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Highlights • A new form composite piles is proposed. • The new pile is made of pervious geopolymer concrete, geogrid, PVC and FRP. • Axial compression experiments of this new form piles were conducted. • The mechanical behaviour of this new form piles is significantly improved. Abstract The use of fibre reinforced polymer (FRP) and polyvinyl chloride (PVC) as strengthening materials for piles was found to be a promising scheme, due to their high strength-to-weight ratio, high durability and high anti-corrosion ability. This study presents an experimental investigation of a new form of composite piles: geogrid-confined pervious geopolymer concrete piles (GPGCPs) with fibre reinforced polymer (FRP)-polyvinyl chloride (PVC)-confined concrete core (FPCC). The GPGCP with FPCC consists of a circular geogrid outer tube, a FRP-PVC-confined normal geopolymer concrete core, and pervious geopolymer concrete (PGC) filled in between. The reason for applying PGC into piles is to increase the rate of consolidation. The aim of using FPCC is to improve the compressive strength and ductility of the concrete. In this study, two groups of GPGCPs (without and with FPCC) were prepared and tested under axial compression. In each group, one layer, two layers, and three layers of geogrid were used to investigate the influence of the outer tube. The test results show that the FPCC can significantly improve the mechanical behaviour of the GPGCPs. In comparison with GPGCPs without FPCC, the maximum axial loads of GPGCPs with FPCC were higher, and the ductility was improved significantly. [ABSTRACT FROM AUTHOR]

Highlights • Optimum compaction time for concrete is proposed. • Under compacting concrete will lead to a reduction in compressive strength. • Compaction up to three minutes does not reduce the properties of concrete. Abstract The purpose of this study was to evaluate the effect of over-compaction on the strength of concrete with regards to commercial and industry practices. Normal concrete, which is commonly used in construction was chosen. Samples were cast using a varying vibration time and testing was performed to determine concrete compressive strength, air content, density and a measure for segregation. These parameters were used to determine the relative sensitivity of concrete to under- versus over-compaction. If segregation was present, it was hypothesized the results would indicate a mathematical relationship between the segregation and strength reduction. This relationship would allow for determination of an optimum vibration time range. It was found in this study there was no segregation or strength reduction in vibrated samples. This result proved the concrete was far more sensitive to under-compaction, with over-compaction not being a practical concern. It was also determined that concrete compressive strength and vibration time had a basically logarithmic relationship and 30 s of continuous internal vibration provided the most efficient result of approximately 92% of maximum strength. The study recommends adjustment of standard concrete vibration practice to accommodate the more efficient 30 s duration. Alternatively, a 1.4x 'vibration factor' can be applied during design of compressive strength of concrete to accommodate the current 5–15 s vibration time window. [ABSTRACT FROM AUTHOR]

