Composite Section Research Articles

Flexural behavior of large-scale U-shaped steel-concrete infilled composite beams with flat and embossed webs

Most popular shape of steel-composite beams is the exposed type in which wide-flange steel sections are connected to the reinforced concrete (RC) slab through shear connectors. However, recently innovative U-shaped steel–concrete infilled type composite beam sections are introduced which demonstrated promising structural performance. In these composite beams, the U-shaped steel section filled with concrete serves as formwork in fresh state of concrete while it behaves as main reinforcement during the service life of the structures. Although, active research has been conducted on former type, but research on the later infilled type beams seems insufficient. There exist several research questions which need to be addressed for optimized and efficient design of these innovative composite sections. In this paper, six large-scale U-shaped steel–concrete infilled composite beams with flat and embossed webs were tested to investigate their flexural behavior. The tested composite beams were designed with angle shear connectors which provide efficient shear transfer mechanism with economy. The main parameters of the tests were the shape of web and the spacing of the shear connectors. The effects of embossed web on horizontal shear transfer and its contribution to the flexural capacity were mainly focused. In addition, a detailed section analysis was conducted to comprehend the experimental observations.

Optimizing bending strength of laminated bamboo using confined bamboo with softwoods

Abstract The objective of the study was to improve the stiffness and bending strength of laminated bamboo through confinement with softwood. A total of 144 beams were tested, divided into 6 groups of 24 specimens each. The tests were conducted on specimens of laminated bamboo, wood, and composite sections with different levels of confined bamboo laminate (20, 40, 60, and 80%). The results indicated that the composite exhibited optimal behavior when the ratio of bamboo to wood was between 46 and 54%. Furthermore, the composite demonstrated a bending modulus of elasticity that was 16.6% higher and a modulus of rupture that was 18.3% higher than the values predicted by the mixing rule. A mathematical model was developed to predict the design mechanical properties based on composite thickness. This model was validated through 18 additional bending tests. This new material is an environmentally sustainable alternative that has the potential to be used as beams in buildings, providing improved mechanical performance, reduced weight, and lower manufacturing cost compared to bamboo laminates.

Formulation of a generalized truss analogy for the analysis of shear behavior of short jacketed columns

Short columns in a story of a reinforced concrete building tend to fail in shear during an earthquake. They can be strengthened using concrete jacketing. A performance-based evaluation requires the modeling of nonlinear lateral load versus deformation behavior of such a column. While previous studies are available to analyze the behavior of a flexure-critical column, computationally simple method of analysis of the shear behavior of a short column is lacking in the literature.A generalized truss analogy is proposed to predict the shear behavior of short columns beyond diagonal cracking and till failure. Its formulation satisfies equilibrium of forces in the concrete strut and reinforcing bar ties, compatibility of strains in the concrete and ties of the web region of a column, and suitable constitutive relationships of the materials. First, the formulation and computation algorithm as applicable to an original column, are presented in this paper. Next, the method is extended to columns strengthened by concrete jacketing. Its application to a composite jacketed section is implemented using a sandwich model.The validation of the proposed method is presented, comparing the predictions with the lateral load versus deflection behavior curves obtained from the tests of five large-scale shear-critical column specimens (two original and three jacketed), tested as part of this research. The good correlation of the predicted and test results confirmed the application of the proposed method for the nonlinear analysis of shear for short columns.

STRUCTURAL PERFORMANCE OF COMPOSITE BOX BEAMS WITH CORRODED BOTTOM FLANGE UNDER MONOTONIC AND REPEATED LOADS

The current research is dedicated to studying the flexural behavior of composite box beams with corroded bottom flanges. Six simply supported beam specimens were manufactured and tested. The composite box beams were fabricated with steel box beams of 1100mm, 100mm, and 100mm for length, width, and height, respectively, while the concrete deck slabs were made with dimensions of 1100mm, 400mm, and 50mm for length, width, and thickness, respectively. The composite sections were formed by connecting the RC deck slabs with the steel box beams by using a headed shear connector. Three main variables were considered; the load type (monotonic or repeated), bottom flange thickness (with or without corrosion), and whether to consider or ignore the strengthening by CFRP strip. Experimental results indicated that the ultimate loads were decreased by 29-33% for the corroded bottom flange beam specimens; while the ultimate loads for the strengthened beam specimens were increased by 60-67% as compared with the un-strengthened corroded corresponding beam specimens. Also, the change of the applied loads from monotonic to repeated leads to a reduction of the ultimate load by 17-22%.

