Concrete Layer Research Articles

Study of the Vibration Reduction Performance of Rubberized Self-Compacting Concrete Filling Layer in Prefabricated Slab Track

Study of the Vibration Reduction Performance of Rubberized Self-Compacting Concrete Filling Layer in Prefabricated Slab Track

Geant4 Simulation of Muon Absorption in Concrete Layers

Muography requires a detailed understanding of the absorption of muons in the material situated between the muon source and the detector. A large-statistics (>3 billion event) Geant4 simulation was run to simulate the absorption of muons in different thicknesses of concrete layers and to determine the effect of the material on the energies of muons that were not absorbed. The Geant4 simulation included a simple detector placed directly behind the absorbing material. A Geant4 simulation was also run for the same detector for alpha sources with no absorbing material and the results of this simulation were compared to the signals from the physical detector built in the laboratory and measured using standard alpha sources. The large-statistics simulations using muons of different energies were compared to the predictions of muon absorption from existing literature. The results of the simulations were in good agreement with both the measured signals from the laboratory as well as the predictions from the literature and the general method is found to be well-suited for studies used for muography involving material layers of uniform thickness.

Thermal-mechanical coupled XFEM simulation of low temperature cracking behavior in asphalt concrete waterproofing layer

Asphalt concrete waterproofing layer (ACWL), which is used to reduce the moisture impact on high-speed railway structure, tends to crack at low temperatures and thus reduces its durability. Therefore, understanding the low-temperature cracking behavior of ACWL from both the material and structure perspectives is of great significance. In this study, thermal-mechanical coupled simulation based on extended finite element method (XFEM) was employed for research on this aspect, with the experimental and numerical monotonic-loading overlay test (ML-OT) to determine the fracture parameters of railway asphalt concrete materials and full-scale model to characterize the thermal cracking behaviors of ACWL. The results firstly showed that both the ML-OT and thermo-mechanical simulation on ACWL structure presented a four-stage fracture process, i.e. elastic response, crack initiation, crack propagation and final failure stage, at the temperature of −20 °C. Secondly, the effects of material formulation and structure design on the low-temperature cracking resistance was investigated: 1) In terms of material formulation, the binder B and gradation AC-13 was superior to their counterparts; 2) In terms of structure design, the ACWL layer thickness of 8 cm was the most unfavorable in the range of 6–16 cm, and the increased temperature difference accelerated the thermal cracking propagation in ACWL at the average temperature of −20 °C. In addition, two thermal stress mitigation strategies, namely laying the geotextile at base joints and setting expansion joints, were found to effectively prevent and delay the emergence of thermal cracks in ACWL at low temperatures. For recommendation, the developed thermal-mechanical coupled simulation framework, the custom-designed railway asphalt concretes, and the recommended ACWL thickness of 12 cm were applicable in future studies and engineering projects.

CHARACTERISTICS OF THE MIXTURE OF LATASTON (HRS-WC) WITH DOLOMITE LIMESTONE AS A FILLER IN ASPHALT MIXTURE

Indonesia is a country that has a lot of natural resources; one of the natural resources in Indonesia is lime. In Palembang, there is a large-scale dolomite lime-producing company that covers the territory of Indonesia. The content in the dolomite lime is Magnesium Oxide (MgO) ≥ 18% and Calcium Oxide (CaO) ± 30%. The purpose of this study is to utilize dolomite lime as a mixture of asphalt concrete layers and to find out changes in the characteristics of the HRS-WC mixture due to the use of dolomite lime as a filler. The experiment refers to Bina Marga 2018 revision II. The method used in this study is the experimental method, which is carried out by conducting experimental activities to obtain data. The aggregate specific gravity test obtained more than 2.5 gr/cm3 results, which qualify the 2018 Bina Marga revision II specifications. Examination of the wear of the coarse aggregate yielded results that fulfil the 2018 Bina Marga revision II specifications. The filler used in this mixture is applied on combination with a percentage of 0% rock ash and 100% dolomite lime, then 25% rock ash and 75% dolomite lime, then 50% rock ash and 50% dolomite lime, then 75% rock ash and 25% dolomite lime, and 100% rock ash and 0% dolomite lime. %. The Marshall results from the percentage of 100% rock ash filler content and the percentage of 0% OAC dolomite lime filler content of 6.5% obtaine a stability value of 914.821 Kg, a flow value of 3.45 mm, and a Marshall Quotient value of 265.286 Kg/mm. The volumetric value of the percentage of 100% rock ash filler content and the percentage of dolomite lime filler content of 0 % OAC 6.5% deliver a VIM value of 4.153%, a VMA value of 18.391%, a VFB value of 79.671%.

