Eccentric Compression Loading Research Articles

Experimental study on the behavior of eccentrically compressed corrosion-damaged reinforced concrete columns

This paper presents an experimental study of corrosion-damaged reinforced concrete (RC) columns under eccentric compression. Three RC concrete column specimens, identical in geometry, reinforcing steel bars, andconcrete mix, were fabricated. One undamaged control specimen served as the control group, while the othertwo column specimens underwent corrosion due to chloride ion exposure. All specimens were subjected to aminor eccentric compressive load. The test results have revealed the behavior of RC columns damaged by steelcorrosion. Additionally, a comparison of the load-bearing capacity of corrosion-damaged RC columns wasconducted between calculation and experiment. The results indicate a close alignment between calculated andexperimental outcomes. Furthermore, the degree of decrease in the load-bearing capacity of corrosion-damaged RC columns over time was evaluated based on the axial load-moment interaction diagram. This evaluation considered the influence of the reduction in concrete strength and the cross-sectional area of the reinforcement.

Behavior of large-scale FRP-confined square RC columns with UHP-ECC section curvilinearization under eccentric compression

Implementing section curvilinearization (SC) by curving flat sides into curved sides before fiber-reinforced polymer (FRP) jacketing has been proposed to enhance the FRP confinement effectiveness of FRP-confined rectangular concrete columns. In this paper, ultra-high performance engineered cementitious composite (UHP-ECC) is proposed as the added concrete for SC, with an aim to enhance both bending and axial strengths of concrete columns given that the UHP-ECC can contribute to resisting tensile stresses for columns. Thirteen large-scale FRP-confined square reinforced concrete (RC) columns with SC using UHP-ECC were tested under eccentric compression loading to explore their eccentric compressive behavior. The test parameters included the rise-to-span ratio, the FRP thickness, the eccentricity and the surface roughness of the old concrete. The test results show that FRP confinement with SC using UHP-ECC can substantially enhance the peak axial load and the bending moment than those without SC, while the ultimate lateral displacement is marginally increased. An increase in the rise-to-span ratio leads to an increase in the peak axial load.

Performance of round-ended CFST columns under combined actions of eccentric compression and impact loads

Round-ended concrete-filled steel tubular (RECFST) columns are gaining increasing usage in bridge structures. During their service life, RECFST columns under eccentric compression may suffer from impact loading. This study conducted test and numerical investigations to assess the performance of RECFST columns under the coupled actions of compression, bending and lateral impact loads. Fourteen columns were fabricated and tested, considering the influences of axial-load ratio, bending moment and impact energy. The damage mode and the time histories of impact force and displacement were accessed and analyzed. The experimental findings revealed that the initial bending moment negatively affected the impact resistance of RECFSTs. In addition, finite element model was established in ABAQUS and calibrated against the test results. The calibrated model was then employed to conduct the failure mechanism analysis and parametric study. Finally, a single-degree-of-freedom (SDOF) analysis was conducted to predict the mid-height deflection of RECFST columns under combined action of compression, bending and lateral impact loads, by incorporating the influences of pre-axial load and initial bending moment.

Eccentric load-carrying capacity calculation of L-Shaped Columns with recycled aggregate concrete-filled tubes

A composite L-shaped column made of square steel tubes filled with concrete is well-suited for residential steel structures because it effectively prevents the beams and columns from protruding from the walls, thus maximizing the usable space within a room. Recycled aggregate concrete (RAC), a sustainable material, can efficiently recycle construction waste and reduce energy consumption. However, compared to natural concrete, RAC has lower elastic modulus and compressive strength. When RAC is filled into steel tubes, it effectively restrains the RAC and allows it to support the internal buckling of the steel tubes. This study investigates L-shaped columns of recycled aggregate concrete-filled steel tubes (L-RACFST) through eccentric compression tests and numerical validation. By applying the superposition principle, the study evaluates the eccentric compression strength calculation method of L-RACFST columns and plots the N-M relationship curve. Comparing the results of the tests and numerical studies, it is evident that the derived formula is reliable for predicting the eccentric compression bearing capacity of L-RACFST columns. Furthermore, the N-M relationship curve drawn from the formula provides a more accurate prediction of safety. This paper delves into the stress mechanisms of L-RACFST columns under eccentric compression loads. The calculation formula can be used to determine the bearing capacity of L-RACFST columns under eccentric compression loads, and the N-M relationship curve can be employed to predict the safety performance of L-RACFST columns under such loads.

