Load Transfer Mechanism Research Articles

Investigations on Microstructure, Mechanical, and Wear Properties, with Strengthening Mechanisms of Al6061-CuO Composites

Metal matrix composites (MMCs) reinforced with Copper Oxide (CuO) and Aluminum (Al) 6061 (Al6061) alloys are being studied to determine their mechanical, physical, and dry sliding wear properties. The liquid metallurgical stir casting method with ultrasonication was employed for fabricating Al6061-CuO microparticle-reinforced composite specimens by incorporating 2–6 weight percent (wt.%) CuO particles into the matrix. Physical, mechanical, and dry sliding wear properties were investigated in Al6061-CuO MMCs, adopting ASTM standards. The experimental results show that adding CuO to an Al6061 alloy increases its density by 7.54%, hardness by 45.78%, and tensile strength by 35.02%, reducing percentage elongation by 40.03%. Dry wear measurements on a pin-on-disc apparatus show that Al6061-CuO MMCs outperform the Al6061 alloy in wear resistance. Al6061-CuO MMCs’ strength has been predicted using many strengthening mechanism models and its elastic modulus through several models. The strengthening of Al6061-CuO MMCs is predominantly influenced by thermal mismatch, more so than by Hall–Petch, Orowan strengthening, and load transfer mechanisms. As the CuO content in the composite increases, the strengthening effects due to dislocation interactions between the matrix and reinforcement particles, the coefficient of thermal expansion (CTE) difference, grain refinement, and load transfer consistently improve. The Al6061-CuO MMCs were also examined using an optical microscope (OM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) before and after fracture and wear tests. The investigation shows that an Al6061-CuO composite material with increased CuO reinforcement showed higher mechanical and tribological characteristics.

Deflection function of a novel bolt-connected precast concrete floor

Owing to the post-cast procedure and relatively complex joint configuration, composite precast floors limit the full display of advantages of precast concrete systems. The development of fully assembled precast floors is of necessity; therefore, a novel bolt-connected precast concrete floor was proposed in this study to meet the increasing demand for quick assembly, lightweight, and good insulation in flooring systems. The proposed floors consist of precast sandwich unit slabs that are fully assembled to an integral floor with dry-type bolted connectors. Field static loading tests were conducted on four full-scale precast concrete floors. The test results indicate that the floors exhibited a two-way flexural ability due to the involvement of the bolted connectors. The restraining mechanism at anchorage and load-transferring mechanism at joints were investigated through a theoretical analysis. Based on the theory of plates and shells, a simplified theoretical method of solving the deflection function of the floors was established and validated to provide a reference for designing such fully assembled floors. The comparison between the theoretical and experimental results indicates that the arrangement of joint connectors could affect the theoretical calculation accuracy due to its influence on the performed continuity simplification. The application scope of the proposed theoretical method was evaluated through a finite element analysis.

Load transfer mechanism of floating pile-supported embankments under cyclic loading

Pile-supported embankments are one of the most commonly used techniques for ground improvement in soft soil areas. Existing studies have mainly focused on embankments supported by end-bearing piles under static loading, with limited research on floating pile-supported embankments under cyclic traffic loading. In this study, model tests for unreinforced floating, unreinforced end-bearing, geosynthetic reinforced floating, and geosynthetic reinforced end-bearing pile-supported embankments were conducted. Cyclic traffic loading was simulated using a three-stage semi-sinusoidal cyclic loading. Comparative analyses and discussions are performed under floating and end-bearing conditions to investigate the influence of floating piles on the soil arching evolution and membrane effect under cyclic loading. The results indicate that floating piles result in earlier stabilization of surface settlement. There is less arching and membrane effect induced by floating piles, and the arching does not continue to degrade under cyclic loading. Less membrane effect in floating pile-supported embankments results in less geosynthetic and pile strain. The degree of membrane effect in floating pile-supported embankment largely depends on the pile-end condition.

