Conventional RC Research Articles

Investigation on Reinforced Concrete Beams with High-Strength FRP Composite

This study examines an advanced material called High Strength Fiber Reinforced Polymer Composite (HSFRPC). The flexural characteristics of RC beams with dimensions of 2000 × 100 × 150 mm, strengthened with a HSFRPC overlay were investigated. The control RC beam was tested under four-point bending until failure. Two test RC beams were subjected to a preload of 70% of their ultimate load, while the third one was subjected to a preload of 65% of the ultimate load of the control beam. The preloaded RC beams were reinforced by applying a HSFRPC overlay to the lower surface. The overlay was applied across the whole width of one of 70% preloaded RC beams. The overlay was applied only in the area for the other 70% preloaded and the 65% preloaded RC beam, where the bending moment is constant. Strengthened beams underwent testing using a four point bending load. During the testing process, many factors like load, deflection, cracks and failure patterns were closely monitored. The experimental investigation revealed that beams with HSFRPC overlay showed enhanced load carrying capacity and ductility compared to conventional RC beams.

Development of MRE-based metamaterial with adjustable frequency bandgap for seismic vibration isolation

A seismic isolation system is an engineering method to prevent structures from the undesirable vibrations of earthquake. It involves using isolators, dampers, and bearings to decouple the superstructure from the ground during seismic waves by reducing the forces and accelerations transferred to the structure. The goal of this research is to investigate the tunable MRE-based metamaterial foundation for seismic vibration isolation. Metamaterials with adaptive and variable frequency band gaps are preferred because earthquakes have a wide range of frequencies. By varying the magnetic field intensity, a magnetorheological elastomer (MRE)-based metamaterial foundation can modify its Young's modulus and stiffness. The frequency band gap or frequency range of the MRE-based metamaterial foundation can be shifted by tunable material properties. Under the effect of a magnetic field, a uniaxial compression test was conducted to evaluate the Young's modulus of three types of MRE samples. Following the compression test, a series of numerical simulations in ABAQUS were carried out using a two-story framed building with RC and MRE-based metamaterial foundation. Three earthquake excitations are used: Bishop, Oroville, and Imperial Valley. The experimental results suggest that the magnetic field influences the MRE's Young's modulus. Similarly, numerical simulation studies indicate that the magnetic field influences the frequency band gap of the MRE-based metamaterial foundation. The FRF results of conventional RC foundation and MRE-based foundation are compared, highlighting the efficiency of MRE-based foundation in vibration control by reducing the seismic vibration of a structure by 68.5 %.

Strengthening and Crack Prevention of Conventional Rc Structure by Retrofitting Technique

Strengthening and Crack Prevention of Conventional Rc Structure by Retrofitting Technique

Strategic Integration of a Vegetative Component on a Metal Roof Base: An Evaluation of Its Impacts on Thermal and Acoustic Performance in the Tropics

This paper attempts to ascertain the thermal and acoustic impacts of introducing a vegetative roof layer on insulated and uninsulated metal roofs for tropical climates, through field measurements in Skudai, Johor, Malaysia, that were conducted for both dry and wet days. Four small-scale roof modules were tested, namely an uninsulated metal roof (uiMDR), an insulated metal roof (iMDR), and two identical corresponding modules with an additional vegetative component (uiGR and iGR, respectively). Outdoor ambient temperature (Tamb) was the most influential correlated variable affecting the roof outer surface temperature (RTOS) in 50% of the assessed scenarios. On the selected dry day, the inter-quartile ranges (IQR) of iGR, iMDR, uiGR, and uiMDR were 6.21 °C, 8.32 °C, 6.69 °C, and 1.66 °C, respectively; the IQRs were 1.6 °C, 4.11 °C, 2.59 °C, and 1.78 °C, respectively, on the selected wet day. Based on design U-value calculations, iGR was better than iMDR and uiMDR for both dry and wet days. The U-value of uiGR was also better than iMDR under dry-day conditions. The Wilcoxon signed-rank test also indicated a statistically significant difference in the roof inner surface temperature (RTIS) measurements (p-value = 0.00) during Malaysian daylight hours, between 8.00 a.m. and 6.00 p.m., regardless of the weather. In terms of sound level reduction under dry-day conditions, the Kruskal–Wallis and Wilcoxon signed-rank tests showed statistically significant differences in sound level reductions, with iGR and uiGR performing better than iMDR and uiMDR (p-values = 0.00). The sound level reductions for iGR, iMDR, and uiGR were 51%, 32%, and 31%, respectively, while uiMDR experienced sound level amplifications by 6%, possibly due to the acoustic resonance effect. This proof of concept may encourage a broader application of extensive GRs in Malaysia using metal roofs, beyond the conventional RC base construction method.