Seismic Evaluation of Building having Steel Concrete Composite Columns and RC Beams

Abstract: Steel concrete composite structures are gaining popularity due to the advantages they offer over the conventional reinforced concrete and steel structures like the ease and speed of construction. In the light of this, it becomes essential to understand the behaviour of this type of structures when used in buildings. This study mainly focuses on the use of building frame consisting of steel-concrete composite column section with the reinforced concrete beams. To achieve this objective, the seismic analysis of the buildings was chosen for evaluating the performances of the buildings designed and analyses using Indian standards. The building selected for the study was rectangular in plan andhad an elevation of 30 meters with no plan or vertical irregularity present. The gravity loads considered for the building are in compliance with the IS 875 Part 1 and IS 875 Part 2. However, the gravity loads used in case of both buildings were kept to be same as the prime focusof the study was seismic analysis. The materials used for the design of the building with respect to Indian standards are E345 grade of steel and M30 grade of concrete. Various codes of practices including IS 456, IS 11384, IS 1893 and IS 13920 have been used throughout the study in case of the building designed and analysed with respect to Indian standards. The assumptions regarding the seismic characteristics of the buildings are also selected of the same nature for both the buildings. A finite element modellingbased software ETABs is used to carry out the design and analysis for the buildings. The buildings were designed with respect to the selected gravity loads and the seismic loads to obtain the section details to be used for seismic analysis. The building with finally obtainedsection sizes is used for carrying out the nonlinear analysis. This includes both the nonlinear static and nonlinear dynamic analysisas they both have their respective advantages in predicting the behaviour of the structure. For carrying out nonlinear analysis both material as well as geometric nonlinearity is considered. In case of the nonlinear dynamic analysis, the ground motions with respect to the guidelines of FEMA P695 and ASCE 7-16 were selected and scaled to perform the analysis. A total of 11 time histories were considered for NLTHA to have a thorough analysis. Various factors such as thecapacity curves, story displacements, base shears and story drifts were considered for evaluation of the seismic performance of both the buildings. The results obtained from the analysis of both thebuildings are represented in the form of tables and graphs, and are compared with each other to study the differences observed. It can be concluded that the buildings designed composite columns offers a better ductility and thus is more earthquake resistant

Magnetostratigraphy of the Mercia Mudstone Group (Devon, UK): implications for regional relationships and chronostratigraphy in the Middle to Late Triassic of Western Europe

Global synchronization of environmental change in terrestrial successions in deep time is challenging owing to the paucity of dating methods, a case also applicable to the Middle to Upper Triassic Mercia Mudstone Group in Britain. Using coastal cliff sections, magnetostratigraphy was evaluated at 263 horizons, defining 53 magnetozones. Magnetozones from the lower 140 m of the group demonstrate correspondence to those from the mid-Ladinian to early Carnian polarity timescale, dating that is compatible with magnetostratigraphy from the underlying Sherwood Sandstone Group. Magnetostratigraphy of the Dunscombe Mudstone Formation, and associated palynological data, suggest a late Carnian to earliest Norian age, and a dramatically lower accumulation rate than for adjacent formations. The polarity record demonstrates coeval flooding events, evaporite deposits and intervals of sand supply between the Wessex Basin and the Central European Basin in the Carnian. This is the result of linked climatic and eustatic changes between these separate basins, related to aeolian dust supply and the shrinkage of hyper-arid source regions for the fine material. Magnetostratigraphy from the Branscombe Mudstone and Blue Anchor formations demonstrates their Norian and early Rhaetian age. These and other data suggest an alternative synchronization of marine and non-marine polarity records for the Norian polarity timescale. Supplementary material : Section details and detailed logs of the sampled sections and inferred sequence boundaries, magnetic mineralogy data, demagnetization behaviour and mean directions, summary of virtual geomagnetic pole data and a comparison with other European poles, construction of other composite reference sections and revised polarity scales, an Excel sheet of magnetic data, statistically evaluated correlation models and age models are available at https://doi.org/10.6084/m9.figshare.c.6613788

