Complete Stress-strain Curves Research Articles

Experimental study of rock fracture behavior under direct tension using three-dimensional digital image correlation

Understanding the mechanical characteristics of rocks when subjected to direct tension is crucial for assessing the stability of rock formations. Within the scope of this research, a series of tests was conducted using Tage tuff to assess the deformation behavior and crack extension of rock under direct tension. The axial, lateral, and shear strain fields as well as crack propagation, localized deformation behavior, and failure mode of the rocks were analyzed using three-dimensional digital image correlation method. The results showed that the axial strain fields on the specimen surface were heterogeneous, with different locations and localization occurring in the pre-peak stage, which was similar to the evolution of shear strain, whereas the lateral strain only showed slight changes. The crack extension direction was inferred, indicating that both tensile and shear stress occurred in the tests. Furthermore, different stress–strain responses were observed for the inside and outside of the localized bands. Then, the surface patterns of specimen failure were scanned and analyzed to assess the failure mode and residual strength of the specimen under direct tensile stress. Finally, the results of direct tension, uniaxial compression, and Brazilian split tests for Tage tuff were compared, and the complete stress–strain curve of uniaxial tension (UT) was simulated using a nonlinear-variable-compliance constitutive equation. This study provides a deeper understanding into the damage behavior of rocks under direct tension.

Stress-strain modelling of circular concrete-filled FRP–steel composite tube columns under axial compression load

Concrete filled-circular steel tube (CFCST) columns, when externally confined with carbon or glass fiber-reinforced polymers (FRP) sheets and subjected to axial load, exhibit improved strength and ductility compared to unconfined cases. The mechanical properties of the confinement materials are crucial in determining the stress-strain relationship of the confined concrete. This study presents an in-depth analysis of the stress-strain behavior of FRP-confined CFST columns, based on data from 252 specimens. It examines a range of factors, including various infill concrete grades from 14.15 to 140.39 MPa, two types of carbon steel outer tubes with yield strengths (fy) from 226 to 466.5 MPa, and two types of FRP (CFRP and GFRP) with tensile strengths from 1260 to 4900 MPa. The complete axial stress-strain curve is divided into four phases according to a mathematical expression by Wu and Wei (2015): the elastic phase, nonlinear transition phase, linear softening phase, and residual phase. New formulas for ultimate stress, based on confinement stress, were proposed by Hassanin et al. (2023), while the ultimate strain was calculated using the classical formula by Richart et al. Peak stress and strain were determined through statistical linear regression analysis using SPSS software, based on 252 experimental data points and involved using a combined factor of steel contribution (Elsfco) and FRP contribution (Elffco). Eight specimens were specifically used to validate the models through Finite Element Method (FEM) simulations. The accuracy of the predicted analysis results was also assessed by comparing them to existing models. The evaluation showed that the models successfully simulated the complete stress-strain curve of FRP-wrapped CFST columns under axial load, producing satisfactory results. These four models provide reliable results for calculating ultimate stress, ultimate strain, peak stress, peak strain, and the complete stress-strain behavior of these columns.

Identification of failure behaviors of underground structures under dynamic loading using machine learning

Understanding the dynamic responses of hard rocks is crucial during deep mining and tunneling activities and when constructing nuclear waste repositories. However, the response of deep massive rocks with openings of different shapes and orientations to dynamic loading is not well understood. Therefore, this study investigates the dynamic responses of hard rocks of deep underground excavation activities. Split Hopkins Pressure Bar (SHPB) tests on granite with holes of different shapes (rectangle, circle, vertical ellipse (elliptical short (ES) axis parallel to the impact load direction), and horizontal ellipse (elliptical long (EL) axis parallel to the impact load direction)) were carried out. The influence of hole shape and location on the dynamic responses was analyzed to reveal the rocks' dynamic strengths and cracking characteristics. We used the ResNet18 (convolutional neural network-based) network to recognize crack types using high-speed photographs. Moreover, a prediction model for the stress-strain response of rocks with different openings was established using Deep Neural Network (DNN). The results show that the dynamic strengths of the granite with EL and ES holes are the highest and lowest, respectively. The strength-weakening coefficient decreases first and then increases with an increase of thickness-span ratio (h/L). The weakening of the granite with ES holes is the most obvious. The ResNet18 network can improve the analyzing efficiency of the cracking mechanism, and the trained model's recognition accuracy reaches 99%. Finally, the dynamic stress-strain prediction model can predict the complete stress-strain curve well, with an accuracy above 85%.

