Reduce Material Consumption Research Articles

Heat-resistant concretes based on cement binders and waste from the metallurgical industry

The main direction of the development of heat-resistant concrete production is the use of new materials, ensuring mechanization and industrialization of construction, increasing the performance characteristics of refractory compositions, reducing material consumption, introducing waste-free technologies in the production of concrete with increased physical and mechanical characteristics under prolonged exposure to high temperatures on cement binders and waste from the metallurgical industry and reducing environmental pollution. A significant environmental impact on the environment is exerted by large-tonnage technogenic waste produced by JSC «Aluminum of Kazakhstan» – bauxite sludge obtained by processing bauxite into alumina containing 42.7% Fe2O3. The prospects of its application as a filler in heat-resistant concretes are considered, which makes it possible to increase the physico-mechanical and thermal characteristics. The composition and properties of this waste and the change in the properties of heat-resistant concrete during the introduction of filler have been studied. Reactive alumina has been studied, which is 99.9% submicron alumina with a very low content of Na2O oxide. It is shown that the properties of concrete change after the introduction of iron-containing waste in the amount of 5% and reactive alumina – 37.5% and 38.8%. Their volumetric weight, control strength, and other properties are increased. The improvement of physical, mechanical, and thermal characteristics depends on the structure and neoplasms in the obtained samples. Samples of heat-resistant concrete were analyzed using electron probe X-ray spectral qualitative and quantitative microanalysis and X-ray fluorescence spectrometry and it was shown that the iron-alumina waste contributes to the compaction of the structure due to its resistance to delamination and has increased fluidity at low humidity in the cementing mass. For further investigation of the physical-thermal characteristics, depending on the structure and neoplasms in the obtained samples, a petrographic method using a polarization microscope in transmitted and reflected light is required.

Tradeoffs and synergy between material cycles and greenhouse gas emissions: Opportunities in a rapidly growing housing stock

AbstractManagement of building materials’ stocks and flows is a major opportunity for circularity and de‐carbonization. We examine the relationship between material consumption and associated greenhouse gas (GHG) emissions under different scenarios in Israel, a developed country with an already high population density that expects tremendous growth in its housing stock by 2050. We created scenarios of varying housing unit sizes and additional material efficiency practices: fabrication yield, lifetime extension, material substitution, recycling, and their combination, resulting in 18 scenarios. In each scenario, the material flows and stocks needed to supply the housing demand and the resulting life‐cycle GHG emissions are quantified. No single material efficiency practice achieves a reduction in all indicators, suggesting a potential conflict between circular economy and decarbonization policies: The material substitution scenario allows for the biggest reduction in material consumption (12%–40% concrete reduction and 15%–51% steel reduction in 2050 compared with the baseline), while the recycling scenario achieves the biggest reduction in GHG emissions (22%–43% reduction in 2050 compared with the baseline). In the long‐term, the life‐extension scenario reduces most demolition waste. These findings can help policymakers and stakeholders consider the impacts of raw materials consumption and implement this knowledge in light of their priorities in policy packages. The results suggest a narrow window of opportunity within the next decade to influence material consumption and emissions to 2050. The findings could also shed light on the sustainability trajectories of other countries with similarly rapidly developing building stock, which have received little attention in this field.

Efficient Large Area Semi‐Transparent Dye‐Sensitized Solar Cells (DSSCs) Printed with DMD400 Technology

