High-strength Concrete Members Research Articles

Experimental Study of Shear Performance of High-Strength Concrete Deep Beams with Longitudinal Reinforcement with Anchor Plate.

As a transfer member at the discontinuous place of vertical load, the deep beam has a complex stress mechanism and many influencing factors, such as compressive strength of concrete, shear span ratio, and reinforcement ratio. At the same time, the stress analysis principle of traditional shallow beams is no longer applicable to the design and calculation of deep-beam structure. The main purpose of this paper was to use the strut-and-tie model to analyze its stress mechanism, and to verify the applicability of the model. Nine high-strength concrete deep-beam specimens with longitudinal reinforcement with an anchor plate of the same size were tested by two-point concentrated loading method. The effects of shear span ratio (0.3, 0.6, and 0.9), longitudinal reinforcement ratio (0.67%, 1.05%, and 1.25%), horizontal reinforcement ratio (0.33%, 0.45%, and 0.50%), and stirrup reinforcement ratio (0.25%, 0.33%, and 0.50%) on the failure mode, deflection curve, characteristic load, crack width, steel bar, and concrete strain of the specimens were analyzed. The results showed that the failure mode of deep-beam specimens was diagonal compression failure. The normal section cracking load was about 15 to 20% of the ultimate load, and the inclined section cracking load was about 30~40% of the ultimate load. The shear span ratio increased from 0.3 to 0.9, and the bearing capacity decreased by 32.9%. When the longitudinal reinforcement ratio increased from 0.67% to 1.25%, the ultimate load increased by 42.6%. The shear span ratio and longitudinal reinforcement ratio have a significant effect on the bearing capacity of the high-strength concrete deep beams with longitudinal reinforcement with an anchor plate. The shear capacity of nine high-strength concrete deep-beam specimens with longitudinal reinforcement with an anchor plate was calculated by national standards, and the results were compared with the calculation results of the Tan-Tang model, the Tan-Cheng model, SSTM, and SSSTM. The analysis showed that the softened strut-and-tie model takes into account the softening effect of compressive concrete, and is a more accurate mechanical model, which can be applied to predict the shear capacity of high-strength concrete deep-beam members with longitudinal reinforcement with an anchor plate.

Effect of retrofit type on the blast performance and failure mode of HSC beams retrofitted with UHPFRC

This paper presents a strategy to prevent shear failure and improve the structural performance of existing high-strength concrete (HSC) beams under blast loading. The strategy involves retrofitting with ultra-high performance fiber reinforced concrete (UHPFRC), a novel material which is well-adapted for the blast hardening of concrete structures. Shock-tube air-blast tests are conducted on seven HSC beams which are retrofitted with UHPFRC. The objective was to characterize the effectiveness of various retrofit types on the blast behaviour of both shear-deficient and flexural-dominant HSC members. Three retrofit types were considered: U-jacketing (UJ), full-jacketing (FJ) and a tension-sided (T) overlay. Other parameters included the effects of the concrete substrate roughening method, as well as the tension steel ratio (1.6% or 2.4%) and presence of stirrups in the beams. Both the UJ and FJ retrofits were found to be effective in preventing shear failure in shear-deficient HSC beams having varying shear demands. In addition, both retrofits increased member strength and stiffness, thereby reducing blast-induced displacements and increasing overall blast resistance. Comparing the two retrofits, optimal performance was obtained with full-jacketing due its ability to delay concrete crushing. In HSC beams with sufficient stirrups, both the T-sided and FJ retrofits reduced blast-induced displacements; however, the use of full-jacketing was better able to control damage and increase blast capacity. The roughening method had no substantial effect on the FJ retrofit performance or failure mode, with no debonding observed in the tests.

Prediction of ultimate strain and strength of CFRP-wrapped normal and high-strength concrete compressive members using ANN approach