Retrofitting of Thermally Affected Structural Compression Member Using Basalt FRP Laminates

Concrete structures exposed to high temperatures often experience thermal damage, which can significantly reduce their structural integrity. Fiber-Reinforced Polymer (FRP) wrapping is a common retrofitting technique used to restore the strength and durability of thermally affected concrete. This study investigates the effectiveness of Basalt Fiber-reinforced Polymer wrapping on different concrete specimens with varying orientations of wrapping. This study mainly focuses on various parameters as fiber orientation and wrapping methodology. A series of 15 columns of dimension 150mm x 150mm with a length of 700mm are cast and subjected to axial compression loading in a pre-heated condition until the initial cracking occurs. These cracked columns are made to strengthen using Basalt Fiber with different patterns of orientation of laminates. The retrofitted columns are subjected to axial compression loading to determine their maximum load-bearing capacities. The test results of this experiment is assessed and compared with conventional RC columns of same grade. The strength of retrofitted columns versus conventional ones are compared and analyzed. The maximum load bearing capacity for a particular pattern of wrapping is determined.

Quantification of the seismic design coefficients for composite special moment frames with reinforced concrete columns and steel beams

This paper explores the performance of the reinforced concrete column and steel beam (RCS) structural system at the frame-level, with a focus on evaluating the seismic design coefficients ( R-factor, Ω0, and C d) using the FEMA-P695 methodology. The RCS system offers a more efficient and cost-effective solution compared to conventional steel and RC moment-resisting frames, with higher damping and lateral stiffness of RC columns and greater energy dissipation capacity of steel beams. Although several experimental and numerical studies have evaluated the performance of the RCS system, most of them have focused on the connection-level. In this study, 32 archetypes are designed with varying building height, span length, concrete strength, gravity load level, seismic load level, and column-beam strength ratio. Nonlinear analytical models are developed for the selected archetypes, and the modeling assumptions are validated through five distinct experimental tests. The models are then subjected to both static pushover and response history analyses, and the seismic design coefficients of the archetypes are evaluated and discussed based on the FEMA-P695 methodology. The results indicate that the design requirements of the RCS system are efficient, providing a high safety margin. However, the level of conservatism is found to be excessively high. Thus, it is possible to use a larger R-factor in the design process or make some relaxations in the design requirements related to this structural system. While further research should be carried out to validate the results, this study shows that as long as the R-factor is less than R = 10, the building can be deemed sufficiently safe for seismic loadings.

Seismic performance of a novel hemisphere-based rocking hinge realizing self-centering damage-free bridge system

The rocking column with post-tensioned (PT) strands is shown able to provide satisfactory self-centering capacity for bridge systems after earthquakes. However, local damage to concrete at the rocking interface and consequent losses of PT force may occur during ground motions. To minimize the local damage and facilitate the construction procedure, this paper proposes a novel hemisphere-based rocking hinge (HRH) at the rocking interface. For the columns with the proposed HRH, self-centering capacity is provided by PT strands, and energy dissipation is supplied by oval-shaped metal dampers. Hemispheres are adopted to achieve pre-determined rotation center, as well as reduce stress concentration and avoid local damage to the rocking interface. The construction of the HRH is first described, followed by an analytical model characterizing the hysterical behavior of the column with this HRH. The analytical model is then numerically validated using models developed by both the Abaqus and the OpenSees softwares. Accordingly, a design procedure is presented for columns utilizing this HRH, achieving damage-free and self-centering seismic performance. Finally, the HRH is implemented in an illustrative bridge, and its efficiency is verified by comparing the seismic responses with the conventional RC bridge. Results show that the HRH bridge possesses an excellent self-centering capacity and is able to maintain operational even after a major earthquake.