Exploring the axial performance of protective sheathed rock bolts through large-scale testing

Understanding the axial load transfer mechanism of rock bolts under diverse conditions is essential for optimizing reinforcement in rock structures, advancing our comprehension of rock support, and facilitating the design of robust engineering solutions. This paper reports the outcomes of an extensive experimental investigation, focusing on the axial behavior of protective sheathed rock bolts employed in corrosive environments, assessed through pullout tests. Three distinct testing setups were designed to evaluate comprehensively the performance of these rock bolts in various scenarios. The results indicated that the failure characteristics and axial behaviors of sheathed rock bolts differ significantly from conventional counterparts. The findings revealed two primary failure modes in sheathed rock bolts: bolt rupture and slip at the grout-sheath interface, based on the testing arrangement and encapsulation length. The lack of adhesion and interlocking at the grout-sheath interface prevents shear stress at the bolt-grout interface from reaching its maximum potential strength, resulting in grout damage manifesting as circumferential cracks. This, in turn, initiates crack formation, reducing the system’s bond strength. Additionally, it causes slip at the grout-sheath interface to occur at lower pullout loads. It can be inferred that the inner surface of the plastic sheath lacks the necessary structural integrity to withstand high loads, significantly impacting bond stress distribution and failure modes. The results demonstrate that the protective sheath remains intact up to an axial displacement of 28 mm, irrespective of the testing configuration. Additionally, it was observed that the maximum bond stress at the bolt-grout interface falls within the range of 6–8.7 MPa, which is below the shear strength of the grout. Consequently, achieving failure at the bolt-grout interface is not feasible.

Investigation on load - transfer characteristics of spherical hinge structure of swivel bridge based on scale distortion model

The mechanical properties of the swivel spherical hinge, a critical component in swivel bridge structures, remain inadequately understood. This study precisely examines the load-transfer characteristics of the swivel spherical hinge using a combination of finite element simulation and scaled model loading tests. An optimized hinge model, accounting for distortion effects and strategic placement of measurement points, was constructed and tested in the laboratory. Results indicate that the scaled model exhibited consistent elastic deformation, ensuring structural integrity and stability. The results indicate that under a 122 kN load, the average discrepancy between the experimental data and numerical predictions was only 1.53 %, highlighting the numerical model's accuracy and reliability. Additionally, the center of the slider experienced a compressive stress of approximately 2.7 MPa, while the edge endured 5.3 MPa, reflecting a non-uniform load distribution. Stress concentrations at the slider's projection were 2–5 times greater than at other measurement points on the steel-concrete interface of the hinges. The lower spherical hinge surface displayed a complex stress pattern combining tensile and compressive stresses, resulting from slider compression and hinge surface expansion. This research provides valuable insights into the load-transfer mechanisms of swivel spherical hinges, offering guidance for the design and construction of swivel bridges.

The Correlation between the Elastic Modulus of the Achilles Tendon Enthesis and Bone Microstructure in the Calcaneal Crescent.

The calcaneal enthesis, an osseous footprint where the Achilles tendon seamlessly integrates with the bone, represents a complex interface crucial for effective force transmission. Bone adapts to mechanical stress and remodels based on the applied internal and external forces. This study explores the relationship between the elasticity of the Achilles tendon enthesis and the bone microstructure in the calcaneal crescent. In total, 19 calcaneal-enthesis sections, harvested from 10 fresh-frozen human cadaveric foot-ankle specimens (73.8 ± 6.0 years old, seven female), were used in this study. Indentation tests were performed at the enthesis region, and Hayes' elastic modulus was calculated for each specimen. Micro-CT scanning was performed at 50-micron voxel size to assess trabecular bone microstructure within six regions of interest (ROIs) and the cortical bone thickness along the calcaneal crescent. Significant Spearman correlations were observed between the enthesis elastic modulus and trabecular bone thickness in the distal entheseal (ROI 3) and proximal plantar (ROI 4) regions (R = 0.786 and 0.518, respectively). This study highlights the potential impacts of Achilles tendon enthesis on calcaneal bone microstructure, which was pronounced in the distal calcaneal enthesis, suggesting regional differences in load transfer mechanism that require further investigation.

