Concrete Tension Research Articles

Evaluating fracture characteristics of ultra-high-performance fiber-reinforced concrete in flexure and tension with size impact

This study highlights the size impact on the fracture characteristics of ultra-high-performance fiber-reinforced concrete (UHPFRC) under flexure and tension through a series of experiments. The studied UHPFRC contained 1 % twisted steel macro and 1 % smooth steel microfiber by volume. The flexural specimens were rectangularly prism-shaped, while the tensile specimens were bell-shaped. To assess the size impact, only the volume change was investigated in flexure, while changes in gauge length, thickness, section area, and volume were studied in tension. The partial/total energy, partial/total toughness, and length of the cohesive zone of UHPFRC were determined. First, the studied UHPFRC produced a normal size effect on partial/total fracture toughness, complementary toughness, and microcrack number in both flexure and tension. The hardening fracture toughness was noticeably higher than the complementary toughness. Second, the length of the cohesive zone of UHPFRC was much higher than that of conventional concrete. Third, the Weibull modulus values of UHPFRC for the hardening fracture toughness, complementary toughness, and number of microcracks per 100 mm were drawn based on the Weibull statistical theory. The normal size effect of UHPFRC on these parameters under tensile load was more obvious than that under flexural load.

Mechanical and Durability Performances of Alkali-resistant Glass Fiber-reinforced Concrete

Concrete, being the most widely used construction material in the world, lacks strength in direct tension and flexure. Attempts to reinforce concrete in tension include the use of steel rebars to strengthen the tensile side of concrete as well as the use of discrete fibers as a reinforcing medium. The study conducted in this manuscript details the effects of including alkali-resistant glass fibers in concrete. Mechanical strength, such as strength in compression and flexure, chord modulus of elasticity and bond pull-out strength, have been measured along with porosity and resistance to accelerated carbonation. Five different water to binder ratios in a range of 0.4 to 0.6 had been used to prepare the design mix proportions. The optimum fiber dosage was found to be 1.5% by weight of cement used. The same had been adopted in the design mix proportions. The average increase in compressive strength and flexural strength was 13% and 28%, respectively. Alkali-resistant glass fiber concrete showed less resistance to carbonation when compared to control mix. Results indicate that glass fibers play a predominant role in providing flexural strength to concrete. The pull-out strength of fiber was added to extra post-cracking flexural strength. The inclusion of alkali-resistant glass fibers imparted a maximum addition of 44% increase in the flexural strength compared to control concrete. The inclusion of alkali-resistant glass fibers in concrete paves the way for a leaner mix and eradicates the possibility of congestion of steel reinforcement for certain structures. KEYWORDS: Alkali-resistant glass fibers, Accelerated carbonation, Bond strength, Compressive strength, Flexural strength.

Linear Concrete Tension Stiffening Model for Reinforced Concrete Elements

Linear expressions for tension stiffening of concrete are nowadays widely used in software packages of structural analysis. Nevertheless, more elaborated expressions of tension stiffening available in the literature have been used successfully in the past. The use of linear approximations is justified since the influence of the tension stiffening effect in the deformation of the structure is small but not negligible. In this sense, linear approximations are simpler and can be accurate enough. However, this linear approximation, in its present form, does not provide good results in terms of deformations at the element level. This paper proposes a linear expression of the tension stiffening supported by the experimental formulation used to predict the flexural behavior of concrete beams. A detailed example is presented.

Study of the strength properties of modified concrete in tension

The resistance of concrete to axial tension is much less than the resistance to compression and is largely determined by the adhesion of its components. The low tensile strength of ordinary concrete is explained by the heterogeneity of its structure and the discontinuity of concrete, which contributes to the development of stress concentration, especially under the action of tensile forces. To increase the tensile strength of concrete, it is necessary to eliminate, first of all, the heterogeneity of the structure of concrete - one of the main reasons for the large dispersion of the results of mechanical tests of this material, which affects the experimental determination of compressive strength. A significant difference between the compressive strength for ordinary concrete indicates a rather large spread of such values. This scatter is explained by the different influence of factors on tension and compression. For example, for ordinary concretes, it was found that with an increase in W/C , the tensile strength decreases, but to a lesser extent than the compressive strength. With an increase in the grade of concrete, the tensile strength increases. High-strength concretes, as a rule, prepared on concrete mixes with low W/C and on clean conditioned aggregates in the form of crushed stone and sand, have an increased density, therefore, they have less variation in strength readings both in compression and at stretching [1-4].