Development of lightweight CFS composite built-up beams: Tests and flexural response

Although previous attempts for enhancing the buckling resistance of cold-formed steel (CFS) built-up beams through intermittent stiffening, external stiffening and adoption of concrete as composite sections were successful, they may compromise the lightweight constructional feature of these elements. This paper presents a test program aimed at developing CFS composite built-up beams with superior buckling performance and low self-weight for ensuring lightweight construction. Unlike concrete, lightweight stiff boards of timber and glass fibre reinforced polymer (GFRP) were sandwiched between the CFS channels in the web and flange region to construct the lightweight composite beams. All of the beam specimens were subjected to four-point bending with simply supported boundary conditions. Peak strength, load-deformation curves, initial stiffness, strength-to-weight ratios, failure modes and the normalized yield and plastic moment strengths were compared. This study established the structural feasibility of developing lightweight CFS composite built-up beams from timber and GFRP boards, indicating that the flexural strength and stiffness are significantly improved by 150% and 80%, respectively, as compared to the unstiffened CFS built-up beams. Moreover, the studied composite beams were shown to attain their full yield moment capacities, and in some cases more than 90% of their plastic moment capacity, resulting in built-up members with a higher structural efficiency.

Deoxidation capacity of aluminum in ferromanganese carbon-containing melts

Deoxidation (reduction of oxygen concentration dissolved in liquid metal) is an integral part of steel production technology. For obtaining deeply deoxidized metal, mainly aluminum is used at metallurgical enterprises. It should be taken into account that alloying elements of steels and alloys under certain conditions can act as deoxidizing elements, contributing to the complex nature of the deoxidation process. Almost all steels contain manganese in one concentration or another. The study of interaction processes in the Fe – Mn – Al – O – C system at steelmaking temperatures is of applied importance. In this paper, a thermodynamic analysis of the deoxidation ability of aluminum in oxygen-containing iron-manganese melts was carried out. At the same time, influence of carbon on course of the deoxidation process was taken into account. In the study, it is effective to use a technique for constructing the solubility surface of components in metal (SSCM) – a diagram that connects the compositions of liquid metal with the compositions of conjugated non-metallic phases. In the course of this work, oxygen solubility isotherms in the Fe – Mn – O system were calculated for the temperature range of 1550 – 1650 °C. For the Fe – Mn – Al – O – C (1600 °C) system, composite sections of the SSCM were constructed at fixed carbon concentrations in steel [C] = 0; 0.1; 0.4; 0.8 and 1.2 % (hereafter by weight). It is shown that with the simultaneous presence of manganese and aluminum in an oxygen–containing iron-based melt (at industrially significant concentrations [Al] = 0.001 – 0.010 % and [Mn] – less than 1.0 %), aluminum in the liquid metal will act as a deoxidizing agent, and corundum inclusions will be formed as interaction products. Complex deoxidation by aluminum and manganese with the formation of spinel is typical only for manganese-alloyed steels, where the concentration of manganese is more than 1.5 %.

Effects of size and location of magnetorheological segments on random vibration response of laminated composite beams using an N-layer of layerwise theory

