving coarse steel slag and fine basalt aggregate (named SB-SMA), and coarse and fine basalt aggregates (named B-SMA), respectively, were conducted. The results indicated that SR-SMA (dynamic stability of 4865 passes/mm) shows the best rutting resistance, followed by SB-SMA (dynamic stability of 4312 passes/mm), and B-SMA (dynamic stability of 4135 passes/mm) comes in last. Additionally, the dynamic stability values of three SMAs have significant differences. SR-SMA has better low-temperature cracking resistance with a failure strain of 3150 με, between SB-SMA and B-SMA (failure strain values are 4436, 2608 με). Compared to B-SMA and SB-SMA, the moisture stability of SR-SMA is relatively poor but meets Chinese specification. While the fatigue resistance of SR-SMA is the worst among three SMAs, their differences are insignificant. Furthermore, SR-SMA reduces material cost by approximately 35% per ton compared to conventional B-SMA. Overall, SR-SMA is cost-effective and can be used as an alternative material to traditional B-SMA. Full article

The main causes of damage include poor site selection, such as building on fault lines or on fill soil, as well as deficiencies in design, materials, and workmanship. Damage levels are also linked to the economic conditions of the region. In the 1939 earthquake, there were high casualties due to the magnitude of the earthquake, lack of engineering design in traditional structures and unsuitable soil conditions. Similarly, in the 1992 earthquake, unexpected damage occurred due to faulty designs created by inexperienced engineers who lacked sufficient knowledge of the seismic behavior of structures, errors in craftsmanship and workmanship, and unsuitable residential area selection for construction. These problems continue today and put most of the building stock at risk in case of a major earthquake. Seismic steel isolators are used in two new buildings in the city; if they are effective, they should be made mandatory in new construction. Otherwise, consideration should be given to relocating the city to the more stable southern rocky areas, which were unaffected in both 1939 and 1992. Full article

This study investigated the status of anchors for small fishing vessels that correspond with the risk factors of submarine cables, which are essential elements for offshore wind farms. As for target vessels, small coastal fishing vessels of less than ten tons were divided into four categories by tonnage, and 71 locations were compared from a total of 59 fishing vessels. In the results, the shank showed a difference of approximately 18.2% from 119.3 to 145.8 cm on average, while the stock exhibited a difference of approximately 18.9% from 130.3 to 160.6 cm. The size of the anchor, however, was not proportional to the increase in the tonnage of the fishing vessel, and the anchors were produced in their own forms, based on the experience of the crew in many cases. In the statistical processing results, significant differences occurred in all areas except for the fluke. The stock and shank, which affect the dragging anchor, showed significant differences at a level of p < 0.05 while the bill, bill to bill, and bill to shank exhibited differences at a level of p < 0.01. This indicates that standardized criteria are required for the anchors of small coastal fishing vessels of less than ten tons, and that design standards for materials and reinforcements also need to be prepared as thin rebars or wooden columns are used, in addition to steel pipes, as the materials of the stock in many cases. Full article

Medicinal plants are rich in nutrients and bioactive compounds, making them potentially suitable for use as chemotherapeutic agents and as additives in aquafeed. Our research evaluated the effects of purslane (Portulaca oleracea) extract supplemented in sunflower-based diets on the growth, carcass composition, blood indices, mineral content, liver antioxidant enzyme profile, and immune response in Cirrhinus mrigala (8.26 ± 0.07 g/fish). The juveniles were fed one of seven different diets—T₀ (no extract), T₁ (0.5%), T₂ (1%), T₃ (1.5%), T₄ (2%), T₅ (2.5%), and T₆ (3%)—twice daily, at a feeding rate of 5% of their live body weight. They were stocked in V-shaped steel tanks for 90 days, with 15 juveniles per tank and three replicates per dietary treatment. The results of this research revealed that 1–2% purslane extract substantially enhanced growth indices in fish (p < 0.05). Furthermore, the supplementation of 1–2% dietary purslane extract in the diet significantly lowered fat content and improved protein content (p < 0.05) compared to the diets with 0% and 3% purslane extract inclusion. The outcomes also indicated that the hematology and mineral content in the bodies of juveniles were significantly improved (p < 0.05) at all levels of purslane supplementation, relative to the control groups with 0% and 3% inclusion levels. Moreover, the administration of purslane extract markedly increased the liver antioxidant profile, including glutathione peroxidase, superoxide dismutase, and catalase. Additionally, there was a notable reduction in malondialdehyde levels when fish were fed diets having 1% and 1.5% extract. The findings of this study also revealed improvements in immunological markers, characterized by increased lysozyme activity and elevated total globulin levels. The current research suggests that supplementing C. mrigala diets with 1% purslane extract optimally enhances growth and immunity. Full article

Parabolic leaf springs are components typically found in suspensions of freight railway rolling stock. These components are produced in high-strength alloyed steel, DIN 51CrV4, to resist severe loading and environmental conditions. Despite the material’s good mechanical characteristics, the geometric notches and high surface roughness that features its leaves might raise local stress levels to values above the elastic limit, with cyclic elasto-plastic behaviour models being more appropriate. In this investigation, the parameters of the Chaboche model combining the kinematic and isotropic hardening models are determined using experimental data previously obtained in strain-controlled cyclic tests. Once the parameters of the cyclic hardening model are determined, they are validated using a finite element approach considering the Chaboche cyclic plasticity model. As a result, the material properties specified in this investigation can be used in the fatigue mechanical design of parabolic leaf springs made with 51CrV4 (local approaches to notches and at surface roughness level) or even in other components produced with the same steel. Full article

