Load-bearing Strength Research Articles

Synergistic impact of geopolymer binder and recycled coarse aggregates on the performance of concrete masonry units

This study examines the combined effect of geopolymeric binder and recycled coarse aggregates (RCA) on the properties of concrete masonry units (CMU). A target 1-day compressive strength of at least 13.8 MPa was attained for all mixes to satisfy the load-bearing strength requirements. Geopolymer mixes made with RCA at replacement rates of up to 100 % were evaluated and compared to a cementitious control mix made with natural coarse aggregates. The environmental and economic impacts were then integrated with the quantity of waste valorized and compressive strength in a multifunctional performance index. Experimental results showed that the utilization of geopolymers as a substitute for Portland cement in the production of CMU did not impact the oven-dry density but reduced the water absorption capacity by up to 26 %. Although the incorporation of RCA negatively impacted these two properties, their values remained within the acceptable range stated by the standards. The geopolymer CMU mix made without RCA had 9 and 25 % lower 28-day compressive and splitting tensile strengths compared to the cement control mix, respectively. Subsequent RCA replacement further reduced these mechanical properties. While the linear drying shrinkage was reduced upon substituting the cementitious binder with the geopolymeric counterpart, RCA replacement of up to 100 % increased the linear drying shrinkage to reach 0.091 %, exceeding the limit set by the standard. Overall, the CMU mix made with geopolymer binder and 75–100 % RCA was found to be optimal for load-bearing applications.

Fundamental mechanical relations of open-cell metal foam composite materials with reticular porous structure

The compressive behavior is one of the most fundamental mechanical properties for engineering materials. In this paper, the octahedral structure model of porous materials is used to evolve the mechanical analysis model under compressive loading for the porous composite materials, which are resulted from reticular metal foams with pore struts presenting multilayered structure. Starting from this analysis model, some fundamental mechanical relationships, including those of the safe load-bearing and overall strength, have been deduced for these porous composite materials. The compressive strength has been characterized for the porous composite body, corresponding to the overall failure caused by the prior breakage of the strut core and by the prior breakage of the strut shell, respectively. The nickel foam products manufactured on the production line of enterprise were used to make porous composite materials by coating the pore struts with epoxy resin, and the metal foam composite material was obtained with the composite pore-struts of metal/resin multilayered structure. Using this porous composite material for compression experiments, it is found that the experimental data match well with the mathematical relationship from the present theoretical model. The results verify the feasibility of this analysis model and the practicality of the relevant mathematical relationship.

Investigating the effect of zirconium dioxide micro and nano particles on the mechanical characteristics of Al-7075 alloy

ABSTRACT The study investigates the influence of zirconium dioxide (ZrO2) particles on the mechanical properties of Al7075 alloy and aims to assess the potential for tailored compositions to meet specific engineering requirements, particularly in aerospace applications. Al7075-ZrO2 composite was fabricated with varying percentages of micro (µ) ZrO2 (1%, 2%, and 3%) and nano ZrO2 (0.17%, 0.34%, and 0.51%) particles using the stir casting technique. Mechanical testing was conducted to evaluate the peak stress, load, and yield strength of the resulting Al7075-ZrO2 composites. Experimental findings reveal that the highest peak stress and load were achieved at 0.51% nano ZrO2 content, indicating a reinforcement effect. Moreover, the composite with 0.34% nano ZrO2 exhibited 59% increased peak stress of 153 MPa and 24% decreased strain 3.7% compared 125 MPa and 4.9% for pure Al7075. Al7075-µZrO2 composite has shown 125 MPa of peak stress and 2.9% maximum strain. These properties highlight the potential of Al7075-ZrO2 composite for applications requiring high resistance to tensile failure. Incorporating nano ZrO2 particles positively impact the load-bearing capacity and strength of Al7075 alloy matrix. Specifically, compositions with tailored ZrO2 content percentages demonstrate the potential for meeting the stringent requirements of aerospace applications.