Crack Resistance of RC Columns Strengthened By CFRP Under 30% of Uls Loading

Abstract Nowadays, among many existing reinforced concrete (RC) columns, it is impossible to find samples that work only as centrally compressed members – their vast majority work as eccentrically compressed members. On the other hand, the significant volumes of reconstruction in Ukraine will require studies of the work of various RC structures strengthened under different load levels. In addition to choosing the method of strengthening itself, the relevant tasks will be studies of bearing capacity, crack resistance, reliability (including residual resource) of structures, etc. This article presents the method of crack resistance experimental study of eccentrically compressed RC members. The proposed method was tested on unstrengthened (ordinary) and strengthened (in a stretched zone) RC columns; the results of experimental studies for ordinary and strengthened samples were also obtained. The columns were strengthened with a composite material (from many carbon-fiber-reinforced polymers) – the Sika Carbodur S512 strip. The feature of the crack resistance study of columns was that they were strengthened under the initial load level of 30 %. As a result of experimental research on the samples strengthened under load, we stated that the width of the crack decreased on average by about 36 % (at the comparable values of the active load). In turn, the average maximum length of cracks decreased to about 50 % of the height of the cross-section (for unstrengthened samples, this value was approximately 80 %), and the eccentric compressive ultimate load was increased by about 33 %.

Numerical investigation on the behavior of eccentrically loaded lightweight reinforced concrete columns at elevated temperature

AbstractIn this paper, a numerical model is presented to simulate the behavior and failure of lightweight reinforced concrete (LWRC) columns subjected to eccentric compressive load at elevated temperature using the finite element code ABAQUS. Validation of the numerical model was ensured throughout comparison numerical results with the available published experimental tests results. The validated numerical model was implemented in conducting extensive parametric study to understand the effects of important parameters on the response of eccentrically compressed LWRC column at elevated temperature. These parameters include the effect of concrete cover, the effect of exposure time, the effect of the exposed temperature, the effect of temperature distribution around column section, the effect of temperature distribution along column length, and the effect of eccentricity ratio. The numerical results indicated that increasing the concrete cover of the column section results a considerable increasing of the ultimate load capacity. In addition, there is an increase in the ultimate load capacity when the temperature exposure time is reduced to the half of the original exposure time. Whereas, if the exposure period is increased to twice and three times the original exposure time, the ultimate load shows a slight decrease. Moreover, the ultimate load capacity of the LWRC column decreases when temperature is increased. Finally, the ultimate load capacity increased of the LWRC column when the temperature is distributed over larger distance of the column length.

Behavior and design of concrete filled stainless steel tubular columns under concentric and eccentric compressive loading

Concrete Filled Stainless Steel Tubular (CFSST) column is a novel type of composite columns that features excellent structural performance, corrosion resistance as well as aesthetic appearance. Owing to the differential mechanical properties between stainless steel and carbon steel, extending the current design codes of conventional CFST columns to CFSST columns may cause unreliable predictions. To this end, this paper summarizes the current state-of-art of CFSST columns and compiles the database of CFSST columns subjected to concentric compressive loading and eccentric compressive loading. Based on the analysis of current studies, the applicability of current international design codes is comprehensively evaluated, and the numerical simulation is also performed through three-dimensional Finite Element (FE) modeling and two-dimensional Fiber Section (FS) modeling technique, where the concrete confinement effect is properly incorporated. Parametric study is then conducted using the validated FS model to investigate the influence of concrete compressive strength, steel yield strength and section slenderness ratio on load-carrying capacity. Finally, a new approach is proposed to construct the axial force-bending moment interaction diagram of CFSST columns, which is simple to use and generates enhanced prediction accuracy as compared with the current design method.