This review studies the availability of post-consumer steel scrap in Europe until 2050. We introduce the indicator potentially available domestic post-consumer scrap (PADPS), which measures the amount of (steel) scrap from obsolete products available for recycling prior to trade in scrap. We analyze material flow studies from the academic literature and international organizations to quantify this indicator. The studies suggest a rising trend of post-consumer scrap amounts until a saturation level is reached and the expected yearly steel product obsolescence of the system stabilizes. Between 2010 and 2050, PADPS is expected to rise by approximately 1.6% per year. We identify in-use steel stocks, recycling rates, and product lifetimes as the three commonly gauged factors determining PADPS. While recycling rates and product lifetimes range comparatively close in the studies, the estimation of in-use stocks displays much greater variation and introduces an element of uncertainty in the estimation of post-consumer scrap amounts that can be expected in the coming decades. Full article

The construction sector is one of the largest creators and distributors of wealth, contributing to economic growth worldwide. However, this economic growth comes together with very high environmental impacts. Thus, rehabilitation solutions that can adapt the current building stock to today’s structural requirements are needed, increasing structural safety, while avoiding the production of demolition waste and the extraction of virgin raw materials, hence lowering the construction sector’s environmental impacts. Such rehabilitation solutions need to be environmentally and economically sound so that stakeholders can make informed decisions based on their needs and priorities. This paper presents a case study of an existing reinforced concrete beam, whose flexural resistance is increased using four alternative strengthening solutions: concrete jacketing, without and with increasing the cross-section size, and plate bonding, using either carbon fibre-reinforced polymer (CFRP) strips or steel plates. These solutions are studied via an environmental and economic cradle-to-gate life cycle assessment (LCA), resulting in a comprehensive comparison of their environmental and economic impacts, followed by a multicriteria and sensitivity analysis and eco-cost approach to determine the optimal solution. According to the criteria considered in the study, when environmental impacts are more valued, the concrete jacketing solution presents the best results and, when cost is dominant in the decision, the bonding of CFRP strips becomes the optimal solution. Full article

The mechanical behavior of corroded steel reinforcement under dynamic loadings is crucial for the entire structural response of reinforced concrete elements located in seismic regions. Taking into account the need to assess the structural integrity of existing building stock and the fact that the majority of the existing RC structures in Greece are constructed with the use of steel grades of S400 (equivalent to BSt 420s) and Tempcore B500c, the present study examines the dynamic behavior of rebars of different grades under low cycle fatigue (LCF) at a constant strain amplitude of ±2.5% and compares their performance through a quality material index. In the margin of the current research, the study also included two different grades of hybrid rebars, Tempcore B450 and dual-phase F (DPF). The outcomes demonstrated that single-phase S400 steel underwent mild degradation in its ductility, whereas its bearing capacity was significantly decreased due to corrosion. In contrast, B500c illustrated its superiority in terms of strength, yet recorded extremely limited service life, even in uncorroded conditions, raising questions about its reliability and the structural integrity of existing building stock. However, in corroded conditions, even if B500c corroded rebars showed higher mass loss values than the other examined grades, the degradation of their mechanical behavior due to corrosion was found to be minimal. Furthermore, dual-phase DPF rebars, with their homogeneous microstructure, appeared particularly promising with respect to Tempcore B450 if one considers the span of its service life compared to the extent of corrosion damage. Full article

In tool and mold making, components are typically first pre-machined in a soft state with residual stock allowance, as economical production is not possible in a hardened state due to the enormous tool wear. This extends the process chain and therefore also the throughput times. This paper presents an innovative tool concept for a solid carbide end mill in order to be able to carry out roughing and finishing in a hardened state. First, the structure of the innovative solid carbide end mill is described. Afterwards, the results of experimental tests are presented and discussed. These describe the suitability of the tool concept and include further investigations that examine the influence of the helix angle on the process behavior during the machining of the tool steel Toolox 44. To evaluate the process behavior, the development of process forces, chip formation, tool wear and component quality over the tool life are analyzed. Full article

ŠTORE STEEL Ltd. is one of the three steel plants in Slovenia. Continuous cast 180 mm × 180 mm billets can undergo cooling to room temperature using a turnover cooling bed. They can also be cooled down under hoods or heat treated to reduce residual stresses. Additional operations of heat treatment from 36 h up to 72 h and cooling of the billets for 24 h, with limited capacities (with only two heat treatment furnaces and only six hoods), drastically influence productivity. Accordingly, the casting must be carefully planned (i.e., the main thing is casting in sequences), while the internal quality of the billets (i.e., the occurrence of inner defects) may be compromised. Also, the stock of billets can increase dramatically. As a result, it was necessary to consider the abandoning of cooling under hoods and heat treatment of billets. Based on the collected scrap data after ultrasonic examination of rolled bars, linear regression and genetic programming were used for prediction of the occurrence of inner defects. Based on modeling results, cooling under hoods and heat treatment of billets were abandoned at the casting of several steel grades. Accordingly, the casting sequences increased, and the stock of billets decreased drastically while the internal quality of the rolled bars remained the same. Full article