Axial Compression Performance Research Articles

Compression behavior of truss-reinforced double steel plate-recycled aggregate concrete composite low wall: A numerical investigation

Truss-reinforced double steel plate-recycled aggregate concrete composite (TSRCC) walls are novel composite walls that provide an effective way to recycle waste concrete. Based on the results of relevant tests, the finite element (FE) software ABAQUS was adopted to simulate the axial compression performance of the TSRCC low wall. Influences of different parameters on the mechanical response of the TSRCC low wall were studied. Finally, the results of the parametric analysis were compared with those obtained by relevant calculation formulas. The comparison revealed that main factors affecting the bearing capacity include the replacement ratio of recycled coarse aggregate, the strength and thickness of the steel plate, the strength of recycled aggregate concrete (RAC), the truss horizontal spacing, the wall thickness and width. The bearing capacity calculated by the T/CECS 625–2019 method was the closest to the FE simulation result, while the AISC 360–16 method presented the most conservative estimate.

Axial stress-strain behavior of pre-stressed CFRP confined concrete columns

Bonded carbon fiber reinforced polymer (CFRP) confined concrete presents issues such as stress hysteresis and easy detachment at the interface between CFRP and concrete. Applying prestress to CFRP can improve this situation. To investigate the stress-strain behavior of prestressed CFRP strengthened plain concrete columns (PC) under axial compression, a total of 1 unreinforced concrete column, 9 bonded CFRP strengthened concrete columns, and 27 prestressed CFRP strengthened concrete columns were designed. Including CFRP layers and the level of prestress were taken as the study factors, and axial compression tests were conducted on each specimen to analyze their axial compression performance. The test results indicated that applying prestress to CFRP results in the core concrete being constantly subjected to triaxial compression, with initial transverse compressive strain and longitudinal tensile strain, thereby increasing the initial stiffness of the core concrete. In contrast to bonded CFRP-strengthened columns, the ultimate axial stress, ultimate axial strain, and initial stiffness of prestressed CFRP-strengthened columns increased with the level of CFRP prestress, with a more pronounced improvement observed in columns wrapped with a higher number of layers of CFRP. For a 4-layer CFRP strengthened column prestressed at 0.3, the ultimate axial stress and ultimate axial strain increased by up to 13 % and 20 %, respectively, compared to bonded 4-layer CFRP strengthened columns, with the initial stiffness increasing by up to 30 %. On the other hand, applying prestress to CFRP can significantly enhance the effective utilization of CFRP, but it is negatively correlated with the number of CFRP layers. Compared to bonded 1-layer CFRP strengthened columns, the effective utilization rate increased from 0.63 to 0.91, a 44 % increase, when prestressing CFRP at 0.3. Finally, based on existing relevant research, a peak stress and strain model considering the ratio of confinement stiffness to strain ratio was proposed. Based on the fundamental assumptions of curve analysis, the design-oriented axial stress-strain model suitable for prestressed CFRP strengthened concrete columns was established, with good match between theoretical and experimental curves.

Performance degradation evaluation of square steel tubes with local penetration damage

Steel tubular structures are susceptible to welding defects, cracking defects and environmental corrosion, which can negatively affect the stability and reliability of structure. This study tested the axial compression performance of twenty-six square steel tubular stubs with localized penetration damage simulated by artificial notch, considering the influence of notch length, orientation, and position. The test results showed that the failure mode of the specimens was dominated by the local buckling along the direction of the notch axis. The failure mode of the specimen with vertical notch showed notch opening, while those with horizontal notch showed notch closing, resulting in the secondary peak value in the load-displacement curve. The existence of local penetration damage reduced the ultimate strength and ductility of the tubular stubs. Compared to the ultimate strength of the specimens with middle notch, those with corner notch were weakened more, up to 27 %. Furthermore, the effects of notch dimension, position, orientation, and tube wall thickness on the axial bearing capacity of square steel tubular stubs are discussed by using a validated finite element model. Owing to the analysis, the ultimate strength of the stubs is reduced by increasing notch length, width and depth, whereas the reduction effect tends to be weakened as the notch orientation angle increases. The notch located in the corner is the most unfavorable for the axial compression performance of the square steel tubular stubs. A semi-empirical formula for evaluating the ultimate strength of square steel tubular stubs with local penetration damage is proposed by introducing the strength reduction factor. An artificial neural network-based ultimate strength prediction model is developed that can consider the effects of wide-range parameters, achieving high accuracy.