The literature is deficit in predicting the axial strength (AS) and axial strain of carbon fiber reinforced polymer (CFRP)-wrapped normal strength concrete (NSC) and high strength concrete (HSC) compressive members using machine learning techniques. The already proposed models for predicting the AS and axial strain of CFRP-wrapped NSC compressive members were developed using a general regression analysis technique based on a small number of noisy data points by considering the limited parameters of specimens. Therefore, there is a need for a refined and accurate theoretical model for capturing the AS and axial strain of compressive members. The main objective of the current study is to develop the theoretical models for predicting the AS and axial strain of CFRP-wrapped NSC and HSC compressive members using machine learning methods. Two different analysis approaches are employed for securing the objective of the present study. The first approach is using the general regression analysis technique, and the second one is employing artificial neural networks (ANN) modeling. The testing database employed in the analysis consists of the testing results of 364 concrete compressive members subjected to compressive loading. The accuracy of the proposed empirical and ANN models is evaluated and compared on the basis of the testing results. Three statistical indices were employed to determine the performance of the currently proposed models developed in the present study. The ANN models presented the accuracy with the statistical indices = 0.984, = 0.112, and = 0.097 for the strength model and = 0.942, = 1.211, and = 0.978 for the strain model. The suggested empirical model presented the statistical indices = 0.90, = 0.33, and = 2.45 for the strength model and = 0.80, = 2.05, and = 5.34 for the strain model. The statistical evaluation showed that the ANN models are more effective and precise than the empirical ones in predicting the AS and axial strain of CFRP-wrapped circular concrete compressive members.

Stress–Strain Model of High-Strength Concrete Confined by Lateral Ties under Axial Compression

High-strength concrete can effectively reduce the cross-sectional size, increase space usage, and cut material costs. To analyze the mechanical properties of high-strength concrete vertical members, various confinement models have been proposed to define the ties-confined concrete stress–strain relationship. However, most existing models are divided into ascending and descending segments. These are continuous but not derivable at the peak point, which does not facilitate numerical calculations. Moreover, these models have a large number of parameters that are mostly obtained based on the fitting of experimental data, which may also lead to the limited applicability of the models. In this study, existing confinement models for high-strength concrete under axial compression are reviewed, and the differences between the models are discussed. Based on the results of normal triaxial experiments on high-strength concrete and the test data from other studies on ties-confined concrete columns, the effective confinement coefficient and empirical formula of ties strain at the peak stress of confined concrete are proposed. A confinement model is proposed based on the continuous derivable function, and it is validated based on the available experimental data. Results show that the proposed model can reflect the stress–strain relationship of the test specimens more simply while keeping the basic accuracy with other models.

Effect of type, amount and configuration of reinforcement in HSC box-girders reinforced with BFRP bars and steel stirrups under torsion-shear-bending

There has been no research on the performance of high-strength concrete (HSC) hollow members reinforced with basalt fiber reinforced polymer (BFRP) bars and steel stirrups under combined torsion (T), shear (V), and moment (M); this study examines the above scenario. Six specimens of identical size and length were constructed and tested, each having a total quantity of reinforcement of 2.5%. The supports were restrained against twisting and the load was applied at a transverse eccentricity of 1.67 m at midspan, producing the required T-V-M ratio, with torsion as the dominant action. The proportion of longitudinal to transverse reinforcement, the number and diameter of longitudinal BFRP bars, and the diameter and spacing of steel stirrups, were the factors investigated. The experimental results were evaluated in terms of strength and stiffness, deflection and angle of twist, cracking pattern, and failure modes. For the same total amount of reinforcement, the best results were achieved utilizing specimens with BFRP bars and steel stirrups of smaller diameter at closer spacings. Employing more longitudinal BFRP bars ( ρ l = 1.58 ρ t ) produced better outcomes than using more steel stirrups ( ρ t = 1.32 ρ l ), indicating that the amount of BFRP bars is as critical as or more important than the amount of steel stirrups. The experimental results of cracking torque and twist, and ultimate torque were compared to the code and other available expressions. It was found that ACI, CSA, and EC equations can be extrapolated without any modification to predict the torsional strength of HSC box-girders longitudinally reinforced with BFRP bars under combined T-V-M. In addition, a new approach was suggested, which can predict the ultimate torsional twist capacity reasonably well.

