Software ATENA Research Articles

Experimental and numerical analysis of the flexural behavior of slab beam in a 30-year-old reinforced concrete bridge

This paper presents experimental results analyzing the flexural behavior of a 30-year-old reinforced concrete bridge that was dismantled for replacement. The results revealed that the beam underwent three main phases: elastic, cracking, and failure, with a maximum load capacity of 226 kN. The primary failure mode was flexural, characterized by concrete crushing in the compression zone, yielding of the tensile reinforcement, and crack widening up to 1.2 mm. Simultaneously, a numerical model using ATENA software was developed to specifically analyze the flexural behavior of the beam and compare it with experimental results. These results provide important quantitative data for assessing load-bearing capacity and proposing effective repair and strengthening solutions.

The Impact of Hydration Heat on the Formation of Cracks in Massive Concrete Structures

The article deals with the analysis of the development of hydration heat in massive concrete structures and focuses mainly on risk factors which could lead to the appearance of early age cracking in the structure shortly after concreting. As part of the analysis, a parametric study was carried out, which was focused not only on the size of cracks on the surface of the structure, but also on the evaluation of the temperature gradient, where the ratio of the temperature difference and the distance between two points was investigated. During the study, different variants of the type and length of surface covering and different boundary conditions in terms of ambient temperature during individual seasons were considered. The numerical analysis was performed using nonlinear numerical calculations in ATENA software. At the conclusion, an evaluation of the effect of different types of covering of the concrete structure on the reduction of the number and size of surface cracks caused by hydration heat is carried out.

The effect of different wrapping schemes on the shear capacity of rc beams using the finite element method

Structural strength degradation was a highly important issue in the construction sector. In recent years, studies on the use of Natural Fiber Reinforced Polymer (NFRP) composites as external reinforcement have been started. The innovation of using abaca fibers as a mixture in NFRP composites provides a sufficiently high tensile strength. This innovation has the potential to be further developed to optimize the mechanical properties and applications of the composite. With the current technological advancements, numerical analysis carried out using various software based on finite element methods is one tool to solve the engineering problem. One of them was the ATENA software. This research aimed to strengthen the shear capacity of reinforced concrete beams using abaca FRP composites with various wrapping schemes (two sides wrap, U wrap, and complete wrap). The beams were modeled and analyzed by ATENA software. The solution of this problem was solved using the arc-length method. The numerical analysis results showed an increase in the maximum shear capacity by 11%, 14%, and 18% for two sides, U, and complete wraps, respectively. The crack angle on the complete wrap beam occurred at 37 degrees, and it was the largest among the other beams.

Predição da capacidade última de elementos em concreto armado usando metodologias de análises não linear

Abstract This work aims to investigate the ultimate capacity of reinforced concrete elements in terms of cracking and stiffness loss. Nonlinear finite element analysis (NLFEA) was performed in the ATENA software and compared with a proposed numerical simulation of nonlinear static analysis (NLSA), where material cracking is evaluated based on the loss of tangent stiffness of the elements. The analysis was applied to a low-rise reinforced concrete frame with constant axial loads in the columns, and monotonic lateral load applied at the top beam level. Both methodologies showed good agreement regarding the capacity curve and crack patterns, and the numerical simulation NLSA allowed the identification of the sequence of elements' stiffness loss. The results indicated a substantial similarity between the numerical simulation NLFEA and NLSA and the experimental test, indicating a high potential in predicting the nonlinear behavior of reinforced concrete.

Modeling of Axially Loaded Reinforced Concrete Columns Using the Finite Element Method

The use of numerical methods in solving engineering problems can save both time and costs compared to experiments. In this study, the finite element analysis software ATENA Science was employed to model reinforced concrete columns subjected to axial compressive loads. The columns modeled in this study had previously undergone experimental compression tests. The primary objective of this modeling was to assess the compatibility of ATENA Science simulations with the experimental results. Based on a comparison between the ATENA analysis and experimental data, the ATENA analysis produced results that closely matched the experimental outcomes. In this case, the study specifically focused on the L-D relationship and crack patterns. The alignment of these results is important as it serves as validation, allowing for future modifications to the test specimens as required.