Stainless-steel square hollow tubes subjected to low-temperature eccentric compression loads

To promote the applications of stainless-steel square hollow tubes (SSHTs) in cold regions, the low-temperature eccentric compression behaviours of SSHTs were investigated. Twelve SSHTs were tested at four eccentricity ratios (e/r) of 0, 0.33, 0.72, and 1.00 and four low temperatures (T) of 20, −30, −60, and − 80 °C. Test results showed that inward and outward plastic local buckles alternatively took place in the axially-loaded SSHTs at ambient/low temperatures, and inward plastic local buckles occurred to the cross-sectional compression tip of eccentrically-loaded SSHTs. Low temperatures improve the load carrying capacity of SSHTs subjected to compression. Reducing low temperature increased the ultimate bending resistances of SSHTs. Increasing the e/r generally reduces the yielding and ultimate loads of SSHTs. Different code prediction equations were used to estimate eccentric-compression capacities of SSHTs at low temperatures. Validations showed that the SEI/ASCE802, EC3, and ANSI were conservative to predict N-M interactions of SSHTs subjected to low-temperature eccentric compression.

Nonlinear-finite-element analysis of reactive powder concrete columns subjected to eccentric compressive load

AbstractStudies on the behavior of reactive powder concrete (RPC) columns under eccentric loading are limited. The effect of materials used in manufacturing these RPC columns has not yet been investigated. This research aimed to perform a nonlinear-finite-element analysis to determine the load-carrying capacity and displacement of RPC columns made of different RPC mixes and subjected to various loading eccentricities. This research investigates two types of parameters. The first parameter is the column’s geometric parameters (the heightLand the load eccentricity distancee). The second is the RPC material parameter (regarding the silica fume or fly ash used as pozzolanic material and the type of fibers used, whether steel or glass fiber). Results indicate that eccentric-loaded slender columns exhibit much less load-carrying capacity than the corresponding short columns. The 2 m-long columns with eccentricity ratioe/t= 0.2 resulted in a 65% average reduction in the ultimate load (Pu) compared to the corresponding 1 m-long columns. Using fly ash as a pozzolanic material instead of silica fume reduces the ultimate load (Pu) of an RPC column by an average of 60%. Using glass fibers instead of steel fibers also reduced Pu by 50%. The average percentage increase in the maximum vertical deflection (Δymax) of the short column (L= 1 m) is found in the range of 18–31% for eccentricity ratioe/t= 0.1 but 45–69% fore/t= 0.2. In contrast, for a slender column (L= 2 m), the percentage increase in Δymaxis in the range of 10–30% for bothe/t= 0.1 and 0.2.

Axial-flexural performance of columns reinforced by steel-FRP composite bars and FRP ties

The ductile and corrosion-resistant steel-FRP composite bar (SFCB) is a promising longitudinal reinforcement for marine engineering in harsh environments. However, the study about the axial-flexural performance of longitudinal SFCBs reinforced concrete columns, especially combined with corrosion-resistant FRP ties, is very limited. The lack of valuable experimental observations and design methods seriously limits its design and application. Here, 15 square concrete member specimens with different reinforcement types are tested under concentric compression, eccentric compression, and pure flexural loading, to investigate the effect of longitudinal SFCB and FRP tie on the axial-flexural behavior of columns. Results show that the yielding characteristic of longitudinal SFCB leads to two representative failure modes (tension-controlled and compression-controlled failure). Using equal-stiffness SFCB to replace steel bar contributes to a better axial-flexural behavior of columns, including the same failure mode, similar deformation, and higher load capacity. Furthermore, a theoretical model that considers the unique constitutive relationship of SFCB and confinement conditions of different ties is developed to predict the failure modes and axial-flexural capacity of columns, showing great accuracy. These findings provide a valuable experimental basis and safe design tactics for this corrosion-resistant and ductile hybrid reinforcement scheme of marine infrastructure.