REVIEW OF THE MECHANICAL PROPERTIES OF FIBER CONCRETE UNDER DANIAMIC TENSION AND COMPRESSION

This article is a review of the mechanical properties of fiber-reinforced concrete at high strain rates under tensile and compressive stresses. Fibre-reinforced concrete is widely used in the construction of protective structures, in tunnels, engineering structures in seismic areas, airport runways, river and marine engineering structures and is an important substitute for classic concrete. The review covers the following aspects: advantages and disadvantages of various test methods used to determine the dynamic properties of fiber-reinforced concrete; studies of the dynamic characteristics of fiber-reinforced concrete in compression and tension, including their strength, deformation capacity and ability to absorb energy. The purpose of this review is to expand fundamental knowledge about the dynamic properties of fiber-reinforced concrete and to promote further research on its physical and mechanical characteristics and applications for increasing the strength of brittle materials. At the beginning of the review, the most commonly used test setups and methods for dynamic testing are considered. The Kolsky method is most widely used to determine properties in dynamic compression, tension, and tensile splitting at high strain rates. Further, the main part of the review considers the mechanical properties of fiber-reinforced concrete under dynamic compression and tension, including strength, impact strength, and the ability to absorb energy. Studies have shown that with an increase in the rate of deformation, the dynamic strength of fiber-reinforced concrete increases. The use of an appropriate amount of fiber leads to a significant improvement in dynamic properties. However, there is a threshold fiber content. In conclusion, by summarizing and comparing previous studies, the advantages and disadvantages of existing studies are emphasized, and suggestions for further research are made.

МОДЕЛЬ ПЛАСТИЧНОСТИ ЖЕЛЕЗОБЕТОННЫХ КОНСТРУКЦИЙ

A model of plasticity of reinforced concrete structures is considered, based on on the transformations of the intensity of the “stress-strain” connection by projecting the tensors of this connection, using special transitions for the main angle of deformations, total shear deformations, etc.). At the same time, the modulus of plasticity of concrete, the coefficient of transverse deformations are determined, and complex functions are constructed for linear and angular deformations in sections, taking into account deformation, gradients of deformations during the formation of cracks and stiffness changes. The hypotheses adopted for the calculation model determine the distribution of force flows - blocks for compressed and stretched concrete (first object), "main cracks" from the mechanics of destruction of reinforced concrete, complex functions and a two-cantilever element for modeling the deformation effect of reinforced concrete, developed by the author (second object). Tensile concrete resistance is transferred to the working reinforcement and is modeled using the sum of the average values of the longitudinal and transverse forces, as well as the average reduced coefficient of tension concrete. The "pin (nagel)" effect in the reinforcement crossed by a crack was obtained using the model of the second level of structural mechanics for a reinforcing bar with two pinched ends. The opening of the crack and the shift of the crack edges are simulated. The main force vector in the reinforcement is characterized by the values of longitudinal and transverse displacements (the third object).

Numerical investigation on DE-strengthened-RC beams without steel shear reinforcement

This study presents a two-dimensional nonlinear finite element (FE) model for Deep Embedment (DE) strengthened reinforced concrete (RC) beams without existing steel shear links. The FE model was developed and validated against experimental results reported in published literature. The parametric study was thereafter conducted to examine important parameters influencing the strengthened behavior. The parameters were concrete compressive strength, beam width, beam size, and tension reinforcement ratio. The FE model accurately predicted experimental results with a mean predicted-to-experimental value of 1.04. The FE results showed that the percentage of shear strength provided by embedded steel bars was almost constant once both concrete strength and tension reinforcement ratio were increased. However, an increase in the beam width resulted in a decrease in the percentage of shear strength gain due to embedded steel bars. Shear stress at failure decreased once beam size was increased for both unstrengthened (control) and DE-strengthened beams. The percentage of shear strength provided by embedded steel bars decreased from 47.9% to 27.6% as effective depth was increased from 261.5 mm to 523 mm.