AbstractThis work presents the development of fully printed, large‐area, semi‐transparent Dye‐Sensitized Solar Cells (DSSCs) using TiO2 nanoparticles treated with TiCl4, a “D35” push‐pull dye sensitizer, and I3−/I− redox mediator. Cells with areas of 4 and 200 cm2 were printed using hexagonal, stripe, and standard designs, employing digital materials deposition (DMD) technology. The porous films printed via DMD, confirmed by scanning electron microscopy (SEM), improved solar cells performance by enhancing the Open Circuit Voltage (Voc) and fill factor (FF). The hexagonal design, in particular, facilitated better electrolyte impregnation in the TiO2 mesoporous structure, boosting current density. This design yielded a power conversion efficiency (PCE) of 7.05% for 4 cm2 DSSCs, surpassing the stripe (5.50%) and standard (5.48%) designs. Its higher performance can be attributed to lower interfacial charge recombination rates and improvedcharge transfer and collection efficiency. Photophysical measurements indicated faster charge transfer rates in hexagonal cells (≈ 1.3 × 109s−1) compared to the stripe (9.8 × 108 s−1) and standard (9.5 × 108 s−1) designs. Hence, our work highlights the potential of hexagonal design to improve both efficiency and transparency while reducing material consumption, offering a promising approach for manufacturing semi‐transparent solar cells.

Design and Optimization of LPG Safety Cap using Finite Element Method

This paper presents a comprehensive study on the design and optimization of LPG safety caps, aimed at enhancing safety, reducing material consumption, and optimizing performance. The project employs SolidWorks simulation tools to conduct research and concept design phases. The primary objective is to ensure product safety while minimizing costs through Finite Element Analysis (FEA). The final product undergoes rigorous evaluation for performance and consumer safety. Three main goals guide this investigation: to scrutinize existing LPG safety cap designs, minimize material usage, and simulate the optimal design for enhanced safety. Analysis of the current design reveals vulnerabilities, including theft of LPG gas from sealed cylinders and escalating HDPE prices. Proposed designs simplify the current model and economize material consumption, successfully addressing the second objective. Through simulation, an optimal design (Design 8) emerges with superior characteristics compared to the existing model. Design 8 demonstrates a reduced total weight, higher safety factor, and lower maximum von Mises stress value. Notably, it exhibits enhanced safety and resilience, mitigating failure risks under stress conditions. The findings highlight the potential for creating stronger and safer designs while minimizing material requirements. In conclusion, Design 8 emerges as a superior alternative to the current design, boasting advantages in weight reduction, stress tolerance, safety factor, and optimization potential. This study underscores the significance of utilizing advanced computational methods to refine engineering designs for improved safety and efficiency in LPG safety caps.

Axial compression stress-strain relationship of lithium slag rubber concrete

Replacing cement with lithium slag and fine aggregate with rubber in concrete solves waste disposal, reduces material consumption, boosts sustainability, and enhances concrete performance. A set of prismatic concrete specimens with varying proportions were designed and experimentally tested in order to study the compressive stress-strain behavior of lithium slag rubber concrete (LSRC). The main factors affecting the specimens were lithium slag substitution ratio (SL=0%, 10%, 20%, 30%) and rubber substitution ratio (SR=0%, 5%, 10%, 15%). The results demonstrated that the LSRC exhibited good integrity during the damage. Furthermore, the incorporation of lithium slag (LS) was found to effectively compensate for the reduction in compressive strength due to the incorporation of rubber. When 10% of the fine aggregate was replaced with rubber and 20% of the cement was substituted with lithium slag, the axial compressive strength, elastic modulus, and peak strain of the tested specimens increased by 21.57%, 6.92%, and 17.26%, respectively. Compared with ordinary concrete, LSRC has good toughness, impact resistance and durability with minimal loss of strength, and has broad application prospects in engineering fields (such as airports, highways, housing expansion joints, concrete floors and railway concrete sleepers, etc.). Based on the experimental data, simplified modified equations to predict the compressive strength, elastic modulus, peak strain and axial stress-strain constitutive model of LSRC were proposed, so as to promote the development of LSRC.