Analytical evaluation of stress–strain behavior of rubberized concrete incorporating waste tire crumb rubber

The advancement of rubberized concrete technology and its application in engineering can significantly promote the complete recycling and safe disposal of waste tire rubber. Integrating crumb rubber into concrete alters its compressive stress–strain behavior. This study investigated the stress–strain characteristics of rubberized concrete containing waste tire crumb rubber, addressing the absence of standard guidelines for the design of rubberized concrete. By examining the complete stress–strain curves of rubberized concrete, key parameters such as peak stress, initial elastic modulus, peak strain and secant modulus were meticulously evaluated. The study delved into the mechanisms through which crumb rubber influences the stress–strain behavior of concrete, considering factors including variations in rubber content and pretreatment methods. The experimental data were analyzed using conventional concrete constitutive theories to quantify the impact of crumb rubber on rubberized concrete's stress–strain relationship. Significant variations were observed, including a notable decline in strength with increasing rubber content. For instance, increasing the rubber content from 0.0% to 5.0% led to reductions of 44.2% in peak stress and 47.0% in secant modulus compared to the reference concrete. In addition, pretreating the crumb rubber markedly improved rubberized concrete strength, and the peak stress of concrete with 1.0%–5.0% pretreated crumb rubber increased by an average of 7.0% compared to that with untreated crumb rubber. The study identified that crumb rubber's inclusion significantly altered the coordination of stress and strain in concrete, thereby affecting its stress–strain behavior. A set of evaluation equations for the stress–strain relationship of rubberized concrete was developed, offering a reliable method for predicting its behavior. This research fills a critical gap in the analytical assessment of rubberized concrete and marks a significant stride towards its broader use in sustainable construction practices.

Effect of internal fractures on mechanical properties and failure of sandstone under multi-physical fields

Under deep mining conditions, rocks are subjected to complex multi-physical fields and can contain numerous pores and fractures. To explore the influence and correlation of these factors on the physical and mechanical properties of fractured rock samples, this study conducted triaxial compression tests on sandstone specimens under various physical conditions using a rock full stress multi-field coupling triaxial tester. Additionally, a random fracture model for multi-field coupling numerical simulation was established. This allowed the study to obtain the mechanical parameters, failure mode, and internal fracture development of rocks under multi-physical field conditions. By analyzing the complete stress-strain curve, mechanical characteristic points, and permeability, a combination of laboratory tests and numerical simulations was used to examine how temperature, seepage, and stress fields affect the development of pores and fractures in rocks. It was found that the temperature field, under conventional geothermal conditions, generates tensile force through thermal expansion and the presence of fluid, thereby promoting fracture development within the rocks. This mechanism is similar to that of seepage. The confining pressure caused by deep geo stress uniformly inhibits the expansion of pores and fissures within the rocks.

A Continuously Derivable Uniaxial Tensile Stress-Strain Model of Cold-Formed Circular Steels

Promoting prefabricated steel structures is considered one of the crucial approaches to meeting the objectives of “carbon peak” and “carbon neutrality” in the construction industry. Due to insufficient practical experience and incomplete fine engineering techniques in civil construction, the sustainable development of prefabricated building systems in China faces many challenges. Taking steel components as an example, the design process of tubular columns does not pay enough attention to the influence of the cold-working effect on material mechanical properties, and the constitutive relationship of cold-formed steels is not clear, which will cause an engineering economic burden and may affect the judgment of catastrophic problems. To serve the refined design and meet the intelligent construction technology using the computer platform, a modified Menegotto-Pinto model using a continuously derivable function is proposed in the paper. The proposed model can successfully describe the complete stress-strain curve of cold-formed circular mild steels as long as the basic mechanical parameters of the parent material are determined. Taking into account the influence of the strength and thickness of the parent steel sheets, as well as the internal bending radius r, on the cold-rolling effect, the model can also flexibly track the elastic-plastic nonlinearity of the cold-formed materials. In addition, the research shows that the cold-rolling effect will weaken with the increase of the yield strength fsy,0 of the parent steels and r/t ratio, and may disappear when fsy,0 reaches 1748 MPa or the r/t ratio is approximately 60, which can be used as economic indicators during the design process.