Characteristic Compressive Strength of Concrete with the Use Granite Powder Additive

Granite Powder (GP) is industrial byproducts generated from the granite polishing and milling industry in powder form. The byproduct is left largely unused and is hazardous materials to human health because they are airborne and can be easily inhaled. GP was used as an additive to the concrete to explore the possibility of increasing the mechanical properties (compressive strength) of the concrete. The slump, compressive strength and water absorption test were performed on fresh and hardened concrete. The addition of GP to concrete to serve as an additive shows an improvement in the compressive strength of the concrete. The highest 3-day compressive strength (23.03 N/mm2) was recorded at 10% GP addition level while the lowest 3-day compressive strength (20.47 N/mm2) was recorded at 2.5% GP addition level. The highest 28-day compressive strength (28.29 N/mm2) was recorded at 10% GP addition level while the lowest 28 days compressive strength (27.40 N/mm2) was recorded at 2.5% GP addition level. Peak compressive strength of 33.40 N/mm2 was obtained at 56 days when 10% GP was added in the concrete production. The workability of the concrete decreased with increase in GP replacements. Therefore a higher water to cement ratio will be required to maintain a certain level of workability. In conclusion, employing GP as an additive in concrete helped in boosting the mechanical properties of concrete. The GP at 10% addition is the best choice among other concrete mixtures as it is equivalent to grade 30 concrete suitable for producing post tensioned concrete.

Time‐dependent elongation and cracking behavior of fiber reinforced concrete tension chords

AbstractThe long‐term (LT) tension stiffening effect in fiber reinforced concrete (FRC) tension chords is investigated in this paper. Six tension tie specimens with varying fiber types (either no fibers, polypropylene, or steel fibers) and reinforcement ratios were subjected to a sustained tensile in‐service load for 560 days. The LT specimens were fitted with gauges to monitor their elongation over the test period. In addition, 12 specimens were subjected to instantaneous loading to capture the entire load‐deformation response of the tension ties, up to and beyond the yielding of the reinforcement. A complete suite of material characterization tests were conducted in conjunction with the tension tie testing. The results from this investigation indicate that the inclusion of the fiber types and dosages adopted in this program improve the short‐term performance with respect to stiffness, tension stiffening, and cracking. Steel fibers improved the LT behavior, while the polypropylene fibers used in this study led to mixed results. Models previously developed by the authors have been shown to describe the behavior with good accuracy.

Ultra high performance concrete and C-FRP tension Re-bars: A unique combinations of materials for slabs subjected to low-velocity drop impact loading

In this research work, different combinations of normal strength concrete (NSC), ultra-high-performance concrete (UHPC), and steel fiber-reinforced UHPC (SFR-UHPC) concrete with re-bars of conventional steel and of carbon fiber-reinforced polymer (C-FRP) are used in a two-way square slab of size 1000mm x 1000mm x 75mm subjected to 2500 mm free-fall impact loading. Experimental arrangement consisting of 105 kg dropping weight with the circular flat impacting face of 40 mm diameter used for carrying out impact test is modeled using a high-fidelity physics-based finite element computer code, ABAQUS/Explicit-v.6.15. After validating the experimental results of the NSC slab with steel bars, analyses are extended by replacing NSC and steel bars with UHPC/SFR-UHPC and C-FRP bars, respectively, under the same dropping weight. Only the remote face (tension face) of the slabs is provided with the re-bars. Widely employed and available with the ABAQUS, the Concrete Damage Plasticity model with strain-rate effects has been entrusted for simulating the concrete plastic response. Re-bars of steel are idealized with the Johnson-Cook plasticity damage model. C-FRP re-bars are defined with the classical plasticity model following the elastic-plastic constitutive laws. The impact responses of the slabs consisting of NSC/UHPC/SFR-UHPC concrete with re-bars of steel, and C-FRP combinations considered are discussed and compared. Slabs made of UHPC/SFR-UHPC concrete with the C-FRP re-bars are found to offer a promising combination of materials to withstand low-velocity impact load with little damage and extraordinary impact performance.

Pure and mixed-mode (I/III) fracture toughness of preplaced aggregate fibrous concrete and slurry infiltrated fibre concrete and hybrid combination comprising nano carbon tubes