Preface: 13th Ranshofener Leichtmetalltage

Abstract What strategies are available to minimize resource consumption in the light metal industry through recycling and energy efficiency? How can lightweight design make mobility more sustainable? And what role will artificial intelligence play in future processes in the metal processing industry? These and other questions are addressed at the 13th Ranshofener Leichtmetalltage 2024, which take place on the 26th–27th of September 2024 at the Hotel Gut Brandlhof in Saalfelden, Austria, and are organized in accordance with the criteria of the Austrian Ecolabel for Green Events. Under the guiding theme of “Light Metals Innovations for Environmental and Economic Sustainability”, this year’s conference offers an exciting program in three sessions “Digitalization in the Context of Circularity”, “Sustainable Process Development” and “Innovative Light Metals and their Characterization”. The focus is on decarbonization and digitalization in process and material development as well as the material characterization of light metals. A balanced spectrum of international presentations from universities, RTOs and industry provides participants with an up-to-date overview of the latest scientific findings and successful light metal applications. The 13th Ranshofener Leichtmetalltage 2024 are thus clearly focused on decarbonization and digitalization – even in times of diverse challenges. The first session, “Digitalization in the Context of Circularity”, highlights best-practice examples from the aluminium industry, the balance between sustainability and performance in metal processing and the implementation of complex geometries using wire-based additive manufacturing. The second session, “Sustainable Process Development”, is dedicated to the decarbonization and reduced material consumption of industrial processes, for example through GigaCasting, or the use of innovative recycling technologies. The third session, “Innovative Light Metals and their Characterization”, addresses forward-looking topics such as the development of special aluminium alloys for additive manufacturing, the use of old car scrap for innovative alloys and the decarbonization of the magnesium industry. The conference proceedings contain scientific contributions to the conference. We would like to thank all the authors for their high-quality work and the participants of the 13th Ranshofener Leichtmetalltage 2024 for their interest. We wish you stimulating reading and creative impulses! List of Scientific committee, Organizing committee are available in this Pdf.

ОСОБЛИВОСТІ ОЦІНЮВАННЯ ТЕХНОЛОГІЧНОЇ ПОШКОДЖЕНОСТІ БЕТОНУ

The article deals with the issue of obtaining building materials and equipment with specified quality parameters with reduced material consumption. It is shown that one of the possible ways to reduce the material density of structural building materials is the use of fillers. In this article, considering concrete as a structural material, it is stated that it is the formation of the structure or product that is difficult to control its quantitative and qualitative parameters, but it is practically possible only after receiving the finished product or structure. Properties of the structure are determined as individual properties of all subsystems (concrete, reinforcement), and changes in these properties during structural interactions. In turn, the construction material (concrete) is a subsystem that consists of characteristic structural inhomogeneities. Since the composition of concrete affects the structure, strength characteristics and deformable properties of reinforced concrete structures operating under the influence of external influences, there is a need for a more thorough study of it and the determination of optimal components in order to ensure the operational reliability of structures. During the technological processing of concrete into products, at all levels of structural in homogeneities in the material, technological cracks appear, which, being the structural parameters of concrete, determine the damage of structures, and thus their operational reliability. Research has established that technological damage significantly affects the strength and deformation properties of concrete.

Enhancing structural efficiency with digital concrete – Principles, opportunities and case studies

This paper explores the opportunities of digital fabrication with concrete (DFC) to improve structural efficiency and achieve sustainable construction. Efficient structural solutions that drastically reduce material consumption can be achieved by ensuring direct load flow and placing material where needed. More than 50 % of material savings can be achieved by using flanges or hollow sections, providing continuity in beams or slabs, reducing the span of structures or using structural systems such as arches, trusses or deep beams. These concepts are not fully exploited as they often require expensive and complex formwork. DFC tackles the latter point, as it promises to produce complex geometries, minimising extra effort, cost, or waste. The paper discusses the optimisation potential of DFC for several structural elements and presents existing applications that demonstrate this potential. Five case studies of different technological approaches are discussed in detail, highlighting advantages and disadvantages to be addressed for widespread adoption.

