Longitudinal Steel Bars Research Articles

Corrosion characteristics of tapered sleeve locking-type splicing reinforcement in precast segmental bridge piers

Tapered sleeve locking-type splicing (TSLTS) reinforcement joint is a new type and efficient way of mechanical reinforcement connection, which can be used for connecting of longitudinal steel bars in precast segmental bridge (PSB) piers. Since the TSLTS reinforcement joints are located at the bottom zone of the PSB piers, the PSB piers are often poured with self-compacting concrete (SCC) in this part, which is a new and convenient construction method of PSB piers. In this paper, the corrosion characteristics of TSLTS reinforcement in PSB piers in coastal environment were investigated. Through the accelerated corrosion test, the connection performance of corroded TSLTS reinforcement joints was studied. Then, the corrosion characteristics of TSLTS reinforcement in SCC segment and ordinary Portland concrete (OPC) segment of the PSB piers were discussed, and effect of the interface between the two segments on the corrosion of TSLTS reinforcement was analyzed. The results showed that the critical mass loss for slip failure of TSLTS reinforcement joints was about 7.2%. The mean mass loss of TSLTS reinforcement in SCC segment was larger than that of TSLTS reinforcement in OPC segment, and the corrosion rate of TSLTS reinforcement joints in SCC segment was about 1.54 times that of TSLTS reinforcement in OPC segment. The uneven corrosion coefficient of the TSLTS reinforcement joint was the largest, which increased first and then decreased with the increase of corrosion time. The uneven corrosion coefficient of TSLTS reinforcement in SCC segment was approximately equal to that of in OPC segment, and the uneven corrosion degree of the TSLTS reinforcement joint was about 1.98 times that of TSLTS reinforcement in SCC segment. The mean mass loss of TSLTS reinforcement at the interface was greater than those of in SCC and OPC segments, and the pitting corrosion of TSLTS reinforcement at the interface was more serious. However, with the increase of corrosion time, the uneven corrosion coefficient of TSLTS reinforcement at the interface tended to be equal to those of TSLTS reinforcement at other parts (except the joint). The research results can provide references for the popularization and application of the TSLTS reinforcement joints in PSB piers in coastal environment.

Efficient modeling of steel bar slippage effect in reinforced concrete structures using a newly implemented nonlinear element

In structural modeling of reinforced concrete (RC) structures, a common assumption lies in perfect bonding between steel reinforcing bars and the surrounding concrete. This paper aims to assess this assumption and investigate the need and importance of considering imperfect bonding (i.e., steel bar slippage or bond-slip) for predicting the nonlinear behavior of RC columns. To this end, an efficient finite element model capable of capturing bond-slip is required to evaluate the effect of imperfect bonding. Thus, this study first developed a geometrically nonlinear fiber-based frame element considering steel bar slippage and implemented this element in OpenSees with hybrid corotational transformation. Subsequently, using the newly developed element, the effect of imperfect bonding on the behavior of RC columns was investigated. In this regard, the role of bond-slip was studied under different scenarios, including hooked or unhooked ends of longitudinal steel bars in the anchorage area, low or high load levels, and short- or long-duration earthquake ground motions. The results reaffirm the need for prudent consideration of imperfect bonding for advanced finite element modeling of RC structures in several scenarios.

Research on the seismic behaviour of hollow prefabricated square column with high-strength reinforcement using UHPC grouting materials

In this study, a hollow prefabricated square column with high-strength reinforcement is developed to realise optimum seismic performance and promote the application of high-performance materials in columns. A column and cap constructed for testing using the ultrahigh-performance concrete grouting material are connected using grouted sleeves. The seismic performance of the proposed column is evaluated by comparing and analysing the responses of the proposed column and that of two other types of columns under cyclic load. Further, the effects of the longitudinal steel bars strength and volume of the hollow part of the column on the seismic performance of the proposed column are studied. The experimental results shown that the configuration of the high-strength reinforcement in the column positively influence its seismic performance. The modification of the reinforcement strength and hollowing rate of the column have some degree of influence on the structural response of the proposed column under cyclic loading, which lay a foundation for optimal design of the structure of the proposed column.