Laminated composite beams are widely used in engineering applications, including wind turbine blades and automobile, where the structures are highly subjected to non-deterministic random loadings, requiring a reliable technique to ensure the stability of the structure during operation. Recently, to mitigate the effects of random loadings on the structural stability of the structure, segments of magnetorheological (MR) fluids have been embedded in the laminated beams (MR-laminated beams). In this work, the effects of the size and location of MR-fluid segments on random vibration characteristics are investigated. A laminated beam is considered in which several layers/segments are filled with MR fluids and are subjected to several random loads. An N-layer model of layerwise theory (LWT) developed by the present authors in previous work is considered for computational purposes. A finite element model based on LWT is developed to study the numerical examples. MR-laminated beams consist of five sections; two MR-fluid sections and three composite sections have been studied using LWT. To justify the numerical results, the first three natural frequencies of a laminated beam without an MR layer are solved using a 3D model in COMSOL software which shows a close match with the results of LWT. An in-house experimental setup has been developed to verify the simulation results. The simulation results are then compared with the first-order shear deformation theory (FSDT) and verified by several experimental tests. The effects of MR fluid segments on the dynamic response of MR-laminated beams for six different configurations have been investigated. In addition, the effects of thicknesses of MR fluid section on the dynamic behavior of structures have been investigated. Effects of magnetic fields on statistical properties, correlation, and autocorrelation on MR-laminated beams made of E-glass and fiber-carbon have been investigated. As a case study, the vibration response of a wind turbine blade made of an MR-laminated beam has been investigated using a narrow band process.

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

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

Friction and Cohesion Interface Shear Factors of Ultra-High-Performance Concrete (UHPC) Cast on Hardened Conventional Concrete

In composite structures, interface shear resistance is a critical design criterion for transferring forces between interconnected elements at the contact surface. Recently, Ultra-High-Performance Concrete (UHPC) applications in construction have been growing rapidly due to superior mechanical and durability properties; however, there is no guidance on how to predict the interface shear resistance of UHPC cast on hardened conventional concrete (CC). This paper presents the experimental and analytical investigations conducted to develop friction and cohesion factors of the shear friction theory for UHPC cast on hardened CC in composite sections. Push-off shear tests and slant shear tests were conducted to evaluate and validate the effect of interface surface texture, interface reinforcement ratio, CC and UHPC compressive strength, and fiber presence. A friction factor of 1.0 was adopted—as in the current code provisions—while a cohesion factor of 3.45 MPa (0.5 ksi) between UHPC cast on intentionally roughened hardened CC was proposed, which is significantly higher than that in the current code provisions of CC. Also, increasing the interface shear reinforcement ratio increased the interface shear resistance significantly and resulted in a more ductile failure. Neither UHPC compressive strength nor the presence of steel fibers had a significant effect on the interface shear resistance of UHPC cast on hardened CC.

Vibration Serviceability Evaluation of a Single Span Steel–Concrete Composite Foot Bridge under Dynamic Pedestrian Loadings Considering Moving Mass Effect

In this paper, we present the analysis results on the vibration serviceability of a pedestrian bridge considering the effect of pedestrian moving mass inertia. Using dynamic finite element analysis, we considered different walking scenarios, including pedestrian density, walking speed, random walking, and synchronized walking, to analyze the acceleration response of a 40m long single-span bridge with a steel composite box cross section. We showed that the equivalent fixed mass analysis method did not significantly differ from the moving mass analysis in the random walk scenario and a wider frequency excitation band may be useful to consider when evaluating vibration serviceability in a random walk scenario.

Comparative Analysis of Composite Structure by STADD Pro Software

Abstract: In comparison to many other emerging nations, India uses a fairly little amount of steel in the construction industry. Other nations' experiences suggest that this isn't because steel isn't economically viable as a building material. Maximum Axial Forces On Column Base Of The Structure Column RCC Structure (kN),steel Structure (kN) ,Difference in Foundation Size and Reinforcement Requirements Property RCC Structure, Steel Structure Size:- are found by staad pro software. .With the existing development requirements in India, there is a tremendous opportunity for raising the volume of steel in teaching. A significant loss for the nation results from not utilising steel where it is cost-effective as an alternative construction material. Also, it is clear that modern composite sections made of steel and concrete are a time, money, and cost-effective alternative for important civil structures like bridges and tall skyscrapers.

Numerical simulation on heat transfer enhancement of free piston Stirling engine heater with composite cross section mini channels

Integral fin with micro-channels have been widely used in small free piston Stirling engines heater due to their high heat transfer rate, low flow loss, and high machining accuracy. A β-type free piston Stirling engine heater with composite cross section mini channels(CCSMH) is designed for heat transfer enhancement applying to solar dish power generation system. Investigation on heat transfer performance of the heater under oscillating flow is carried out by CFD method, which is compared with smooth annular tube heater. The influence of geometry parameters on the performance of heat transfer and pressure loss is investigated. A improved performance evaluation criteria PEC is proposed for the condition of equal flow velocity to evaluate the enhanced heat transfer performance of the heater. The results show that the maximum value of the comprehensive performance evaluation index PEC can reach 3.14, the maximum mean pressure drop increment of CCSMH compared with the smooth tube heater is 38.4 Pa, which is much lower than the minimum pressure of 2.3 MPa and can be neglected.