Photoelectric conversion performance of Ga0.47In0.53As/Ge0.79Sn0.21 dual-junction thermophotovoltaic cell

Based on the photovoltaic characteristics of GeSn-based materials and the theory of stacked solar cells, Ga0.47In0.53As/Ge0.79Sn0.21 dual-junction thermophotovoltaic cell has been simulated and studied for the first time. According to existing experimental material parameters, the structure of the cell is optimized, and the photoelectric performance of the cell is profoundly studied. The findings indicate that the doping concentrations of the top/bottom cell are N a(d),t/N a(d),b = 50(7) × 1016/17(2) × 1019 cm−3, which exhibits superior photoelectric conversion performance. For reducing material consumption and achieving high performance, the thickness of the emitter (base) of the top/bottom cell can be selected as 0.8~2.0(2.0~4.0)/0~0.2(1.0~4.0) μm (T BB = 1500 K). With radiator temperatures increasing, the conversion efficiency of the cell significantly improves, and the open circuit voltage of the cell can reach 0.70~0.91 V (1000~2000 K). The research results can guide the design and fabrication of high-efficiency and economical GeSn-based multi-junction thermophotovoltaic cells, and can also provide a new research and development direction for low-cost thermophotovoltaic cells.

Invited Article: The oxidation kinetics and mechanisms observed during ultra-high temperature oxidation of (HfZrTiTaNb)C and (HfZrTiTaNb)B2

Ultra-high temperature ceramics (UHTCs), most notably transition metal carbides and borides, exhibit melting temperatures exceeding 3000 °C, making them appropriate candidates to withstand the extreme temperatures (∼2000 °C) expected to occur at the leading edges of hypersonic vehicles. However, their propensity to react rapidly with oxygen limits their sustained application. The high entropy paradigm enables the exploration of novel UHTC compositions that may improve on the oxidation resistance of conventional refractory mono-carbides and -diborides. The oxidation kinetics of candidate high entropy group IV + V (HfZrTiTaNb)C and (HfZrTiTaNb)B2 materials were evaluated at 1500–1800 °C using Joule heating in one atmosphere 0.1%–1% oxygen/argon gas mixtures for times up to 15 min. Possible mechanisms based on the resulting complex time, temperature, and oxygen partial pressure dependencies are discussed. The carbides formed porous and intergranular oxides. Oxidation resistance was improved upon a continuous external scale formation. The diborides formed dense external scales and exhibited better oxidation resistance compared to the carbides. This improvement was attributed to the formation of liquid boria. Both compositions showed an unexpected reduction in material consumption at 1800 °C for all times tested, compared to results at lower temperatures. An in-depth analysis of the composition and morphology of the oxide scale and sub-surface regions for specimens tested at 1800 °C revealed that the formation of denser group IV-rich (Hf, Zr, Ti) oxides mitigated the formation of the otherwise detrimental liquid-forming group V (Ta, Nb) oxides, leading to the improved oxidation resistance.

Dematerialization of Concrete: Meta-Analysis of Lightweight Expanded Clay Concrete for Compressive Strength

The construction industry is responsible for a significant share of global material consumption, including natural resources. Therefore, the United Nations Sustainable Development Goal 12.2 on sustainable management and efficient use of natural resources cannot be achieved without significant advances and contributions from the construction sector. Furthermore, various materials used by the construction industry contribute to the development and expansion of the LEED (Leadership in Energy and Environmental Design) system. LECA (Light Expanded Clay Aggregate) is one such material that enhances LEED performance through its key benefits, including lightness, thermal insulation, sound insulation, and fire resistance. One of the most effective methods for reducing the weight of concrete is the incorporation of lightweight aggregates, and the advantages of LECA include lessening loads and enabling reduced cross-sections, directly improving the sustainability of the built environment via reduced materials consumption. This study aims to develop a prediction model for the compressive strength of LECA-incorporated concrete through a meta-analysis. More than 140 data points were compiled through literature via 15 separate studies, and results were analyzed to conduct the meta-analysis. Moreover, an experimental program was carried out to verify the model and evaluate its accuracy in predicting compressive strength. Results from the developed model and the experimental program were in accordance with concrete having lower compressive strengths compared to those at high strength values. Likewise, more accurate results were obtained for concrete mixes that have w/b ratios of 0.5 or higher. Concrete mixes that have higher amounts of LECA by volume of concrete yielded more accurate results when using the prediction model. A sensitivity analysis was carried out to quantify the impact of several parameters on the compressive strength of LECA concrete.