Shear behavior of high-strength square concrete filled steel tube members

This paper experimentally and numerically investigates the shear behavior of high-strength square concrete-filled steel tube (HS-SCFST) members. A total of 20 specimens were first tested. The test parameters were the shear span-to-depth ratio, width-to-thickness ratio of the steel tube wall, yield stress of steel, and compressive strength of concrete. Detailed finite element (FE) models were then developed and benchmarked. The benchmarked models were then used to conduct a total of 87 parametric studies. It was shown that (i) the shear strength and stiffness increased with decreasing shear span-to-depth ratio or width-to-thickness ratio, and (ii) the increase in yield stress of steel and compressive strength of concrete improved the shear strength, but had a minor effect on the stiffness. Results from the experimental tests and finite element analyses were also used to evaluate the applicability of several international design provisions (e.g., AASHTO BDS, Eurocode 4, WSDOT BDM and CECS 28) for estimating the shear strength of HS-SCFST members. It was shown that CECS 28 provided the most reasonable estimation of the shear strength, but the contribution of steel tube and concrete infill was not accurately calculated. A new design equation was therefore proposed, considering the effect of shear span-to-depth ratio and the contribution of the steel tube and concrete infill. • Investigates the shear behavior of high-strength CFST members. • Conducts experimental tests and FEM analysis. • Discusses the shear transfer mechanism. • Evaluates the applicability of several international design provisions. • Proposes a design equation considering the effect of shear span-to-depth ratio.

Effect of reinforcement type on the behavior of rectangular HSC box-girders under combined torsion-shear-flexure: An experimental study

The durability and sustainability of structural members subjected to torsion can be improved using a combination of non-corrosive reinforcement, high-strength concrete (HSC), and hollow members in engineering structures. The applicability of basalt fiber reinforced polymer composite (BFRP) bars and stirrups for HSC box-girders exposed to a combination of torsion, bending, and shear, was investigated in this novel study. Four specimens of equal size and length were made and tested. The amount of reinforcement in each specimen kept about 2.5%, but the type of reinforcement varied. A box-girder with ordinary steel reinforcement was chosen as control specimen. Another specimen with fully BFRP reinforcement was utilized. The other two specimens had BFRP longitudinal bars and BFRP stirrups, and vice versa. The results show that, the BFRP longitudinally-reinforced specimens had the least cracking and ultimate capacities with the maximum angle of twist compared to the control specimen, while the specimen with longitudinal steel and BFRP stirrups had improved results with larger torsion capacity and lower angles of twist. The stiffness and toughness values of the totally BFRP-reinforced specimen were the lowest. The usage of BFRP for longitudinal bars and steel for stirrups resulted in increased stiffness and toughness compared to the fully BFRP reinforced specimen.

Anchorage performance of bolt connection embedded in thin UHPC members

Ultra-High-Performance Concrete (UHPC) has the remarkable durability and outstanding mechanical properties such as exceptionally high compressive strength and superior tensile strength. Therefore, the cross section of UHPC structure is generally optimized to make members light and thin. This paper investigated the behavior of single bolt embedded in thin HSC (high strength concrete) and UHPC members under tension loading. Fourteen tension tests were conducted to study the influences of concrete type, embedment depth and diameter of bolt on anchorage performance. The anchorage performance of these anchors embedded in UHPC were significantly improved compared with the bolts in HSC concrete, in both load capacities and displacement capacities. The superior strength and fiber bridging reduced the Angle of fracture, which is approximately 20° to 24°. As a result, the concrete breakout failure area was improved, resulting in an increase in breakout strength and displacement capacity. The test results were discussed in detail to emphasize the influence of concrete splitting on the anchorage performance of bolts embedded in UHPC members. Compared with HSC members, due to the fiber bridging, failure of UHPC members did not happen when splitting. However, the concrete splitting resulted in the decrease of breakout strength. Finally, a splitting modification factor is proposed to predict anchorage strength based on the test results obtained in this paper and others.

Torsional Behavior of High Strength Concrete Members Strengthened by Mixed Steel Fibers

Twelve mixing steel fibers-reinforced high strength concrete beams were experimentally tested under pure torsion to investigating the concrete member torsional behavior. The first cracking torque, ultimate torsional resistance, crack patterns, effect of steel fiber ratio, effects of shape and size of hollow cross-section, and effect of stirrups reinforcement were discussed. The ratio of mixing steel fiber, different shape and size of hollow cross-section, and ratio of stirrups reinforcement were considers as major parameters. The results are shown that the width of cracks decreases and the cracks number increases with mixing steel fibers ratio increased. The first cracking torque and ultimate torsion load increased with decrease in the hollow cross-section area of high strength concrete members strengthened by steel fibers.