Feasibility of using Static-Cast Concrete Transmission Poles fully reinforced with glass-fibre reinforced polymer bars and stirrups: A case study

The findings of cantilever beam bending tests conducted on a series of full-scale glass fibre-reinforced polymer (GFRP) and steel-reinforced concrete utility poles are presented. The poles were reinforced by (i) longitudinal steel bars and steel stirrups (ii) longitudinal GFRP bars and steel stirrups, and (iii) longitudinal GFRP bars and GFRP stirrups. Crack initiation and propagation as well as load carrying capacity and free end deflections of GFRP reinforced poles were obtained and compared with their counterpart steel reinforced poles. Based on the results all longitudinal GFRP reinforced poles have shown higher load-carrying capacity than that of steel reinforced poles, while due to the lower stiffness of GFRP bars in comparison to steel bars, at a certain load, higher free-end deflections were observed in GFRP reinforced poles. However, the permanent deformation of GFRP-reinforced poles was small. Furthermore, comparable results obtained for poles reinforced with GFRP stirrups than those of poles reinforced with steel stirrups, showed that GFRP stirrups could also be used safely instead of steel stirrups. However, due to the low elastic modulus, GFRP-reinforced poles likely fail to satisfy the deflection criterion specified in some standards. But, if adequate stiffness is provided for GFRP-reinforced concrete poles to satisfy the deflection criterion, due to the vulnerability of steel-reinforced utility poles when subjected to corrosive environments, using fully GFRP-reinforced concrete poles could be a feasible option.

Performance evaluation of normal- and high-strength concrete column specimens reinforced longitudinally with different ratios of GFRP bars

Glass fibre-reinforced polymer (GFRP) bars, as reinforcement in concrete structures, have several desirable properties over conventional steel bars, such as high tensile strength, low density and resistance to corrosion. However, there are still some concerns about using GFRP bars as longitudinal reinforcement in concrete columns primarily due to their low compressive strength and low modulus of elasticity. It is evident that the compressive behaviour of GFRP bars as longitudinal reinforcement in normal strength concrete (NSC) and high strength concrete (HSC) columns has not been extensively investigated to formulate adequate design guidelines. In this study, 12 reinforced concrete column specimens were tested under concentric compression loading. All the tested column specimens were 600 mm in height and 154 mm in diameter. The column specimens were divided into two groups as per the compressive strength of the concrete used in casting the column specimens, which were 45 MPa and 90 MPa. Each group consisted of six column specimens, one plain concrete column specimen and five column specimens reinforced transversely with 6 mm steel helices spaced at 40 mm pitch (transverse reinforcement ratio ρt = 2.2 %). Out of those five column specimens, one had no longitudinal reinforcement (ρ = 0), one was reinforced longitudinally with steel bars (ρ = 2.4) and the rest were reinforced longitudinally with GFRP bars (ρ = 2.7, 3.2, and 4.3 %). From testing results, it was observed that steel and GFRP bar reinforced NSC column specimens exhibited two peak axial loads, with a higher second peak axial load than the first peak axial load, whereas steel and GFRP bar reinforced HSC column specimens exhibited one peak axial load only. It was also observed that the contribution of the longitudinal steel bars was about two times the contribution of GFRP bars in both NSC and HSC column specimens. Finally, the ductility of GFRP bar reinforced NSC column specimens was greater than the steel bar reinforced NSC counterpart, whereas this trend was the opposite in the column specimens cast with HSC.

Axial compression behavior of strength-gradient composite stub columns encased CFST with small diameter: Experimental and numerical investigation

In order to investigate axial compression behavior for strength-gradient composite stub columns encased concrete filled steel tube with small diameter (SGCC), the axial compression experiments of 13 SGCCs and 1 reinforced concrete (RC) stub column were carried out. The influence regularities of height-width ratio, confinement index (θ), stirrup ratio per unit volume (ρv) and axial compressive strength of core concrete on the failure modes, load–displacement curves and load–strain curves of SGCCs were explored. The results showed that SGCCs mainly exhibited three failure modes under axial compression, including shear failure, central crushing and punching failure. By increasing θ and ρv approximately, SGCCs could exhibit ductile failure instead of brittle failure. The deformations of steel tube, longitudinal steel bars, and concrete for SGCCs maintained coordinated during the loading process. Compared with ordinary RC column, the ultimate bearing capacity (Nu) of SGCCs under axial compression was almost doubled. Based on the experimental results, 30 finite element (FE) models were designed to obtain the influence regularities of various parameters on Nu of SGCCs. Applicability of existed design code to predict Nu of SGCCs was also evaluated. Finally, a novel calculation formula for Nu of SGCCs considering constraint effect of stirrups and steel tubes could be proposed, which were in good agreement with the experimental results.