AN APPROACH OF WEB STIFFENER CALCULATION IN THIN-WALLED COLUMNS

This article presents an analytical approach for calculating web stiffeners in thin-walled columns. A novel method is introduced, which treats each bending point in the cross-section web as a separate stiffener. The advantages of this calculation method are discussed, highlighting its increased versatility in designing cross-section geometry. The load-bearing strength of axially compressed thin-walled closed cross-section columns, calculated using this method, is compared to analytical calculations based on the Eurocode 3-1-3 methodology and to the finite element method analysis. Calculation results of columns with cross-sections including shallow web stiffeners were up to 9.22% less conservative when compared to the Eurocode 3-1-3 methodology. The results demonstrate great compliance of the proposed method for column crosssections with deep stiffeners. Finite element method (FEM) analysis was performed to verify the calculated load bearing strengths of the columns according to both calculation methodologies. FEM analysis confirmed the reliance of the calculated results and showed, that the load bearing strengths calculated using the newly presented methodology were ranging from 88.77% to 97.86% of load bearing strength calculated using finite element method. These results proved, that the proposed method provides an accurate load bearing strength of thin-walled columns with web stiffeners.

Structure and Properties of Metastable β Ti-25Nb-8Sn Alloy following Cold Rolling and Aging Treatments.

Metal implants require an elastic modulus close to cortical bone (<30 GPa) to avoid stress shielding and ensure adequate load-bearing strength. The metastable β-type Ti-25Nb-8Sn alloy has a low elastic modulus (52 GPa), but its yield strength (<500 MPa) needs enhancement. This study enhances Ti-25Nb-8Sn's elastic admissible strain through cold rolling and aging heat treatments, investigating the microstructure's impact on mechanical and corrosion properties. The results show that lower-temperature aging (<450 °C) leads to ω-phase precipitation, yielding a 300% increase in yield strength (>1900 MPa). However, this also increases the elastic modulus (~80 GPa), limiting the deformation ability. Higher-temperature aging (>500 °C) eliminates the ω phase, transforming it into α precipitates, resulting in a lower elastic modulus (~65 GPa) and improved deformation ability, with substantial yield strength (>1000 MPa). In summary, the optimal process conditions are determined as 90% cold rolling followed by aging treatment at 550 °C. Under these conditions, Ti-25Nb-8Sn achieves the most suitable yield strength (1207 MPa) and high corrosion resistance, retaining a relatively low elastic modulus (64.7 GPa) and high elastic admissible strain (1.93%). This positions it as an ideal material for biomedical implants.

АNALYSIS OF SOFTWARE PACKAGES APPLYING IN THE INVESTIGATION OF THE DAMAGE EFFECT TO REINFORCED CONCRETE BEAMS ON STRENGTH AND DEFORMABILITY: THE REVIEW

Currently, on the world market, there are trends in the construction of a large number of monolithic and prefabricated reinforced concrete structures, and individual parts of these structures are operated with damage or defects, and the causes of these damages are quite diverse. In modern conditions, such work can be facilitated and analyzed in more detail with the help of specialized software, which can include all the necessary characteristics of material behavior and include existing defects or damage. This problem of damage to reinforced concrete structures will become extremely relevant in Ukraine, especially after the completion of a full-scale armed attack by the Russian Federation, and therefore, the study of various types of damage and defects that will affect the load-bearing capacity and strength of reinforced concrete elements require a quick and high-quality analysis of this damage, and most likely aggregates of damage.

Experimental study on the behavior of damaged CFRP and steel rebars RC columns retrofitted with externally bonded composite material