Abstract This technical note presents an experimental study on the bond behaviour of chequer steel plate reinforcements in concrete members based on the beam-end method. The effects of lozenges of the chequer steel plate, the use of steel bolts, and the thickness of the concrete cover on the bond behaviour are investigated. The experimental program includes five specimens designed as beam-end pullout members. Each specimen is 225 mm wide, 300 mm high and 600 mm long. Stirrups with 80 mm centre-to-centre spacing are used as confinement for all specimens. The first specimen is reinforced with a deformed steel bar whereas the remaining specimens are reinforced with steel plates. All specimens except for the one reinforced with a smooth steel plate failed by pullout accompanied by splitting crack. The lozenges of chequer steel plate increased the ultimate pullout failure load by 80% compared to that of the specimen reinforced with a smooth steel plate. It has also been found that the pullout failure load of a steel plate reinforced concrete member can be significantly affected by the thickness of the concrete cover. Two other significant findings are that the pre-ultimate slippage of a steel plate reinforced concrete member is much less than that of a deformed steel bar reinforced one, and that the post-ultimate behaviour of the former is much more ductile than the latter. Comparisons between the present test results and the earlier test results involving reinforced concrete beams subjected to four-point bending tests suggest that the beam-end method may not be an appropriate method for comparing the bond strength of a chequer steel plate against that of a reinforcing bar. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study on the bond behaviour of glass fibre reinforced polymer (GFRP) I-section embedded in concrete. A total of five specimens with the same cross-section dimension were cast and tested using push-out test. The main parameters investigated in this study were bond length (300 mm and 450 mm), transverse stirrups and sand coating. The experimental results show that the ultimate bond stress can be improved by a longer bond length and sand coating. However, the ultimate bond stress was reduced when stirrups were used, and the reason may be because the application of stirrups affected the vibration of the concrete, causing a weak bond at the interface. The bond stress distribution at the web and the flange is analysed based on the strain of the I-section. Finally, a bond stress-slip model is proposed for the GFRP I-section with a smooth surface. Based on this model, the theoretical results are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally the influence of type, content and geometry of steel fibre (industrial/waste) on the mechanical properties of reactive powder concrete (RPC) in terms of compressive strength, tensile strength, modulus of elasticity and stress-strain behaviour under compression. Three types of steel fibres were used: industrial micro steel fibre (MF), industrial deformed steel fibre (DF) and waste steel fibre recovered from discarded tyres (WF). Steel fibres were added to RPC at 1%, 2%, 3% and 4% of the total volume. Two forms of steel fibres’ hybridizations were explored: industrial hybridization (HF) and waste-industrial hybridization (WHF). Results of testing demonstrate that the addition of DF and WF up to 3% and 4%, respectively, significantly affected the flowability of RPC. The addition of 4% MF achieved the highest increase in the compressive strength, tensile strength, modulus of elasticity, peak stress and the corresponding strain. The inclusion of HF increased the RPC toughness by 245%. Moreover, the inclusion of the waste steel fibre as full replacement (WF) or partial replacement (WHF) was comparable to the industrial steel fibre in enhancing the mechanical properties of RPC in addition to the increase in the toughness of RPC by 158.8% and 211%, respectively. Finally, WF is considered as a promising material in the structural applications and can fully or partially replace industrial steel fibres in RPC. [ABSTRACT FROM AUTHOR]

This study aims to investigate the structural behavior and failure modes of fiber-reinforced-polymer (FRP) confined concrete wrapped with different FRP arrangements. A total of twenty four specimens were cast and tested, with three of these specimens acting as reference specimens and the remaining specimens wrapped with different types of FRP (CFRP and GFRP) by different wrapping arrangements. They include fully wrapped, partially wrapped and non-uniformly wrapped concrete cylinders. The non-uniformly wrapped concrete cylinders provided higher compressive strengths and strain for FRP-confined concrete, in comparison with conventional fully wrapping arrangements. The effect of confinement level on the effectiveness of FRP confinement is also investigated. In addition, the partially wrapping arrangements changes the failure modes of the specimens and the angle of the failure surface. [ABSTRACT FROM AUTHOR]

Highlights: [•] We use MR damper linkages to reduce seismic response of buildings. [•] We use fuzzy controller with GA to reduce drift storey responses. [•] The response control is better for the shorter building. [•] Decreasing the number of dampers increases the system efficiency. [Copyright &y& Elsevier]

Abstract: Strengthening concrete columns with fibre-reinforced polymers (FRP) has been studied extensively, but the majority of published studies have focused on circular columns. Most concrete columns in the field have square or rectangular cross sections and resist eccentric loading as well. The objective of this study is to investigate the performance of square reinforced concrete (RC) columns wrapped with carbon FRP subjected to eccentric loading. The influence of two parameters was studied including the number of FRP layers and the magnitude of eccentricity. Compression testing was conducted on twelve short square RC columns wrapped with CFRP composites. The columns had a dimension of 200mm x 200mm x 800mm and a round corner with a radius of 34mm. The results of the study demonstrated that wrapping the square RC columns under eccentric loading with CFRP enhanced their performance by providing higher load carrying capacity and ductility compared to unwrapped RC columns. [Copyright &y& Elsevier]

Abstract: Studies undertaken in the past years concentrated on studying FRP-confined columns subjected to concentrated loads. Only a few of these studies addressed the engineering behaviour of such members when subject to eccentric load. In view of this scarcity in research on columns subjected to eccentric loads, this paper presents results of testing wrapped columns subjected to eccentric loads. Nine short columns with the same dimensions were cast and tested. Three columns were identically reinforced with steel bars, three columns were made of plain concrete and wrapped with three layers of carbon FRP strips, and the remaining three columns were made of plain concrete and wrapped with three layers of E-glass FRP strips. From each group, one column was tested under concentric load, one under a 25mm eccentric load and one under 50mm eccentric load. An eccentric load system was developed specifically for the application of the eccentric load. The experimental results showed that eccentric load could obviously lower down the maximum failure load of FRP-confined concrete columns, compared to the columns under concentric load. However, compared to the internally reinforced concrete columns, FRP-confined columns displayed a higher load capacity and ductility, both when tested concentrically and eccentrically. [Copyright &y& Elsevier]