Creep and post-creep mechanical properties of reinforced concrete columns

In this study, 32 groups of reinforced concrete axial compression columns were examined using creep tests and axial compression failure tests after creep. The reinforced concrete columns were of strength grade C30–C60, load level 0.09–0.38, and total reinforcement ratio 0.79–2.01%. This study investigated the effects of the axial compressive strength of concrete under loading, the load level, and the total reinforcement ratio of longitudinal compression steel bars on the creep and post-creep mechanical properties of reinforced concrete short columns under axial compression. A formula for calculating the creep of reinforced concrete short columns under axial compression is proposed. A formula for calculating the peak compressive strain of reinforced concrete short columns under axial compression considering the effect of creep is established.

Mechanical Behavior of Special-Shaped Reinforced Concrete Composite Columns Encased with GFRP Core Columns

In order to investigate the mechanical behavior of special-shaped reinforced concrete composite columns encased with GFRP core columns (EGCSSCs) subjected to axial load, twenty-seven full-scale EGCSSCs were designed with varying parameters: axial compressive strength of core concrete (fcc), axial compressive strength of peripheral concrete (fco), thickness of GFRP tube (tgfrp), ratio of longitudinal reinforcement (ρv), stirrup ratio (ρs) and GFRP ratio in the cross-section (α). The three-dimensional finite element refined models of EGCSSCs were established by ABAQUS finite element software, and the response of EGCSSCs under axial load was studied based on the verification of finite element modeling. The influence of different parameters on the ultimate axial compressive strength (Nus), initial stiffness (K), and ductility index (µ) of EGCSSCs was obtained, and the typical failure mode of EGCSSCs was clearly described. The results showed that the main failure mode of the EGCSSCs subjected to axial load was bulging outward at the middle of the EGCSSCs, showed yielding of the longitudinal steel bars, and was crushing both ends of the peripheral concrete. When the column was damaged, the peripheral concrete reached peak stress earlier than the core concrete. All specimens exhibited excellent load-carrying capacity and good ductility. Moreover, with the existence of GFRP core columns, the Nus and µ of the columns were increased by 11.61% and 140.86%. In addition, K increased with the increase in fcc, fco, tgfrp and α, and the largest increments were 23.99%, 50.54%, 21.77%, and 34.19%, respectively. µ decreased with the increase in fcc and fco, which decreased by 14.05% and 40.28%, respectively. By using statistical regression and introducing the constraint effect coefficients and the reduction coefficient, the calculation formula for the axial compression-bearing capacity of EGCSSCs was derived, which could lay a foundation for the popularization and application of this kind of composite column in practical engineering.

The effect of Corroded Longitudinal Steel Bars on Flexural Behavior of Reinforced Concrete Beams

This study aims to examine the relationship between the corrosion rate of longitudinal tensile steel bars and the maximum flexural strength of reinforced concrete RC beams. The study's methodology is designed to show the structural behavior of corroded and non-corroded RC beams, such as ultimate load, deflection, stiffness, crack patterns, and failure mode. Three rectangular beams were cast with dimensions (150× 200 ×1200) mm, and all specimens have the same amount of longitudinal and transverse reinforcement and the same concrete strength. The major parameter is the theoretical mass loss level due to corrosion (0, 10, 15) %. Electrochemical technique was used to accelerate the corrosion in the longitudinal tensile bars. All RC beams were tested under four-point monotonic loading. The test results confirm that the cracking load in corroded beams decreased by 25% comparative to the non- corroded beam. The increase of the percent of corrosion experimental mass loss by 8.25 and 14.15 % decreased the ultimate load by about 14 % and 27%, respectively. This reduction coincided with the decrease in deflection values in mid-span for the ultimate load, which decreased by 53.9% and 46.3%. However, the flexural stiffness was reduced by 13.4 and 15.6% for corroded beams with mass loss (8.25 and 14.15), respectively, compared to the control beam (non-corroded RC beam).