The structural behavior of concrete columns reinforced with CFRP bars has been the focus of many researches over the past two decades. There is a dearth of comprehensive research concerning the axial compressive performance of retrofitted CFRP bars reinforced concrete (RC) columns. To fill this gap a thorough investigation was carried out to understand failure mode, load–displacement response, axial deflection, axial load-bearing strength, ductility index (DI), stiffness index (KI), and strength index (SI) of retrofitted CFRP bars RC columns. The experimental matrix comprised 14 short circular columns, seven reinforced with CFRP bars and hoops and the other seven with steel bars and hoops. Initial damage was induced through axial loading until a 35% reduction in peak axial strength was observed, after which damaged columns were repaired and retrofitted using CFRP sheets. The parameters of the study include concentric and eccentric compressions, transverse reinforcement spacing, CFRP wrapping, steel, and CFRP reinforcements. According to the findings, lowering transverse hoop spacing enhanced the utmost capacity and ductility of both types of retrofitted columns. The average peak strength and corresponding axial displacement of CFRP RC columns were 22.63% and 14.87%, and ductility (at a 20% load decrease) was 118% higher after CFRP retrofitting. The axial stiffness of damaged CFRP bars RC columns after strengthening with CFRP sheet were not fully rehabilitated and on average SI under concentric loading was 3.22% lower while DI under eccentric loading was 2.71% higher than steel RC columns.

Static Stability Behavior-Based Seismic Damage Endurance Assessment of Long-Span Single-Layer Spherical Lattice Shells

ABSTRACT This paper presents a modified evaluation approach for the structural-capacity-reserve (SCR) based on the static stability behavior of single-layer spherical lattice shells to achieve more accurate assessment results of seismic damage endurance. The SCR index in this paper is calculated by integrating the redefined residual structural capacity (RSC) ratio based on post-earthquake static stability behavior within the range of damage degrees caused by strong earthquakes. Compared with the assessment work for seismic damage endurance in the existing literature, the proposed RSC ratio in this paper could take into account both ultimate load-bearing strength and residual deformation. Additionally, the specific quantitative indicator in the proposed assessment method should also be determined according to whether the residual nodal displacement of the lattice shell after an earthquake exceeds the limit value state specified by the design code. The numerical results in the case study indicate that the residual load-bearing strength of the lattice shell remains relatively constant under the same damage state induced by different earthquakes, with residual deformation significantly impacting the assessment of seismic damage endurance. Thereby, the required RSC can be controlled by reducing the residual nodal displacements of the lattice shell under strong earthquakes to achieve a well-balanced design scheme.

Using extrusion-based 3D printing technology to investigate the impact of changing print conditions on tensile characteristics

PurposeThe purpose of this study, most recent advancements in threedimensional (3D) printing have focused on the fabrication of components. It is typical to use different print settings, such as raster angle, infill and orientation to improve the 3D component qualities while fabricating the sample using a 3D printer. However, the influence of these factors on the characteristics of the 3D parts has not been well explored. Owing to the effect of the different print parameters in fused deposition modeling (FDM) technology, it is necessary to evaluate the strength of the parts manufactured using 3D printing technology.Design/methodology/approachIn this study, the effect of three print parameters − raster angle, build orientation and infill − on the tensile characteristics of 3D-printed components made of three distinct materials − acrylonitrile styrene acrylate (ASA), polycarbonate ABS (PC-ABS) and ULTEM-9085 − was investigated. A variety of test items were created using a commercially accessible 3D printer in various configurations, including raster angle (0°, 45°), (0°, 90°), (45°, −45°), (45°, 90°), infill density (solid, sparse, sparse double dense) and orientation (flat, on-edge).FindingsThe outcome shows that variations in tensile strength and force are brought on by the effects of various printing conditions. In all possible combinations of the print settings, ULTEM 9085 material has a higher tensile strength than ASA and PC-ABS materials. ULTEM 9085 material’s on-edge orientation, sparse infill, and raster angle of (0°, −45°) resulted in the greatest overall tensile strength of 73.72 MPa. The highest load-bearing strength of ULTEM material was attained with the same procedure, measuring at 2,932 N. The tensile strength of the materials is higher in the on-edge orientation than in the flat orientation. The tensile strength of all three materials is highest for solid infill with a flat orientation and a raster angle of (45°, −45°). All three materials show higher tensile strength with a raster angle of (45°, −45°) compared to other angles. The sparse double-dense material promotes stronger tensile properties than sparse infill. Thus, the strength of additive components is influenced by the combination of selected print parameters. As a result, these factors interact with one another to produce a high-quality product.Originality/valueThe outcomes of this study can serve as a reference point for researchers, manufacturers and users of 3D-printed polymer material (PC-ABS, ASA, ULTEM 9085) components seeking to optimize FDM printing parameters for tensile strength and/or identify materials suitable for intended tensile characteristics.