Experimental study on axial compression performance of circular CFST columns considering extreme ambient temperature

To examine CFST short columns’ mechanical properties under extreme temps, 14 specimens were designed, focusing on temp’s impact on materials. Axial compression tests revealed temp-dependent changes: concrete strength surged at low temps but ductility diminished, while steel’s properties stayed stable. Concrete strength gains boosted columns’ strength, enhancing steel-concrete synergy. Shear failure dominated at low temps. Ductility improved with thinner diameters or wetter mixes. Calculations underestimated actual capacity, likely due to temperature neglect in design codes, EC4 most notably. Finally, incorporating the experimental results, the bearing capacity calculation formula of CFST based on the unified theory was modified and accounts for ambient temperature.

Novel low-carbon eco-concrete filled-FRP tubes under axial compression: Experimental behavior and analytical model

Concrete is essential in global construction but significantly contributes to carbon emissions, primarily due to cement production. The cement industry is adopting low-carbon practices, such as using supplementary cementitious materials (SCMs) to reduce emissions. Concrete prepared with calcined clay can achieve a carbon reduction effect of approximately 30 % compared to ordinary cement. Current studies highlight the reuse of kaolin clay, the predominant constituent of engineering sediment in Shenzhen, China, providing raw materials for sustainable low-carbon and eco-friendly concrete. However, high substitution rates of calcined clay can compromise concrete strength, posing a challenge for the application in load-bearing structures. This study proposed a novel low-carbon eco-friendly concrete (i.e., using calcined clay as supplementary cementitious materials) filled into FRP tubes (i.e., Low-Carbon Eco-Concrete-Filled FRP Tubes, termed LCE-CFFTs) aiming to enhance substitution rates of calcined clay and to improve compressive strength and ductility. This paper provides a detailed description of the preparation method, chemical reaction process, chemical composition, and microstructure of calcined clay. Experimental tests investigated the axial compressive performance of LCE-CFFTs, considering calcined clay substitution rates and FRP thickness as key parameters. The experimental work and theoretical analysis indicated that: the inclusion of 10 % and 40 % calcined clay led to a reduction in carbon emissions, resulting in a decrement of 5.8 % and 23.3 %, respectively; confinement provided by FRP tubes mitigated the reduction in axial compressive strength resulting from calcined clay inclusion, particularly evident at higher substitution rates (40 %); the effect of FRP tube confinement in improving peak stress and axial performance of LCE-CFFTs became more pronounced with higher calcined clay substitution rates; to more accurately predict the axial compressive behavior of LCE-CFFTs of this study, it is essential to consider the biaxial stress-strain state of filament-wound FRP tubes.

Axial compressive performance of unsymmetrical steel-reinforced concrete stub columns

Axial compressive performance of unsymmetrical steel-reinforced concrete stub columns

Simultaneous enhancement of axial/transverse compressive strength of aramid fibers by the construction of branched multi-hydrogen bonding sites

The terrible compressive strength is a prominent issue that restricts the broad application of organic fibers in multi-dimensional stress scenarios. Traditional strategies focus on enhancing the axial compressive performance of fibers, simultaneously improving the axial and transverse compressive properties of fibers still poses significant challenges. Inspired by the octopus's tentacles that can conduct stress in multiple directions, a novel strategy by constructing branched multi-hydrogen bonding sites structure in aramid fiber was conducted to solve the problem. The branched multi-hydrogen bonding sites constructed on nano-silica (SiO2–B) offer excellent dispersibility within the poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) matrix. Composite fibers (PBIA-SiO2-B) co-mixed with SiO2–B and PBIA were prepared using a solution spinning technique. The results of Fourier-transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA) reveal that the introduction of SiO2–B significantly enhances the intermolecular interactions within the composite fibers, and this enhancement mechanism has been elaborately elucidated through molecular simulations. Furthermore, finite element simulations confirmed that the incorporation of branched structure exhibits enhanced stress-bearing capabilities under multi-directional stress and offers outstanding support when subjected to transverse compressive stress compared to linear molecular chains. Hence, compressive property testing revealed that the PBIA-SiO2-B composite fibers achieved axial compressive strengths and transverse compressive strengths of 714.3 MPa and 305.8 MPa, respectively, representing increases of 68.8 % and 26.8 % over pure PBIA fibers. Moreover, with the enhancement of transverse compressive strength, the Young's modulus and interfacial shear strength of PBIA-SiO2-B fibers were also increased by 7.1 % and 20.9 %, respectively.