Steel tube filled with recycled concrete incorporating steel-fiber reinforcement and self-stressing effect

To widespread use of construction and demolition waste (CDW), an innovative steel-fiber-reinforced self-stressing recycled aggregate concrete filled steel tube (SFRCFST) is put forward. The mechanical behavior of SFRCFST under compression-bending is explored in this study. 27 specimens are conducted under eccentric compressive load, and the considered parameters are eccentricity ratio, steel tube thickness, concrete strength grade, quality replacement rates of recycled aggregate, steel fibers content and self-stress. Test results reveal that eccentric loaded SFRCFST fails in the same way of ordinary CFST columns. As the eccentric ratio is increased, the adverse impact of alternative recycled aggregates is more distinct. A double-reduction of load (Nu) and moment bearing capacities (Mu) of the specimens is observed when recycled aggregate replacement rate is increased. Introducing self-stress improves Nu and Mu with the average amount of 14.90% and 10.55%, respectively. Moreover, the flexural rigidity of SFRCFST columns is also enhanced. Moderate amount steel fibers with volume content of 1.2% ∼ 1.8% bring the improvement of Nu and Mu, as well as greater plastic development potential of SFRCFST columns. A refined FE model is proposed to simulate the eccentric loaded behavior of SFRCFST columns. Numerical results show that self-stress contributes to the confining effect throughout the loading process.

Circular hollow stainless-steel tubes subjected to low-temperature eccentric compression loads

To investigate the eccentric compression behaviours of circular hollow stainless-steel tubes (CHSSTs) at low temperatures, 12 CHSSTs using SS 30408 tubes were tested. The studied low temperatures (T) were 20, −30, −60, and −80℃ and four eccentricity ratios (e/r) of e/r = 0, 0.33, 0.72, and 1.00 were considered in the eccentric compression testing program. The tests show that alternative inward and outward local buckles occurred to CHSSTCs under axial compression whilst inward local buckles were observed in those eccentrically-loaded CHSSTCs. The low temperatures do not exhibit obvious influence on their failure modes and positions of local buckles. Decreasing T from 20 to −80℃ increases the ultimate compression capacities (Pu) of axially and eccentrically loaded CHSSTCs by about 20%. As the T reduces from 20 to −30, −60, and −80℃, the ultimate bending resistances of CHSSTCs tested at e/r = 1.0 are increased by 15%, 16%, and 17%, respectively. With the increasing e/r ratio from 0 to 0.33, 0.72, and 1.00, the Pu of CHSSTCs tested at −60℃ are reduced by 50%, 59%, and 66%, respectively. Different code equations were used to estimate the compression capacity of these eccentrically-loaded CHSSTCs. The CSM method offers the closest estimations on ultimate resistances of CHSSTCs tested at different low temperatures. The EC3, ANSI-370, and SEI/ASCE 8 provide close and much more conservative estimations on the low-temperature N-M interactions of CHSSTCs.

Eccentric compressive behavior of PBL-stiffened double-skin composite walls in bridge pylons

Double-skin composite walls (DSCWs) stiffened with perfobond ribs (PBLs) have gained popularity for use in large-scale structures. This investigation aims to provide valuable insights into the performance of PBL-stiffened DSCWs when subjected to eccentric compressive loads. An experimental investigation was conducted on eight PBL-stiffened DSCWs. The failure modes, local buckling behavior, load-deflection behavior, moment–curvature relationship, and strain distribution were analyzed. The results indicate that an increase in the interval of longitudinal PBLs on the compressive zone of the DSCW specimens leads to a reduction in eccentric compressive resistance due to premature local buckling. However, the transverse PBL interval and removal of transverse rebars had negligible effects on the local buckling behavior of the faceplates and did not affect the resistance of the specimens. The ductility index of DSCWs slightly increased with an increase in concrete strength and was further enhanced by the presence of headed studs. The introduction of studs on the faceplates effectively delayed the onset of local buckling and improved the resistance of the DSCWs under eccentric loads. Throughout the loading process, the longitudinal strain remained almost linear, and the neutral axes remained unchanged, indicating that the plane section assumption works for PBL-stiffened DSCWs. To develop N–M interaction curves of PBL-stiffened DSCWs under eccentric loads, the effective area method was introduced to predict the post-buckling strength of unilaterally restrained PBL-stiffened plates. The proposed curves provided accurate and relatively conservative predictions of the experimental results due to the reasonable consideration of the local buckling effect.