Effect of blind-bolt repair method on vibration and compression characteristics of delaminated composite aircraft panels

The paper investigates the validity and reliability of the blind-bolt repair method for repairing delaminated composite aircraft panels. The delaminated specimens are prepared by inserting Teflon films during the manufacturing process to simulate interlayer damage. Subsequently, these specimens are repaired using the blind-bolt method. Modal and uniaxial compression tests are conducted to quantitatively evaluate the natural frequency, mode shape and load-bearing strength of both delaminated and bolt-repaired specimens. Digital image correlation and ultrasonic phased array techniques are employed to characterize buckling instability and damage evolution of specimens. The results reveal that the natural frequency and compressive buckling strength of delaminated specimens significantly decrease. The mode shape also changes nonlinearly with the stiffness reduction. This variation is proportional to the size and the quantity of delaminations. The blind-bolt repair method effectively restores the vibration and mechanical properties of the delaminated composite structure by reconnecting separated sub-laminates. A repair tolerance of 20 mm–60 mm is recommended for a single blind-bolt. When the delamination length is 35 mm, the repair efficiency for the critical buckling load and the ultimate load is the highest, at 58.3% and 64.4%, respectively.

Properties of an active film based on glutenin/tamarind gum and loaded with binary microemulsion of melatonin/pummelo essential oil and its preservation for Agaricus bisporus.

In order to improve the effectiveness of the active packaging, we aimed to develop an active packaging film with unidirectional sustained release, high barrier protection, and seamless attachment between the layers. An active film based on glutenin/tamarind gum loaded with the binary microemulsion of melatonin/pummelo essential oil (G/T-M-E) with sustained release and combination effects of internal and external layers was prepared. The outer barrier layer exerted an excellent protective barrier effect after adding (3-chloropropyl) triethoxysilane, which effectively reduced external interference and the ineffective diffusion of active substances in the inner layer. The effective attachment of melatonin and essential oil layer in the G/T-M-E film enhanced antioxidation, microorganism inhibition, and free-radical-scavenging properties, which effectively delayed the senescence of post-harvest white mushrooms. Furthermore, the G/T-M-E exhibited excellent tensile strength, barrier capacity, and load-bearing strength, which had a potential, positive effect on food preservation. Therefore, this film is highly recommended for packaging purposes.

Analytical Study Of Load Rating On RCC Box Girder Superstructure Under The Effect Of IRC Loadings

It is observed that over the course of time structural components weakens and their ability to carry the self weight along with the superimposed load decreases. Consequently, it becomes very much important and vital to periodically assess the strength, stability and the performance of the bridge and other structure in order to ascertain their remaining residual strength and to ensure safety. There are different experimental methods available which uses the concept of Non-Destructive testing in order to ascertain the performance and the condition of any structure at any point of time. There are numerous experimental method which are used to perform the Load Rating Analysis but there is no provision to perform the same rating analysis analytically as per the Indian code on bridge related software. This paper generally deals with providing an analytical solution which can be used in order to estimate the residual strength of the bridge structure and perform the Load Rating Analysis analytically on Midas Civil Software. The study basically involves the modelling and Analysis of 2 Reinforced Concrete Box Girder Superstructure, each of span length 40m situated in Lucknow analyzed as per the Indian Standard Codes. Both of the bridge model represents the condition of the bridge structure at a specific time period. The time gap between the analysis of the two models is assumed to be 70 years. The bridge model is modelled and analyzed with the help of Midas Civil Software and the Load carrying capacity of the structure is evaluated based on the different statistical parameters such as Vertical Displacement, Shear Force and Bending Moment. At last a comparative study is conducted between the two models. The analysis revealed that the Bridges Lose their load bearing capacity and strength after a time period of 70 years. A considerable increase in the value of vertical displacement and bending moment was observed beyond the safe and permissible limit of the structure. The analytical approach demonstrated in this study can be applied to various bridge structure such as RCC and PSC Tee Beam Bridge, I Girder bridge, cable stayed bridge etc.