Analysis of thermal cycles during DED-Arc of high-strength low-alloy steel and microstructural evolution

Additive manufacturing (AM), specifically Directed Energy Deposition (DED)-Arc, holds great potential for the fabrication of individually designed components. In the construction industry, the demand for tailored steel nodes is increasing, particularly for large-scale structures, where high-strength steel deployment can significantly reduce material consumption and production time. However, the thermal material deposition process has a strong impact on the technical properties of high-strength steel. Parameters like heat input, interpass temperature (IPT), and cooling strategies modulate cooling times and peak temperatures in thermal cycles, which are crucial for estimating mechanical properties indispensable for safety certification. The development of digital twins or digital shadows emerges as the primary approach for quality assurance and certification, deploying real-time monitoring of manufacturing parameters such as voltage, current, wire feed, thermal history, and bead shapes. This data can be correlated with specific regions in the fabricated part to draw quality inferences. To interpret this data effectively, an understanding of the influence of these process parameters on resultant properties is indispensable. Given that the resulting microstructure strongly depends on the thermal history in AM parts, temperature monitoring during DED-Arc using thermography emerges as a promising method. This article aims at providing fundamental knowledge about phase transformations of a high strength steel feedstock under repeated reheating and gaining comprehensive knowledge about microstructural evolution during DED-Arc Additive Manufacturing. This is done by the analysis of time-temperature profiles, resulting microstructure and mechanical properties, linking it to CCT diagrams. A novel approach for describing the degree of tempering in different regions of the samples by deploying tempering parameters for anisothermal heat treatments is presented. By using this approach, an estimation about the resulting microstructure and hence the mechanical properties can be drawn.

INTEGRATION OF HYBRID ENERGY PLANT OPERATION

Integrated use means the use of several energy sources, all at the same time or in some combination. At the same time, it is possible to use exclusively renewable sources, which significantly limits user capabilities. More common and justified from many points of view is the use of both renewable and traditional sources, autonomous (universal boilers, diesel generators, gas turbine units, etc.) or centralized (power grid) sources. A correct assessment of such a combined energy system also requires taking into account the main component of the system - the consumer, that is, taking into account the features of the local network and nearby consumers, which will have a direct or tangible indirect effect on the operating mode of the complex of renewable sources. To ensure adequate power quality, energy storage systems can be used, and the need for them depends on the discreteness of energy flows and the requirements for power quality. In foreign terminology, combined systems are often called hybrid, reflecting the diversity of both energy sources and methods of combining them (sometimes this name extends to arbitrary complexes). However, the term “hybrid power supply” usually refers to a combination of installations using renewable and traditional energy sources. The article presents a new hybrid energy system that provides private households with electricity, hot water supply, heating and hot air in the required temperature range for comfortable living. Together with a wind power generator and an electric water heater, a heat pump, electricity and heat accumulators are used, which allows: - reducing the cost of thermal energy by reducing material consumption and equipment costs, saving organic fuel; produce electricity and send the excess to the state power grid; reduce heat load and environmental pollution. The automation system allows you to control the hybrid installation without human intervention all year round.