Shaking table tests on 0.5-scale multistory models of plate-type modular steel and composite buildings with semi-rigid corner connections

To study the dynamic properties and seismic response of global plate-type modular steel and composite structures with semi-rigid corner connections, shaking table tests were conducted on three 0.5-scale multistory plate-type modular models. This paper presents the testing program and results, including the dynamic characteristics and earthquake performance. Under the excitation of seismic loads, the bolts connected to the corners were easily loosened, the gaps between the composite wall plates increased, and the concrete surface layer of doorways and windows was damaged and fell off. The test results showed that as the peak ground acceleration increased, the fundamental frequency decreased, the damping ratio increased, and the acceleration amplification factor decreased. The initial lateral stiffness of plate-type modular composite structures with wall panels was eight to nine times that of plate-type steel frame structures owing to the strong skin effect of the wall panels. The stiffness of complete composite structures decreased by approximately 50% under a nine-degree rare seismic intensity owing to the deterioration of the bolt rotation stiffness and damage to the wall panel. The maximum interstory drifts of the complete plate-type modular building under rare earthquakes were small, which meets the requirements of the seismic design code.

Full-scale model testing of a graded crushed stone sandwich structure within the ballastless track subgrade

ABSTRACT This paper aims to analyse the static and dynamic characteristics of the sandwich structure consisted of an upper ballastless track structure layer, middle graded crushed stone interlayer, and lower foamed concrete subgrade layer, and clarifies its long-term dynamic stability. A full-scale test model of the sandwich structure being optimized was established, and then the static and dynamic loading tests were carried out. The results show that the use of foamed concrete as the subgrade filler can make the sandwich structure subgrade have better static stress and vibration diffusion effect compared with the traditional ballastless track subgrade. Under the loading conditions of this model test, the sandwich structure does not produce a resonance phenomenon when the loading frequency increases from 1 Hz to 10 Hz. And the sandwich structure has good vibration characteristics and long-term dynamic stability under cyclic loading. All these indicate that the graded crushed stone sandwich structure of the ballastless track foamed concrete subgrade can provide a smooth and long-term stable foundation for the line.

Measured noise levels beneath type B flat metal roof assemblies during rainfall

Flat metal roof assemblies are common in steel building design. Since they can produce high levels of rainfall generated noise, quiet roof assemblies are desirable over noise sensitive spaces. To determine the relative effects of assembly variations, a pair of fixtures were constructed to measure the noise levels beneath 2 x 4 ft sections of selected roof assemblies subjected to rainfall. Each test item was assembled from precut 2 x 4 ft sections of Type B metal roof (with or without a concrete layer), cover boards, and insulation, membrane and ballast as required. The fixtures were equipped with tipping buckets to measure rainfall rate. A microphone located inside each box and connected to a digital recorder, picked up ambient noise, rainfall generated roof assembly noise and the tipping bucket signal. To calibrate the recordings, the sound pressure level of the tipping bucket signal at the recording microphone was measured before testing. Recordings were analyzed to calculate indicated octave band sound power levels versus rainfall rate for the various tested roof assemblies.

Experimental Study on Flexural Behavior of RC–UHPC Slabs with EPS Lightweight Concrete Core

This paper presents an experimental investigation that focuses on the flexural behavior of an innovative reinforced concrete–ultra-high performance concrete slab with an expanded polystyrene lightweight concrete core. This type of slab is proposed to serve the semi-precast solution, in which the bottom layer is ultra-high performance concrete working as a formwork during the construction of semi-precast slab, the expanded polystyrene lightweight concrete layer is used for the reduction of structure self-weight, and the top layer is normal concrete designed to withstand compressive stress when the slab is loaded. Two similar large-scale specimens with dimensions of 6200 mm × 1000 mm × 210 mm were fabricated and tested under four-point bending conditions to investigate the flexural behavior of composite slab. Test results indicated that three different layers of materials can work effectively together without separation. The bottom ultra-high performance concrete layer leads to the high ductility of the slab and has a good effect in limiting the widening of the crack width by forming other cracks. According to design code ACI 544.4R, a modified distribution stress diagram on the composite section was proposed and proven to be suitable for the prediction of flexural strength of the composite section with an error of 3.4% compared to the experimental result. The effect of the ultra-high performance concrete layer on the flexural strength of the composite slab was clearly demonstrated, and for the case in this study, the ultra-high performance concrete layer improves the flexural strength of the slab by about 11.5%.