DESIGN AND FABRICATION OF ELECTRIC MOTOR CYCLE CHASSIS FRAME

Our undertaking centers on the plan and creation of an electric scooter's chassis frame, underlining execution and security. Using progressed computer aided design and FEA apparatuses; we enhance plan boundaries like material choice and burden dissemination. Fabricating joins conventional and current strategies for mechanical effectiveness and simplicity of creation. Thorough actual tests approve load-bearing limit and strength. Our work adds to feasible metropolitan transportation by making a lightweight, strong body Chassis (frame), improving electric motorcycle (scooter) well being and proficiency. The design process consists of several steps, including: ➢ Defining chassis requirements ➢ Doing data analysis of existing chassis models ➢ Creating a quantity design concept ➢ Choosing the best design concept ➢ Select Finite Element Analysis of Design (FEA) ➢ Chassis fabrication The final design is an incredibly light and strong chassis that meets the requirements of the power plant. The final analysis results show that the chassis can withstand the expected loads during normal operation. The chassis is made by a combination of welding and machining. KEYWORDS: An unnatural weather change, Electric Bike, Case, Triangulation, Ansys.

Study on Effects of Geometric Parameters on Tensile Strength of Hybrid Bonded-Rived Joint of Fiber Reinforced Polymer Plates

Hybrid bonded-rived joint combines bonding and riveting and has become one of the most important connection forms in composite materials. This paper investigates and analyzes the influence of geometric parameters of CFRP hybrid bonded-rived joints on load-bearing strength. The finite element method is used to analyze the strength of the hybrid bonded/riveted joint between carbon fiber composite and metal under tensile load. The different ratios of the hybrid joint’s e/D, w/D, and w/e are analyzed. It is shown that e/D and w/D significantly impact damage loads and failure mode of the hybrid bonded/riveted joint. The increase of e/D will change the joint from shear-out to net tension failure, and the effect of w/D is opposite to that of e/D. Under the same bonding area, different w/e impacts the damage load of the joint, and the larger w/e makes the joint have a larger failure load, and the stiffness of the joint is also large.

Influence of isothermal tempering on microstructures and hydrogen-environmentally embrittlement susceptibility of laser additively manufactured ultra-high strength AerMet100 steel

Good hydrogen-environmentally embrittlement (HEE) resistance is necessary for safe service of critical main load-bearing ultra-high strength steel (UHSS) components of advanced aircrafts in marine atmosphere environment. Controlling isothermal tempering time is one important heat treatment method to optimize HEE resistance of UHSS by designing microstructure. Influence of isothermal tempering time at 482 °C on microstructures and HEE susceptibilities of laser additively manufactured (LAM) AerMet100 steel was investigated by several material characterization methods and slow strain rate tensile (SSRT) tests in both of air and 3.5 wt% NaCl aqueous solution. Results mainly indicate that microstructure evolution behaviors of LAM AerMet100 steel successively include martensite and retained austenite decomposition, M2C carbide formation and coarsening, and film-like reverted austenite formation and thickening. Short-time tempering specimens of LAM AerMet100 steel has the highest strength-loss-index in all of the specimens due to the lowest austenite amount. The lower HEE susceptibility of LAM AerMet100 steel in long-time tempering condition is mainly corresponding to M2C carbide coarsening and film-like reverted austenite thickening. Furthermore, difference of hydrogen charging method strongly influences macro-fracture behaviors of the SSRT specimens, but micro-cracking modes of the steel in different conditions are predominantly martensite packet/plate boundary cracking. Under open-circuit potential condition, HEE cracking zone is prone to be origin from pitting corrosion sites, and the SSRT specimen in long-time tempering condition have a good ductility; in contrast, under cathodic polarization condition, HEE cracking zone is around the circumferential zones, and the tensile specimens are brittle fracture. These findings are important when considering achieving improved HEE resistance for LAM AerMet100 steel tempered at 482 °C of a longer isothermal tempering time at the strength level of interest.