A large-scale demonstration and sustainability evaluation of ductile-porous vascular networks for self-healing concrete

Self-healing cementitious materials show potential to reduce material consumption, maintenance costs, and environmental impacts within the construction sector. This study explores the feasibility of installing a ductile-porous vascular network in a series of retaining walls under realistic construction conditions, with the objective of both assessing the efficacy of the self-healing system and addressing any constructability issues that may arise. Numerical modelling was performed first to determine a suitable mix design and wall configuration that would promote cracking, so cracks would appear without mechanical intervention. The predicted crack distribution informed the optimal network configuration. Healing and sustainability considerations are discussed, and the benefits of implementing this technology are evaluated. When comparing a single maintenance activity using a vascular network versus manual repair, there is no significant benefit of using a vascular network. However, environmental impacts are substantially reduced when using a vascular network once multiple repair actions are considered.

Damped rigid substructure system for seismic protection of structures

Building codes commonly accept inelastic deformations that inevitably occur due to seismic excursions in structures. To control the damage, limits on the inelastic deformations have been established. Standard passive energy dissipation systems have been used to reduce the damage, generally with some effectiveness. The damped rigid substructure (DRS) passive damping system, proposed in this article, geometrically amplifies the damper displacements and exerts a re-centering force, leading to effective discharge of the seismic energy to the extent that structural damage can be prevented. This is achieved using common damped and undamped diagonals arranged per implementation and design principles introduced in this article. The DRS system can considerably reduce material consumption and construction costs, leading to more sustainable structures when seismic forces govern the design. It can also benefit from the usage of high-strength materials to enhance its re-centering mechanism. The system is adaptable to the architectural needs and can be used for all categories of importance and height variation, made of steel or concrete.

Challenges to establishing and maintaining kidney transplantation programs in developing countries: What are the coping strategies?

Kidney transplantation (KT) is the optimal form of renal replacement therapy for patients with end-stage renal diseases. However, this health service is not available to all patients, especially in developing countries. The deceased donor KT programs are mostly absent, and the living donor KT centers are scarce. Single-center studies presenting experiences from developing countries usually report a variety of challenges. This review addresses these challenges and the opposing strategies by reviewing the single-center experiences of developing countries. The financial challenges hamper the infrastructural and material availability, coverage of transplant costs, and qualification of medical personnel. The sociocultural challenges influence organ donation, equity of beneficence, and regular follow-up work. Low interests and motives for transplantation may result from high medicolegal responsibilities in KT practice, intense potential psychosocial burdens, complex qualification protocols, and low productivity or compensation for KT practice. Low medical literacy about KT advantages is prevalent among clinicians, patients, and the public. The inefficient organizational and regulatory oversight is translated into inefficient healthcare systems, absent national KT programs and registries, uncoordinated job descriptions and qualification protocols, uncoordinated on-site investigations with regulatory constraints, and the prevalence of commercial KT practices. These challenges resulted in noticeable differences between KT services in developed and developing countries. The coping strategies can be summarized in two main mechanisms: The first mechanism is maximizing the available resources by increasing the rates of living kidney donation, promoting the expertise of medical personnel, reducing material consumption, and supporting the establishment and maintenance of KT programs. The latter warrants the expansion of the public sector and the elimination of non-ethical KT practices. The second mechanism is recruiting external resources, including financial, experience, and training agreements.

Study and Design of Corrugated Cardboard Trays With Microwaves by Experimental Analysis (EA) and Finite Element Methods (FEM)

ABSTRACTThe purpose of the work is to study by experimental analysis and finite element methods the mechanical response of a packaging, consisting of a corrugated cardboard container, used for the transport of fruit and vegetables. During the container design, three different configurations were selected which differ both in the choice of liner and in the type of wave. In particular, the type E, F and N microwaves were chosen. They are characterized by a lower amplitude than the high and medium waves commonly used in corrugated cardboard packaging, making it possible to reduce material consumption and, consequently, costs. In the initial phase of the study, experimental tests were performed to evaluate the mechanical strength of the liners. In addition, edge compression tests (ECTs) were performed to determine the stacking resistance of the structure. The break‐in resistance of the structures was analysed using a test conducted according to an internal standard, called strength packaging test (SPT). Subsequently, a parametric study was set up with the finite element method for the simulation of the mechanical behaviour of the three structures, using the homogenization technique. The comparison between the maximum total deformations, measured experimentally and calculated numerically, has highlighted the need to introduce corrective coefficients to improve the homogenization of the wave structure. In this way, it was possible to improve the matching of the results obtained on the structures simulated by the homogenization technique and those obtained on the corresponding real structures.