Experimental Study on Axial Compressive Performance of Recycled Steel Fiber Reinforced Concrete Short Columns with Steel Pipes

Experimental Study on Axial Compressive Performance of Recycled Steel Fiber Reinforced Concrete Short Columns with Steel Pipes

Experimental Investigation of a Novel CFRP-Steel Composite Tube-Confined Seawater-Sea Sand Concrete Intermediate Long Column

In order to fully utilize sea sand in offshore engineering, a novel carbon fiber-reinforced polymer (CFRP)-steel composite tube-confined seawater-sea sand concrete (FCTSSC) column structure has been developed. This study conducts experimental investigations on FCTSSC intermediate long columns for the first time. It investigates the failure modes and the impact of the external CFRP layers number on the axial compression performance. The results reveal that the FCTSSC intermediate long column specimens exhibit the failure modes of global buckling and localized steel tube bulging. After CFRP restriction, the ultimate load bearing capacity of the specimens increased from 12.51% to 20.87%. The ultimate load bearing capacity, its enhancement percentage, and peak lateral deformation are all positively correlated with the external CFRP layers number. Finally, a summary and assessment were conducted on the applicability and accuracy of the existing load bearing capacity models, providing a reference for subsequent research.

Research on axial compression performance test and bearing capacity calculation method of newly assembled hollow lattice wallboard

Research on axial compression performance test and bearing capacity calculation method of newly assembled hollow lattice wallboard

Behaviour of steel-fibre-reinforced geopolymer concrete-filled square steel tubular stub column under axial compression

Resource utilisation of industrial waste has become a crucial issue in construction aiming for sustainable development. Research on geopolymer concrete-filled square steel tubular (GCFST) structures is limited. Moreover, methods for calculating the bearing capacity of steel-fibre-reinforced GCFST (SFRGCFST) structures require further investigation. This study presents an experimental and analytical investigation of the axial compression performance of SFRGCFST stub columns. Twenty-four specimens were tested to assess the effect of steel tube thickness, steel fibre (SF) volume fraction, SF aspect ratio, and concrete strength grade on failure modes, load–deformation behaviour, load–strain response, ultimate resistance, and ductility of SFRGCFST columns. The results indicated that the failure modes of SFRGCFST columns are influenced by the coefficient index, which varies with the test parameters. When the coefficient index exceeded 0.88, the failure mode of the specimens transitioned from shearing failure to waist-drum-shaped failure. The average ultimate bearing capacity of the SFRGCFST columns increased by 35.13 % compared with that of the plain concrete-filled steel tubes (CFSTs). When the SF volume fraction reached 0.9 %, the ultimate bearing capacity of the SFRGCFST columns increased by 21.85 % compared with that of steel-fibre-reinforced concrete-filled steel tube (SFRCFST) columns. The incorporation of SF significantly improved the deformation capacity and ductility of the SFRGCFST columns and moderated the slope of the post-peak load–displacement and load–strain curves, slowing the descent of the curve. Utilising the multi-axial strength criterion and mechanical equilibrium equation for square CFSTs, a formula for calculating the ultimate bearing capacity of SFRGCFST stub columns was developed. This formula enables accurate prediction of the axial compressive load capacity of SFRGCFST stub columns and provides a basis for revising relevant standards.

Experimental study on the axial compressive mechanical performance of concrete short columns jointly confined with CC and CFRP after sulfate attack

By conducting axial compression tests on square concrete columns jointly reinforced by concrete canvas (CC) and carbon fiber-reinforced polymer (CFRP) after sulfate attack, the influences of the number of CFRP layers, the degree of erosion (number of wet and dry cycles) and the number of CC layers on the mechanical properties under axial compression were researched, and the failure morphologies, bearing capacities and deformation capacities of square concrete columns with joint reinforcement were analyzed. The results showed that sulfate attack would change the internal structure of the concrete, reduce the deformation capacities of the specimens, and make the brittle characteristics obvious. The square concrete column confined by CFRP after sulfate attack caused brittle damage to the specimen without obvious warning due to the stress concentration at the corner. The introduction of CC could relieve the corner stress concentration, improve the utilization of CFRP, avoid failure due to local destruction, and effectively improve the failure morphologies of the specimens so that the specimens had obvious precursors at failure. Based on the experimental study, the calculation model of the bearing capacity and the strain‒stress model of the square concrete column jointly confined by CC and CFRP after sulfate attack were established.