Heat treatment effect on mechanical and wear properties of hypereutectic Al-Si-Cu-Ce alloy

ABSTRACT The influence of ageing and ageing time on the mechanical properties, such as tensile strength and wear behaviour, of Al18Si3.6Cu0.34Ce alloy have been discussed. The As-cast alloy was subjected to T6 heat treatment (solutionization at 510° for 1 hr and ageing at-210°C) for different ageing durations like 1 hr, 3 hr, 5 hr and 7 hr, the morphology of as-cast and age hardened samples is examined by SEM and optical images, the sharp edges of primary-silicon and α-Al matrix with a columnar grain structure of untreated alloy changed after ageing, they are rounded off, spheroidisation with uniform redistribution of Al2Cu blocks, Al2CeSi intermetallic precipitates are formed with improved grain boundaries, and it develops obstacles in larger scale to the flow of dislocation mechanism, so it strengthens the metal matrix. Compared to as-cast alloy, the mechanical properties are improved after ageing. For 5-hr aged samples, the yield strength (YS) elevated to 127.44 MPa (improved by 83%) with an elongation rate of 1.64% (41.4%) as compared to as-cast alloy, and the ultimate tensile strength of as-cast alloy (158.2 MPa) enhanced to 193.835 MPa and 168.7 MPa after 1 hr and 3 hr ageing, respectively. Ageing improves the flow stress, which is predominantly the effect of homogenisation. Considerable improvements in the wear resistance after age hardening were noticed; both VWR and COF both a linear relation, with applied load at constant speed. As-cast and 7-hr aged samples show poor wear resistance due to co-existence of incoherent phases (Al2Cu and Si) in the metal matrix, and alloy ageing for 1 hr, 3 hr and 5 hr improves the load bearing and shear strength.

Optics-Free, In Situ Swelling Monitoring of Articular Cartilage with Graphene Strain Sensors.

Articular cartilage derives its load-bearing strength from the mechanical and physiochemical coupling between the collagen network and negatively charged proteoglycans, respectively. Current disease modeling approaches and treatment strategies primarily focus on cartilage stiffness, partly because indentation tests are readily accessible. However, stiffness measurements via indentation alone cannot discriminate between proteoglycan degradation versus collagen degradation, and there is a lack of methods to monitor physiochemical contributors in full-stack tissue. To decouple these contributions, here, we developed a platform that measures tissue swelling in full-depth equine cartilage explants using piezoresistive graphene strain sensors. These piezoresistive strain sensors are embedded within an elastomer bulk and have sufficient sensitivity to resolve minute, real-time changes in swelling. By relying on simple DC resistance measurements over optical techniques, our platform can analyze multiple samples in parallel. Using these devices, we found that cartilage explants under enzymatic digestion showed distinctive swelling responses to a hypotonic challenge and established average equilibrium swelling strains in healthy cartilage (4.6%), cartilage with proteoglycan loss (0.5%), and in cartilage with both collagen and proteoglycan loss (-2.6%). Combined with histology, we decoupled the pathologic swelling responses as originating either from reduced fixed charge density or from loss of intrinsic stiffness of the collagen matrix in the superficial zone. By providing scalable and in situ monitoring of cartilage swelling, our platform could facilitate regenerative medicine approaches aimed at restoring osmotic function in osteoarthritic cartilage or could be used to validate physiologically relevant swelling behavior in synthetic hydrogels.