Flexural behavior of high-strength, steel-reinforced, and prestressed concrete beams

To study the flexural behavior of prestressed concrete beams with high-strength steel reinforcement and high-strength concrete and improve the crack width calculation method for flexural components with such reinforcement and concrete, 12 specimens were tested under static loading. The failure modes, flexural strength, ductility, and crack width of the specimens were analyzed. The results show that the failure mode of the test beams was similar to that of the beams with normal reinforced concrete. A brittle failure did not occur in the specimens. To further understand the working mechanism, the results of other experimental studies were collected and discussed. The results show that the normalized reinforcement ratio has a greater effect on the ductility than the concrete strength. The cracking- and peak-moment formulas in the code for the design of concrete (GB 50010-2010) applied to the beams were both found to be acceptable. However, the calculation results of the maximum crack width following GB 50010-2010 and EN 1992-1-1:2004 were considerably conservative. In the context of GB 50010-2010, a revised formula for the crack width is proposed with modifications to two major factors: the average crack spacing and an amplification coefficient of the maximum crack width to the average spacing. The mean value of the ratio of the maximum crack width among the 12 test results and the relative calculation results from the revised formula is 1.017, which is better than the calculation result from GB 50010-2010. Therefore, the new formula calculates the crack width more accurately in high-strength concrete and high-strength steel reinforcement members. Finally, finite element models were established using ADINA software and validated based on the test results. This study provides an important reference for the development of high-strength concrete and high-strength steel reinforcement structures.

Compressive Strength Variability Limits of High-Strength Cementitious Grouts

Abstract The quality of grout becomes more important as many projects utilize precast concrete elements and systems to accelerate the delivery of a project. Also, the use of high-strength grout materials increases to properly connect high-strength concrete members. In the present study, two high-strength, cementitious grout materials were tested for their compressive strength to estimate a coefficient of variation (cv), to investigate effects due to curing condition and initial curing time, and to evaluate the strength ratio between cube and cylinder specimens. The 28-day strength of tested grouts reached more than 62.1 MPa (9,000 psi). The estimated cv was 2.3 %, which was slightly higher than the value of 2.1 % used in ASTM C109, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50 mm] Cube Specimens). Based on the estimated cv, the variability limits of compressive strength in ASTM C109 can be 9.5 % (from 8.7 %) for three cubes and 8.4 % (from 7.6 %) for two cubes. There was not a substantial difference in compressive strength between water-cured and moist-cured cubes. Also, the difference of compressive strength is minimal between cubes initially cured for 24 hours and 48 hours before demolding. The compressive strength ratio of ϕ100 mm × 200 mm cylinder specimens to 50 mm cube specimens was between 0.78 and 0.90 for different test ages. The mean ratio was 0.83. These observations can help engineers and practitioners to use ASTM C109 and ASTM C1107, Standard Specification for Packaged Dry, Hydraulic-Cement Grout (Nonshrink), with more confidence when they test high-strength, cementitious grout materials.

Strength of Bridge High-Strength Concrete Slender Compression Members Reinforced with GFRP Bars and Spirals: Experiments and Second-Order Analysis

Design for slender high-strength concrete (HSC) bridge compression members (columns, piers, and piles) reinforced with glass fiber-reinforced polymer (GFRP) has yet to be addressed in the relevant American and Canadian codes and guidelines. Including such provisions undoubtedly requires a comprehensive assessment of the structural performance of such members, as well as a definition for the slenderness limit below which second-order responses can be discarded. Consequently, full-scale slender GFRP-HSC columns with a concrete compressive strength of 80 MPa and measuring 2,500 mm in height and 305 mm in diameter were prepared and tested at four eccentricity levels (0%, 16%, 33%, and 66% of the column size). The influence of HSC on the behavior of slender GFRP-HSC columns was also assessed with respect to reference normal-strength concrete (NSC) counterparts. Moreover, the effect of two different longitudinal GFRP-reinforcement ratios (3.28% and 4.66%) on the performance of the test specimens was investigated. The test results herein indicate the ability of HSC and GFRP reinforcement to improve column strength and to maintain stability at various loading stages. An analytical second-order model was then developed to extend the research program to include a wide range of parametric studies. The developed model was validated against the test results for 47 FRP-HSC columns selected from the current study and the literature. Lastly, the applicability of the current slenderness limit to HSC columns was verified and a modified slenderness limit was proposed to account for HSC columns with compressive strengths up to 125 MPa.