Experimental study of multiscale hybrid fiber-reinforced ambient-cured LEGC under uniaxial compression

This study proposed the addition of cellulose nanofibers (CNFs) and basalt fibers (BFs) as hybrid fibers (HFs) into lightweight expanded polystyrene (EPS) geopolymer concrete (LEGC) to enhance its mechanical properties from chemical and physical perspectives. First, uniaxial compression tests were performed on LEGC specimens with moderate densities (1120–1920 kg/m3) reinforced with HF prepared with different CNF weight ratios (0.1%, 0.2%, and 0.3%) and fixed BF volume content of 0.6%. The test results demonstrated that the integrity of the specimens under the effect of the suitable dosing of HF was better maintained at final destruction, and the enhancement rates of the compressive strength and elastic modulus of the specimens with HF were superior to those with a single fiber type. The suitable dose of CNF was 0.2% for EPS volume contents of 10% and 20%, while 0.1% was suitable for EPS volume contents of 30% and 40%. Meanwhile, the cracking resistance mechanism of HF specimens was analyzed from chemical and physical perspectives, and the synergistic mechanism was determined quantitatively. In addition, the enhancement rates of the energy absorption capacity of the specimens with a suitable dose of HF were also more effective, which ensured the light weight of the material and improved its energy absorption capacity. Finally, this study developed a nine-parameter damage constitutive model that could better describe the five-stage characteristics of the complete stressstrain curve of the specimens, providing a certain theoretical basis for the structural design and analysis of LEGCs.

Use of hardness, PIP and tensile testing to obtain stress-strain relationships for metals

Both hardness testing and Profilometry-based Indentation Plastometry (PIP) can be used to obtain features of (tensile) stress-strain curves. The two tests are superficially similar, involving penetration (under a known load) of an indenter into the flat surface of a sample, followed by measurement of dimensional characteristics of the residual indent. The associated data handling procedures, however, are very different in the two types of test. Hardness numbers, which are commonly based on measurement of the lateral extent or depth of the indent, essentially give a semi-quantitative indication of the resistance to plastic deformation: going beyond this to infer features of the (nominal) stress-strain curve – notably the yield stress (YS) and Ultimate Tensile Stress (UTS) – can only be done via empirical correlations (often restricted to certain types of alloy). PIP testing, on the other hand, involves measurement of the complete indent profile, followed by (automated) iterative FEM modelling of the indentation, allowing the complete (true) stress-strain curve to be obtained. This paper covers application of both approaches to 12 different alloys, with inferred stress-strain characteristics being compared with those from tensile testing. Insights are provided relating to the very different levels of detail and reliability offered by the two procedures.

Experimental Study on Permeability Evolution of Sandstone during Triaxial Compression Damage

In order to investigate the mechanical properties and permeability characteristics of sandstone during damage evolution under hydromechanical condition, a series of coupled hydro-mechanical triaxial tests on sandstone specimens were conducted based on the Rock Top 50HT full-stress multi-field coupling triaxial test system. Variations in permeability as a function of confining pressure, seepage pressure gradient, and volumetric strain during damage evolution were obtained. The results show that: (1) When the confining pressure is constant and the specimen is gradually changed from a dry to a saturated state, the failure mode of sandstone changes from shear failure to single-slope shear failure. (2) There are four distinctive stages in the permeability evolution of sandstone: gradual decrease, steady development, gradual increase, and rapid growth. These stages correspond to the complete stress–strain curve under the respective working conditions. (3) Employing the Weibull distribution formula, this study investigates the evolution of fracture damage under varying working conditions and determines the permeability evolution relationships associated with damage variables. This exploration reveals an intrinsic link between permeability and damage variables. These findings enhance our understanding of the interplay between stress, deformation, permeability, and damage evolution in seepage-stress coupled sandstone. The results contribute valuable insights to the field of rock mechanics and hold implications for diverse geotechnical and engineering applications.

An accelerated strategy to characterize mechanical properties of polymer composites using the ensemble learning approach

Screening new materials and decoding their structure-property relationships is a time-consuming and costly task in the laboratory. This research proposes the use of machine learning (ML) algorithms with a new train-test splitting strategy to predict the complete stress-strain curves of polymer composites based on their compositional, environmental, and processing conditions using data extracted from an open-source database. Both the artificial neural network (ANN) and ensemble learning (EL) models demonstrated acceptable fit to the training datasets, yielding root mean squared errors (RMSEs) below 3.2 MPa. However, EL models demonstrated superior performance by reducing the RMSE of the testing data by an average of 61% for polyethylene terephthalate (PET) composites and 30% for polycarbonate (PC) composites, compared to the wide ANN models. Additionally, the developed EL models reduced the training time from a few hours (∼4 h on average) for wide ANNs to just a few seconds. The results of this study imply that relying solely on ANN models may not always provide the best solution for a given problem in materials science, and that EL models should be considered as a viable alternative, particularly in cases where data are limited. This study will pave the way for the automated design and characterization of advanced composites, while reducing the costly and laborious experiments in keeping with the vision of smart manufacturing and Industry 4.0.