Blast resistance of single steel‐concrete composite slabs under contact explosion

AbstractTerrorist attacks or contact explosions could trigger severe damage to structural components or even cause the local or global collapse of the structure in civil engineering and infrastructures. Single‐steel‐concrete (SSC) slabs consist of a concrete core and one steel faceplate combined with shear studs or tie bars that can be applied in resisting explosion or blast load. This paper experimentally and numerically studies the blast performance of the scale SSC specimens under a contact explosion. The damage modes, deflections, and acceleration response of the SSC specimens are obtained and compared by experimental and numerical methods. And then the influences of the explosive, the shear stud length, and the steel plate thickness on the damage modes, acceleration, and displacement response are studied parametrically. It is observed that both of the concrete layers in SSC slabs have crater failure at the impacted surface and steel plates occur local deformation or buckling. No penetrability failure generates in the slabs because of the existence of the steel plate, which can improve the blast resistance and decrease the maximum deflections of the specimens. Finally, an empirical equation is developed to estimate the midspan displacement of the slab using the multivariable regression method (MNRM).

Experimental and numerical investigation on the flexural performance of RC slabs strengthened with EB/NSM CFRP reinforcement and bonded reinforced HSC layers

In this paper, one-way reinforced concrete (RC) slabs were strengthened using External Bonding (EB) and Near Surface Mounted (NSM) techniques and tested under flexural loading until failure. The area of internal and external reinforcement, shape of strengthening elements (bars, strips, and reinforced high strength concrete (HSC) layers) and strengthening method (EB and NSM) were the experimental tested variables. The experimental results showed significant increases in the load capacities of the upgraded slabs ranging between 133.8% and 264.5% compared to their corresponding un-strengthened slabs. Consequently, the NSM technique showed higher load efficiency than the EB, even though they had nearly the same strengthening properties and area. Compared to the control slab, using NSM strips instead of EB strips or NSM bars amplified the slab load capacity by about 51.7% and 33.2%, respectively, while using NSM HSC layer instead of EB HSC layer increased slab load capacity by 74.7%. Moreover, doubling the area of EB strips improved the load capacity by 10.3%, while increasing the internal steel area by 195% enhanced the slab load capacity by 21% to 48 %, depending on the strengthening method. However, depending on the distance between internal and external strengthening elements the cracks were initiated at the ends of the strengthening element causing the slab shear failure at dissimilar loads. Finally, a verified finite element (FE) model was built to study the effect of bond length, material, and area of the strengthening element on the slab behavior.

Preliminary optimization design of inverted asphalt pavement structure using response surface method

Inverted asphalt pavement (IAP) has the advantage of maintaining good performance under the condition of thin asphalt concrete (AC) layer compared with conventional flexible asphalt pavement. The stress-dependent property of unbound aggregate base (UAB) plays an important role in mechanistic responses of IAP. The focus of this paper is to quantitatively analyze the function of UAB’s stress-dependent property on the structure combinations design of IAP using response surface method (RSM). In this paper, an improved UMAT subroutine was developed to characterize the stress-dependent stiffness of UAB. The three-dimensional FE pavement model was established and validated against KENLAYER calculation and field FWD test deflection data. The critical mechanical response, maximum principal strain and bulk stress, were selected to evaluate the fatigue performance of AC layer and stress-dependent property of UAB. The significance analysis was conducted to describe the relationship between input variables (thickness and stiffness of structural layers) and the critical mechanical response variables. An optimization design method to balance the fatigue performance and stress-dependent property was proposed to obtain the optimal structure combinations of IAP. Research results demonstrate that the thickness and stiffness of the AC and UAB layers present a clearly significant impact on the maximum principal strain at the bottom of AC layer and the bulk stress in UAB, particularly during the summer season, whereas the thickness and stiffness of CTB and stiffness of subgrade have a minor impact. The responses of bulk stress and maximum principal strain can be empirically predicted by 2FI and Quadratic models. Optimal structure combinations (13.6 cm AC layer and 10 cm UAB) were recommended after quantifying the stress-dependent properties of UAB. The recommended structural combination has good fatigue resistance and can also efficiently minimize AC and UAB layer thickness.