Concrete is the most widely used and inexpensive material in the construction sector. However, due to its weakness in tension, the cracking and brittle fracturing of concrete is considered a major deficiency. Advancements in fibrous concretes have recently been emerged to mitigate this issue. Preplaced Aggregate Fibrous Concrete (PAFC) and Slurry Infiltrated Fibrous Concrete (SIFCON) are unique cement composites made of fibres with surpassing mechanical properties and exceptional toughness values. The production of PAFC and SIFCON involves packing of aggregates and fibres in the mould and filling the gaps between the aggregates with the high flowability injected cement grout. Nevertheless, the mono and hybrid layered effect of PAFC and SIFCON on fracture toughness is still unexplored and needs special attention to bridge this research gap. This research examined the pure (I and III) and mixed (I/III) modes of fracture toughness of PAFC, SIFCON and hybrid two-layered PAFC-SIFCON samples. For this purpose, many notched specimens of circular disc shapes were prepared using single and double-layer concepts. To investigate the effect of fibres, three different fibre types were used; hooked-end steel fibre, macro polypropylene fibre and hybrid shape of crimped-hooked end steel fibre with dosages of 2.4% and 8% by volume to produce PAFC and SIFCON, respectively. Additionally, multi-walled nano-carbon tubes (MWCNT) were added to the composites with a dosage of 0.1% by cement weight. The compressive strength, stress intensity factors, effective stress intensity factors, mixity parameter, failure pattern, range of fracture toughness and scanning electron microscope were examined, discussed, and compared. Results indicated that pure mode III has a greater cracking risk than both mode I and mixed-mode I/III. The mixed-mode fracture toughness of PAFC specimens improved by 33.07 to 67.94%. Similarly, this improvement ranged from 59.77 to 210.70% for SIFCON and from 51.0 to 131.55% for PAFC-SIFCON. In addition, the fracture toughness of SIFCON is considerably higher than the PAFC and hybrid combination. In all three composite types, the hybrid shape steel fibre outperformed the hooked-end steel and polypropylene fibre under all three modes.

General Mathematical Model for Analysing the Bending Behaviour of Rectangular Concrete Beams with Steel, Fibre-Reinforced Polymers (FRP) and Hybrid FRP–Steel Reinforcements

The design guidelines available in building codes for steel and fibre reinforced polymer (FRP) reinforced concrete (RC) beams have been developed on the basis of empirical models. While these models are successfully used for practical purposes, they require continuous improvements with more experimental data. This paper aims to develop a general mathematical model derived from the intrinsic material properties of concrete and certain reinforcements to analyse the bending behaviour of reinforced concrete beams. The proposed model takes into account the effects of non-linearity and ductility on the real behaviour of concrete under compression as well as the concrete tension stiffening. The model focused on analysing the flexural behaviour of rectangular steel, FRP and hybrid FRP–steel RC beams, using the moment–curvature relationship. A general static equilibrium equation was developed and mathematically solved with precise methods to establish a moment–curvature relationship. The effective flexural stiffness (EFS) is therefore calculated by the slope of the moment–curvature diagram, and then the load–deflection response is immediately deduced according to the loading conditions. The present model results were compared with numerous test data reported by various researchers. The comparisons reveal a good accuracy for predicting the EFS and load–deflection response for either steel, FRP, and hybrid reinforced concrete beams, with an error average less than 10%.

Exploring the performance of experimentally benchmarked RC bridge pier models when subjected to sequential seismic shocks

In this paper we explore the performance of RC bridge piers to seismic ground motion sequences, using both experimental and numerical models. Four RC columns were tested on the University of Bristol’s shake table. These columns contained both well-confined and poor-confined cases. Spectrally matched by near-field without pulse (NFWP), near-field pulse-like (NFPL) and far-field (FF) ground motion records where employed in a sequential/progressive fashion ranging from (I) slight damage (II) extensive damage (III) complete damage and (IV) aftershock cases. These experimental test results are then used to develop a benchmarked OpenSees model of this bridge pier. The importance of the concrete tension constitutive model is highlighted. The differences between sequential (progressive damage) and neglecting sequential seismic events are discussed. The benchmarked model is then used for a heuristic case using incremental dynamic analyses. A comparison is made between drift and energy dissipation performance measures, that suggests drift cannot identify the increased system damage induced by sequential events.

3D mesostructure generation of fully-graded concrete based on hierarchical point cloud and aggregate coarsening