Axial Compressive Performance of CFRP-Confined Corroded Reinforced Concrete Columns

In saline environments, it is difficult for reinforced concrete structures to meet normal durability requirements, which in turn affects the mechanical properties of the members. In this context, this paper proposes a reinforcement method that involves wrapping corroded reinforced concrete columns with CFRP (carbon fiber reinforced polymer) cloth. By conducting axial compression tests on four specimens, key mechanical performance indicators such as failure mode, ductility, and bearing capacity during the entire stress process of the specimens were analyzed, revealing the failure mechanism of CFRP-confined corroded reinforced concrete columns. A refined finite element model of CFRP-confined corroded reinforced concrete columns was established using ABAQUS software. The influence of key parameters such as the number of CFRP wrapping layers, longitudinal reinforcement corrosion rate, and axial compression ratio on the mechanical properties of the specimens was studied, and the influence of each parameter was determined. Furthermore, a formula for the axial compression bearing capacity of CFRP-confined corroded reinforced concrete columns was proposed. The results indicate that in the presence of corroded steel reinforcement, specimens confined with CFRP undergo substantial lateral constraints during the mid to late stages of loading. This approach effectively alleviates the transverse deformation of the concrete. The specimen demonstrated yield bearing capacities and peak loads of 1441 KN and 1934 KN, respectively, representing a 2.2-fold and 2.5-fold increase compared to the non-reinforced specimen. With the increase in the transverse strain of concrete, CFRP begins to play a restraint role, and a more obvious restraint role in the failure stage of members. It is recommended to apply 1–3 layers of CFRP wrapping for a longitudinal reinforcement corrosion rate of 5%, 3–5 layers for a rate of 10%, and 6–8 layers for an overall corrosion rate of 15%. This paper establishes a theoretical framework for investigating the performance characteristics of such columns and offers technical assistance for practical engineering purposes.

Numerical Study on the Axial Compression Behavior of Composite Columns with High-Strength Concrete-Filled Steel Tube and Honeycombed Steel Web Subjected to Freeze–Thaw Cycles

To investigate the axial compression behavior of composite columns with high-strength concrete-filled steel tube flanges and honeycombed steel web (STHHC) under load during freeze–thaw cycles, 48 full-scale composite column specimens were designed with different parameters: the restraint effect coefficient (ξ), concrete strength (fcu), number of freeze–thaw cycles (nd), slenderness ratio (λ), space–height ratio (s/hw), and hole–height ratio (d/hw). The finite element models of STHHC composite columns were simulated using ABAQUS finite element software (Version: 2021). The modeling method’s rationality was verified by comparing simulation results with experimental outcomes. Based on the finite element model, a parametric analysis of the composite columns under freeze–thaw cycles was conducted, analyzing their failure modes and load-bearing processes. The results indicate that the bearing capacity of the STHHC increased with increases in ξ and fcu, and decreased with a rise in λ. In contrast, the influence of s/hw and d/hw on the ultimate bearing capacity of the composite columns was relatively minor. An equation for calculating the axial bearing capacity of the STHHC composite columns under freeze–thaw cycles was derived using statistical regression methods and considering the impact of different parameters on the axial compressive performance of the composite columns, laying the foundation for the promotion and application of this type of composite column in practical engineering projects.

Axial Compression Performance of Structural Ceramsite Concrete Reinforced with Steel Fiber

Axial Compression Performance of Structural Ceramsite Concrete Reinforced with Steel Fiber

Axial compression performance of concrete-filled steel tubular columns with damaged BFRP jackets

Concrete-filled basalt fiber reinforced polymer (BFRP) -steel composite tube (CFBCT) columns have become a highly anticipated composite structure. The lateral confinement provided by BFRP can effectively suppress the possible local buckling of the steel tube, thereby achieving the goal of optimizing axial compression performance. With the widespread application of CFBCT in engineering practice, the BFRP outer layer is likely to be affected by factors such as construction accidents or connection design, resulting in slotting and drilling damage to the BFRP outer layer. Therefore, the mechanical properties of CFBCT subjected to local damage are critical. This article examined the effects of slotting and drilling the BFRP outer layer on the axial compression performance. The non-uniform strain distribution at the damaged site was analyzed using digital image correlation (DIC) testing technology. The results show that the local damage can lead to a decrease in the bearing capacity and ductility. Compared with drilling damage, slotting has a more significant impact on axial behavior. Due to the local damage, the ultimate stress decrease by 8.1 % and 12.4 % respectively. A new computational method was introduced to predict the quantitative impact of local damage on CFBCT.