A comparative study of microstructure and mechanical properties for carbon fibers and carbon nanotubes reinforced copper composites doped by Zr70Cu30 particles

Carbon fibers (CFs) and carbon nanotubes (CNTs) reinforced Cu composites doped by Zr70Cu30 alloy particles were fabricated by a conventional vacuum hot-press technique and their microstructures, mechanical properties and electrical conductivities were compared. The results revealed that the CNTs/Cu composite exhibited a superior combination between mechanical properties and electrical conductivity, having the highest relative density of 94.8 %, the maximum microhardness of 85.7 HV and the maximum electrical conductivity of 84.2 % IACS among various composites. The incorporation of Zr70Cu30 alloy particles led to limited contacts with CFs (or CNTs) reinforcements but caused the decrease of relative density and consequently the deleterious mechanical and electrical properties. The dominant strengthening mechanism for the fabricated Cu matrix composites was load transfer mechanism. The CNTs reinforcements demonstrated the highest reinforcement efficiency in the Cu matrix composites, which can provide some new insights for designing novel high-strength and high-connectivity Cu matrix composites.

Bond-slip behavior of Aluminum Alloy (AA) bars for near-surface mounted (NSM) technique

An experimental study consisting of 22 pull-out tests was carried out to investigate the bond-slip performance and load transfer mechanism between near-surface mounted (NSM) Aluminum Alloy (AA) bars and concrete when the AA bars are inserted into pre-cut grooves on the surface of the host structure and bonded with an appropriate bonding agent. The effects of several design parameters were evaluated including bond length, diameter of AA bars, bar surface treatment, and adhesive type. A digital image correlation (DIC) system was used to measure the slips and surface strain and four failure modes were observed in the tests, being concrete splitting failure, epoxy splitting, debonding at the bar-epoxy interface, and AA bar rupture. Results showed that an increase in bond length could make the failure mode more ductile, while AA bars with rough surfaces exhibited a relatively satisfactory bond-slip behavior when a suitable epoxy was used. Finally, the test data from this study were used to examine three bond-slip models based on fiber reinforced polymers (FRP) for the NSM technique. A new bond-slip model considering the influence of the bar external surface was proposed and validated by the test results from both this study and literature.

Influence of block arrangement on mechanical performance in topological interlocking assemblies: A study of the versatile block

Topological interlocking assemblies (TIA) are arrangements of blocks kinematically constrained by a fixed frame, such that all rigid body motions of each block are prevented by the neighbouring blocks and the frame. In the literature, several blocks are introduced that can be arranged into interlocking assemblies, however only few of them can be arranged in non-unique ways. This study investigates a particularly versatile interlocking block called the Versatile Block: this block can be arranged in three different doubly periodic ways given by wallpaper symmetries. We investigate the hypothesis that the arrangement of copies of the same block influences the mechanical response of a TIA. We examine the interlocking mechanism and the correlation between arrangement and overall structural performance in planar TIA consisting of the Versatile Block. Furthermore, we analyse load transfer mechanisms within the assemblies and from the assemblies onto the frame. For fast apriori evaluation of the load transfer onto the frame we introduce a combinatorial model called Interlocking Flows. To investigate our assemblies from a mechanical point of view we conduct several finite element studies. These reveal a strong influence of arrangement on the structural behaviour, for instance, an impact on both the point and amount of maximum deflection under a given load, thereby confirming our hypothesis. We also evaluate the accuracy of the proposed Interlocking Flow model by a comparison with the finite element simulations.