Effective Width of the T-section Flange of Ribbed Slabs

Ribbed ceilings in reinforced concrete, and more recently in steel-reinforced concrete and wood-concrete versions, occupy a significant place in the total volume of buildings and structures. An analysis of the regulatory and technical literature shows that in domestic and foreign sources, empirical dependencies are proposed for assigning the effective width of a T-section flange, which does not lead to economical and reliable design solutions.The purpose of the study is to determine the calculated effective width of a flange of a tee monolithic section or a composite section of a floor. Based on the analysis of the stress-strain state of a bent tee section, analytical ex-pressions are written and formulas are obtained for determining the design flange width.

Experimental study on bonding performance of GFRP bars-recycled aggregate concrete under sulfate attack environment

The sufficient bonding performance between glass fiber reinforced polymer (GFRP) bars-concrete is essential for the composite section's integrity. In addition, sulfate attack is one of the primary causes of concrete damage, which will inevitably lead to a decline in bonding performance between GFRP bars and recycled aggregate concrete (RAC). This paper uses the GFRP bar-RAC pull-out test to study the effect of recycled aggregate (RA) replacement rate and RAC protective layer thickness on bonding performance under continuous sulfate immersion. The results indicated that as the sulfate attack time increases, the bond strength of various GFRP bars-RAC specimens rises and then decreases. At the same time, as the RA substitution ratio grows, the specimen requires less time to reach its peak of bond strength, and the bond strength decreases rapidly in the later stages of erosion. When the erosion age reaches 360 days, the bond strength of specimens with recycled RA rates of 0%, 25%, 50%, and 100% drops by 12.93%, 15.18%, 17.99%, and 28.22%, respectively, compared to those without erosion. Since sulfate attacks RAC from the outside, the bond strength of the specimen with a thin protective layer thickness decreases faster after long-term erosion. Through the fitting analysis of the variation law of bond strength of 7 groups (147) specimens, a prediction model of GFRP bars-RAC bond strength is developed, considering the influence of RA substitution ratio and protective layer thickness under continuous sulfate immersion. The ratio of all predicted values to experimental values ranges between 0.94 and 1.133. It provides reliable guidance for the GFRP bar-RAC structure's durability design.

Experimental study on the flexural performance of steel-concrete composite section of self-anchored suspension bridge

In order to study the flexural performance of the steel-concrete composite section of self-anchored suspension bridge, a test model of the steel-concrete composite section was fabricated according to the scale of 1 : 3 based on the Wushui Bridge, and a four-point negative bending test was carried out. The results show that the residual displacement ratio is 0.7%, and the experimental model is in the elastic stage under the design load condition, which incidate that the component is safe under normal service condition. Under the overloading condition, the residual displacement ratio is 19%, the experimental model is in the elastic-plastic stage, but the stress of materials still meets the requirements. Under the two conditions, the deformation angle of the composite section is small and the stiffness transition is stable. The relative slip between the steel plate and concrete in the composite section is small (no more than 0.25 mm). The stress in the top steel plate and bottom steel plates of the composite section are gradually decreases during the transfer from the steel stiffening beam to the concrete side. The design of the steel-concrete composite section is reasonably loaded, and the mechanical properties are smoothly transferred.