• A novel method for generating fully-graded concrete mesostructures is presented. • Aggregate coarsening is performed to improve the achievable volume fraction. • 3D mesostructures of practical fully-graded dam concrete are generated. • The damage and cracking behavior of fully-graded concrete in tension is studied. The fully-graded concrete (FGC) is widely used in hydraulic mass concrete structures. An exquisite mesoscale model for FGC is essential for accurately simulating its complex damage and cracking behavior. However, due to the presence of massive aggregates and the requirement of high aggregate volume fraction, it is still challenging to generate the three-dimensional (3D) mesostructure of FGC close to reality. A novel and efficient method, termed the hierarchical point cloud method, is proposed for generating the 3D FGC mesostructures. Innovatively, a hierarchical four-level point cloud with a specific spatial structure is defined within the designated domain and serves as the basis for efficiently placing the four-graded aggregates in FGC. The aggregate coarsening is adopted as a supplementary way to achieve the target aggregate packing density in high volume fraction case. In addition, the four virtual aggregate storage piles containing sufficient aggregates within different grading segments are pre-established for providing the required four-graded aggregates. The method efficiency is evaluated by comparison with two traditional methods. The standard samples of mesostructure with an aggregate volume fraction of up to 63.63% are generated for the practical FGC used in Jinping-I arch dam. The numerical tension tests are further carried out for gaining insights into the damage and cracking behavior of FGC. The results show that the arrangement of relative large aggregates, especially the extra-large aggregates, dominates the localization of damage and the final crack distribution.

Experimental Study on Shear Performance of Post-Tensioning Prestressed Concrete Beams with Locally Corroded Steel Strands

To study the effect of the local corrosion of prestressed steel strands on the shear failure mode and shear bearing capacity of concrete beams, unilateral steel strands in four post-tensioning prestressed concrete (PC) beams are corroded, and the shear test of four PC beams are performed. Moreover, a simplified calculation method for the shear bearing capacity of concrete beams with diagonal steel bars is proposed considering the effect of cross-sectional reduction of steel bars, the degradation of mechanical properties, and the cross-sectional damage of concrete. Results shows that the crack propagation mode and failure mode are unrelated to the corrosion of prestressed steel bars when the shear span ratio of beam is the same. The shear capacity of the beam decreases with the increase of corrosion rate, but the decreasing rate is lower than the increasing rate of the corrosion rate. The growth rate of stirrup stress is much greater than that of load after concrete tension and compression loss cracking, and the yield of stirrup can be used as a sign of the ultimate bearing capacity of the beam. In addition, by comparing the experimental and numerical simulation results, the proposed simplified calculation method for the shear bearing capacity of concrete beams is of high accuracy.

Performance Evaluation of Bio Concrete by Cluster and Regression Analysis for Environment Protection.

The focus of this research is to isolating and identifying bacteria that produce calcite precipitate, as well as determining whether or not these bacteria are suitable for incorporation into concrete in order to enhance the material's strength and make the environment protection better. In order to survive the high “potential of hydrogen” of concrete, microbes that are going to be added to concrete need to be able to withstand alkali, and they also need to be able to develop endospores so that they can survive the mechanical forces that are going to be put on the concrete while it is being mixed. In order to precipitate CaCO3 in the form of calcite, they need to have a strong urease activity. Both Bacillus sphaericus and the Streptococcus aureus bacterial strains were evaluated for their ability to precipitate calcium carbonate (CaCO3). These strains were obtained from the Department of Biotechnology at GLA University in Mathura. This research aims to solve the issue of augmenting the tension and compression strengths of concrete by investigating possible solutions for environmentally friendly concrete. The sterile cultures of the microorganisms were mixed with water, which was one of the components of the concrete mixture, along with the nutrients in the appropriate proportions. After that, the blocks were molded, and then pond-cured for 7, 28, 56, 90, 120, 180, 270, and 365 days, respectively, before being evaluated for compressibility and tensile strength. An investigation into the effect that bacteria have on compression strength was carried out, and the outcomes of the tests showed that bacterial concrete specimens exhibited an increase in mechanical strength. When compared to regular concrete, the results showed a maximum increase of 16 percent in compressive strength and a maximum increase of 12 percent in split tensile strength. This study also found that both bacterial concrete containing 106, 107, and 108 cfu/ml concentrations made from Bacillus sphaericus and Streptococcus aureus bacteria gave better results than normal concrete. Both cluster analysis (CA) and regression analysis (RA) were utilized in this research project in order to measure and analyze mechanical strength.