Fiber takviyeli beton döşemenin doğrusal olmayan zımbalama davranışı üzerine parametrik bir çalışma

This paper investigates the effect of fiber on the behavior of punching shear slabs; a finite element modeling approach is used to simulate the case study. The proportion mix of hybrid fiber-reinforced concrete, which contains 0.2 percent macro synthetic fibers and 0.68, 0.8, and 0.96 percent steel fibers, compressive strengths of 50 MPa, different longitudinal reinforcement used, and slab thicknesses of 150, 200, and 250 mm are all joined and investigated in this study. The ATENA software is used to perform nonlinear finite element analysis. The slab results validation was done similar to previous experimental work and the acquired results indicated that a great agreement was found. Thirty-six specimen two-way slabs with dimensions of 1900 × 1900mm were modeled in this investigation. All four sides of the slabs are simply supported. The results displayed that the ultimate shear capacity of the slabs increases with hybrid steel fiber. Nevertheless, the ultimate capacity of the slabs has decreased due to an increase in the reinforcement ratio and slab thickness.

Application of Interval Analysis to Assess Concrete Cover Degradation in Accelerated Corrosion Tests.

This paper presents the application of interval algebra in affine formulation to assess damage propagation in test reinforced concrete elements subjected to accelerated corrosion of rebar, taking into account the uncertainty of parameters. Corrosion interactions were captured by introducing the interval tensor of the velocity of volumetric strain. Analysis of the model for limit values of velocities of volumetric strains (inf(ε¯˙V) and sup(ε¯˙V)) using the finite element method for locally and gradient-formulated concrete models with degradation, elastic, and elastic-plastic was conducted using ANSYS and ATENA software. Computer calculations were performed assuming a parameter uncertainty of 0, 10, and 20%. The results of the calculations were compared with the results of detailed tests of elements subjected to accelerated corrosion of reinforcement using an electrolyzer with full monitoring of the electrical parameters of the system. The obtained results of the calculations were verified using the Monte Carlo method, treating the model parameters as random variables with a uniform distribution.

Calibrating of a Simulation Model to Predict the Flexural Capacity of Pre-Stressed Concrete Beams

Simulation models based on finite elements are currently indispensable tools for predicting the structural behavior of both reinforced and pre-stressed concrete elements. This work develops a simulation model of structural linear elements of pre-stressed concrete, using the finite element method (FEM). The main aim was to calibrate the model to predict the flexural capacity of structural elements, and so be able to undertake a double optimization through the design and the resistant behavior of the elements. Different flexural experiments were conducted in laboratory conditions on real concrete elements of different types (pre-stressed joist and tubular pre-stressed joist). In parallel, the same structural elements were analyzed by MEF simulation to calibrate the model to the real experiments. FEM analysis was performed using the ATENA software developed by Červenka Consulting (Czech Republic), especially recommended for the analysis of structural concrete elements using non-linear methods. The model was calibrated using the results obtained in real load test experiments obtained in a loading frame of 500 kN capacity. The calibration analysis shows a good fit of the results to the actual test experiments, obtaining average errors of 6% in the analysis–experiment comparison. The results of the simulation suggest that to obtain the optimum strength levels for the different typologies analyzed, it is essential to control the pre-stressing losses in the manufacturing process of the joist. The flexural capacity of all elements can be increased by around 20–30% when the real pre-stressing losses are fitted to the theoretical ones estimated.

Experimental and Numerical Characterization of Non-Proprietary UHPFRC Beam—Parametric Analyses of Mechanical Properties

Fabrication of ultra-high-performance concrete (UHPC) is costly, especially when commercial materials are used. Additionally, in contrast to conventional concrete, numerical procedures to simulate the behaviour of ultra-high-performance fibre-reinforced concrete (UHPFRC) are very limited. To contribute to the foregoing issues in this field, local materials were used in the fabrication process, while accounting for environmental issues and costs. Micro steel fibres (L: 13 mm, d: 0.16 mm, and ft: 2600 MPa; L: length, d: diameter, ft: tensile strength) were used in 2% volumetric ratios. Compression and indirect tests were carried out on cylindrical and prismatic beams according to international standards. To further enrich the research and contribute to the limited simulation data on UHPFRC, and better comprehension of the parameters, numerical analyses were performed using the ATENA software. Finally, nonlinear regression analyses were employed to capture the deflection-flexural response of the beams. The results were promising, indicating cost-effective fabrication using local materials that met the minimum requirements of UHFRC in terms of compressive strength. Furthermore, inverse analysis proved to be an easy and efficient method for capturing the flexural response of UHPFRC beams.