Experimental study on rotary inter-module connections with corrosion-resistant metal materials: Under axial tension

Modular construction is an innovative construction technology that has attracted considerable attention for its pronounced advantages in reducing reliance on on-site labor, speeding up construction, enhancing productivity, and ensuring superior quality. To extend the applicability of modular construction to structures in corrosive environments, such as ocean floating structures for exploring renewable energy, a rotary inter-module connection employing corrosion-resistant metal materials was proposed herein. Six full-scale inter-module connection specimens made of grade S30408 austenitic stainless steel, grade S220503 duplex stainless steel, and grade A96061-T6 aluminum alloy were tested under axial tension. The load-displacement relationships of each specimen were recorded to enable a thorough analysis of the strength, stiffness, and ductility of the tested specimens. As compared to the conventional carbon steel counterparts, the stainless steel specimens showed superior load-bearing capacity with improved ductility, while the aluminum alloy specimens experienced brittle fracture at the bolt shank-bottom plate junction with reduced load-bearing capacity. Three typical failure modes were identified in the experimental study, namely, plastification of the connector and lower corner fitting, plastification of the connector and both corner fittings, and fracture of the bolt. The load-strain relationships of each specimen were also discussed to analyze the load transfer mechanism and structural behavior of the connection. In addition, the applicability and accuracy of the simplified calculation methods based on beam bending theory and Navier solution for rectangular thin plates, respectively, were discussed based on the test results.

Explorations of mechanical and corrosion resistance properties of AA6063/TiB2/Cr2O3 hybrid composites produced by stir casting

Mechanical and Corrosion characteristics of composite materials made from Aluminum alloys (AA) 6063 supplanting as the material of choice for automotive, aerospace, and marine applications by systematically varying ceramic reinforcements developed through controlled stir cast technique ensuring uniform dispersion are explored. The hardness, density, impact and tensile strength, corrosion resistance, and microstructural characteristics of Aluminum Matrix Composites (AMCs) reinforced with titanium diboride (TiB2) at 7.5, 10, and 12.5 wt% and chromium oxide (Cr2O3) at 3, 6, and 9 wt% were assessed according to ASTM standards. The microstructural analysis revealed a reduction in the growth of reinforcement clusters within acceptable limits. The addition of reinforcements to the matrix resulted in improved tensile strength, ranging from 124.6 to 188.7 MPa, and hardness, increasing from 71.5 to 144.32 VHN. This improvement is attributed to the strengthening or load transfer mechanism facilitated by the reinforcements. Additionally, the impact strength of the composites increased from 11.845 to 21.16 J, while the density showed slight variations. Consistent corrosion tests demonstrated that the chemical and interfacial interactions between the matrix material and the reinforcements significantly enhanced the corrosion resistance, reducing the corrosion rate from 570 to 499 mm/year.

Shear and bonding performances between Fe-SMA and steel for strengthening of steel structures

Iron-based shape memory alloy (Fe-SMA) has been employed in China and the Czech Republic to reinforce steel bridges due to its outstanding self-prestressing characteristics. Nevertheless, the lack of theoretical guidelines necessitates this study to align with the practical Fe-SMA-reinforced applications in civil engineering. This study experimentally investigates the shear performance and load-transfer mechanism of 45 Fe-SMA/steel adhesive joints. Specifically, the shear characteristics of the adhesive joints affected by the various parameters of bonding layer thickness, steel plate thickness, bonding length and adhesive type are explored, the failure mode and load-displacement relationship are assessed, and some suggestions for optimization design are proposed. The experimental results demonstrate that the Fe-SMA/steel adhesive joints experiencing interface failure exhibit a linear load-displacement relationship. Contrarily, the load-displacement relationship of the adhesive joints under cohesive failure modes contains a yield segment. Longer bonding length results in more considerable failure evolution distances for Sika S02 and LPdur 03 specimens with cohesive failure, indicating better ductility of these specimens. Additionally, the epoxy adhesives of Sika S02 and LPdur 03 are preferred while employing Fe-SMA plates for bonding reinforcement of steel structures, which can maximize the characteristics of Fe-SMA to obtain stable and superior reinforcement performance. The experimental achievements have remarkable potentials for improving the in-service performance of old and damaged steel structures and other infrastructures.

