General Purpose Finite Element Research Articles

Evaluation of various FRP strengthening configurations for RC beam-column joints

There are several methods for strengthening reinforced concrete joints. Due to the unique properties of FRP (Fiber Reinforced Polymer) composites, the use of FRP laminates is one of the most commonly used techniques. The high cost of preparing concrete surfaces and attaching FRP laminates is a restricting factor for its application in reinforced concrete joint retrofit. Therefore, determining proper configurations that reduce the needed FRP material, as well as the surface preparation required for attaching FRP is an important factor in decreasing the strengthening cost. The proper arrangements of FRP strips can improve their performance in the rehabilitation and retrofit of reinforced concrete joints. To determine the proper configuration of FRP strips, finite element modeling was employed. The connection specimens are modeled in ABAQUS general-purpose finite element software and are classified into 10 general groups. To improve the performance of FRP strip configuration, the determined arrangement is investigated for different thicknesses and different widths of the FRP strips, and their results are compared with those of the connection specimen strengthened with full FRP coverage. The analysis results indicated that the load-bearing capacity of the connection retrofitted by the combined configuration of X-shape and orthogonal strips of FRP is close to that of the specimen with full FRP coverage. In this suitable configuration, the required FRP strips are reduced by about 30% , which decreases the cost and construction works needed for concrete joint rehabilitation.

Behaviour of glass and sisal incorporated gypsum based composite panels under axial compression–experimental and numerical study

Gypsum based composite (GBC) Wall panels are being used in precast concrete industry as the panels are low cost, energy consumption, good habitability, and good fire resistance. This paper presents the studies related to gypsum based composite panels incorporated with glass and sisal fibers. The main objective of the research is to investigate the capacity of gypsum based composite wall panel subjected to axial compression with and without eccentricity. The panels were loaded in axial compression with and without eccentricity. Gypsum, white cement, fibres (glass fibers or sisal fibers) are used to prepare composite panels of size 1000 (length) × 500 (width) × 125 (thickness) mm. Total four panels (two with glass fibers and two with sisal fibers) were tested under axial compression (two panels without eccentricity and two panels with eccentricity) were tested under load control. From the tests, it was observed that the eccentric load application on the panels is very significant compared to normal load application. Significant decrease in the ultimate load is observed for the case of panels subjected to eccentric loading. Nonlinear finite element analysis for the fibre incorporated (E-glass and sisal) gypsum based composite panels under axial compression has been carried out by using the general purpose finite element software.

A novel resilient system of self-centering precast reinforced concrete walls with external dampers

The seismic vulnerability of concrete structures has prompted the development of innovative approaches to enhance earthquake resistance. Recent earthquakes have demonstrated the challenges of repairing concrete buildings damaged beyond feasible restoration. In response, research in structural engineering has increasingly focused on damage-resisting reinforced concrete walls, offering improved self-centering behavior and damage mitigation compared to traditional counterparts. Self-centering walls, employing a rocking mechanism, exhibit effective damage minimization and residual deformation reduction. This study introduces a robust approach to precast reinforced concrete walls, comprising a precast reinforced concrete shear wall integrated with an external energy dissipation component. The energy dissipation element, a reinforced concrete column attached externally on both sides of the wall, acts as a new damage-limiting component with enhanced energy dissipation capacity. Utilizing the general-purpose Finite Element (FE) software ABAQUS, a three-dimensional simulation of experimentally investigated self-centering precast reinforced concrete walls was developed. The finite element model was validated and subsequently employed to assess the performance of the proposed system under cyclic loading. Various design parameters of the reinforced concrete energy dissipation element, including cross-sectional area, wall height proportion, concrete strength, primary reinforcement yield strength, and reinforcement ratio, were investigated. Additionally, the suggested system underwent cyclic loading in multiple scenarios simulating subsequent earthquakes. The finite element analysis results indicate that the proposed method, with a well-designed energy dissipation element, ensures minimal damage, a controlled increase in lateral resistance, sufficient energy dissipation capacity, and the required resilience following successive seismic events.