Shaking Table Test of a Split-Foundation RC Frame Structure with One Lower Story Compared with a Conventional RC Frame Structure

Split-foundation (SF) building structures, as a kind of hill-side buildings, are widely used in mountainous regions due to the scarcity of plain areas. In order to experimentally investigate the seismic responses of the SF structure, shaking table test was carried out on two 1/8-scale models: a split-foundation RC frame structure supported by foundations at two different levels and a conventional RC frame structure supported by foundations at one single level. The failure patterns, dynamic characteristics, acceleration responses, displacement responses, and torsion responses of the two models were assessed and compared under seismic ground motions. The test results indicate that the two models were severely damaged after the last intensity level excitation and showed an intermediate failure mechanism. The damage to the SF model was uneven and special with relatively severe damage of the upper grounded columns. The difference in natural frequencies between the two models resulted from the effect of the lower story on lateral stiffness, and the effect was relatively dramatic in the transverse direction. The difference in structural stiffness led to larger acceleration amplification factors of the SF model and smaller acceleration amplification factors in the longitudinal direction. Although the restriction at upper ground level created a certain effect on displacement responses of the SF model especially in the first story, the curve shapes of displacement responses of the two models were similar from the first floor to fourth floor. In addition, the torsion responses of the SF model, especially in the first story (upper ground story), were obviously much larger than those of the conventional model. The torsional effect cannot be ignored in the SF structure which is a torsionally sensitive structure.

Blast resistance of ultra high performance concrete-filled steel tube (UHPC-FST) pier against vehicular bombs

Bridge piers will lose axial bearing capacities under accidental or deliberate explosions, which may cause partial or even multi-span collapse of the bridges. Compared with the conventional RC pier, the ultra high performance concrete-filled steel tube (UHPC-FST) pier exhibits superior strength, ductility, and durability, thus having promising applications in the field of blast-resistant bridges. This study aims to experimentally and numerically examine the blast-resistant performance of the UHPC-FST pier under the near-range explosion of Vehicle-Borne Improvised Explosive Devices (VBIED). Firstly, a prototype UHPC-FST pier with earthquake intensity VII was designed following the Chinese specifications, and four 1/4-scale UHPC-FST specimens were scaled and fabricated accordingly. The near-range explosion and succeeding axial compression test were carried out on the specimens with TNT masses of 3 kg, 4 kg, 7 kg, and 10 kg, respectively. Then, full parameters of the Karagozian & Case (K&C) concrete material model applicable to UHPC were systematically calibrated based on the available test data, and the refined finite element (FE) models were established correspondingly based on the explosion and axial compression test. The verification of FE modeling approach was verified by comparing the failure modes and axial force–displacement curves of specimens obtained from the numerical simulation with the test. Finally, two types of VBIED (compact sedan and cargo van) and three standoff distances were selected from the report FEMA-428 and Chinese specifications, and six explosion scenarios were designed correspondingly. The shock wave propagation, shock wave-pier interaction, and the damage evolutions of prototype piers were numerically reproduced. The blast-resistant performance of the prototype UHPC-FST pier was assessed from the aspect of the failure modes and residual axial bearing capacities, which were quantitatively compared with those of conventional RC pier with identical earthquake intensity.

Experimental study on the collapse-resistant performance of unbonded prestressed PC beam-column sub-assemblages with pinned connections

In precast concrete frame structures, it is imperative that beam-to-column connection has appropriate robustness and reliable axial resistance to defense against progressive collapse. Hence, a method of using pinned connection and unbonded posttensioning strands (UPSs) to mutually improve the collapse-resistant performance of precast concrete structures was proposed in this study. The pinned connections are used for connecting precast beams with columns at precast beam ends, and UPSs with straight profile are placed at the bottom of beam cross-section. In order to investigate whether the proposed method can enhance collapse-resistant capacity of precast concrete structures, static progressive collapse tests were conducted for the newly proposed precast concrete frame substructures with UPSs (UPPC frame substructures) and without UPSs (PC frame substructure). Moreover, influences of effective prestress level upon the collapse-resistant capacity of UPPC substructure were also investigated. Test results demonstrated that, similar to conventional RC frame structure, the compressive arch action (CAA) and catenary action (CTA) could also develop in the proposed UPPC substructures to avert progressive collapse. The UPPC substructure was able to develop 32% higher CAA capacity and 162% larger CTA capacity as compared to the PC substructure, indicating that the UPSs play a positive role in enhancing both its CAA and CTA. The CTA capacity of the PC substructure was 53.8% higher than that of CAA, which signifies that the pinned connection can be employed to improve structural robustness to mitigate progressive collapse. In addition, the increase of effective prestress level of UPSs is beneficial to the enhancement of CAA capacity of the UPPC substructure. However, higher effective prestress level is limited to improve its CTA capacity due to lower deformation capacity of UPSs. Subsequently, three-dimensional finite element models (FEMs) of the UPPC and PC substructures were developed by using ABAQUS software. By comparing experimental data with FEM results, it was concluded that the FEM could accurately predict the load–displacement curves, crack patterns and reinforcing ruptures of all the test specimens.