In-situ formed TiCx reinforced Ti composites derived from polyzirconocarbosilane precursor: Synthesis, characterization and mechanical properties

Discontinuously reinforced titanium (Ti) matrix composites (DRTMCs) strengthened by in-situ TiCx particles are synthesized via pyrolysis of polyzirconocarbosilane (PZCS) and pressureless sintering. The Ti matrix reacts with the pyrolysis product of PZCS to form TiCx particles, which effectively refine the α-Ti grains and create a clean, well-bonded semi-coherent interface. A notable orientation relationship is observed between the TiCx and α-Ti phases: (111)TiCx||(101¯1)Ti and [1¯10]TiCx||[12¯10]Ti. The Ti-2PZCS composite demonstrates a significant reduction in average grain size, from 101.5 μm in pure Ti to 39.49 μm, coupled with superior comprehensive mechanical properties: an ultimate tensile strength of 710 MPa, a yield strength of 588 MPa, and an elongation of 9.5 %. The enhanced strength of Ti/PZCS composites is mainly due to grain refinement, solid solution strengthening, and load transfer mechanisms. This study introduces a novel approach for fabricating high-performance Ti composites, highlighting the potential for advanced material applications.

Passive earth pressure on vertical rigid walls with negative wall friction coupling statically admissible stress field and soft computing

It is well known that the roughness of a wall plays a crucial role in determining the passive earth pressure that is exerted on a rigid wall. While the effects of positive wall roughness have been extensively studied in the past few decades, the study of passive earth pressure with negative wall friction is rarely found in the literature. This study aims to provide a precise solution for negative friction walls under passive wall conditions. The research is initiated by adopting a radial stress field for the cohesionless backfill and employs the concept of stress self-similarity. The problem is then formulated in a way that a statically admissible stress field be developed throughout an analyzed domain using a two-step numerical framework. The framework involves the successful execution of numerical integration, which leads to the exploration of the statically admissible stress field in cohesionless backfills under negative wall friction. This, in turn, helps to shed light on the mechanism of load transfer in such situations so that reliable design charts and tables be provided for practical uses. The study continues with a soft computing model that leads to more robust and effective designs for earth-retaining structures under various negative wall frictions and sloping backfills.

Finite Element Modeling of Beam-to-Column Steel Timber Composite Joints with Different Parameters

This study presents a comprehensive three-dimensional finite element modeling and parametric analysis of composite beam-to-column joints in steel–timber composite structures. The investigation encompassed a variety of shear connector configurations, end plate designs, and bolt dimensions, aiming to elucidate their respective influences on the structural performance and behavior of these joints. Through meticulous numerical simulation, this research sought to enhance the understanding of the interactions and load transfer mechanisms within composite connections, thereby contributing to the optimization of design practices in the field of structural engineering. The load–displacement relationship for timber–steel composite joints subjected to monotonic loading was investigated using ABAQUS 6.14 software. This study systematically analyzed the effects of various parameters, including different configurations of shear connectors, end plate thicknesses, and bolt dimensions, on the overall performance of the joints. Through this comprehensive numerical analysis, the research aimed to provide deeper insights into the mechanical behavior and structural integrity of these composite connections under the applied loading conditions. A non-linear finite element model of timber was developed and verified with the results of the experiment in this study. The findings are discussed in detail, highlighting the intricate relationships between the selected parameters and their respective effects on the performance and overall stability of the composite connections. This thorough evaluation aimed to enhance the understanding of how these variables interact within the context of composite joint design and behavior. Finally, design recommendations for composite structures, such as the dimensions of the bolt, end plate thickness, and different sizes of shear connectors are provided.