Analytical and numerical investigation of polyvinyl chloride (PVC) confined concrete columns under different loading conditions

ABSTRACT To study the performance of PVC-confined concrete columns under concentric and eccentric axial compression loads, a numerical simulation using ABAQUS software was conducted. The correctness of the model was validated with the existing test results of the stress-strain curve and failure modes of specimens. Then, the compression load was applied at 20, 30, 40, and 50 mm eccentricity. The mechanical behavior, concerning the influence of different loading conditions, the diameter of specimens, the height of specimens, and the strength of unconfined concrete were investigated. The FEM and experimental results of loads and strains had AAE of 6.46 and 11.28%, respectively. In addition, the analytical and experimental strain values had an AAE of 36.24%. The COV was 7.57 and 12.26% between experimental and FEM results for loads and strain, respectively. An analytical model was developed to predict the ultimate stress and strain of PVC-confined concrete columns, which was compared with the existing models available in the literature with AAE of 13.4 and 29.5% for loads and strain respectively. Due to small F-values between FEM, analytical, and experimental values, indicating closer to their mean values, the analytical model can be adopted in the design of these short columns.

Study on the Eccentric Compressive Performance of Steel Fibre Reinforced Coal Gangue Concrete Columns

Coal gangue is the waste created in the coal mining process and can be utilised as a coarse aggregate in construction projects to solve the environmental problems it causes. To study the mechanical properties of steel fibre reinforced coal gangue concrete (SFCGC) columns under eccentric compression, two natural aggregate concrete (NAC) columns and eight SFCGC columns were designed and fabricated for eccentric compression loading tests. The variables involved in the tests include gangue substitution rate (0%, 30%, 50%, 70%), steel fibre volume content (SFVC) (0%, 0.5%, 1%, 1.5%), and eccentricity (0.25, 0.5). The experimental work and theoretical analysis were used to investigate the failure mode, cracking, and ultimate bearing capacity of SFCGC columns. The effects of various variation parameters on the longitudinal strain, concrete strain, transverse displacement, crack width, and bearing capacity were analysed in detail. The digital image correlation (DIC) technique was used to compare with the conventional observation and to analyse the cracking trend of the specimens. The testing results revealed that the damage pattern of SFCGC columns under eccentric compression was similar to that of NAC columns. The eccentricity significantly affected the damage pattern (or bearing capacity) of SFCGC columns. The effect of the coal gangue replacement rate on the lateral displacement corresponding to the ultimate load can be neglected under the same eccentricity. The incorporation of steel fibres effectively inhibited the development of cracks in the columns, with an average increase in crack load and ultimate load of 7.36% and 17.1%. The equations were also established to determine the crack width and bearing capacity of the studied SFCGC columns, and the theoretical predictions agreed with the experimental results.

Experimental and numerical studies of the eccentric compressive behavior of circular RC columns strengthened with grouting-filled steel tubes

The reinforcement of concrete columns with steel tubes is a convenient and economical technique in civil engineering. To investigate the mechanical behavior of short circular concrete columns strengthened with grouting-filled steel tubes under eccentric compressive loads, five specimens with different eccentricities were tested in the present work. Finite element simulations were carried out in ABAQUS software to analyze the mechanical behavior of the reinforced columns. A parametric study was performed to evaluate the influences on the SRF, RCR, P-M, and P/Pu-M/Mu curves of the reinforced columns. The results showed that increasing the yield strength and thickness of the steel tube improved the performance of the reinforced columns. The ultimate load-carrying capacities of the specimens determined by the codes were compared with those determined by the proposed formulas. The results also showed that the ultimate load-carrying capacities of the specimens determined by the proposed formulas were more accurate.