Seismic behavior of a precast RC frame–shear wall structure using full/half grout sleeve connections

To investigate the seismic behavior of precast RC frame–shear wall structures using full/half grout sleeve connections, two RC frame–shear wall structure specimens were constructed and tested under cyclic loadings: the first specimen was a precast RC frame–shear wall structure (Specimen PCFW), and the second specimen was a conventional RC frame–shear wall structure (Specimen RCFW) cast in situ. The seismic performance of Specimens PCFW and RCFW including the failure modes, hysteretic responses, and energy dissipation capacities was investigated. Furthermore, the mechanical behavior of Specimen PCFW was numerically simulated using the OpenSees software. The test results show that the crack distribution of Specimen PCFW is more dispersed than that of Specimen RCFW. In particular, few cracks appear in the area of full/half grout sleeves in Specimen PCFW. However, the damage to the concrete around the half grout sleeves of the side columns in the shear wall of Specimen PCFW in the 1st story was more severe than that in the corresponding region of Specimen RCFW for a less thick concrete cover. Compared to Specimen RCFW, Specimen PCFW exhibits higher lateral bearing capacity, better energy dissipation ability, and slightly lower ductility. In addition, assuming the equivalent principle of rebar area, the mechanical behavior of Specimen PCFW can be effectively simulated using the nonlinear multilayer shell element in the OpenSees software.

Radiated Susceptibility Assessment of Interconnected Systems Within Dual Reverberation Chamber

The interconnected systems (ISs) are commonly exposed to electromagnetic environments with different maximum field levels, and the measurement technique on how to perform radiated susceptibility (RS) test is one of the most attractive research topics of the electromagnetic compatibility (EMC) community. In this work, the dual reverberation chamber (DRC) is used to reveal the potential EMC issues of the IS, which also provides a comparison with the RS tests performed in a conventional RC. By using a typical IS on the ship, we highlight the evidence supporting IS to conduct the RS tests in the DRC. Taken together, the results show that the IS will be more sensitive within the DRC and expose more acute EMC problems on one hand; on the other hand, the IS also presents a larger probability of sensitivity.

Failure Mode Analysis of Reinforced Concrete Beams Using GFRP Sheet as Shear Strengthening

Corrosion is an electrochemical reaction that can cause deterioration to the reinforcing steel which has implications for the decrease in the flexural capacity of the beam. The use of corrosion resistant GFRP bar as a substitute for conventional reinforcement and GFRP sheets as a substitute for shear reinforcement without a concrete cover can increase the flexural capacity of RC beams. This study aims to analyze the flexural capacity and failure mode of reinforced concrete beams with GFRP bar and GFRP sheet, with variations in width of 50 mm (BFGS50) and 100 mm (BFGS100). Conventional RC beams (BK) and beams with GFRP bars as tensile reinforcement and conventional shear reinforcement (BFSB) were made as control beams. The beam is given a static-monotonic load until failure. The results showed that the flexural capacity of the BFGS50 and BFGS100 beams was higher than the control beam (BK and BFSB). From the failure mode analysis, the control beam experienced compression failure, while BFGS50 and BFGS100 experienced shear failure.

Seismic response of a RC structure with new self-centering metallic dampers under biaxial near-field ground motions: Shake table tests

A new metallic energy dissipation device (EDD) with self-centering capability is proposed, and its effectiveness in controlling the seismic response of buildings subjected to near-fault earthquakes is investigated experimentally in combination with an inherently very flexible structural system: the RC waffle-flat plate structure. The new EDD combines the high energy dissipation capacity of stainless steel with the super-elastic properties of shape memory alloys. EDDs are installed in a 2/5 scale portion of a prototype RC waffle-flat plate structure designed only for gravity loads and tested on a shake table. The specimen is subjected to two horizontal components of a ground motion scaled in amplitude to represent different levels of seismic hazard at the building site. The RC structure with EDDs performed basically elastic under frequent earthquakes, remained “operational” under the design-level earthquake, and performed within the limits of “operational” and “life safety” under maximum credible earthquakes. The new EDD substantially reduced the maximum residual inter-story drifts —up to 1/10 of those of a conventional metallic EDD without self-centering capability. The response was also compared with a counterpart conventional RC structure without EDDs. The importance of providing the metallic EDDs with self-centering capability is highlighted.