Experimental and numerical investigations on the axial compression performance of precast geopolymer concrete sandwich wall panel

This paper investigated a novel precast concrete sandwich panel (PCSP) which made by the geopolymer concrete and enabled by the glass fiber reinforced polymer (GFRP) hexagonal tube connector. Six precast geopolymer concrete sandwich wall panel (PGCSP) specimens were fabricated and tested under axial compression load. The investigating parameters included the connector spacing, panel height, and panel thickness. The failure mode, axial load capacity, load-axial deflection relationship, and load-concrete strain relationship were studied and discussed. Moreover, two-dimensional (2D) finite-element (FE) analysis was conducted to reproduce the test. Parameter analysis was then performed to modify the axial load capacity formula in the Chinese code GB50010-2010. The results indicated that: all specimens exhibited large eccentric compression failure due to the second-order effect, which was caused by concrete crushing and horizontal cracking in the two wythes, respectively; with the decrease of the connector spacing, the crushing area of the specimens would be enlarged, the out-of-plane lateral deformation would be decreased, and the axial load capacity decreased by 17 % and 42 % when the connector spacing changed from 300 mm to 600 mm and 900 mm, respectively; with the decrease of the panel height and the increase of concrete wythes thickness, the axial load capacity of the specimens almost presented a linear increase; the established 2D FE model and the modified formula effectively reflected the axial load capacity of the specimens.

Axial compressive performance of CFRP-steel composite tube confined seawater sea-sand concrete intermediate slender columns

To alleviate the scarcity of river sand resources and fully utilize the advantages of Carbon Fiber Reinforced Polymer (CFRP), a new type of CFRP-steel composite tube was developed to confine seawater-sea sand concrete (FCTSSC) column structures. This study conducted experimental research on FCTSSC intermediate slender columns for the first time, analyzing their failure modes and working mechanisms. The investigation explored the effects of outer CFRP layers and slenderness ratios on the mechanical performance. The results indicate that the FCTSSC intermediate slender column specimens exhibited global buckling accompanied by local bulging of steel tubes as their failure mode. The load-displacement curves can be divided into strong confinement and weak confinement models. Specimens confined by CFRP exhibited a 12.51–31 % increase in ultimate bearing capacity. The ultimate bearing capacity and its enhancement rate were positively correlated with the outer CFRP layers and negatively correlated with the slenderness ratio. Peak lateral displacements were positively correlated with both parameters. Finally, the model for calculating the axial compression ultimate bearing capacity of FCTSSC intermediate slender columns was proposed, providing a reference for future practical applications in offshore engineering.

Structural implementation of recycled lump prepared from waste concrete after elevated temperatures: Mechanical and environmental performances

To find a sustainable treatment for construction and demolition waste, the utilization of recycled lump (RL) prepared from waste concrete after elevated temperatures as coarse aggregate in concrete was investigated. The mechanical and environmental properties of recycled lump concrete (RLC) and reinforced recycled lump concrete (RRLC) were discussed with three RL replacement ratios and five treatment temperatures. The results show that increasing the RL replacement ratio would reduce the slump, and axial compressive performance of RLC, resulting from the presence of old adhered mortar on RL. The treatment of elevated temperature for RLC would improve the adverse effect of increasing the RL replacement ratio, resulting from the decreasing amount of old adhered mortar and interfacial transition zone on RL. The prediction formulas for the mechanical model of RLC were proposed while the design method for the axial compressive strength for RRLC was modified against the existing standard to conduct the full-range parametric analysis. The environment assessment indicates that the sustainable utilization of RL as coarse aggregate could reduce the environmental impact and global warming from concrete production whilst the RL prepared from waste concrete after 400 °C treatment is an appreciated option for the production of RLC and RRLC products from a mechanical and environmental perspective. In addition, the increase in external diameter would remarkably dwindle the environmental impact caused by the utilization of RL in structural members.

A Compressive Load Bearing Analysis of 3D-Printed Circular Elements

Large-scale construction 3D printing is a promising platform technology that can be leveraged to fabricate structural elements such as columns, piers, pipes, and culverts. In this study, the axial compression and split tensile performance of 3D-printed steel-fiber-reinforced circular elements fabricated with different configurations (hollow, hybrid, mold-cast, and fully 3D-printed) is evaluated. This study further investigates the performance of multi-material circular hybrid elements (3D-printed shells with different backfilled core materials) in an attempt to assess their suitability as a new construction paradigm. The experimental results revealed that the fully 3D-printed steel-fiber-reinforced circular elements exhibited a higher load capacity (up to 36%) and a distinct crack pattern compared to the other configurations. The void ratio of circular elements has varying effects on its axial load capacity depending on the printing material and significantly influences its splitting tensile load capacity. Furthermore, the compatibility between the 3D-printed shell and the cast-in-place core is identified as an influential factor in the structural performance of the hybrid elements. The results suggest a promising construction approach where low-cement material can be utilized as infill material for a cost-effective 3D-printed permanent formwork, offering a viable solution for specific infrastructure development applications.