Ultimate Failure Mode Research Articles

Seismic Performance of X-shaped Stud Steel Reinforced Concrete Columns Under Composite Torsion

To investigate the seismic performance of X-shaped steel-reinforced concrete (SSRC) columns subjected to combined torsion, eleven specimens were designed with varying parameters including torsion-to-bending ratio, axial load ratio, steel ratio, longitudinal reinforcement ratio, stirrup reinforcement ratio, and stud spacing. Quasi-static loading tests were conducted to observe the failure process and failure modes. The results indicate that the SSRC column ultimate failure mode is predominantly determined by the stirrup reinforcement ratio, leading to either flexural-torsional failure or torsional failure. The torque-torsion angle hysteresis loops exhibit a pinched, inverted "S" shape, while the moment-displacement hysteresis loops display a more pronounced, spindle-like shape. The axial load ratio and torsion-to-bending ratio exert the most significant influence on the seismic performance of the specimens. As the steel ratio, longitudinal reinforcement ratio, and stirrup reinforcement ratio increase, the ductility, energy dissipation capacity, and other seismic performance indicators of the components improve to varying degrees. Among these parameters, the steel ratio has the most pronounced impact on energy dissipation capacity. When the steel ratio increases from 2.39% to 2.90%, the energy dissipation capacity of the component improves by 36.8%. Reducing the stud spacing appropriately enhances the seismic performance of the component, but excessively sparse or dense stud spacing can have detrimental effects. Based on the experimental results and existing research, a formula for calculating the torsional capacity of X-shaped SSRC columns subjected to combined torsion was developed using the superposition principle. The calculated results align well with the experimental results, with an average error within 5%.

Using Triaxial Geogrid in Reinforcing Crushed Rock Base Constructed on Soft Soil Subgrade

This study examined the performance of an unpaved road reinforced with a triaxial geogrid built on a soft clay subgrade. The test setup featured a fully instrumented unpaved road model comprising a 0.2-m-thick crushed rock base supported by a 0.8-m-thick soft clay subgrade. The triaxial geogrid was positioned between the base and subgrade layers. Plate bearing tests were performed following ASTM standards. The thickness of the triaxial geogrid-reinforced base layer played a critical role in determining the unpaved road model’s ultimate bearing capacity and failure modes. Results showed that the reinforced model with a base layer of 0.2 m thick exhibited the highest bearing capacity compared with the unreinforced model, with an enhancement factor of 1.44. Furthermore, the reinforced section outperformed the unreinforced one, even with a reduced base thickness of 0.15 m. This suggests that triaxial geogrid reinforcement offers a viable solution for enhancing the sustainability of unpaved road construction on weak subgrades.

Influence of Plate Thickness on the Mechanical Behaviour of Mild Steel Curved Plates: An Experimental Study

This paper aims to investigate the influence of plate thickness on the strength, failure load and deformation behaviour of mild steel curved plates. Experimental tests were conducted on curved plates with varying thicknesses, subjected to static loading conditions. The ultimate load, deflection and failure modes were recorded and analysed. Results indicate a significant relationship between plate thickness and mechanical properties. Thicker plates exhibited higher load-carrying capacity and different deformation patterns than thinner plates. Major Finding: The findings provide valuable insights for designing and optimising curved plate structures in various engineering applications.

A FEM‐DEM Coupling Analysis on Bearing Capacity of Sandy Soil Foundation Considering Fabric Anisotropy

ABSTRACTWith the acceleration of urbanization, the stability of the foundation is being more crucial to the performance and service of the superstructure. As our understanding of the factors influencing soil's physical and mechanical behavior deepens, it becomes increasingly challenging for traditional limit equilibrium and limit analysis methods to accurately consider the complex factors affecting foundation stability, such as initial fabric anisotropy caused by the particle morphology and geological deposition in sand. Although some scholars had used advanced constitutive models in the finite element method (FEM) to investigate the influence of initial fabric anisotropy on mechanical responses of foundations, this approach failed to reveal the microscopic information underlying the shear failure of sandy soil foundations. In this study, the influence of the initial fabric anisotropy of sandy soil on the ultimate bearing capacity and shear failure mode of shallow foundation is studied using the hierarchical FEM and discrete element method (DEM) coupling analysis method. Four representative volume elements (RVEs) with varying initial bedding plane angles are constructed in DEM for characterizing different initial fabric anisotropies, and the specific stress–strain information of DEM RVEs is directly passed into the corresponding Gauss points in FEM to replace the conventional constitutive model. Numerical results show that the initial fabric anisotropy affects the ultimate bearing capacity and shear failure mode of shallow foundations significantly, and the corresponding micromechanical behaviors at different local Gauss points have been explored, which advances our understanding of the micromechanisms underlying the progressive shear failure of sandy soil foundations significantly.