Seismic Pushover Analysis of Global Emulative Response of Precast Reinforced Concrete Frames with Dextra Groutec Couplers

The effects of Dextra Groutec couplers on the global performance of precast reinforced concrete frames are investigated by comparing the performance criteria of conventional RC structures to that of the said structures such that precast elements are connected end-to-end using these couplers. As couplers provide continuity of the reinforcement, precast elements that are connected using this mechanism can perform as a unit, and the entire structural system can be considered emulative as long as the structural performance is comparable to that of the conventionally designed cast-in-place. Dextra couplers inherently have lower strain compared to reinforcing rebar, affecting the global performance of a structure if placed within critical regions such as near the beam-column connection. The present study is conducted therefore to perform a comparative study to determine the effect of these couplers on the emulative behavior of the precast frames to the cast-in-place frames by considering the following factors: Coupler location, Dextra Groutec Coupler size and length, and the story height of the frame. Static pushover analysis of 30 models is carried out using the finite element software, Seismostruct. Pushover curves are compared based on the three criteria such as global ultimate displacement, displacement ductility, and energy dissipation. The results revealed that the Dextra Groutec Couplers reduce the capacity of the precast frame according to the three performance criteria. Hybrid configuration, where the bottom part is CIP and the upper part is precast connected by couplers is found to be the most viable option to obtain an emulative response. The longer and bigger Dextra Groutec coupler, S28 also manifested more inferior performance compared to S25. Lastly, the height of the structure is not a strong factor in the emulative response except for the hybrid and coupler placed at D distance away from the joint face configurations.

Experimental and Analytical Investigation of R.C Beam with HPC Containing Nano Silica

Abstract: Concrete is the most widely used construction material in the world. It is a heterogeneous material composed of cement, fine aggregate, course aggregates and water. The proportion of these constituents affect the mechanical properties and durable properties of concrete. Also it is a versatile material due to the continuous demand. In recent years, lot of researches has been focused on improving the quality of concrete. This lead to the extension in the limitations to improve the performance of concrete with the addition of various admixtures super plasticizers subsidiary cementitious materials like silica fume, fly ash, blast furnace slag, metakaoiln, rice husk, etc. the properties like compressive strength, flexural strength, durability and workability of concrete enhances due to the addition of these materials. The concrete thus formed with high strength and durability compared to normal concrete are called High Performance Concrete. The compressive strength of HPC may be greater than 50Mpa. This HPC with compressive strength greater than 50Mpa can be used for structural members like beam, column, slab etc In this investigation the cement is replaced by 1%, 2% and 3% of Nano silica. Experimental and analytical investigation were done to investigating the flexural behaviour of conventional RC beam and R.C beam with HPC containing optimum percentage of Nano silica. Analytical investigation was done by ANSYS. This chapter discusses about the HPC, its mechanical strength properties like compressive strength, split tensile strength, flexural strength, effect of Nano materials like Nano Silica in HPC, determining the optimum percentage of Nano silica which gives maximum strength, investigating its durability property, investigating the strength development of RC beam with HPC containing optimum percentage of Nano silica, examining the load deflection behaviour of beam with HPC containing Nano silica and finally analysing the deflection of beam using Ansys. The key objective of this project is to investigate the importance of Nano silica as a replacement for cementitious materials in normal concrete and this paper presents strength and durable properties of HPC containing Nano silica.

Harnessing Tensor Structures—Multi-Mode Reservoir Computing and Its Application in Massive MIMO

In this paper, we introduce a new neural network (NN) structure, multi-mode reservoir computing (Multi-Mode RC). It inherits the dynamic mechanism of RC and processes the forward path and loss optimization of the NN using tensor as the underlying data format. Multi-Mode RC exhibits less complexity compared to conventional RC structures (e.g. single-mode RC), and offers comparable generalization performance to its single-mode counterpart. Furthermore, we introduce an alternating least square-based learning algorithm as well as the associated theoretical analysis for Multi-Mode RC. The result can be utilized to guide the configuration of NN parameters to sufficiently circumvent over-fitting issues. As a key application, we consider the symbol detection task in multiple-input-multiple-output (MIMO) orthogonal-frequency-division-multiplexing (OFDM) systems with massive MIMO employed at the base stations (BSs). Thanks to the tensor structure of massive MIMO-OFDM signals, our online learning-based symbol detection method generalizes well in terms of bit error rate even using a limited online training set. Evaluation results suggest that the Multi-Mode RC-based learning framework can efficiently and effectively combat practical constraints of wireless systems (i.e. channel state information (CSI) errors and hardware non-linearity) to enable robust and adaptive communications over the air.