Experimental and numerical investigations of textile-reinforced concrete thin-wall panel bolted connections

Textile Reinforced Concrete (TRC) is a novel building material that merges fine-grained concrete with textile fibers to produce a composite material exhibiting enhanced mechanical characteristics. This study examined the behavior of thin-walled TRC structures connected by bolts and found that the open box panel member is a promising solution for wall, floor, and roof applications. The investigation focused on three types of connections: moment joints, shear joints, and half-box connections. The study also revealed that bolt-to-edge distance significantly affects the bearing capacity of TRC structures. The location and type of cracks in moment-type joints depend on the number of bolts used during fabrication. All four specimens experienced damage at the bolted side in the half-box connection test, with significant cracks around the steel bolts. The specimens failed at about 74 % and 70.6 % of the original panel's bearing capacity. It could be concluded that the bolted connection was the weakest link in the structure. Improving the bolt structure or increasing the thickness of the ribs is necessary to maximize the panel's bearing capacity. Finite element models of the full panels and half-box connections on the ATENA software package were developed and verified with the experimental results. The proposed models accurately captured the load-carrying capacities, load-deflection relationships, and failure modes for both panels and connections.

A new shear test setup for determining shear strength of normal and high strength concrete

Since the start of the 20th century various investigators proposed different shapes, sizes of specimens to determine the shear strength of concrete and proposed several models. Several disagreements and discussions were surrounding the concept of shear strength, particularly in case of High strength concrete (HSC). In order to compare the shear strengths of Normal Strength Concrete (NSC) with High Strength Concrete, a “New shear test setup” was proposed in this study. From literature and different standard codes, it was found that, the shear strength of plain concrete becomes constant after certain compressive strength. Different authors and codes proposed different strength of concrete beyond which the shear strength becomes constant. The aim of the study was to find the compressive strength beyond which the shear strength becomes constant using the proposed shear test setup. In order to obtain the shear strength, 42 cubes of 150 mm × 150 mm × 150 mm of concrete of varying strength of 20 MPa to 80 MPa were cast and tested. The experimental results were compared with a numerical model based on FEM software ATENA and the existing models proposed in the literature. It was found from the experimental work that the shear strength became constant after a compressive strength of 50 MPa- 60 MPa. According to the shear strength results, there was a significant correlation between experimental results and results predicted using ATENA software. Moreover, the experimental results were compared with the shear strength values predicted by various national building codes and various shear models proposed using the different shear test setups. It was found that the experimental results closely match with the values obtained by AS: 3600–2018 equation and Mattock equation's based on the push-off specimen.

Modelling of corroded RC members subjected to four point bending test: A numerical study

Reinforced Cement Concrete (RCC) buildings are confronted with a wide range of environmental variables and consequences during their service life. Corrosion of steel reinforcement is the most common deteriorating process of Reinforced Concrete (RC) members. It is often regarded as one of the negative factors contributing to the deterioration of serviceability and durability. In general, numerous computations, mathematical simulations, and finite element models are used to determine the effects of reinforcement corrosion on the structural behaviour of RC members. Despite abundant experimental methods, accelerated corrosion tests are often adopted to save the resources and time necessary for conducting corrosion. In this paper, the modelling of corrosion in reinforced concrete members is performed using finite element (FE) software ATENA -GiD. The predominant aim is to analyze the strength reduction of corroded RC slabs subjected to a four-point bend test. The results obtained from the FE model prepared are compared with the experimental results obtained from the accelerated corrosion test and analytical results from the literature. Numerical ultimate load capacity and theoretical ultimate load capacity values are approximately 95 to 98 per cent accurate. It was concluded that the prepared FE model can be utilized to understand the behaviour of corroded RC slabs under four-point bending. The model can be utilized for different types and grades of concrete as well as reinforcement.

Non-Linear Analysis of Flat Slabs Prestressed with Unbonded Tendons Submitted to Punching Shear

This article describes a numerical study for the evaluation of the punching shear behavior of non-adherent prestressed flat slabs without shear reinforcement. Nonlinear three-dimensional models were used, along with the finite element method (FEA) through the ATENA software in order to validate the constitutive models adopted for concrete and steel. The numerical results were compared with the experimental results. The results revealed a good agreement among load capacity, deformations, and cracking panorama, as well as the relation between numerical and experimental failure loads. After validation, a parametric study was carried out to analyze the influence of tendon spacing, slab thickness, and column rectangularity in prestressed flat slabs. Finally, the results obtained in the numerical models in relation to the failure load were compared with the estimated values for the failure load according to the main normative predictions dealing with the flat slab system.