Numerical Simulation of Three-Point Bending Test on Steel Fiber-Reinforced Concrete Specimens Using DIANA FEA

This study presents a numerical investigation of the behavior of steel fiber-reinforced concrete specimens under three-point bending tests employing different model approaches. Steel fiber-reinforced concrete has gained significant attention in the construction industry due to its enhanced mechanical properties, including improved ductility and crack resistance. Understanding its behavior under loading conditions is crucial for optimizing structural design and ensuring durability. The simulations were conducted using DIANA Finite Element Analysis (FEA) software, and the comparative analysis was design to compare their effectiveness in predicting the structural response. The simulations were validated against experimental data from laboratory tests to ensure the accuracy and reliability of the numerical predictions. Through comparative analysis, this study evaluates the performance of each modeling approach in predicting key parameters such as load-displacement response, crack mouth opening and ultimate failure mode. Insights gained from these comparisons will provide valuable guidance for selecting the most appropriate modeling technique for similar structural analyses in practical engineering applications.

Particle flow simulation of fracture responses and anchoring mechanisms of cemented materials subjected to static-dynamic combined loads

This study aims to reveal the evolution of energy, cracks, force chain, and ultimate failure modes of cemented gangue backfill materials subjected to static-dynamic combined loads, as well as the reinforcement mechanisms of pre-tightening bolts on mechanical performance and progressive damage. The particle flow models with various fractal dimensions (D) of particle size distribution were established, and irreversible damage accumulation during dynamic loading was achieved through a nonlinear parallel-bonded stress corrosion model. The simulation results show that, compared to uniaxial compression, the energy release lag at peak strength is eliminated under static-dynamic combined loading, and the brittle failure feature becomes more pronounced. The filling effect of fine aggregates optimizes the uniformity of internal stress distribution, with the peak parallel bond strain energy increasing by 9.60%, 8.42%, and 14.81% as D increases from 2.1 to 2.85. At initial dynamic loading, the instantaneous increase in axial stress reaches the crack initiation stress, significantly increasing the number of tensile cracks. As pre-static load increases, the model sample is subjected to a higher internal stress environment during dynamic loading, leading to more remarkable force chain breakage observed at peak strength. Shear failure, including oblique shear failure and tensile-shear mixed failure, is the primary failure mode under static-dynamic combined loading. The additional constraints provided by bolts increase strain energy stored in particles and contacts and reduce the crack number at peak strength, with the constraining effect exhibiting more pronounced as preload increases. For anchored samples, the end of pallets is the initiation point for shear cracks, which extend along the edge of the preload concentration area, while tensile cracks initiating from the sample ends propagate toward the preload concentration area.

The influence of anchored CFRP on the torsional and bending behavior of sulfate damaged RC beams

Reinforced Concrete (RC) structural elements are subjected to continuous capacity deterioration due to different overloading situations or environmental conditions, such as sulfate attack, steel corrosion, and alkali-activated binders. Therefore, ensuring the system's integrity is a challenging issue faced by municipal and governmental agencies. This raises the need to upgrade the structural capacity by the utilization of strengthening materials of different material types, such as the externally bonded Carbon Fiber Reinforced Polymer (CFRP) that proves efficiency in increasing the flexural and shear capacities of the strengthened system along with maintaining their ductile type of failure. In contrast, a major deficiency exists in the externally bonded technique, the debonding failure, limiting the benefits from the FRP material's high tensile strength and could be solved using a proper and efficient anchoring method. A new and novel use for the CFRP anchored strengthening system was proposed in this study to upgrade the beam's capacity against the effect of sulfate attack damage. The behavior of simply supported strengthened beams was examined in this study under the effect of combined torsional and bending stresses using the Nonlinear Finite Element Analysis (NLFEA) technique using twenty-two models that are divided into six main groups. The investigated parameters were the depth of the anchored CFRP (wfa) (0.00 hf, 0.25 hf, 0.50 hf, 0.75 hf, and 1.00 hf) and sulfate damage cycles (0 (without), 60, 90, and 150 cycles). The structural efficiency of the modeled beams was examined using the torsion-twist curves, the torsion and twist capacities at the ultimate stage, failure mode, stiffness (pre and post-cracking), steel, stirrups, and CFRP strains, and finally, the energy absorption. It has been found that the resulting improvement percentage has a directly proportional relationship with the depth of the anchored CFRP. In contrast, an inversely proportional relationship exists between the improvement percentage and the number of exposed sulfate damage cycles. In conclusion, applying externally boned anchored CFRP has a superior contribution to the RC beams structural performance.