Extraction of Equivalent Stress Versus Equivalent Plastic Strain Curve of Necking Material in Tensile Test Without Assuming Constitutive Model

Abstract An algorithm for extracting the equivalent stress versus equivalent plastic strain curve of a necking material in tensile test is proposed (the curve is called here the equivalent-plastic (EP) stress–strain (SS) curve). The presented algorithm traces the force–elongation curve via iterative finite element (FE) simulations without assuming a constitutive model and is suitable for a general-purpose FE solver available to a general audience. In the FE simulation and experiment, a slightly tapered geometry was employed around the specimen center to stably initiate necking there. The proposed algorithm and mentioned necking initiation method have been applied to extracting the EP SS curve of a high-strength steel material using an axisymmetric specimen. Because necking was initiated stably in simulation at the specimen center for a range of mesh sizes, the convergence of the extracted EP SS curve with the mesh size could be successfully verified. The EP SS curve of the tested material was extracted up to an EP strain of 0.85 with average strain intervals of approximately 2.5 mili-strain. The error values were less than 0.2 and 0.1% after four and seven FE simulations, respectively. The presented algorithm and necking initiation method in simulation can also be used for simultaneously quantifying the fracture EP strain of a necking material in the tensile test.

Analytical and numerical investigation of second-order infinitesimal mechanism in rigid origami

This study investigates second-order infinitesimal mechanisms and bifurcation paths of rigid origamis with multiple-degree-of-freedom mechanisms. A truss model, consisting of pin-connected rigid bars, is employed for the infinitesimal mechanism analysis. The conditions for the existence of a second-order infinitesimal mechanism are analytically solved to investigate the combinations of the infinitesimal mechanism modes that are the potential finite mechanisms. Analytical solutions for simple crease patterns show the bifurcation of the deformation paths at the flat state, some disappeared combinations of the mechanism modes in a single path, and the relationship between the nodal displacement and axial force distribution. This comprehensive analysis, using analytical solutions, lays the foundation for understanding bifurcation and finite mechanism of rigid origami, which have not yet been fully explored. These properties are also verified in the finite deformation paths generated by large deformation analysis of a frame model consisting of frame members and hinges, which is suitable for the analysis using general-purpose finite element analysis software. The second-order infinitesimal mechanisms found in this study are confirmed to be able to be extended to the finite mechanisms.

Investigation of bending behavior of foam core sandwich plates with different face and core materials at different layer thicknesses

Sandwich plates consist of a total of three layers with a thick core layer between two thin face layers. While the face layers provide resistance against bending, the core layer provides resistance against shear. General purpose finite element software programs are one of the most convenient and widely used analysis procedures for investigating the behavior of structures. Many design parameters can be easily examined by these analysis programs. In this study, the bending behavior of simply supported sandwich square plates on four sides with a ratio of core layer thickness to face layer thickness between 7 and 9 was investigated by using the general purpose finite element software program. The effect of the thickness change was investigated by changing the face and core layer thicknesses of the sandwich plates with a fixed total thickness. At the same time, the face and core materials were changed and the most suitable design in bending behavior was revealed. For this purpose, 110 analyzes were performed with 2 different face materials, 5 different core materials, 11 different thickness ratios, and the results were presented with graphics.

Influence of elevated temperature on buckling capacity of mild steel-based cold-formed steel column sections– experimental investigation and finite element modelling