Evaluating the potential of geopolymer concrete as a sustainable alternative for thin white-topping pavement

Introduction: The construction industry uses a large quantity of natural materials in the production of concrete. Although attempts to incorporate green materials in concrete began years ago, not every building uses such materials today, and roadways, particularly, still rely on unsustainable materials.Methods: Therefore, this study used alternative materials, including fly ash, manufactured sand aggregates, and different molarities of alkaline activators, to incorporate waste byproducts in a geopolymer concrete white-topping pavement layer. Recent developments have led to the emergence of geopolymers as distinct classes of materials. In the 1990s, fly ash-based geopolymers became more popular than other kinds, as they are more efficient compared to Portland cement concrete.Results: Aluminosilicate gel can be obtained by combining fly ash and alkaline solution. A comprehensive literature review of geopolymer concrete was performed in this study. It examines its critical design parameters, including alkaline solutions, curing temperatures, curing methods, workability, and compressive strength under various environmental conditions. This review provides a unique opportunity for researchers to understand how geopolymer concrete performs.Discussion: A range of conditions were investigated to determine how to enhance and use this material in a variety of ways. The fresh characteristics of different mixes were studied using slump and Vee-Bee tests, and the characteristics of the cured concrete mixes were determined using flexural, compressive, and flexural fatigue tests. The results indicated that the use of manufactured sand and fly ash with high-molarity alkaline activators results in a geopolymer concrete with an excellent maximum resistance of 5.1 N/mm2 workability, strength, and fatigue properties, making it suitable for use in roadway pavement.

Experimental and Numerical Study on Axial Compression Cold-Formed Steel Composite Wall under Concentrated Loads

This paper presents the experimental and numerical studies in the investigation of the concentrated compressive behaviors of cold-formed steel-foam concrete composite wall. The failure modes, load–displacement curves, and load–strain curves of the specimens were obtained from the experiments. The infilled specimen failed due to distortional buckling of the end stud and cracking of the concrete near the corner of the wall. The strength of the high strength cold-formed steel was not being fully utilized. A finite element model was established by ABAQUS software and validated by the test results to investigate the effect of the concrete strength, steel strength, the spacing between stud openings, and the thickness of the concrete protective layer on the behaviors of the composite wall. The results indicate that the improvement of concrete strength has the most obvious effect on the bearing capacity of the composite wall, while the changes in steel strength, concrete cover thickness, and hole spacing have limited effects.

Investigation on the change of shear strength of concrete with cold joint under the action of sulfate dry–wet cycles

Large-volume concrete structures in the saline areas of Western China often have cold joint structural surfaces due to the improper handling of construction joints, dividing them into old and new layers of concrete. In this sulfate-rich environment, the shear strength of concrete with cold joint and the evolution pattern of its composition with the sulfate dry–wet cycles are particularly important in assessing the quality of the interface between old and new concrete bond surfaces. Therefore, in this paper, direct shear tests and microscopic scans were performed on concrete specimens with cold joint at different pouring age intervals and numbers of sulfate dry–wet cycles. The mechanism of the effect of both on the shear strength and failure mode of concrete was analyzed. Results show that the sulfate dry–wet cycles of erosion and the age interval have significant effects on the shear strength of the cold with cold joint and their components. As the number of sulfate dry–wet cycles increased, the shear dilation of concrete specimens with cold joints under direct shear action was reduced, the internal friction angle initially increased and then decreased for specimens with a short pouring interval (0–0.25 day), and the reduction of the internal friction angle of the specimens with a long pouring age interval (0.25–28 days) was nonlinear. The shear dilation of the specimen increased, and the internal friction angle decreased nonlinearly with the increase of the pouring interval. In addition, the failure criterion of specimens transformed from the bilinear Mohr–Coulomb criterion before erosion to the linear Mohr–Coulomb criterion under the action of sulfate dry–wet cycles.