Study on the microstructure, mechanical and corrosion behaviors of 2A12 Al matrix composites containing B4C and 50% K2TiF6 flux

This study presents an innovative exploration into the development and characterization of boron carbide (B4C) reinforced aluminum (Al) metal matrix composites (AMMCs), specifically focusing on the 2A12 Al alloy. Utilizing a cutting-edge vacuum induction melting process, the research investigates the effects of varying B4C particle concentrations in conjunction with 50% K2TiF6 flux additions. This novel approach aims to enhance the microstructural integrity, mechanical properties, and corrosion resistance of the AMMCs. The research unveils a significant improvement in microhardness and tensile strength with the increase of B4C content. This enhancement is attributed to the efficient load transfer mechanism from the aluminum matrix to the B4C phase and the thermal expansion coefficient mismatch-induced dislocations. A critical finding of this study is the uniform distribution of B4C particles and the formation of a Ti-rich layer around these particles, facilitated by the K2TiF6 flux. This layer acts as a barrier, minimizing interfacial reactions. Electrochemical testing reveals that there is a slight decrease in corrosion resistance with increased B4C content. The outcomes of this research contribute to the field of metal matrix composites, offering a path forward for the application of B4C-reinforced AMMCs in demanding industrial environments where high strength, stiffness, and durability are critical. The study's findings open new avenues for advanced materials development in aerospace, automotive, and energy sectors.

Ultimate Capacity and Load Transfer Mechanism of Ground Anchors in Granular Soils: State-of-the-Art

The grouted ground anchor is the most used geotechnical element to transfer the tension load from the superstructure or the soil mass in front of the potential failure surface (active zone) to a deeper, efficient soil layer for its reliability and feasibility. It was originally constructed by inserting the tendon, usually a steel strand, into an already drilled borehole filled with cement grout. It was successfully used in the Cheurfas dam in Algeria in (1934). According to the load transfer mechanism, there are two types of ground anchors: tension-type and compression-type. The names of these two types of anchors refer to the developed stresses in the grouted body. The present work presents a literature survey about the load transfer mechanism for both types of anchors: tension and compression embedded in granular soil. Many factors affecting the load transfer mechanism have been reviewed. The main factor affecting the load transfer mechanism is the confining pressure of the borehole. The recently developed methods of estimating the ultimate pullout capacity of the anchor have been reviewed and discussed.

Performance and behaviour of prebored and precast pile with floating pile tip based on A full-scale field static axial load test

This study investigates the load transfer mechanism of a Prebored and Precast pile (PP pile), constructed installed in accordance with the rules applicable to the Hyper-Straight pile method (HS pile), in clay soils. While the HS pile method, developed in Japan, typically results in high bearing capacity piles in various soil types, its performance in clay soils remains understudied. Our research focuses on a unique configuration where the pile tip “floats” within a soil–cement mixing (SCM) column near the bottom of the borehole, a condition that significantly influences the system’s performance.We conducted a full-scale axial static load test on a 500 mm diameter and 140 mm thickness straight shaft precast prestressed concrete spun pile. The pile was instrumented with vibrating wire strain gauges (VWSG) and displacement measuring devices (tell-tales), embedded 15 m deep in a 750 mm diameter SCM column (15.75 m long). The pile tip was positioned 75 cm above the bottom of the borehole, creating a floating condition within the SCM material. Both the pile and the surrounding SCM were instrumented to provide comprehensive data on the system’s behavior.The test involved two loading–unloading cycles. The 1st Cycle reached a maximum load of 3627 kN, resulting in a 75.52 mm pile head settlement. The 2nd Cycle achieved a maximum load of 4181 kN, leading to a 118.04 mm pile head settlement. In the 1st Cycle, we observed upward movement of the SCM material around the shaft after the pile skin friction reached its maximum capacity. Stress at the pile tip exceeded the unconfined compressive strength of the SCM material, indicating potential local shear failure.Contrary to expectations based on HS pile performance in other soil types, the ultimate bearing capacity of our pile was determined to be 2000 kN, comprising 545 kN from skin friction and 1455 kN from end bearing. This result aligns more closely with the behavior of conventional bored pile rather than the “hyper” capacity typically associated with HS pile. Consequently, we classify our pile as a “prebored and precast pile,” like systems used in China and Korea.Our study concludes that the strength of the SCM material and the pile tip location significantly influence the pile’s bearing capacity in clay soils. These findings highlight the critical impact of soil type on the performance of piles constructed using the HS method. The observed behavior suggests that current design methods for HS pile may overestimate capacity in clay conditions, emphasizing the importance of soil-specific analysis and testing.This research contributes to the understanding of PP pile behavior in clay soils, providing valuable insights for geotechnical engineers. It underscores the need for refined prediction models and design methods specific to these soil conditions, paving the way for more accurate and reliable foundation designs in regions with predominant clay soils.