Performance of concrete columns longitudinally reinforced with steel and GFRP bars and confined with GFRP spirals and cross ties under reversed cyclic loading

This paper reports the comparative results of an experimental study performed on concrete columns reinforced entirely with glass fiber-reinforced polymer (GFRP) bars and with hybrid reinforcement (longitudinal steel bars and transverse GFRP spirals and cross ties) subjected to quasi-static cycling loading. Four full-scale bridge columns were constructed with longitudinal steel bars and confined with GFRP spirals and cross ties (hybrid-reinforced concrete columns). Four other columns were constructed solely with GFRP reinforcement (GFRP-reinforced concrete columns). The bridge columns had a cross section of 400 × 400 mm with a total height of 1850 mm. The columns were tested to failure under combined constant compressive axial load and quasi-static reversed lateral loading. The columns were investigated in terms of longitudinal bar type, longitudinal reinforcement ratio, and transverse reinforcement ratio. The results show that the longitudinal reinforcement type significantly affected column performance in terms of seismic parameters such as ductility and energy dissipation. The hybrid-reinforced concrete columns exhibited superior ductility and dissipated more energy than the GFRP-reinforced concrete columns. Furthermore, the GFRP-reinforced concrete columns experienced more gradual failure than the hybrid-reinforced concrete columns. Appropriately confined hybrid-reinforced concrete columns attained acceptable drift levels that meet the recommendations in most design codes. The transverse reinforcement ratio and longitudinal reinforcement ratio patently influenced column behavior. The lower elastic modulus of the GFRP bars compared to that of the steel bars had an impact on the theoretical lateral load capacity of the concrete columns.

Performance and modeling of FRP-steel dually confined reinforced concrete under cyclic axial loading

Fiber-reinforced polymer (FRP)-steel tubed reinforced concrete (FSTRC) columns present promising engineering applications due to the reasonable integration of three constituent materials. Compared with the numerous studies on their performance under monotonic loading, relatively few studies have focused on their cyclic axial behavior. Moreover, the available models for plain concrete solely confined by FRP might be incapable of estimating the confined concrete behavior in cyclically loaded FSTRC due to the possible effect induced by the steel reinforcement in concrete, the additional steel tube confinement, and the girth gaps at column ends. To this end, this paper investigated circular FSTRC stub columns under monotonic and cyclic axial loading. The test results confirmed that the inclusion of reinforcement had noticeable effects on the unloading path since the tensile axial stresses in longitudinal steel bars slowed down the stiffness degradation of the inner concrete during unloading. For envelope cycles, the increase of the additional steel confinement level had a negligible impact on the plastic strain and the stress deterioration of the inner concrete. A confinement model was developed to estimate the full-range behavior of the FRP-steel dually confined reinforced concrete under cyclic axial loading with favorable accuracy.

Load versus Strain Relationships of Single and Continuous Span Full-Scale Pre-cast Prestressed Concrete Girders for Monorail Systems

Full-scale testing of multiple span girders is scarce in the literature, often related to the complexity of loading setup and time constraints. The importance of full-scale tests is manifested in the fact that useful information regarding failure mechanisms can be obtained. In addition, important guidelines can be established for structural designers. Further, results from full-scale tests can help establish constitutive laws for various mechanisms involved in the response of actual structures. The structural performance of individual members can be assessed by monitoring their strains at service and ultimate loads. This study presents a comparison of experimentally monitored strains on longitudinal steel bars, stirrups, and prestressing tendons embedded in single and multi-span full-scale precast pre-tensioned girders. These girders were constructed and detailed to simulate the response of newly proposed straddle-type monorail girders. Single-span girders were tested under monotonic two-point service and ultimate loads, whereas multi-span girders were tested under both two- and four-point service and ultimate load. It was revealed that longitudinal steel and prestressing tendon strains monitored within single-span girders at service and ultimate loads were significantly higher than those recorded at corresponding locations in multi-span girders.

Fatigue life prediction for prestressed concrete beams under corrosion deterioration process

The coupled effect of corrosion and fatigue on performance degradation of prestressed concrete (PC) bridges is a dynamic process. This paper proposed a novel framework for the fatigue life prediction of corroded PC beams, where the chloride ingress process, pitting corrosion, cross-sectional area reduction of steel, pretension force loss, and fatigue damage accumulation of materials were considered. A dynamic residual cross-sectional area-based method was developed to estimate fatigue damage accumulation of materials, and competition between concrete failure criterion and Miner’s rule of cumulative damage theory of strand was included. Following this, the fatigue damage of naturally corroded PC beams was discussed, and an experimental study on the fatigue behavior of pre-corroded PC beams was conducted to validate the proposed model. The prediction results agreed well with the experimental observations. The results showed that the effects of load amplitude and vehicle load frequency on the prediction results were clarified. The deterioration of corroded PC beams is more sensitive to load amplitude than load frequency. With the corrosion rate of strand increasing to 3%, the failure mode of pre-corroded PC beams changes from the brittle fracture of steel bars to the brittle fracture of strands. Fatigue failure is caused by the sudden brittle fracture of longitudinal steel bar for naturally corroded beam. The proposed method provides a satisfactory result for evaluating the damage accumulation of PC beams with corroded strands or steel bar.