Experimental investigation on performance of sandwich wall infill in framed structure

The sandwich wall infill in framed structures is a layered structural system made of thermally insulated core material (EPS layer) with concrete layers on either side reinforced to act monolithically. It is the best replacement for concrete, brick, and hollow block walls because of its low self-weight, few connection joints, and easy and fast installation on site. It also has good thermal and noise insulation properties, a better load-carrying capacity, and was found to be cost-effective. This layered system is resistant to alternate cycles of heat and cold, with less penetration from destructive rays and external forces. For this experimental study, sandwich wall panel specimens (0.75 × 0.75 × 0.1 m) are cast with an external layer of concrete and an Expanded Polystyrene layer as a core, varying its thickness (25 mm, 50 mm, 75 mm), and these layers are bonded together by adequate steel reinforcement. A wall is tested to evaluate its structural performance in the context of ultimate strength capacity, load–deflection profiles, cracking patterns, and failure modalities compared with the conventional wall system. The wall specimen with a minimum core thickness of 25 mm has a maximum load carrying capacity of 504 kN, which attains 98.6% of the ultimate load of a conventional wall specimen, and it also possesses very little deflection of 0.37 mm in the front side of the panel. The maximum strains observed in the concrete layer and reinforced steel bar are 0.0012 and 0.0024, respectively. The current study demonstrates that lightweight sandwich wall panels are a superior replacement for traditional wall systems.

Effect of main and NSM reinforcing materials on the behavior of the shear strengthened RC beams with NSM reinforced HSC layers and bars

It became common practice to utilize near-surface mounted (NSM) bars to improve the shear capacity of steel-reinforced concrete (RC) beams. Consequently, carbon fiber-reinforced polymer (FRP) is usually used to improve RC beams' shear performance. Conversely, the use of Glass FRP (GFRP) for enhancing the shear behavior of the steel-RC and GFRP-RC beams is still limited. This study used NSM GFRP or steel bars to strengthen RC beams reinforced in tension with steel or GFRP bars. In addition, a new NSM technique was conducted using high-strength concrete (HSC) layers reinforced with GFRP or steel bars bonded within grooves to enhance beams' shear capacity. The results of seventeen beams used in the tests showed that NSM HSC layers improved the shear performance of RC beams more than NSM bars. Also, the beams reinforced in tension with steel bars had higher shear efficiency and were stiffer than those reinforced with GFRP bars. Conversely, the shear efficiency of steel RC beams strengthened in shear with internal stirrups or NSM reinforcement (or both) increased by 142.8–211.7% compared to GFRP RC beams without internal and NSM shear reinforcement. Conversely, the shear capacity of the steel-RC beams strengthened in shear with internal stirrups or NSM reinforcement (or both) increased by 153.5–279.9% compared to the corresponding beam without GFRP RC beam without internal and NSM shear reinforcement. The numerical analysis using the ABAQUS program showed great effects of the tension reinforcement and the NSM materials on the strain of longitudinal bars, stirrups and NSM reinforcement.

Rutting prediction using deep learning for time series modeling and K-means clustering based on RIOHTrack data

Considering that traditional statistical regression and machine learning rutting prediction models hardly capture time series characteristics of rutting, this study employed deep learning (DL) techniques to develop multivariate time series models to predict the rutting progression curve for asphalt pavements commonly constructed in China from the data relating to the rutting depth of 19 asphalt pavements from RIOHTrack. 32 features related to climate, traffic, pavement structure, and materials, were selected from initial 50 features using variance threshold and feature importance analysis. k-means clustering was used to classify these pavement sections according to their rutting progression pattern. Three DL models (RNN, LSTM, and GRU) with different architectures and sequence lengths (SLs) (24 models produced) were trained from historical rutting depths and the selected exogenous variables, and their performances were then compared with ARIMAX, Gaussian process, and mechanistic-empirical (M−E) models. The results show that the architecture 2 based GRU model with an SL of 11 is found to have the best prediction performance (R2 = 0.90). The DL model can capture the pattern of the observed rutting progression curve which contains linear and seasonal trends. Moreover, the optimal DL model is more accurate than the statistical time series models and the M−E model. Permutation feature importance analysis shows the impacting features mainly include historical rutting depth, temperature, age, as well as binder penetration and air void of the second asphalt concrete layer.