Load transfer model and failure prevention measures of a mechanical-type anchorage for anchor cable in deep roadway

In this paper, the load transfer mechanism of a mechanical-type anchorage is analyzed and studied. The stress distribution on the surface of the anchor cable is clarified, and the means of mechanical analysis and Abaqus finite element method are used. Results indicated there is no stress concentration, and the peak value indicated by the anchor cable appears near the loading end, and the peak value is about 60 MPa larger than the tensile strength. The results of the tensile test show that the failure mode of the anchor cable is the necking fracture of the steel wires, which indicates that the steel reaches the yield limit stress. The anchor efficiency of mechanical-type anchorage is high, which can effectively exert the tensile strength of anchor cable. In deep mine roadway, two failure modes of anchor cable are summarized when mechanical-type anchorage is used. Including shear failure and slippage failure under dynamic action. Aiming at the shear failure behavior, a new type of anchorage was invented, including the self-aligning and shear resistance functions of the anchor cable, and an experiment was carried out. Results indicated anti-shear anchorage can effectively solve the problem of anchor cable failure caused by shear. For the problem of anchor cable slippage failure under dynamic action. The parameters affecting the stability of mechanical-type anchorage are analyzed by means of theoretical analysis and numerical simulation. Results indicated reducing the bevel angle of wedge and barrel, the difference angle between them, and increasing the friction coefficient μ between wedge and barrel can increase the stability of mechanical-type anchorage. The research content of this paper can provide reference for the design of mechanical-type anchorage in similar underground engineering.

Experimental investigations on the flexural behavior of UHPC wet joints for UHPC light-weight rigid frame arch bridges

Wet joints are critical parts of prefabricated ultra-high-performance concrete (UHPC) light-weight rigid frame arch bridges (LWRFAGs), so their mechanical behavior is important to the structural design and applications of these arch bridges. To explore suitable joint configurations and reinforcement arrangements for connecting UHPC components or arch ribs of a practical UHPC LWRFAG, this paper experimentally investigated flexural behavior of several prefabricated UHPC joint beams with various kinds of wet joints through four-point bending tests. Firstly, four different UHPC joint beams with different joint configurations were designed, including (i) vertical joint; (ii) rhombus joint; (iii) vertical joint with top and bottom strips; and (iv) rhombus joint with top and bottom strips, and their flexural performance were compared with a complete UHPC beam. The experimental results revealed that UHPC joint beam employing the rhombus joint with top and bottom strips exhibited superior flexural behavior and cracking resistance among four UHPC joint beams. Subsequently, to achieve optimal and robust joint configurations, bending performance of one complete UHPC beam and three large-scale UHPC joint beams with rhombus joints but different reinforcement arrangements were experimentally studied. It is observed that the beam with the welded twist reinforcements (specimen V-4) shown optimal flexural performance and cracking resistance. Finally, to explore the load transfer mechanism and effects of reinforcement parameters on flexural behavior of specimen V-4, the parametric studies were comprehensively performed using finite element analyses (FEA). This study could serve as both the experimental and theoretical reference for flexural design of UHPC beams with the rhombus wet joints.