Biomechanical Comparison of Spacer Pin Fixation to Two Established Methods of Tibial Tuberosity Transposition Stabilization in Dogs.

The aim of this cadaveric study was to compare the biomechanical outcomes of three methods of stabilization for tibial tuberosity transposition to treat medial patellar luxation: a complete osteotomy with a two-pin and tension band wire (TBW) fixation (TBW group), a partial osteotomy with a two-pin fixation (2 Pin group), and a partial osteotomy with a spacer pin fixation (Spacer Pin group). Thirty medium to large-sized canine cadaveric tibiae were dissected and randomly assigned to one of three groups: TBW, 2 Pin, and Spacer Pin groups. The patellar ligaments were loaded in tension until ultimate failure. Ultimate failure force and mode of failure were documented, stiffness was calculated, and the results were compared statistically between the three treatment groups. There were not any significant differences in ultimate failure force or stiffness between groups. All groups predominantly failed by patellar ligament failure, with distal tibial crest fracture/displacement being the second-most common mode in the 2 Pin and Spacer Pin groups. The mechanical properties of the spacer pin stabilization were not different from the TBW and 2 Pin groups. The spacer pin technique could be an alternative way to stabilize tibial tuberosity following tibial tuberosity transposition with a partial osteotomy based on this cadaveric load-to-failure model.

Asymmetric deformation and failure behavior of roadway subjected to different principal stress based on biaxial tests

The magnitude and direction of stress will affect the failure of roadway. The impact of stress magnitude and direction on roadway failure was investigated using a rock failure system equipped with true triaxial loading, acoustic emission (AE), and digital image correlation (DIC) technologies. The system allowed for the simulation of rock sample failures under various three-dimensional stress conditions, while real-time monitoring was conducted using a high-precision microseismic system. By prefabricating rectangular holes at different angles in sandstone specimens, roadways under different stress effects in engineering can be simulated. Biaxial loading tests were then performed on these prefabricated sandstone cube specimens to observe external fracture characteristics and internal fracture information using acoustic emission equipment. The peak strength of samples with holes is approximately 38–56% of that of intact samples. In the early and middle loading stages, the strain on the surface is on the order of 10-3. In the later loading stage, the strain on the surface is on the order of 10-2. The findings indicate that roadway failure primarily involves local particle ejection, fragment spalling, large-scale particle ejection, plate crack buckling, and eventual failure. The ultimate failure mode varies based on stress deflection angles: with no included angle, the roadway exhibits a ’V’ shaped failure zone on both sides, predominantly experiencing tensile failure. At included angles of 30°, 45°, and 60° between stress and roadway axis, the roadway displays a “—” failure pattern along the diagonal, characterized by a combination of tension and shear failure. The extension angle of the“—” failure zone varies depending on the stress deflection angle. At a 90° included angle, the roadway shows a ’V’ shaped failure in the roof and floor, primarily undergoing tensile failure. Real-time monitoring of the strain field evolution around the roadway during failure using DIC method revealed valuable insights. AE events at different deflection angles reflect the progression of micro cracks in the specimen, showing a strong correlation with macro failure. The research outcomes elucidate the mechanisms behind various forms of roadway failure induced by stress deflection and shed light on the failure mechanism at different stress deflection angles.