Experimental and finite element analysis on the developed real-time form stable PCM based roof system for thermal energy storage applications

Due to the raise in global warming and green house effects, the concept of energy efficiency is increasingly investigated in recent times. Among the different methods of achieving energy efficiency, passive cooling techniques can be suitable option for achieving intensive interior temperature maintenance. In this work, a novel form stable phase change material (FSPCM) was developed using expanded perlite. The developed FSPCM was implemented for a real time building model to understand the efficiency in reducing the internal temperature. In total, four scaled building models were developed with different roof setups such as (i) conventional RC roof installed with clay tiles, (ii) conventional RC roof installed with cool-roof tiles, (iii) Roof installed with macro-encapsulated PCM tile, (iv) roof installed with FSPCM tile. All the scaled prototypes were installed with temperature sensors for monitoring the reduction in internal temperature and to compare the efficiency of the different models. All the temperature data measured were recorded using an Arduino based data acquisition (DAQ) system. In addition to the experimental studies, a detailed 2-D finite element analysis (FEA) was performed using the commercial ANSYS software with the aim of performing a detailed parametric study.

Experimental investigations on the structural performance and calculation analysis of reinforced alkali-activated materials (AAMs) beams

Alkali activated materials (AAMs) concrete incorporating GGBFS and FA as precursors is an alternative to the conventional OPC-based concrete. In order to take fully use of industrial wastes, river sand was partially replaced by water quenched slag (WQS) as fine aggregates fabricating AAMs concrete. It is essential to investigate the performance of reinforced AAMs concrete members based on the material properties as well as the constitutive models. Although some existing concrete structure codes have been used to design conventional reinforced concrete structures authoritatively, there would be a deviation caused by the codes being used to estimate the properties of AAMs concrete structures. In this study, the structural properties of reinforced AAMs concrete beams were initially investigated by conducting four-point bending tests. Specially, six beams with different reinforcement ratios were fabricated and tested in static loads. It was found that the failure modes, crack patterns and deflections of the six AAMs concrete beams were similar to those of conventional RC beams. Compared to the experimental results, structural properties including cracking moment and moment capacity were estimated according the methods recommended by three existing concrete structure codes ACI-318, AS 3600-2018 and GB 50010-2010, respectively. As a result, the calculated cracking moment and the moment capacity of the six AAMs concrete beams were underestimated by 40% and more than 10%, respectively. Based on the constitutive models of the AAMs concrete, nonlinear stress–strain distributions in the cracking state and ultimate state were proposed to establish calculation methods for the structural performance evaluations. The cracking moment and the moment capacity calculated via the proposed methods matched the experimental results well, by the average deviation of 1.2% and 4.2% respectively.

Cyclic behavior of existing flexure-dominated RC bridge columns retrofitted by ECC jackets in the region of plastic hinge

Engineered cementitious composites (ECC) has been implemented to the region of plastic hinge of new-constructed RC bridge column for enhancing the seismic performance. In this study, it is proposed to use ECC jacket as exterior jacketing in the region of plastic hinge for retrofitting seismic performance of existing flexure-dominated RC bridge columns. In order to clarify the effect of ECC jackets for enhancing the seismic performance of existing bridge columns, both experimental and numerical investigations were conducted in this study. Four 1/5-scaled RC bridge columns including one conventional RC column and the rest of three retrofitted by ECC jackets with varying thickness and heights in the region of plastic hinge were tested under the cyclic load. The experimental results revealed that the ECC jacket is capable of retrofitting the seismic performance of existing flexure-dominated RC bridge columns in terms of mitigating damage, increasing load-carrying capacity, ductility and energy dissipation capacity. The initial stiffness and load carrying capacity increases as the increase in the thickness of jackets. Furthermore, numerical study based on the fiber element method were conducted and the results agreed well with experiments. It was found that the thickness of ECC jacket was more important than height of jacket in enhancing the seismic performance of retrofitted RC columns on condition that ECC jacket was higher than the minimum height of plastic hinge specified by seismic code. .