A research study is being undertaken to incorporate the realistic material properties of the pavement layers and the moving traffic load, in the analysis of flexible pavements, using the finite element theory. As a preliminary step taken herein in this direction, a pavement structure where field measurements have been carried out when subjected to a cyclic loading, is selected and modelled as a finite element model. The analysis is being carried out using the finite element computer package ABAQUS/STANDARD, when this pavement model is subjected to static and cyclic loading while considering the linear and non-linear material properties of the pavement layers. The results indicate that displacements under cyclic loading when non-linear materials are present, are the closest to field measured deflections. [Copyright &y& Elsevier]

This paper presents and discusses the applications of neural networks in concrete structures. It aims at introducing neural networks applications in structural design. The paper covers two applications of neural networks in concrete structures. Backpropagation networks are chosen for the proposed network, which is written using the programming package MAT-LAB. The overall results are compared and observed for the performance of the networks. Based on the applications it was found that neural networks are comparatively effective for a number of reasons, which include the amount of CPU memory consumed by neural networks is less than that consumed by conventional methods and their ease of use and implementation, neural networks provide both the users and the developers more flexibility to cope with different kinds of problems. [Copyright &y& Elsevier]

In this research study, the Taguchi orthogonal array (TOA) optimisation method was used to design the optimum mixture proportions of ternary blended Self-Compacting Ultra-High-Performance Geopolymer Concrete (SCUHPGC). The SCUHPGC mixtures, cured at ambient conditions, included Ground Granulated Blast Furnace Slag (GGBFS), Fly Ash (FA), and Silica Fume (SF) as aluminosilicate sources and sodium hydroxide solution and sodium silicate solution as alkaline activators. The effects of six factors at three levels on the compressive strength of SCUHPGC were investigated. The considered factors were the binder content, the ratio of fly ash to ground granulated blast furnace slag (FA/GGBFS), the ratio of silica fume to binder content (SF/Binder content), the ratio of alkaline activator to binder content (AAL/Binder content), the ratio of sodium silicate to sodium hydroxide (SS/SH), and the concentration of sodium hydroxide solution. Twenty-seven SCUHPGC mixtures were evaluated. The slump flow diameter of the optimum SCHUPGC was 740 mm, which satisfies the requirements of self-compacting concrete. The maximum 28-day compressive strength of 132.7 MPa was achieved by the optimum SCUHPGC mixture, which contained a binder content of 1050 kg/m3, a FA/GGBFS ratio of 0.3, an SF/Binder content ratio of 0.05, an AAL/Binder content ratio of 0.4, a SS/SH ratio of 4.0, and an SH concentration of 12 M. The 28-day flexural strength and tensile strength of the optimum SCUHPGC mixture were 9.6 MPa and 4.9 MPa, respectively. • Optimum mixture proportions of ternary blended ambient-cured SCUHPGC are presented. • Silica fume, GGBFS, and FA, mixed with SS and SH, are used to develop the SCUHPGC. • The AAL/binder content is the key factor in the compressive strength of SCUHPGC. • Compressive strength increases as AAL/binder content and FA/GGBFS ratios decrease. • The CO₂ emissions decrease by 40 % using SCUHPGC instead of SCUHPC. [ABSTRACT FROM AUTHOR]

Self-Compacting Concrete (SCC) is an innovative construction material that flows and compacts under its own weight, making it ideal for complex structures due to its high workability. Micro steel fibers, smaller in size than conventional fibers, have recently been adopted in both research and industry due to their limited effect on workability, which facilitates casting and construction process, alongside their promising contributions to enhancing the mechanical performance of concrete. The mechanical, rheological, and electrical properties of micro steel fiber-reinforced high-strength SCC members were investigated in this study. The testing program included prismatic specimens (100 × 100 x 500 mm3), cubic specimens (150 × 150 x 150 mm3), and cylindrical specimens (100 mm × 200 mm). The micro steel fiber contents considered were 0.0 %, 0.35 %, 0.70 %, and 1.05 % by volume. Test results revealed that the inclusion of micro steel fibers reduced workability, particularly above a 0.70 % fiber content, and resulted in maximum enhancement rates of 13.3 % in compressive strength, 52.4 % in splitting tensile strength, and 13.2 % in flexural strength compared to fiber-free specimens. The toughness index (T 150) was enhanced by up to 40 % at higher fiber volumes. These findings highlight the balance between workability and mechanical improvement provided by micro steel fibers. Bulk electrical resistivity exhibited a clear decreasing trend with increasing fiber content. • A detailed approach of producing high-strength self-compacting concrete was presented. • The impact of using different micro steel fiber contents was elucidated. • Straight micro steel fibers improved mechanical properties of concrete. • The electrical resistivity of micro steel fiber reinforced SCC was investigated. [ABSTRACT FROM AUTHOR]