Geopolymer concrete-filled aluminium alloy tubular cross-sections

Composite steel–concrete members are adopted in structural applications as a cost-effective and high-speed construction practice. Exploiting the superior corrosion and strength-to-weight properties of structural aluminium, research on composite aluminium-concrete members has been reported. Aiming for an even more sustainable and durable structural member, this paper proposes combining structural aluminium alloys with low carbon geopolymer concrete (GC) to form a structural member with lower environmental footprint. To this end, an experimental programme on geopolymer concrete-filled aluminium alloy tubular (GCFAT) cross-sections is performed. A total of 24 tests on stub columns and 12 tests on beams were carried out. In particular, 4 square hollow sections infilled with one-part geopolymer concrete were tested under uniform compression and under uniaxial bending. The hollow sections were fabricated from 6082-T6 heat-treated aluminium alloy. The same cross-sections were also tested as bare and infilled with ordinary Portland cement (OPC) concrete for comparison purposes. It is shown that the strength of the composite sections is significantly increased compared to the bare ones. In particular, the average strength increase was in the range of 16.5%–93.3% and of 23%–93.1% for GC and OPC-aluminium stub columns, respectively. In beams, the strength increase was in the range of 14.1%–53.6% for GC-aluminium and of 10.2%–48.9% for OPC-aluminium specimens. In absence of codified design rules for geopolymer concrete-aluminium structures, design formulae based on the European standards for composite steel–concrete members, with the material properties of steel and concrete replaced by those of aluminium alloy and GC, respectively, are adopted. The obtained results demonstrated that the proposed design methodology is suitable for the design of GCFAT cross-sections and beams, providing reasonably accurate and consistent strength predictions. Overall, the potential of geopolymer concrete-filled aluminium tubular cross-sections as a novel cement-free, sustainable, and structurally efficient composite cross-section is demonstrated.

Analysis of lightweight composite sections with reinforced concrete infill with autoclaved aerated concrete (AAC)

The development of composite sections is of great importance in structural design, with the aim of reducing weight and deflection while limiting the effect on the composite section’s strength and durability. This paper examines the computational analysis of composite sections where reinforced concrete was replaced with autoclaved aerated concrete (AAC) in the compression zone. The first principles of concrete combined with Hook’s law were adopted to find a flexure, shear, equivalent modulus of elasticity, effective moment of inertia, and deflection. The results are discussed and investigated using the finite element models developed by ANSYS WORKBENCH software. We found that the proposed analytical model can effectively provide a solution for the composite cross-section. The comparison between the theoretical calculation of the first cracking loads and the finite element percentage ranges from 89 to 110%. The ratio of the computational calculation of the modulus of elasticity to the finite element results ranged from 0.91 to 1.06. The comparison between the theoretical calculation of the effective moment of inertia to the finite element percentage ranged from 92% to 118%. The ratio of the computational calculation deflection to the finite element ranged from 0.87 to 1.15.

Study on the axial compression behavior of RC columns strengthened with cementitious grout

The axial compression behavior of reinforced concrete (RC) columns strengthened with cementitious grout was studied by conducting the axial compressive tests on twelve column specimens. The effects of replacement position and thickness on the failure modes, load–displacement responses, compression capacity, and load–strain curves of the columns were discussed. The results indicated that interfacial cracks were not observed at the interface between the cementitious grout and concrete. The strengthened columns gained peak load enhancements of 10.8–61.0%, while the corresponding displacement increased to a lesser extent and even reduced (−16.8–44.9%). Comparisons of axial compression performance of the strengthened specimens with the same replacement ratio but different replacement positions indicated that the strengthening effects of specimens with different replacement positions listed in descending order was: four side replacement, opposite replacement, adjacent replacement, and unilateral replacement. Moreover, the increase of the compression capacity of strengthened columns increased obviously with an increase in the strength of the cementitious grout and replacement ratio, while decreased with an increase in the strength of concrete. The axial strain of the concrete side was larger than that of the cementitious grout side during the loading process for unsymmetrically strengthened columns with cementitious grout, and the specimen exhibited physical eccentricity. Thereafter, an equivalent compression constitutive model of the composite section of RC columns strengthened with cementitious grout was proposed based on the established compression constitutive models of concrete and cementitious grout. A calculation method for the axial compression capacity of existing RC columns strengthened with cementitious grout was proposed considering the lateral restraint effect of stirrups on concrete and cementitious grout, and reduction of capacity caused by physical eccentricity of specimens. A comparison between the calculated and experimental results demonstrated that the results obtained by the proposed method were in good agreement with that of the experimental results.