Numerical assessment of continuous prestressed NSC and HSC members with external CFRP tendons

Carbon fiber reinforced polymer (CFRP) is a promising material for prestressing tendons. This study assesses the structural performance of continuous prestressed members with external CFRP tendons, focusing on the effect of using high-strength concrete (HSC) instead of normal-strength concrete (NSC). A nonlinear model is introduced and numerical tests are then carried out. Three concrete cylinder compressive strengths of 40, 60 and 90 MPa are used. The area of external CFRP tendons varies from 200 to 1700 mm2. The results show that the effect of using HSC instead of NSC heavily depends on the area of external CFRP tendons. In general, HSC members with external CFRP tendons exhibits considerably different response characteristics from those of NSC ones, including cracking, deformations, tendon and rebar stresses, neutral axis depths and so on. The concrete grade influence on moment redistribution is found to be negligible, provided that the members demonstrate favorable ductility. The rules in ACI 318-14 concerning the unbonded tendon stress and the redistribution of moments are evaluated.

Nominal flexural strength of high-strength concrete beams

The conventional ACI rectangular stress block is developed on the basis of normal-strength concrete column tests and it is still being used for the design of high-strength concrete members. Many research papers found in the literature indicate that the nominal strength of high-strength concrete members appears to be over-predicted by the ACI rectangular stress block. This is especially true for HSC columns. The general shape of the stress-strain curve of high-strength concrete becomes more likely as a triangle. A triangular stress block is, therefore, introduced in this paper. The proposed stress block is verified using a database which consists of 52 tested singly reinforced high-strength concrete beams having concrete strength above 55 MPa (8,000 psi). In addition, the proposed model is compared with models of various design codes and proposals of researchers found in the literature. The nominal flexural strengths computed using the proposed stress block are in a good agreement with the tested data as well as with that obtained from design codes models and proposals of researchers.

Assessing Stress-Block Parameters in Designing Circular High-Strength Concrete Members Reinforced with FRP Bars

Several standards and guidelines allow the use of the equivalent rectangular stress block (ERSB) as a simple concept to accurately predict flexural strength with or without axial force. North American codes (ACI 318 and CSA A23.3) allow the use of the ERSB as an alternate approach to stress-strain relationships in predicting the strength of high-strength concrete (HSC) reinforced with steel bars (steel-HSC-RC). The strength of high-strength concrete specimens reinforced with fiber-reinforced polymer (FRP) bars (HSC-FRP-RC) could be predicted similarly to steel-RC specimens. This research represents an early attempt to investigate the applicability of several ERSBs proposed by different associations to predict the strength of HSC-FRP-RC specimens subjected to combined flexural and compression loads. An experimental database was assembled from 92 specimens studied by the authors and others. The test parameters included concrete strength, level of eccentricity, reinforcement type, glass fiber–reinforced polymer (GFRP) reinforcement ratio, and confinement configuration. Extensive analyses were integrated into the test results to investigate the impact of each test parameter on ERSB parameters. The accuracy and conservativeness of several models were assessed. Comparing the predictions for the tested FRP-RC specimens made with normal-strength concrete (NSC) and HSC revealed that the level of conservatism dramatically decreased for all models, leading to overestimations for some specimens. The American Concrete Institute model always had the lowest level of conservatism, which led to overestimations of some specimens for steel and FRP-RC specimens made with HSC among all the other models. Modified expressions of the ERSB given in ACI 440.1R and CSA S806 were developed. The results indicate good and safe correlation of predicted and measured strength values with reasonable levels of conservatism.

Innovative strategies for enhancing fire performance of high-strength concrete structures

High-strength concrete is being increasingly used in a number of building applications, where structural fire safety is one of the primary design considerations. Many research studies clearly indicate that the fire performance of high-strength concrete is different from that of normal-strength concrete and that high-strength concrete may not exhibit same level of performance as normal-strength concrete under fire conditions. This article outlines key characteristics that influence the performance of high-strength concrete structural members under fire conditions. Data generated in previous experimental and numerical studies are utilized to illustrate various factors that influence fire performance of high-strength concrete structural members. Based on the published data, observations and trends on the behavior of high-strength concrete members, innovative strategies for mitigating spalling and enhancing fire resistance of high-strength concrete structural members are proposed.