Determination of energy dissipation during cyclic loading and its use to predict fatigue life of metal alloys

AbstractAn approach to determine the specific energy dissipated during cyclic loading of metal alloys with load ratios between 0 and 1 is developed. The dissipated energy per cycle is determined by using a limiting procedure to obtain the area enclosed between successive loading and unloading curves and can be used for low‐, medium‐, and high‐cycle fatigue. Comparisons with published data from two aluminum, one titanium, and one steel alloy show that the predictions capture the test results very well. A universal curve relating cycles to failure to two nondimensional parameters is derived. It is shown, in some limiting cases, that the method leads to power law equations with the parameters in these equations determined directly from the complete stress–strain curve of the material with no need to fit experimental data. Furthermore, if certain conditions are satisfied, the method is consistent with the existence of an endurance limit and Miner's rule.

Experimental study on failure evolution mechanism of clastic rock considering cementation and intermediate principal stress

The study of clastic rock failure evolution under true triaxial stress is an important research topic; however, it is rarely studied systematically due to the limitation of monitoring technology. In this study, true triaxial compression tests were conducted on clastic rock specimens to investigate the effect of cementation and intermediate principal stress (σ2) on the failure mechanism. The complete stress–strain curves were obtained, while the acoustic emission (AE) was monitored to indirectly evaluate the evolution of tensile and shear cracks, and crack evolution under true triaxial compression was imaged in real time by a high-speed camera. The results showed that the deformation and failure characteristics of clastic rock were closely related to the cementation type and intermediate principal stress. On the basis of the distribution characteristics of the ratio of rise time to amplitude (RA) and the average frequency (AF) of AE signals, tensile cracks of the contact cementation specimen propagated preferentially. Meanwhile, the enhancement of specimen cementation promoted the evolution of shear cracks, and the increase in σ2 promoted the evolution of tensile cracks. Moreover, the mesoscale cracking mechanism of clastic rock caused by cementation and σ2 under true triaxial compression was analyzed. The failure patterns of clastic rock under true triaxial compression were divided into three modes: structure-induced, structure-stress-induced and stress-induced failures. This study confirms the feasibility of high-speed camera technology in true triaxial testing, and has important implications for elucidating the disaster mechanism of deep tunnels in weak rocks.

Prediction of post-peak stress-strain behavior for sensitive clays

Unlike typical soils, sensitive clays undergo extensive post-peak strength degradation with increasing strain and finally disintegrate into a remolded liquid state. Realization of post-peak stress-strain behavior of sensitive clay up to large strains is vital in assessing large deformation problems such as landslides and mud flows. The conventional experimental approaches are uncertain about accurately determining the post-peak stress curve up to large strains (>100%) owing to rapidly increasing testing problems at increasing strains. This necessitates the exploration of an alternative scientific approach to predict the complete stress-strain curve for sensitive clays, which is addressed in this paper. Post-peak stress-strain curves of sensitive clays for different sites are obtained by converting remolding index vs. strain energy curves. Using site-specific data from eastern Canada sites, a mathematical expression is proposed to predict the complete stress-strain curve. Subsequently, an equation is developed for predicting remolding energy based on the stress-strain curve. Finally, it is observed that the post-peak stress-strain behavior is highly site-specific and can be mathematically expressed with a combination of exponential and linear strain-softening curves. Overall, the knowledge of the complete stress-strain behavior contributes greatly to the prediction of post-failure movements closer to reality.