Research on the transverse flexural performance of T-PBL joints between corrugated steel webs and concrete slabs

To study the transverse flexural performance of the T-PBL joint between a corrugated steel web and a concrete slab, taking the diameter of the perforated rebar, the type of perforated bars, the strength of the concrete and the type of connector as the research parameters, four groups of 10 1:1 full-scale model specimens of the joint between the corrugated steel web and concrete slab were tested. The experimental results show that the failure of the joint of the corrugated steel web and concrete slab specimens under the action of the transverse bending moment mainly occurs on the tensile side, which is mainly manifested as a concrete tension crack on the tensile side. The transverse flexural capacity of the T-PBL joint can be improved by increasing the diameter of the perforated rebar and the strength of the concrete. The failure mode of the specimens with ordinary perforated rebar is ductile failure, while the specimens with FRP perforated bars exhibit brittle failure, and the transverse flexural capacity and ductility of FRP bars are relatively low. The transverse flexural performance of the T-PBL joint is better than that of the stud connector joint and embedded connector joint. At present, the factors and calculation methods considered in the existing calculation formulas are different. Based on the test results in this paper, the existing theoretical calculation formulas for the T-PBL joint of corrugated steel webs and concrete slabs are compared and analyzed. It can be seen that the calculated value of the formula combining the formula proposed in the Chinese standard and the Medberry formula has the best agreement with the test value.

Simplified biaxial tension stiffening model for the analysis of shear panels using softened membrane model

Many of the existing tension stress–strain relations for concrete used in smeared shear models consider the contribution of concrete in tension even after steel yielding. Although the contribution of concrete in tension is less significant than its contribution in compression, the use of these existing models often leads to overestimating the shear response of reinforced concrete (RC) panels. An improved concrete tension stiffening model incorporating the effect of biaxial stresses is proposed in this study. The effect of tension stiffening on the behaviour of shear panels under normal and shear stresses is investigated by incorporating tension stiffening in the softened membrane model (SMM). The existing SMM algorithm can be used to estimate the behaviour of RC panels subjected only to pure shear. In the proposed analysis using SMM, a new secant-based algorithm is used to estimate the behaviour of RC panels under combined normal and shear loads. Estimates from the proposed model are compared with estimates from original SMM and experimental results. The comparison shows that the proposed model provides better estimates of shear response for RC panels that undergo high shear strains than the original SMM. Furthermore, the proposed secant-based algorithm estimates panel behaviour under combined loading in reduced computational time.

Regularisation methods for modelling flexural dominant lightly reinforced concrete walls

Localisation can occur in distributed plasticity fibre models when a strain-softening response at the section restricts the spread of damage due to the unloading of stress in adjacent sections/elements. Past studies have developed regularisation schemes for the concrete compression response and reinforcement tension response to achieve mesh objective simulations for the failure of reinforced concrete (RC) walls. However, for walls designed with low amounts of longitudinal reinforcement, the response and failure are controlled by the tensile behaviour, including concrete cracking and reinforcement fracture. The aim of this study was to develop reliable regularisation approaches that could be implemented into fibre models to simulate the cracking and reinforcement fracture response for lightly reinforced concrete walls. Methods for regularisation of both the reinforcement and concrete material properties using a fracture energy method were proposed to minimise the effect of element size on the strain localisation during nonlinear analysis of lightly reinforced concrete walls. The proposed regularisation techniques were validated against the measured response of tested lightly reinforced walls subjected to both monotonic and cyclic loading to ensure that both the cracking strength, ultimate strength, and ultimate drift capacity could be accurately simulated. The local strain response was also investigated to highlight the post-processing of model outputs required to achieve objective simulation results. The results indicate that the models implementing the proposed regularisation of concrete and reinforcement constitutive models could accurately predict the global hysterical response as well as the local strain response of lightly reinforced concrete walls.

THREE-DIMENSIONAL DISPLACEMENT COMPATIBLE STRUT AND TIE METHOD FOR THREE-PILE CAPS SUBJECTED TO CONCENTRIC AXIAL LOADS

Pile caps are large structural elements that act as an interface between the superstructure and the pile foundation. The displacement Compatible Strut and Tie Method (C–STM) is an effective nonlinear modelling technique that is mainly used to simulate the behavior of structural reinforced concrete elements having considerable disturbed (D-) regions. Unlike STM, which considers only force equilibrium, C–STM considers displacement compatibility and constitutive material relationships as well. Recently, a three-dimensional (3D) C–STM was formulated and validated for the analysis of four-pile cap specimens of various shapes. In this study, the 3D C–STM is used to predict the complete load-deformation response of three-pile caps under concentric axial loads. The constitutive material relations for concrete and steel used in this study accounts for both concrete softening and tension stiffening. The overall load-deformation behavior simulated using the 3D C–STM agrees well with the experimental data. Moreover, the 3D C–STM also envisages the progression of nonlinear events leading up to the failure of three-pile cap specimen quite well.