Seismic Response Evaluation of Reinforced High Strength Concrete Columns based on the Modified Constitutive Model

Current study deals with strength and seismic ductility assessment of reinforced high strength concrete (HSC) columns. We have studied the nonlinear response of HSC columns with various reinforcement and axial force ratios subjected to cyclic loading. Study consists of primary verification of mathematical nonlinear model and further calibration to ensure accuracy. An existing experimental work is assumed as verification pilot that consists of four columns. Column members differ in the strength and axial force. Concrete has 63.1 MPa mean strength and 0.3% crushing strain. The longitudinal and transverse reinforcements are according to ACI 318 regulations in experiment. We used the nonlinear fiber-element code in OpenSees environment for modeling and analysis of models. The existing proposed stress-strain curve is modified to ensure validity of assessment. Calibration procedure led to conclusion that the post-yield slope needs to be modified in HSC model as the average value of ACI 363 reference. We have developed twelve extra models to estimate the interaction of concrete strength, rebar ratio and the axial force effect on the seismic performance. Parametric study of calibrated models reveals that the seismic energy dissipation in HSC members is function of the provided longitudinal reinforcement ratio and lateral confining stirrup amount.

Experimental evaluation of tensile behaviour of single cast-in-place anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete

Abstract Cast-in-place anchor bolts embedded in plain and steel fibre-reinforced normal- and high-strength concrete members were subjected to monotonic tensile loads. The influence of the concrete member thickness, concrete strength, and the addition of steel fibres to the concrete mixture, on the anchorage capacity and performance was evaluated. The experimental results were evaluated in terms of anchorage capacity, anchorage ductility and stiffness as well as failure mode and geometry. Furthermore, the validity of Concrete Capacity (CC) method for predicting the tensile breakout capacity of anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete members was evaluated. The anchorage capacity and ductility increased slightly with increasing member thickness, whereas the anchorage stiffness decreased slightly. In contrast to the anchorage ductility, the anchorage capacity and stiffness increased considerably with increasing concrete compressive strength. The anchorage capacity and ductility also increased significantly with the addition of steel fibres to the concrete mixtures. This enhanced capacity and ductility resulted from the improved flexural tensile strength and post-peak cracking behaviour of steel fibre-reinforced concrete. The average ratio of measured strengths to those predicted by the CC method for anchors in plain concrete members was increased from 1.0 to 1.17 with increasing member thickness. In steel fibre-reinforced concrete, this ratio varied from 1.29 to 1.51, depending on the member thickness and the concrete strength.

Mechanical performance of glass fiber–reinforced polymer tubes filled with steel-reinforced high-strength concrete subjected to eccentric compression

Glass fiber–reinforced polymer tubes filled with steel-reinforced high-strength concrete are proposed as glass fiber–reinforced polymer–steel-reinforced high-strength concrete composite members. Eccentric compression is a typical loading scenario for such column members in practice. Experimental investigation on eight glass fiber–reinforced polymer tubes filled with steel–reinforced high-strength concrete columns subjected to eccentric compression was conducted. The effects of fiber orientation, thickness of glass fiber–reinforced polymer tube, slenderness ratio of columns, and loading eccentricity were investigated. It was found that the compression bearing capacity of glass fiber–reinforced polymer–steel-reinforced high-strength concrete columns increased with the decrease in the fiber tangle angle and the increase in the thickness of the glass fiber–reinforced polymer tube but reduced with the increase in the eccentricity and the slenderness ratio. Corresponding formulas were developed based on the nonlinear full-process analysis theory to describe the compression behavior of glass fiber–reinforced polymer–steel-reinforced high-strength concrete under eccentric loading. Good agreement was found through the comparison between the theoretical and the experimental results. The validated modeling approach was, therefore, employed to develop a parametric analysis that can be used to provide valuable guidance for practical application and further research on such structural members.

Analytical compressive stress–strain model for high-strength concrete confined with cross-spirals

The behavior of high-strength concrete members subjected to seismic loads is mainly based on the ultimate strength of concrete and its ductility. The ductility of reinforced concrete is defined by both axial stresses and strains, which could be represented by the total amount of energy that concrete can absorb before failure. Conventional spiral confinement increases the nominal compressive axial capacity of concrete due to the confinement action of the concrete core, which consequently provides increase in the crushing (failure) strain. The pitch (spacing) of spiral reinforcement has a significant effect on increasing the amount of energy that concrete can absorb. This paper presents a stress–strain model for the prediction of the confined compressive strength of high-strength concrete subjected to axial stress. The stress–strain model is based on confining concrete using cross-spirals. The main parameters were the spiral spacing, and the confinement technique either conventional or cross spirals. The model is based on the results of twenty-one high-strength reduced scale concrete columns that were tested under concentric compressive axial load. The proposed model was compared with two existing models where showed good agreement with the experimental results.