This in-depth review aims to shed light on the application of nanoclay and multi-walled carbon nanotubes in geopolymer concrete. It comprehensively examines the profound impact of these nanomaterials on the physical, chemical, and mechanical properties of geopolymer concrete. The review delves into the intricate details of the properties exhibited by nanoclay and multi-walled carbon nanotubes, providing valuable insights into their unique physical and chemical characteristics. It also explores the methodologies adopted for their dispersion and the underlying functionalities within geopolymer composite. The review highlights advanced imaging and characterization techniques essential for understanding surface and mechanical properties. The review compares imaging techniques (scanning electron microscopy, transmission electron microscopy, helium ion microscopy, and atomic force microscopy), emphasizing their importance in characterizing mechanical properties of nanocomposites. A detailed discussion on the fresh and hardened mechanical properties, specifically compressive and flexural strength, of geopolymer concrete incorporating nanoclay and multi-walled carbon nanotubes is also included. Addressing key challenges and offering perspectives on future developments in the realm of geopolymer concrete, this review serves as a comprehensive exploration of the subject. [ABSTRACT FROM AUTHOR]

• The fatigue behaviour of concrete beams reinforced with geogrid is investigated. • Fatigue life of concrete beams reinforced with geogrid increases up to 60%. • Geogrid can improve the flexural fatigue strength of concrete beams by about 20%. • Geogrid continues in resisting the cyclic loads with formation of visible cracks. This paper investigates the effect of geogrid reinforcement on the flexural fatigue behaviour of concrete pavements subjected to cyclic loads. Fifteen-notched concrete beam specimens with the dimensions of 150 × 150 × 550 mm were either unreinforced, reinforced with a single or a double geogrid layer. The geogrid was placed at a depth of 55 mm from the bottom of the specimen. The specimens were tested under cyclic four-point bending loads at a frequency of 7 Hz. Test results illustrate that significant improvement was achieved in the flexural strength and fracture energy of the concrete specimens reinforced with geogrid. Geogrid reinforced concrete specimens exhibited high resistance of crack mouth opening displacements. Reinforcing concrete specimens with a double geogrid layer significantly prolonged the cyclic life of the specimens. An equation for designing concrete pavements subjected to cyclic loads was developed. [ABSTRACT FROM AUTHOR]

Steel fiber reinforced cementitious composites (SFRCC) have emerged as one of the most efficient techniques to improve the flexural capacity and ductility performance of concrete. However, one of the most significant shortcomings is the randomness of steel fibers direction in the concrete matrix, which influences the extent of mechanical enhancement for a limited fiber content. An experimental approach to control the direction of steel fibers embedded in self-compacting concrete is presented in this study, which is based on generating a driving rotating force to overcome the viscous impeding forces acting onto the embedded fiber. The mechanical performance of micro steel fiber reinforced self-compacting concrete members was investigated. A uniform magnetic field of 9.8 × 10−3 Tesla generated by a cylindrical powered coil was capable of aligning micro steel fibers embedded in fresh self-compacting concrete along the desired direction. The testing program included seven beam specimens of size of 100 × 100×500 mm3. The micro steel fiber contents considered were 0.35%, 0.70%, and 1.05% by volume. Fiber volume fraction of 0.35% was the optimum dosage for magnetic alignment as it achieved the highest extents of mechanical enhancement. The concrete specimens reinforced with 0.35% of steel fiber content have exhibited enhancement rates of 5%, 28%, and 30% in four-point failure load, maximum mid-span deflection, and compressive strength, respectively. Based on the visual analysis of cross-sectional images, the highest orientation factor achieved was 0.91 when steel fiber dosage was 0.35%, whereas the random non-magnetized steel fiber reinforced beams achieved an orientation factor ranging from 0.30 to 0.50. • A detailed approach of aligning steel fibers magnetically in concrete was presented. • Self-compacting concrete of low viscosity promoted a greater efficiency of alignment. • Magnetic alignment of embedded steel fibers improved the mechanical characteristics. • The impact of using different micro steel fiber contents was elucidated. • Detection of orientation factor confirmed the efficiency of magnetic alignment. [ABSTRACT FROM AUTHOR]