Mechanical performance analysis method for ribbed H-section aluminum alloy members with initial curvature and torsion angle

In this study, an experimental investigation was conducted on the axial compression performance of ribbed H-section aluminum alloy members with initial curvature and torsion angle under varying boundary conditions, including one end hinged with the other rigidly connected, and both ends rigidly connected. Ultimate bearing capacity and failure modes were identified under real loads and subsequently compared with previous findings from our research group on members with hinged ends. To account for initial imperfections introduced during processing and transportation, 3D scanning technology was utilized to capture the precise geometrical dimensions, constructing an accurate numerical simulation model. The experimental results were corroborated with numerical simulations, leading to the proposal of an analytical method for members with initial curvature and torsion angle. Furthermore, extensive parametric analysis elucidated the impact of initial curvature, torsion angle, and slenderness ratio on the ultimate bearing capacity, culminating in the formulation of the stability factor and calculated length factor based on numerical outcomes. The study discovered significant variances in bearing capacity under different boundary conditions, with one-end hinged and one-section rigidly connected, and two-end rigidly connected conditions exhibiting 1.4 and 2.1 times the capacity of the hinged-at-both-ends scenario. Under different boundary conditions, the axial compression members were subjected to flexural-torsional buckling failure. Moreover, when the ultimate bearing capacity was reached, the lower flange of the member and the web near the lower flange appeared obvious buckling phenomenon. The numerical analysis aligned well with experimental data, validating the simulation method's reliability and revealing the stress distribution and evolution during member failure. These findings offer vital theoretical insights and technical support for engineering design and practical applications.

Nonlinear Finite Element analysis of concrete corbels with hybrid reinforcements

This study utilizes nonlinear finite element analysis to simulate the structural response of Reinforced Concrete (RC) corbels with hybrid reinforcements under monotonic loading. The models implemented in ABAQUS examine RC corbels with combined Carbon Fiber Reinforced Polymer (CFRP) and steel reinforcing bars to study the interaction between the concrete and hybrid reinforcement system. Specifically Ultimate load capacity, energy absorption and failure mode. Compressive strength, shear span/depth ratio, and the ratio of CFRP/steel reinforcement were the main parameters that considered in this paper. Results demonstrated a significant improvement in the ultimate load capacity of concrete corbels by up to 53% when both conventional steel and CFRP bars were integrated within the concrete corbel. The numerical test outcomes revealed that an increased hybrid reinforcement ratio effectively managed crack distribution, resulting in reduced concrete crack widths.

Mechanical model analysis of column-footing joints with combined socket-corrugated pipe connection

The socket connection method is widely used in precast column, particularly in seismic regions. However, reducing the socket-depth to lower costs may lead to shear failure in the socketed part of the columns. To address this issue and achieve cost objectives, a new approach combines shallow sockets with corrugated pipes for column-footing joints. Comparative tests were conducted to investigate failure in columns with socket-corrugated pipe connections (SCPC), shallow sockets (SSC), and cast-in-place (CIP). Furthermore, finite element models were employed to validate the experimental and simplified model results. The findings suggest potential shear failure in shallow socket connections, which can be mitigated by using the combined socket-corrugated pipe method that alters force transmission paths. As the axial load ratio increases, both the ultimate lateral load capacity of the specimen and the local stresses at the column base increase. In addition, the ultimate lateral load capacity of the column and the stress of the connection reinforcement are increased by increasing the strength of the longitudinal reinforcement, consequently amplifying the extent of joint area damage. Finally, a simplified strut-and-tie model of the SCPC, validated against numerical and experimental data, accurately represents force paths, ultimate lateral load capacity and failure modes in socket joints.

A Gaussian statistics-based unit-cell modeling method for the mechanical behavior prediction of 2.5D shallow straight-link-shaped woven composites

The shallow straight-link-shaped structure of 2.5D woven composites (2.5D-SSLS-WC) is a novel material with a wide range of promising applications, but the randomness of its internal structure has brought challenges to performance prediction and engineering design. The gap of existing unit-cell models in capturing the internal randomness of the 2.5D-SSLS-WC material limits the accurate prediction of properties and the optimization of engineering design. In this work, the modeling method for random unit-cell model based on Gaussian distribution is proposed for 2.5D-SSLS-WC structure considering random distribution property of weft yarns and extrusion effects between structural surfaces and internal yarns during the molding process, which can more effectively reflect the practical mesoscopic structure of the material, reveal the micro mechanical behavior inside materials and provide theoretical basis for material design and performance optimization. The mechanical property and damage evolution of the proposed model is predicted and analyzed using finite element (FE) analysis and progressive damage method. The maximum errors of equivalent stiffness and strength between prediction and experimental values are 6.7% and 2.3%, respectively. The results show that the proposed model has high prediction accuracy and can reasonably reflect the damage extension and ultimate failure mode of the material during the loading process, which verifies the rationality of the proposed unit-cell modeling strategy. The modeling method proposed in this paper provides a new perspective for the in-depth understanding and description of the microstructure and mechanical behavior of 2.5D-SSLS-WC materials, which is of significant theoretical and engineering value and can be extended to the modeling of other woven composites.