Seismic performance of pre-fabricated segmental bridges with an innovative layered-UHPC connection

Ultra-high-performance concrete (UHPC) has been regarded as promising alternative to provide reliable connections between difference segments (e.g., columns and pier footing/cap) during accelerated bridge construction (ABC) procedures. This paper proposes an innovative layered-UHPC connection for the pre-fabricated segmental (PFS) piers, whose seismic performance was validated through quasi-static experiments. Based on the test results, design procedure is presented for PFS pier with this connection, to overcome the observed drawbacks and achieve high-level performance. The layered-UHPC connection ensures the emulative performance of pre-fabricated bridges as cast-in-place (CIP) ones, as well as provides greater economic efficiency than traditional UHPC connections. Based on experimental results, key issues concerning this connection, including the tensile behavior of UHPC, height of connection region, thickness of UHPC layer and steel bars in grouting bed, are presented and discussed. Then a seismic design procedure is proposed utilizing the capacity protection philosophy. The layered-UHPC connection is expected as capacity-protected component without damage, since it provides anchorage for longitudinal steel bars. While the pre-fabricated region is designed as ductile component undergoing nonlinearity during strong earthquakes. Following the detailed elaborations about the design philosophy, requirement and implementation steps, this procedure is further presented through illustration examples using PFS piers with various heights. The results show that PFS piers designed according to this procedure could meet the requirement under both frequent and rare earthquakes. Note that the PFS piers with this layered-UHPC connections could be designed similar to and emulative as CIP ones, which is believed friendly to designers in engineering practice.

Time-dependent behavior of full-scale precast post-tensioned (PCPT) girders: Experimental and finite element analysis

Excessive volumetric changes associated with shrinkage and non-uniform moisture and heat distribution along long-span girders induce unwanted curvatures. This study aims at investigating both short- and long-term measurements of various quantities involving midspan deflections, tendon strains, longitudinal steel bar strains, concrete strains, and thermal changes in precast-post-tensioned (PCPT) girders. A total of 2 PCPT girders were cast in this study with symmetrical structural and geometrical details. Post-tensioning of the first and second girders was performed on the 28th and 120th days of their casting, respectively. Long-term measurement was performed on the first girder. It was observed that all measured parameters increased swiftly during post-tensioning. During the initial 30 days after post-tensioning, a gradual increase in all parameters was observed, whereas all measured parameters exhibited negligible increase beyond that. A Finite Element Model was generated using ATENA to estimate short-term deflections of PCPT girders during post-tensioning. In general, a good agreement between experimental and analytical midspan deflections was observed.

Improving RC Beam-Column Joints Characteristics Using Different Reinforcement Details

This paper aims to study the effect of concrete confining using a new style of internal closed stirrups and longitudinal steel bars along with the middle third of the beam length of the beam-column joints. Also, the influence of concrete compressive strength was investigated using three types of concrete normal strength concrete (NSC), high strength concrete (HSC), and steel fiber concrete (SFRC). Nine reinforced concrete specimens with the same dimensions are divided into three groups according to the concrete type with different reinforcement details in the middle third of the specimen’s length. Four specimens with (NSC) represent the first group, while three specimens consist in the second group with (HSC). Steel fiber of 2% was used in two specimens of the third group (SFRC). The test results showed that using additional reinforcement steel bars as a closed stirrup arranged about the neutral axis improved the flexural strength and enhanced the load-carrying capacity for the reinforced concrete joints. The ultimate capacity of the joints increased by a range (34 to 50) % more than the control specimen. The ultimate strength was also increased for the specimens due to using high-strength concrete with a range (of 13 to 66) % compared with the specimen of normal compressive strength.

Finite Element Simulations of the CFRP Retrofitted Hollow Square Columns

ABSTRACT This article describes the finite element analysis of concrete columns with a hollow square reinforced which restricted with a square Carbon-Fiber-Reinforced polymer (CFRP) tube. In this study, about sixteen square hollow core columns were investigated. These columns were classified into four sets. The set number one was the reference set which involved four unconfined reinforced columns with traditional steel helices and longitudinal steel bars. The columns of the 2nd category have a similar configuration as the set number one except that these columns were restricted outwardly by the CFRP tube. The columns of the set number were restricted outwardly by a CFRP tube and restricted inwardly by a steel tube. Finally, the columns of the 4th category do not have a steel reinforcement where they produced with only an outer CFRP tube and an inner steel tube. These columns were exposed to various loading conditions: concentric, eccentric (22 and 44) mm, and four bendings' points. It was investigated that the CFRP tube confinement faintly improved the columns’ strength. Moreover, the use of a steel tube as inner confinement in the columns with a hollow section led to improve the structural performance and ductility.