Mechanical characterization of the concrete mixture, including steel slag aggregate and steel fibres

Steel slag is a major by-product of the steel industry, its waste management poses serious environmental threats. The slag produced by the steel industries and used as an aggregate in concrete is a sustainable key for the optimal and efficient use of natural mineral resources. In the past, numerous studies have been conducted and engineering solutions have been proposed to find the desired proportion of steel slag in concrete. The present work primarily focuses on the mechanical characterization of concrete mixes adopting Steel Slag Aggregates (SSA) as a substitution for conventional Coarse Aggregates (CA). Furthermore, an optimal concrete composition has been proposed to maximise the load-bearing strength of the concrete. First, following the standard benchmarking procedure, concrete mechanical properties are obtained. Next, the effect of replacing CA (10%, 20%, 30%, and 40%) by weight with SSA in the concrete mix is studied. The required number of cubes was cast for optimisation, and mechanical characterization (compressive, split tensile, and shear tests) was performed on the M45-grade concrete with SSA. Finally, the study has been extended with the inclusion of steel fibres in the previous optimal SSA-concrete mix. The optimum steel fibre volume fraction has been determined by performing various mechanical tests on the steel fibre concrete mix. The experimental results show that SSA can significantly improve the mechanical performance of concrete. The ideal percentage to replace CA with SSA in the concrete mixture (CM2) is 30%, which improves the concrete's compressive strength, split tensile strength, and shear strength in comparison to regular concrete. Additionally, adding steel fibres to the ideal mix (CM2) has very less impact on compressive strength but increases tensile strength and shear strength.

Strength design of prefabricated corrugated steel plate shear walls under combined compression and shear loads

The prefabricated corrugated steel plate shear wall (PCSPSW) embedded within the frames is composed of one corrugated steel plate (CSP) and two vertical boundary elements (VBEs). Both axial compression and shear loads are inevitable in designing PCSPSWs with vertical corrugation in practical engineering. However, almost no research has been conducted on the strength design of PCSPSWs under combined axial compression and shear loads. This paper investigates the load-bearing mechanism and strength design formulas of PCSPSWs under combined axial compression and shear loads. Firstly, the elastic buckling load of the CSP under axial compression is theoretically derived using the orthotropic plate theory. Then the ultimate load-bearing strength factor of the CSP, φs, only under axial compression is established by introducing the revised normalized height-to-thickness ratio of the CSP, λns, which is related to the compressive elastic buckling load. Thus the compressive load-bearing capacity of the PCSPSW could be obtained by superimposing the contribution of the CSP and VBEs. Subsequently, a parametric study is performed to establish the ultimate load-bearing capacity of the PCSPSW under combined compression and shear loads through the correlation curve of N/Nu-V/Vu. The obtained results show that the normalized slenderness ratio λsc of the CSP could significantly affect the correlation curve. Finally, the weaker constraints provided by fishplates are involved in the analysis, and accordingly the prediction formulas for considering the weaker constraints are proposed. Then this complete design method can provide valuable fundamentals for predicting the load-bearing capacity of PCSPSWs in practical engineering applications.

Gradual Deterioration Behavior of the Load-Bearing Strength of Main Cable Wires in a Suspension Bridge

The main cable is the primary load-bearing component of a long-span multi-tower suspension bridge. The interaction between a dead load, vehicle load, wind load, and the corrosion environment leads the main cable wire to exhibit tribo-corrosion-fatigue behaviors. This behavior causes wire wear and deterioration, as well as a reduction in the effective cross-sectional area. This leads to the gradual deterioration of the wire’s load-bearing strength and seriously affects the load-bearing safety of the main cable. In order to ensure the safety of suspension bridges, it is critical to investigate the gradual deterioration behavior of the main cable wire’s load-bearing strength. A wire tribo-corrosion-fatigue test rig was established to test the wire under different friction pairs (saddle groove or parallel wires). The cross-sectional failure area of the wire with different pairs was obtained by super-depth electron microscopy and calculation. The damage degree evolution model and the deterioration model of the wire load-bearing strength were established by combining the theory of damage mechanics and the finite element method. The results show that, as contact and fatigue loads increase, so does the cross-sectional failure area of the fatigue steel wire. The fatigue wire’s damage degree has a good quadratic function relationship with fatigue cycles. The damage degree of the wire increases and the load-bearing strength decreases with increasing contact load and fatigue load. The load-bearing strength of the wire changes little at the beginning and decreases with increasing fatigue cycles. The results have fundamental significance for the life prediction of the main cable wires of suspension bridges.