Highlights • A fiber model is presented for simulating rectangular CFST short columns in fire. • The sequential coupled nonlinear thermal and stress analysis procedure is given. • Local buckling, air gap, moisture content and surface emissivity are considered. • The fire-resistance and behavior of loaded CFST short columns in fire is studied. • The numerical model developed predicts well the fire performance of CFST columns. Abstract Elevated temperatures significantly reduce the local buckling strengths of steel tubes and the ultimate strengths of rectangular concrete-filled steel tubular (CFST) columns exposed to fire. No fiber-based models have been developed that include local buckling effects on the fire-resistance of rectangular CFST columns. This paper presents a new fiber element model for the fire-resistance predictions of axially loaded rectangular CFST short columns at elevated temperatures considering local buckling. The thermal analysis problem of a CFST column is solved by the finite difference method to determine the temperature distribution within its cross-section including an air gap, concrete moisture content and the emissivity of exposure surfaces. The nonlinear stress analysis of axially loaded short CFST columns under fire recognizes the stress-strain behavior of concrete and steel at elevated temperatures. The expressions for initial local buckling and effective widths of steel plates are incorporated in the computational model to include the effects of local and post-local buckling on the fire responses of CFST columns. The existing experimental and numerical results are utilized to examine the accuracy of the fiber-based model. The fiber model developed is used to undertake parametric studies on the effects of local buckling, geometric and material properties and loading ratio on the thermal and structural responses of CFST short columns and the load distribution in steel tube and concrete. The numerical model proposed is demonstrated to simulate well the fire and structural performance of axially loaded CFST short columns under fire. Moreover, computational solutions presented provide a better understanding of the thermal and structural responses of CFST columns in fire. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Engineering properties of FAGP and AAS concrete have been investigated. • The FAGP concrete has been produced by blending an alkaline activator with FA. • The AAS concrete has been produced by blending an alkaline activator with GGBFS. • The FAGP concrete has been produced using heat curing at 80 °C for 24 h. • The AAS has been produced at ambient curing condition. Abstract Fly ash-based geopolymer (FAGP) and alkali-activated slag (AAS) concrete are produced by mixing alkaline solutions with aluminosilicate materials. As the FAGP and AAS concrete are free of Portland cement, they have a low carbon footprint and consume low energy during the production process. This paper compares the engineering properties of normal strength and high strength FAGP and AAS concrete with OPC concrete. The engineering properties considered in this study included workability, dry density, ultrasonic pulse velocity (UPV), compressive strength, indirect tensile strength, flexural strength, direct tensile strength, and stress-strain behaviour in compression and direct tension. Microstructural observations using scanning electronic microscopy (SEM) are also presented. It was found that the dry density and UPV of FAGP and AAS concrete were lower than those of OPC concrete of similar compressive strength. The tensile strength of FAGP and AAS concrete was comparable to the tensile strength of OPC concrete when the compressive strength of the concrete was about 35 MPa (normal strength concrete). However, the tensile strength of FAGP and AAS concrete was higher than the tensile strength of OPC concrete when the compressive strength of concrete was about 65 MPa (high strength concrete). The modulus of elasticity of FAGP and AAS concrete in compression and direct tension was lower than the modulus of elasticity of OPC concrete of similar compressive strength. The SEM results indicated that the microstructures of FAGP and AAS concrete were more compact and homogeneous than the microstructures of OPC concrete at 7 days, but less compact and homogeneous than the microstructures of OPC concrete at 28 days for the concrete of similar compressive strength. [ABSTRACT FROM AUTHOR]