Thin-Layer Fibre-Reinforced Concrete Sandwich Walls: Numerical Evaluation

In this study, structural thin-layer sandwich walls (SWs) made of steel-fibre-reinforced concrete (SFRC) without conventional reinforcements were investigated. Other researchers have shown that SWs with thin wythes can be used as load bearing structures in low-rise buildings, thereby reducing the amount of concrete by 2–5 times if compared to conventional reinforced-concrete SWs. In most studies, relatively warm climatic regions are the focus, and thin-layer SWs with shear connectors to obtain a certain level of composite action are investigated. In almost no studies has sound insulation been evaluated. In this study, a numerical investigation of structural, thermal and sound insulation performances was carried out. The load-bearing capacities of composite and non-composite SWs are compared. Regions with the lowest five-day mean air temperature of −20 ∘C were considered. The characteristics of the SW are compared to the requirements given in relevant European and Latvian standards. The minimum thermal insulation for family houses varies from 120 mm to 200 mm, depending on the material. To ensure sufficient sound insulation, the average thickness of the concrete wythes should be around 60 mm, preferably with a 15 mm difference between them. Structural analysis of the proposed wall panel was performed using non-linear finite element analysis software ATENA Science. The obtained load-bearing capacity exceeded the design loads of a single-story family house by around 100 times, regardless of the degree of composite action.

Evaluation of the Failure Probability of a 2D RC Frame Subjected to Column Loss

Abstract: This study regards the evaluation of the failure probability of a symmetrical 2D reinforced concrete frame composed of 4 spans and 5 floors, in case of an accidental event which causes the central base column loss. The frame is an internal one of a typical building designed in a highly seismic area, characterised by a high ductility class. The frame is modelled in the non-linear finite elements software Atena 2D, accounting for both geometrical and material non-linearities. The uncertainties relevant to the problem are included by sampling both material and action variables, adopting the Latin Hypercube Sampling technique. To compute the failure probability associated to the accidental scenario, two sets of analyses are considered: the first set to compute the capacity of the structure against the column removal by means of displacement-controlled pushdown analysis; the second set to evaluate the demand in terms of external loads, properly combined within the accidental combination according to the codes. The external load is then amplified in order to include the dynamic effects characterising a scenario of a structural member loss. Finally, the probability of the demand exceeding the capacity is evaluated.

Determination of concrete fracture parameters using inverse analysis: Influence of the tensile softening model

The paper is focused on the identification of selected mechanical fracture parameters of concrete. An inverse analysis based on an artificial neural network is used for this purpose. In this approach the laboratory measurements are matched with the results gained by reproducing the same test numerically. The identification of mechanical fracture parameters is carried out from the records of three-point bending and wedge-splitting tests performed using three specimen sizes. The ATENA software is employed for the numerical simulation of the fracture tests. The material model with the exponential and bilinear tensile softening law is selected to govern the gradual evolution of localized damage. The obtained parameters are finally analyzed and discussed in terms of their dependence on the size of the initial uncracked ligament. The results show that both tensile softening models are able to capture the behavior of the specimens in the softening phase reasonably well. The tensile softening model does not affect the modulus of elasticity values but has a slight effect on the tensile strength and fracture energy. For the latter two parameters, both models detected the influence of specimen size on their values.

Development of Moment Coefficients For Two Adjacent Side Supported Slab By Using Yield Line Theory

The slab is a key and generally used structural component. The shape, arrangement, and stiffness of the supporting beams all have a significant role in the slab's performance.IS 456:2000 coefficients are only applicable to rectangular slabs with four non-yielding side supports. But due to architectural requirements, structural engineers are now confronted with a variety of complications, such as slabs supported on two adjacent sides. In the past analytical model was suggested for slab supported over two adjacent edges carrying uniformly distributed area load but design aids were not prepared. The analytical model presented herein to analyze two adjacent edges supported slab carrying uniformly distributed area load on its top edge using yield line analysis. It is also validated with well-established literature. Design aids are also prepared and validated with FE nonlinear analysis in software ATENA and the results are in favour.