Shear behavior of RC beams with openings under impact loads: unveiling the effects of HSC and RECC

Incorporating transverse openings in reinforced concrete (RC) beams reduces their load-bearing capacity and stiffness, making them prone to premature failure. This highlights the need for a more nuanced understanding of their behavior to ensure structural integrity, particularly under impact loads. This research delves into a relatively unexplored area, investigating the impact performance of RC beams containing openings through numerical analysis. By comparing different concrete types, the study seeks to identify optimal materials for such applications. The concrete damage plasticity model, accounting for strain rate effects, will be employed to simulate the material behavior of normal-strength concrete (NSC), high-strength concrete (HSC), and a novel eco-friendly alternative: rubberized engineered cementitious composite (RECC). RECC incorporates recycled tire rubber as a partial substitute for traditional concrete aggregates, offering a sustainable solution while mitigating environmental hazards associated with waste tire incineration. The finite element models are validated with experimental results, accurately predicting ultimate capacities, failure modes, and post-cracking response in RC beams (with/without openings) under static/impact loads. A comprehensive parametric analysis investigates the effects of concrete strength, impact energy, impactor mass, drop height, and opening location, providing valuable insights into how these factors influence the impact behavior under drop-weight testing. The results reveal that openings in RC beams under impact loads significantly reduce strength and stiffness, with detrimental effects observed for dual shear-zone openings. Surprisingly, a small mid-span opening can enhance impact response. HSC beams exhibit lower initial displacements but higher residual values, while RECC improves overall behavior in beams with openings, reducing maximum displacement and promoting energy dissipation for improved post-impact recovery.

Experimental study on the compressive behavior of UHPC filled stainless steel tubes subjected to monotonic and cyclic loading

Ultra-High Performance Concrete Filled Stainless Steel Tubular (UHPCFSST) column is a novel type of composite columns appealing to be adopted in corrosive and marine environment. To explore the axial performance of UHPCFSST columns, this paper initiates an experimental program containing 14 UHPCFSST columns subjected to either monotonic or cyclical axial compressive loading. The test variables in this program mainly include the column dimension, tube thickness and the loading schemes. Based on the test results, the damage evolution process, ultimate failure mode, load-deformation response and the typical mechanical performance indexes inclusive of loading-carrying capacity, stiffness degradation, as well as ductility coefficient are thoroughly examined. After that, theoretical analysis is carried out to explore the interaction behavior between UHPC and stainless-steel tube and hence judge the degree of confinement effect. To assess the applicability of the code equations stipulated in current international design guidelines and the empirical formulas proposed by other researchers, a small-scale dataset containing 41 UHPCFSST columns was compiled to make comparison of axial capacity between test results and analytical predictions. In view of the limited accuracy or the burdensome calculation process, a new formula considering actual loading carrying mechanism was proposed to calculate the axial capacity of UHPCFSST columns, which exhibits enhanced accuracy and efficiency than the current formulas.

Multi-scale analysis of ultimate bearing capacity in composite hull joints: failure mechanism and numerical simulation

ABSTRACT Progressive failure analysis method is the main method to analyse the ultimate bearing capacity and failure mode of composite structures. Multi-scale method can effectively reduce the dependence of damage mode and stiffness degradation analysis on material parameters. Based on the multi-scale method, from micro-scale to mesoscale and then to macro-scale, the equivalent modulus and equivalent strength of fibre bundles, single-layer laminates and multi-directional laminates were predicted respectively, and the prediction method of ultimate bearing capacity of large-scale composite structures from material level to structure level was constructed. The mechanical properties of standard composite materials and the ultimate bearing capacity of full-scale composite joints were tested respectively, and the ultimate bearing capacity and failure mode of L-joints were predicted by numerical method. The results show that the numerical simulation method based on multi-scale can accurately predict the ultimate bearing capacity and failure mode of large-scale joints of the hull.