Abstract Hybrid fibre-reinforced polymer (FRP)-concrete-steel double-skin tubular columns (DSTCs) consist of an outer FRP tube and an inner steel tube, with the space inbetween filled with concrete. In hybrid DSTCs, the outward buckling of the steel inner tube is constrained by the surrounding concrete and the outer FRP tube, but its inward buckling is still possible. Existing research has shown that such inward buckling can become significant in non-circular hybrid DSTCs due to the non-uniform confinement, in hybrid DSTCs with a strong FRP tube due to the large axial deformation of the columns, and/or in hybrid DSTCs with a thin steel tube. In these cases, the stiffening of the inner steel tube is necessary to prevent or delay its inward buckling and to minimize its negative consequences to the column behavior. Against this background, a variation of hybrid DSTCs (hybrid R-DSTCs), in which the inner steel tube is stiffened by a number of vertical rib stiffeners, was recently developed at the University of Wollongong, Australia. This paper presents an experimental study on the axial compressive behavior of the new form of columns. The experimental program included a total of 12 R-DSTC specimens and two DSTC specimens for comparison, with the test variables being the number, thickness and width of rib stiffeners as well as the number of plies of fibres in the FRP tube. The test results confirmed that the additional rib stiffeners on the steel tube are effective in delaying the local buckling of the steel tube and in improving the performance of the columns. The test results also clarified the effects of the tested parameters of the rib stiffeners. [ABSTRACT FROM AUTHOR]

Local buckling remarkably reduces the strength of steel plates in rectangular thin-walled concrete-filled steel tubular (CFST) columns at ambient temperature. This effect is more remarkable at elevated temperature. However, there have been very limited experimental and numerical investigations on the local and post-local buckling behavior of steel plates in CFST columns at elevated temperatures. This paper presents numerical studies on the local and post-local buckling behavior of thin steel plates under stress gradients in rectangular CFST columns at elevated temperatures. For this purpose, finite element models are developed, accounting for geometric and material nonlinearities at elevated temperatures. The initial geometric imperfections and residual stresses presented in steel plates are considered. Based on the finite element results, new formulas are proposed for determining the initial local buckling stress and post-local buckling strength of clamped steel plates under in-plane stress gradients at elevated temperatures. Moreover, new effective width formulas are developed for clamped steel plates at elevated temperatures. The proposed formulas are compared with existing ones with a good agreement. The effective width formulas developed are used in the calculations of the ultimate axial loads of rectangular CFST short columns exposed to fire and the results obtained are compared well with the finite element solutions provided by other researchers. The initial local buckling and effective width formulas can be implemented in numerical techniques to account for local buckling effects on the responses of rectangular thin-walled CFST columns at elevated temperatures. [ABSTRACT FROM AUTHOR]

The axial and flexural behaviors of Concrete Filled Carbon Fiber Reinforced Polymer Tube (CFRP-CFFT) columns have received significant research attention in the last two decades. One of the most attractive advantages of Carbon FRP (CFRP) tube is the high confinement which results in substantial increase in peak axial and flexural loads and deformations. Despite large research efforts, the behavior of CFRP-CFFT with and without CFRP reinforcing bars under different applied axial load eccentricity has not yet been adequately investigated. This study investigates the experimental and analytical axial-flexural ( P − M ) interactions of CFRP-CFFT columns with and without CFRP reinforcing bars. A total of 12 specimens of 204–205 mm outer diameter and 800–812 mm height were tested under concentric axial load, 25 mm and 50 mm eccentric axial loads and four-point load. The effectiveness of CFRP reinforcement (tube and bar) was observed to be reduced with the increase in the applied axial load eccentricity. Analytical P − M interactions were constructed using available FRP confined concrete design codes which matched well with the experimental P − M interactions. The parametric study showed that the actual confinement ratio, orientation of fibers and CFRP bar reinforcement ratio have significant influences on P − M interactions of CFRP-CFFT specimens. [ABSTRACT FROM AUTHOR]

A new composite column named concrete-encased concrete-filled fibre reinforced polymer tube (CCFT) column has been proposed in this study. This composite column consists of an inner concrete-filled fibre reinforced polymer (FRP) tube, outer concrete confined with polymer grid, and concrete cover. In this study, a total of 16 concrete stub columns were cast and tested under axial compression. Columns were divided into eight groups, which included one group of plain concrete columns, two groups of FRP confined concrete columns, and five groups of CCFT columns. For FRP confined concrete columns, one layer and two layers of carbon FRP (CFRP) sheet were wrapped, respectively. For CCFT columns, glass FRP (GFRP) tube was used to confine the inner concrete, and polymer grid was used to confine the outer concrete. The test results show that considerable increase in strength and ductility can be obtained for CCFT columns. An analytical model has been developed to predict the axial compressive behaviour of CCFT columns. The analytical results have been found to be in good agreement with the experimental results. Based on the analytical model, the influences of different parameters on the axial compressive behaviour of CCFT columns have been investigated through parametric analyses. [ABSTRACT FROM AUTHOR]