Investigation on the anisotropy of mechanical properties and brittleness characteristics of deep laminated sandstones

Rock brittleness is a crucial mechanical property and essential for fracability evaluation and fracturing scheme design in unconventional reservoirs. However, the influence of inherent anisotropy on deep laminated sandstone’s mechanical properties and brittleness characteristics is rarely investigated. The energy transformation and damage evolution reflected by complete stress–strain curves are analyzed during the entire process of rock rupture under compressions. A new brittleness index is established based on energy evolution during sandstone failure. Its advantages involve comprehensively considering the energy transformation characteristics at both pre-peak and post-peak stages and the capability to characterize the effect of confining pressure and bedding plane (BP) geometry on sandstone brittleness. The triaxial compression tests on sandstones are conducted to validate the reliability and accuracy of the new brittleness index. Numerical simulations are then performed to further investigate the manner in which BP angle, BP density, and confining pressure control the brittleness anisotropy of deep laminated sandstones based on the finite element method. Then the acoustic emission (AE) characteristics of anisotropic sandstone and correlations between AE mode and brittleness index are discussed. The results indicated that the anisotropy of mechanical properties and brittleness of deep laminated sandstones were significantly affected by BP angle, BP density, and confining pressure. With the increase of BP angle, the brittleness index of deep laminated sandstone decreases first and then increases, showing a U-shape variation law, whose maximum and minimum values are obtained at φ = 0° and φ = 45°, respectively. The AE characteristics were closely related to rock brittleness, which was jointly controlled by BP geometry and confining pressure. The results provide a basis for the brittleness and fracability evaluation and optimum hydraulic fracturing design in deep laminated sandstones.

Mechanical behavior of steel fiber reinforced recycled aggregate concrete under dynamic triaxial compression

An experimental study of cylindrical steel fiber reinforced recycled aggregate concrete (SFRAC) specimens subjected to hydrostatic pressure and dynamic axial loading in a triaxial cell was performed. A confining stress range of 0–40 MPa and strain rate from 10−5 s−1 to 10−2 s−1 were employed using a servo-hydraulic testing system. In addition, two other control variables – volume fraction of steel fiber and replacement ratio of recycled coarse aggregate were also considered. A series of complete stress-strain curves were obtained, and the results were discussed in the aspects of the failure modes, peak triaxial strength, toughness, octahedral stress and failure criterion. The results indicated that an increase in the confining pressure resulted in a change in the failure modes, a significant increase in the peak strength and ductility. In particular, with an increase in confining pressure, the enhancement of strain rate on the peak strength decreased, indicating that there was a coupling effect between these two. The steel fibers had little influence on the failure modes of SFRAC, but significantly improved its ductility and toughness. The addition of recycled coarse aggregates markedly reduced the peak strength and the reduction reached nearly 20%, which was larger than other reports in uniaxial and true triaxial loading. Finally, a failure criterion for SFRAC specimens subjected to dynamic loading was used for validating the experimental results.

A rigid true triaxial apparatus for analyses of deformation and failure features of deep weak rock under excavation stress paths

The squeezing scenario in deep weak rock tunnels can hinder underground construction. However, due to the limitations of test technologies at hand, the real excavation stress path cannot be mimicked in the laboratory. Thus, the large deformation mechanism of deep weak rocks still remains unclear. For this, a true triaxial apparatus (TTA) to investigate the mechanical responses of deep weak rock under excavation stress paths in field and reveal the squeezing mechanism of deep tunnels is assembled and developed at Northeastern University, China. The apparatus can perform instantaneous unloading in σ3 direction based on electromagnetism technology. In addition, uniform loading and deformation measurements can be carried out based on the proposed linked interlocking clamp and antifriction device, even if the sample has a strong dilatation deformation performance. Next, a bore trepanning is designed to capture noiseless acoustic emission (AE) signals for deep weak rock at a low threshold. Finally, two tests were are conducted using this instrument to preliminarily understand the failure and deformation features of deep weak rock based on fractured marble. The results show that the complete stress–strain curves of fractured marble have the characteristics of low strengths and large deformations, and the larger deformation and the more serious failure occur when the fractured marble enters the post-peak state after excavation. The results show that the developed apparatus is likely to be applicable for deep weak rock engineering. © 2022 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

An FDM-Based Dynamic Zoning Method for Disturbed Rock Masses above a Longwall Mining Panel