Effect of connection transverse reinforcement on the behavior of GFRP-RC T-connections: Numerical investigation

This study numerically investigates the cyclic behavior of glass fiber-reinforced polymer (GFRP) reinforced concrete exterior beam-column (T-BC) connections (GFRP-RC T-BC connections) with varying amounts of transverse reinforcement (TR) in the connection panel. The amount of TR required to provide adequate confinement and shear strength to the GFRP-RC T-BC connections has not yet been fully understood. The primary objective of this study was to evaluate the effects of TR configuration and amount of TR on the load-drift ratio response, strain distributions and shear strength of the GFRP-RC T-BC connections. The numerical investigation was conducted using the numerical models developed in ATENA software and validated against the test results of four T-BC connections (one steel-RC and three GFRP-RC). The TR ratio and TR configurations (2 leg, 3 leg, and 4 leg horizontal stirrups) in the connection panel were the main parameters of the numerical study. Results of the numerical study indicated that increasing the TR ratio in the connection panel to 0.72% significantly enhanced the peak load, stiffness and drift ratio capacity of the GFRP-RC T-BC connection. Four leg TR configuration showed significantly better performance of the GFRP-RC T-BC connections due to the higher confinement factor than the other TR configurations. A shear strength equation was proposed for the GFRP-RC T-BC connections, which represents a linear relationship between shear strength and the TR ratio up to 0.60%, followed by stable shear strength of 0.85fc′ for a TR ratio up to 1.30%.

A study on validation of moment-curvature relationship of lime sludge-based blended cement concrete on numerical modeling (ATENA)

It is evident that the deformation capacity of any RCC structure is always very significant in the flexural design, other than the compressive strength aspect. When a structure is fully-loaded, adequate deformation capacity available in the structure can ensure safety. The present study focused on the flexural behavior of RCC beams consisting of industrial by-products from the paper industry known as lime sludge. The parameters considered in the present study include the strength of control mix concrete (30 MPa, 50 MPa, and 70 MPa), the combination of mineral admixtures (fly ash, silica fume, and lime sludge) as a partial replacement of cement in the preparation of blended concrete mix and type of reinforced section (under-reinforced and over-reinforced beams). Beams of size 1800 mm × 100 mm × 200 mm were cast and tested for flexural strength and the moment-curvature relationships. The improvement in the moment carrying capacity of under and over-reinforced RCC beams was noticed to be 40.12 %, 30.64 %, 22.98 %, 34.80 %, 30.13 %, and 19.44 % in 30 MPa, 50 MPa, and 70 MPa concrete respectively. The curvature of under and over-reinforced concrete RCC beams has improved by 7.64 %, 7.58 %, 7.44 %, 10.30 %, 7.30 %, and 5.15 % in 30 MPa, 50 MPa, and 70 MPa concrete respectively. Validation of the experimental M-ϕ relationship was obtained through the numerical model using FEM-based software ATENA. The experimental results of the moment-curvature relationship are in good agreement with the numerical model.

Hybrid Steel Fiber of Rigid Pavements: A 3D Finite Element and Parametric Analysis

Rigid pavements have high compressive strength and low flexural strength due to the brittleness of concrete. This leads to the formation of cracks easily under the applied loads of vehicles; therefore, the design of concrete pavements usually leads to an increase in the high thicknesses. Hybrid steel fibers are used in concrete to increase flexural strength and minimize crack formation. Using concrete with steel fibers in pavements reduces the required concrete thickness. In recent decades, the application of the finite element method to predict the behavior of rigid pavements has increased. This study investigates the influence of hybrid steel fiber on the behavior of rigid pavements; a finite element modeling approach is used to simulate the case study. Several parameters are entered and investigated in this study, including the proportion mix of hybrid fiber concrete (HFC), which contains 0.2% macro synthetic fibers and 0.68, 0.8, and 0.96% of steel fibers, compressive strengths of 25, 35, and 45 MPa, slab thicknesses of 150, 200, and 250 mm, and the load of the tandem axle at the edge of mid slab on the Winkler foundation. The ATENA software package is used to perform a nonlinear finite element analysis. Thirty-six rigid specimen pavements with dimensions of 3600 × 3600 mm were modeled in this investigation. The results showed that the addition ratio (0.68 + 0.2)% of hybrid fibers is more effective in improving the load bearing capacity with a slab thickness of 150 mm and 25 MPa compressive strength.