Bond stress-slip models and behavior of externally bonded aluminum alloy (AA) plates to concrete surface

This paper aims to assess the feasibility of employing high strength aluminum alloys (AA) with a rough (R) surface as externally bonded reinforcement (EBR) material. A comprehensive experimental investigation was carried out to evaluate the bond strength and behavior through single shear tests. The variables considered were concrete strength and bonded length, while the remaining parameters were kept constant. The study measured the ultimate load, extension, and strain values, and subsequently calculated the bond stress and slip. It was observed that the ultimate load, bond stress, and failure modes exhibited variations depending on the concrete strength and bond length. For a concrete strength of 60 MPa and a bonded length of 80 % of the concrete prism length, the ultimate load and maximum bond stress increased by 54.0 % and 66.0 % respectively, compared to those with a concrete strength of 20 MPa and the same bonded length. Additionally, when comparing a bonded length of 80 % (200 mm) of the concrete prism length to a bonded length of 20 % (50 mm), the ultimate load and maximum bond stress increased by 20.0 % and 99.0 % respectively for a concrete strength of 60 MPa. The study also developed bond stress-slip models for the AA-concrete interface, as well as models for predicting the ultimate load based on concrete strength and bonded length. These models displayed high accuracy in their predictions. In conclusion, the results indicate that AA plates are effective and suitable as EBR materials for the reinforcement of RC members.

Flexural behavior of RC beams externally strengthened with side-bonded CFRP laminates with variable internal reinforcement

This study investigates the flexural behavior of reinforced concrete (RC) beams externally strengthened with bottom- and side-bonded carbon fiber-reinforced polymer (CFRP) sheets with variable steel ratio. The choice of applying the CFRP sheets in a bottom- or side-bonded configuration depends on the accessibility of the beam. This experimental investigation is aimed at studying and comparing the efficacy of bottom- and side-bonded CFRP sheets for flexural strengthening of RC beams with variable internal steel ratios. The effect of steel reinforcement ratio, and the number of CFRP plies are examined by testing 10 RC beams under a four-point bending configuration. The results in terms of load-deflection response, ultimate load-carrying capacity, failure modes, and ductility are studied and compared with control unstrengthened beams. The study revealed that side-bonded beams provided flexural capacity comparable to the bottom-bonded beams for both ratios of internal reinforcement used in the study. The study also showed that both strengthening configurations were more effective when the internal steel ratio was low. In terms of ductility, the side-bonded scheme provided ductility indices comparable to the bottom-bonded beams. The findings of this study confirm the feasibility of using side-bonded fiber-reinforced polymer (FRP) sheets as a strengthening technique for RC beams when the soffit of the beam is inaccessible.

Research on Mechanical Properties of New Aluminum Alloy Scaffold Nodes

This article explores the feasibility of using aluminum profiles to design a new type of foldable scaffolding system. To verify the ultimate bearing capacity and failure mode of structural node connectivity points, mechanical performance tests were conducted on the tensile strength of cast aluminum and angle iron nodes to clarify the ultimate bearing capacity and failure mode of the nodes, providing a reference for using aluminum profiles to make new types of scaffolding.

Study on the mechanical properties of recycled brick coarse aggregate concrete based on finite element modeling

In recent years, the use of recycled materials in concrete production has garnered significant attention due to their environmental and economic benefits. To promote the application of recycled aggregates, this study focuses on investigating the utilization of Recycled Brick Coarse Aggregate (RBCA) as a substitute for natural aggregate. This paper presents the development of stochastic convex polygonal RBCA through the utilization of a custom-programmed algorithm and proposes a finite element model designed to simulate the behavior of RBCA concrete under compression and splitting tensile. Numerical simulations were conducted to investigate the effects of brick aggregate Replacement Rate (RR) and porosity on the compressive and splitting tensile properties of RBCA concrete. A strong correlation was found between the Concrete Damage Plasticity (CDP) model developed in this study and experimental results, indicating high reliability. The results indicate that the replacement rate of brick aggregates has a more significant impact on the compressive strength than on the splitting tensile strength of concrete. Furthermore, the distribution of coarse aggregates and pores has a minor influence on the mechanical properties and ultimate failure mode of RBCA concrete but significantly affects the crack distribution pattern. The sequence of damage initiation in RBCA concrete was found to be: pores, old Interfacial Transition Zone (ITZ), old mortar, new ITZ, new mortar, RBCA, and Natural Coarse Aggregate (NCA). These findings contribute to a comprehensive understanding of RBCA's performance and offer valuable insights for optimizing its behavior.