Underground longwall mining can seriously disturb the surrounding rock masses above the panel. A surface cracking zone, continuous deformation zone, fractured zone, and caved zone can be formed in the overlying strata (termed the “four zones”), which may further result in the spontaneous combustion of coal seams and water inrush. It is essential to study and predict the development characteristics of the four zones induced by longwall mining to guarantee mining safety. These four zones are developed during the mining process, and the mechanical properties in different regions correspondingly differ. Thus, the dynamic zoning characteristics of the disturbed rock masses should be considered in any simulations. In this paper, an FDM-based dynamic zoning method for disturbed rock masses above a longwall mining panel is proposed. This method is mainly composed of four stages: (1) establishing a simplified complete stress-strain curve; (2) determining the zoning criteria; (3) adaptively adjusting the mechanical parameters of the disturbed rock mass; and (4) numerically modeling the longwall mining based on the FDM. The proposed method was applied to a study site in the Taixi coal mine. The dynamic development process of the four zones induced by longwall mining was clearly observed in the modeling procedure. The numerical modeling results achieved in this work, including the periodical coal-seam roof caving and the dynamic development characteristics of the four zones, are consistent with the observed distribution and other studies. The heights of the caved and fractured zones are basically consistent with the empirical formula. Thus, the dynamic zoning method can analyze and predict the dynamic development characteristics of four regions.

Development of stress-strain models for concrete columns externally strengthened with steel clamps

A robust and sustainable solution is required to tackle the ever-growing generation of construction waste worldwide. It has been known that construction waste yields concrete with substandard mechanical properties when used as a replacement for natural aggregates. With attributes like easy application and low cost, this study investigated the performance of low cost and easily available steel clamps to improve the compressive stress–strain properties of concrete fabricated with recycled concrete and brick aggregates. Results demonstrate that steel clamps effectively improved the stress–strain behavior of recycled aggregate concrete, and this improvement was more pronounced in concrete with a higher percentage of recycled aggregates. Steel clamps confinement increased the compressive strength by up to 242% and 252% for recycled concrete and recycled brick aggregate concrete, respectively, whereas the corresponding strain was increased by up to 448% and 414%, respectively. The stress–strain response of steel clamp-confined RAC was idealized into two branches: the first branch was assumed to be parabolic in shape till the peak strength, and a linear degrading branch was assumed for the post-peak region. Separate equations were proposed using regression analysis for peak strength, strain, initial modulus, and post-peak degradation modulus. The complete stress–strain curves of steel clamp-confined RAC were generated by utilizing existing equations. The proposed regression equations were combined with existing equations to generate complete stress–strain curves of steel clamp-confined RAC. In general, good agreement between experimental and predicted stress–strain curves was obtained.

Analysis on mechanical behavior and progressive failure of deep-buried marble based on complete stress-strain curves

Analysis on mechanical behavior and progressive failure of deep-buried marble based on complete stress-strain curves

Experimental Study on Steel-Fiber-Reinforced Scoria Aggregate Concrete Subjected to Freeze-Thaw Cycles and Then Exposure to Elevated Temperatures

Steel-fiber-reinforced scoria aggregate concrete (SFSAC), which contains scoria aggregate and steel fiber, was developed to reduce the environmental impacts and improve the energy efficiency of buildings. Experimental studies were performed. The test variables included steel fiber volume contents (0%, 0.5%, 1.0%, and 1.5%), freeze-thaw cycles (0 and 25 times), and temperature (20 °C, 200 °C, 400 °C, 600 °C, and 800 °C). Mass loss, relative dynamic elastic modulus, mechanical properties, and the variation pattern of the complete stress–strain curves were analyzed through rapid freeze-thaw, high-temperature, and mechanical tests. The test results showed that after 25 freeze-thaw cycles and then exposure to high temperatures, the surfaces of SFSAC specimens showed aggregate spalling accompanied by dense cracks. Moreover, the residual mechanical properties of steel-fiber-reinforced natural aggregate concrete (SFNAC) were better than those of natural aggregate concrete (NAC). Although the incorporation of steel fiber cannot significantly improve the anti-freezing performance of SFSAC, it can improve the residual mechanical properties of SFSAC, and the optimal amount of incorporation is 1%, considering the economic cost factors. The stress–strain curves of both SFSAC and SFNAC showed the same trend after freeze-thaw cycles and then high temperatures, i.e., the peak stress decreased, the peak strain increased, and the descending section tended to level off. Finally, based on the concrete damage mechanics theory, considering the role of steel fibers in the uniaxial compression process of scoria aggregate concrete (SAC) and the effect of freeze-thaw and high-temperature tests on the SFSAC, the mechanical damage model and the uniaxial compression stress–strain constitutive model were proposed as being able to highly accurately reflect the overall process damage characteristics of SFSAC after freeze-thaw and then high-temperature tests, and also provided a theoretical basis for the high-temperature resistance assessment of SFSAC structures in cold regions.