Effect of spiral transverse bars on structural behavior of concrete shear walls reinforced with GFRP bars

In the present experimental study, the effect of spiral transverse bars on failure mode and structural behavior of concrete shear walls reinforced with GFRP bars was investigated. Six full-scale shear walls in two aspect ratios (1.08 and 1.75) were tested under constant axial load and cyclic lateral loading. Two specimens were reinforced with longitudinal and transverse steel bars (SRCW1.08 and SRCW1.75), two specimens reinforced with longitudinal and transverse GFRP bars (GRCW1.08 and GRCW1.75), and two specimens reinforced with longitudinal and spiral transverse GFRP bars (S-GRCW1.08 and S-GRCW1.75) were investigated. The experimental results indicate that the spiral transverse bars at two aspect ratios of specimens led to an increase in shear capacity, ultimate lateral displacement, and a change in the failure mode from compression failure to rupture of longitudinal bars in shear walls reinforced with GFRP bars. Comparing GRCW1.08, S-GRCW1.08, and GRCW1.75 with S-GRCW1.75 indicated that parameters such as ultimate lateral loading 23.1 and 9.2%, ultimate lateral displacement 20.1 and 20.4%, cumulative dissipation energy 48.7 and 54.8%, and displacement ductility ratio 18.6 and 20.2% were increased.

Estimation of ultimate bearing capacity of bored piles using machine learning models

The ultimate bearing capacity of bored piles is an essential parameter in foundation design of structure. In the present study, three Machine Learning (ML) methods namely Adaptive Neuro-Fuzzy Inference System (ANFIS), Support Vector Machine (SVM) and Artificial Neural Network (ANN) were utilized to estimate bearing capacity of bored piles based on limited engineering parameters of pile and soil obtained from 75 test sites in Vietnam. These parameters include pile diameter, pile length, tensile strength of main longitudinal steel bar, compressive strength of concrete, average SPT index at the tip of the pile, average SPT index at the pile body. Validation of the methods was verified using standard statistical metrics namely Root Mean Square Error (RMSE) and Correlation coefficient (R). The results show that all the proposed models have good potential in predicting correctly bearing capacity of bored piles on training data (R>0.93) and on testing data (R>0.88) but performance of the SVM model is the best (R:0.985 (training) and R:0.958 (testing). Thus SVM model can be used for the accurate prediction of ultimate bearing capacity of bored piles for proper designing of the civil engineering structure foundation.

Experimental study on the eccentric performances of high predamaged rectangular reinforced concrete columns strengthened with carbon fiber reinforced polymer

The mechanical behaviors of 12 high predamaged reinforced concrete (RC) rectangular columns strengthened with carbon fiber reinforced polymer (CFRP) under eccentric compression were experimentally investigated. The effects of the predamaged degree ( δ), CFRP strips spacing ( s f ) and eccentricity ( e) on failure mode, bearing capacity, strain behaviors of CFRP strengthened predamaged columns were examined systematically. Test results demonstrated that the strengthened RC columns with small-eccentricity were destroyed by the yielding of compressive longitudinal steel bars and the crushing of compression concrete while the transverse CFRP strips were not ruptured. The failure mode of the strengthened RC columns with large-eccentricity was distinguished by the yielding of tensile and compressive longitudinal steel bars, the rupturing of longitudinal CFRP sheet, and the crushing of compressive concrete. With the increase of predamaged degree or eccentricity, the maximum bearing capacity of specimens decreased. In contrast, CFRP strips spacing had little effect on bearing capacity. Considering the effect of predamaged degree and eccentricity, a modified model for conveniently predicting the stress–strain relationship of CFRP strengthened predamaged RC columns under eccentric compression was proposed. On the basis of experimental study, the influence coefficients of predamaged degree and eccentricity and a strain distribution coefficient of CFRP strips were introduced, a calculation formula for predicting bearing capacity of high predamaged rectangular RC columns strengthened with CFRP under eccentric compression was proposed and validated test data with good agreement.