Optimization of Shear Resistance in Precast Concrete Sandwich Wall Panels Using an S-Type Shear Connector

Precast concrete sandwich wall panels (PCSPs) are popular for building exteriors due to their high thermal efficiency, composite performance, and low manufacturing and maintenance costs. Researchers have investigated the possibility of reducing the panel thickness while maintaining the cladding components’ thermal efficiency and strength to further improve efficiency and to reduce material consumption. However, limited research has been conducted on the shear bonding of steel plates, which is critical to ensuring durability and energy efficiency. This study investigated the shear behaviour of PCSPs with an S-type shear connector (SSC) through nine push-off tests and non-linear finite element modelling using Abaqus. Parametric studies were carried out to investigate the influence of the geometric properties of the SSC, the yield strength of the steel and the insulation thickness. The results suggest that the maximum secant stiffness for SSCs was achieved at a width of 101.4 mm and a thickness of 2 mm. Therefore, it is recommended that the width of the SSCs be limited to this value or less. Furthermore, the study found that increasing the yield strength of the steel beyond a thickness of 2 mm and a width of 101.4 mm did not improve the results and had a negative impact on the secant stiffness of the SSCs.

Hierarchical nested honeycomb-based energy absorbers: design factors and tailorable mechanical properties.

This study presents a novel hierarchical nested honeycomb drawing inspiration from the hierarchical structures found in energy-absorbing citrus peels. Our investigation reveals that integrating secondary hierarchical units into primary honeycomb cells results in energy absorption profiles featuring two distinct plateaus. Notably, we found that these profiles can be finely tuned by adjusting the thickness of primary and secondary cell walls. Additionally, our study demonstrates a strategic removal of cell walls at key positions, reducing material consumption without compromising specific energy absorption. By establishing comprehensive structure-property relationships, we offer valuable insights into the design and optimization of hierarchical cellular materials. Compared with traditional honeycomb structures, the nested honeycomb structure shows a twofold increase in compressive strength and a fivefold increase in specific energy absorption, positioning them as promising candidates for applications requiring two-step impact protection and tunable performance, ranging from packaging to high-speed automobiles.

Fire Resistance of Ultra-High-Strength Steel Columns Using Different Heating Rates

Ultra-High-Strength Steel (UHSS) offers several advantages over normal carbon steel, promoting exceptional strength, reducing self-weight, improving fire resistance, enhancing durability, and reducing material consumption. These advantages result in cost savings and sustainable engineering construction. The 3D numerical model is based on Geometrical and Materially Nonlinear Imperfection Analysis (GMNIA) and determines the fire resistance of different cross-section columns. The model is validated with experimental tests, with a maximum relative error of 11%. A parametric analysis is presented, based on 252 simulations, assuming three heating rates, two different cross-sections, two different thicknesses, three lengths, and seven load levels. The fire resistance depends on the heating rate, but the critical temperature is almost equal and independent of the heating rate, if one assumes implicit creep in the constitutive material model. The fire resistance decreases with the load level, as expected. The thickness effect of the hollow section is almost negligible in the fire resistance of UHSS columns. The fire resistance decreases more in higher load levels for slender columns. Columns with Circular Hollow Sections (CHSs) generally show higher fire resistance than hybrid columns in longer columns, but the hybrid columns are subject to much higher loads. New design formulas are presented for the critical temperature of UHSS columns, depending on the load level and slenderness of two different cross-sections.