Research on eccentric-compressive behaviour of steel-fiber-reinforced recycled concrete-filled square steel tube short columns

This study, a total of 25 specimens, aims to assess the influence of the mass replacement percentage of recycled coarse aggregates (0%, 50%, 75%, and 100%), steel tube thickness (3 mm, 4 mm, and 5 mm), load eccentricity (0.10, 0.25, and 0.40), and volume fraction of steel fiber (0%, 0.6%, 1.2%, and 1.8%) on the eccentric-compressive behaviour of steel-fiber-reinforced recycled concrete-filled square steel tube short columns. The post-peak mechanical behaviour, deformation ability, and energy consumption degrade with increasing mass replacement of recycled coarse aggregate; the load eccentricity is detrimental to the ultimate compressive strength and aggravates the lateral deflection; thicker steel tubes and the incorporation of steel fiber improve the ultimate compressive strength, deformation ability, and energy consumption. Moreover, an incremental iteration model is proposed to calculate the ultimate compressive strength of steel-fiber-reinforced recycled concrete-filled square steel tube short columns under eccentric-compressive load. Compared to current codes, the predicted values using the proposed model are close to experimental values and are inclined toward the safe side.

Failure mode-based calculation method for bearing capacities of corroded RC columns under eccentric compression

This paper proposed a failure mode-based calculation method for bearing capacities of corroded RC columns under eccentric compressive loads, which considered corrosion-induced mechanical property degradation of steel bars, cross-sectional reduction of steel bars and cross-sectional reduction of concrete. Through analyzing the stress and strain distributions over the normal cross-section, four balanced failures and six failure modes were identified for corroded RC columns under eccentric compressive loads. Balanced corrosion degrees were defined and methods to calculate them were proposed. Based on corrosion degree and balanced corrosion degrees, the failure mode of an eccentrically compressed corroded RC column could be predetermined in advance. Then, the methods to calculate the eccentric compressive bearing capacity under each failure mode were proposed. Subsequently, a dataset of eccentric compressive tests on 118 corroded and 27 non-corroded RC columns was established. The eccentric compressive bearing capacities calculated by the proposed failure mode-based method were found in good agreement with the test results, which demonstrated the validity of the proposed method. The failure mode-based calculation method will contribute to not only rapid and accurate performance evaluation of existing corroded RC columns, but also fast and efficient time-dependent reliability analysis for planned RC columns.

Analysis on Large Deformation in a Slender Beam subjected to Eccentric Compressive Load (In Case of a Slender Beam with Non-Rotation Fixed Supports)

Analysis on Large Deformation in a Slender Beam subjected to Eccentric Compressive Load (In Case of a Slender Beam with Non-Rotation Fixed Supports)

Experimental and numerical study of resistance of multi-cell L-shaped concrete-filled steel tubular stub columns under biaxial eccentric compressive loading

This study aims to understand the cross-sectional resistance and develop practical resistance equations for multi-cell L-shaped concrete-filled steel tubular (ML-CFST) stub columns under biaxial eccentric compressive loading based on experimental testing and numerical analysis. Eighteen specimens were firstly tested to investigate experimentally their failure modes, nonlinear structural behavior, and the influence of different loading angles (θ) and eccentricities on the load-carrying capacity. Secondly, detailed nonlinear finite element models were developed and validated against test results, and further used for parametric analysis to explore untested scenarios. This facilitated the construction of a failure surface, which was interpreted as a family of Mx-My interaction curves under a variety of axial compression ratios (n), where Mx and My are the bending moments about the minor and major axes, respectively. Results showed that ML-CFST specimens exhibited favorable structural performance, and n and θ had a considerable influence on the normalized Mx-My interaction curves, compared to other geometric and material strength parameters (i.e., depth-to-width ratio of section limb, steel-to-concrete area ratio, steel yield strength and concrete compressive strength) studied. To facilitate engineering use, a dimensionless interaction equation for normalized Mx-My was developed in good agreement with experimental results.