Development and investigation of an innovative, light-weight, two-way spanning timber-concrete composite slab

Timber-concrete composite (TCC) slabs play an essential role in modern timber construction. Consisting of a timber member in the tension zone, a concrete layer in the compression zone and a shear connection between the two parts, TCC slabs feature a number of advantages that make them ideally suitable for use in both office and residential buildings. However, currently used TCC slab systems carry loads only in one direction. In the frame of a large research project in cooperation with the industry, an innovative, light-weight, two-way spanning timber-concrete composite slab using beech laminated veneer lumber with steel tubes as connectors was developed. This paper presents the main results of the research project. First, the structural behaviour of the connection is characterised and discussed based on extensive experimental and analytical analysis. Second, the load-bearing behaviour of the TCC slab investigated in uniaxial bending tests is presented. The uniaxial bending tests showed a remarkably ductile global load-bearing behaviour due to the ductile failure mode in the connectors. A developed analytical model can describe the observed load-bearing behaviour of the tested TCC members accurately. Finally, the biaxial load-bearing behaviour of the TCC slab is characterised and discussed based on a large-scale experiment that allowed to perform static and dynamic tests on the same specimen in different support conditions. A substantial increase in stiffness and fundamental frequency in biaxial versus uniaxial support conditions was observed and accurately modelled, showing the great potential of the novel TCC slab.

Machine learning guided design of microencapsulated phase change materials-incorporated concretes for enhanced freeze-thaw durability

Prolonged exposure to freeze-thaw cycles (FTCs) induces adverse effects in concrete structures in terms of a significant reduction in strength and durability. This paper proposes a microencapsulated phase change material-incorporated concrete (MPCMC) layer to mitigate FTCs in the concrete bridge decks. Toward this, the present work implements finite element analysis (FEA)-based multiscale numerical simulation, which shows the effectiveness of the proposed MPCMC protective layer toward FTC reduction. Moreover, the multiscale framework is leveraged to generate a large dataset containing 8096 data points of FTCs considering a uniform variation of five design parameters, namely the thickness of the protective MPCMC layer, volume fraction, transition temperature, size, and the latent heat of the MPCM. Thereafter, the dataset is leveraged to develop an interpretable neural network (NN)-based predictive model as a computationally efficient alternative to the complex multiscale FEA-based design tools. The interpretable machine learning (ML) model provides a reliable and efficient continuous mapping between the design parameter space and the resultant number of FTCs. Moreover, it explains general engineering intuitions and physics. Besides, the interpretable ML characterizes various underlying interplays of the design parameters in dictating the resultant FTCs.

Seismic performance of elliptical FRP-concrete-steel tubular columns under combined axial load and reversed lateral load

By combining FRP composites with both steel and concrete, double-skin tubular columns (i.e., DSTCs) with a hollow core are a novel structural member to be used as bridge piers or other columns in harsh environments. Up to now, DSTCs with circular or square sections (i.e., C-DSTCs or S-DSTCs) have been investigated extensively, while DSTCs with an elliptical section (i.e., E-DSTCs) are rarely studied. E-DSTCs are composed of two concentric elliptical tubes (i.e., the external FRP tube and the internal steel tube) and a sandwiched concrete layer. E-DSTCs can be designed with two distinct bending stiffness with respect to the two axes of symmetry. Similar to C-DSTCs, E-DSTCs have an FRP tube with a continuously curved circumference, thus effectively confining the concrete layer. To extend the existing research, this paper tested six large E-DSTCs under combined axial load and reversed lateral load to investigate the effect of elliptical aspect ratio. The testing parameters also included the direction of reversed lateral load and the FRP thickness. Experimental results showed that, E-DSTCs performed with rounded hysteresis loops and remarkable ductility even for the specimen with a large aspect ratio (i.e., for the elliptical aspect ratio from 1.0 to 2.0, the ductility index increased monotonically from 6.50 to 7.75); a thicker FRP tube led to marginally higher peak load but noticeably better ductility (i.e., the specimen with 2.10 mm FRP had an average peak load of 77.65 kN and a ductility index of 7.14, while the corresponding specimen with 1.05 mm had an average peak load of 77.35 kN and a ductility index of 6.29); as expected, the specimen bending around its strong axis had much superior ductility than the companion specimen bending around its weak axis. A numerical column model was established based on OpenSees to simulate the hysteretic behavior of E-DSTCs, and a parametric study was conducted to assess the influences of FRP thickness, concrete strength, axial load ratio, steel tube thickness, void ratio as well as elliptical aspect ratio. In practical engineering design, it was recommended that: (a) the elliptical aspect ratio as well as other key parameters (e.g., the FRP thickness, the steel tube thickness, the area void ratio) should be optimized based on specific loading conditions; (b) to make more effective usage of FRP composites, the FRP tube thickness should be optimized for different height regions of the column according to the moment gradient caused by the reversed lateral load.