PurposeThe capability of steel columns to support their design loads is highly affected by the time of exposure and temperature magnitude, which causes deterioration of mechanical properties of steel under fire conditions. It is known that structural steel loses strength and stiffness as temperature increases, particularly above 400 °C. The duration of time in which steel is exposed to high temperatures also has an impact on how much strength it loses. The time-dependent response of steel is critical when estimating load carrying capacity of steel columns exposed to fire. Thus, investigating the structural response of cold-formed steel (CFS) columns is gaining more interest due to the nature of such structural elements.Design/methodology/approachIn this study, experiments were conducted on two CFS configurations: back-to-back (B-B) channel and toe-to-toe (T-T) channel sections. All CFS column specimens were exposed to different temperatures following the standard fire curve and cooled by air or water. A total of 14 tests were conducted to evaluate the capacity of the CFS sections. The axial resistance and yield deformation were noted for both section types at elevated temperatures. The CFS column sections were modelled to simulate the section's behaviour under various temperature exposures using the general-purpose finite element (FE) program ABAQUS. The results from FE modelling agreed well with the experimental results. Ultimate load of experiment and finite element model (FEM) are compared with each other. The difference in percentage and ratio between both are presented.FindingsThe results showed that B-B configuration showed better performance for all the investigated parameters than T-T sections. A noticeable loss in the ultimate strength of 34.5 and 65.6% was observed at 90 min (986℃) for B-B specimens cooled using air and water, respectively. However, the reduction was 29.9 and 46% in the T-T configuration, respectively.Originality/valueThis research paper focusses on assessing the buckling strength of heated CFS sections to analyse the mode of failure of CFS sections with B-B and T-T design configurations under the effect of elevated temperature.

Performance-based wind engineering assessment of a telecommunication mast utilizing Bayesian extreme wind velocity model

A promising design concept, the performance-based wind engineering methodology is adopted, implementing a finite element model (FEM) to analyse the structural behaviour of a telecommunication steel lattice mast. The integration of site-specific wind loading models into the standardized FEM-based design can be a powerful tool for design engineers. The tower being investigated, located in Central Hungary, is equipped with sensors to measure wind velocity and strains in chord members. The stochastic modelling of the extreme wind velocity, i.e., the basic wind velocity is assessed using the peak-over-threshold approach with an automated threshold selection method. To enhance the accuracy of the analysis, Bayesian inference is employed, combining the information from a relatively short duration of measurements collected at the tower site with a more extensive dataset from measurement locations across the country. Numerical model of the telecommunication mast subjected to wind loading is developed in a general-purpose finite element software. The probabilistic design system module is applied for performing probabilistic calculations of both serviceability criterion and load-bearing capacity of the structure using Monte Carlo simulation with Latin hypercube method. Numerical results are compared and validated with measurement data. The accuracy of wind load assessment is examined in this study, considering both the standardized design method according to EN 1993-3-1 and wind tunnel testing. The main objective is to demonstrate the potential of integrating the Performance-based Wind Design framework with a monitoring system and a finite element model, highlighting their combined benefits.

Farklı açılardaki çeşitli çokgen delikli kare plakların burkulma analizi

Buckling of the plates is of great importance in design of structures. If the plate has a hole because of necessity, hole area and shape also affect the critical buckling loads. In this study, buckling analyses of perforated simply supported square plates with various perforation patterns and different loading types were investigated. Three different perforation patterns as circular, hexagonal and square with different orientations were considered. In order to investigate the slenderness ratio effect, samples were calculated with three different ratio values of 100, 20 and 10. The samples were loaded with four different in-plane loads to examine the effect of loading type. Analyses were performed by using a general purpose finite element program and critical buckling loads were determined depending on the orientation angles for square plate models with different hole perforations. The critical buckling load is independent from the orientation angle for circular perforated plates but depends on for hexagonal and square hole perforations. For these plates buckling analyses were performed for different orientation angles of 0 degrees to 90 degrees. The results show that the calculated critical buckling loads did not remain the same although the hole areas were the same.

Effect of masonry infill on the response of reinforced concrete frames subject to in-plane blast loading

This paper presents a numerical study investigating the effect of masonry infill on the response of reinforced concrete (RC) frames subject to in-plane blast loading. Three-dimensional single-bay single-story masonry infilled reinforced concrete (MIRC) frames were modeled, in which a simplified micro-modeling approach was adopted for the masonry infill. The surface-based cohesive model was employed between the expanded brick units by adopting the traction-separation law. A non-integral modeling approach was considered with an appropriate contact algorithm between the infill wall and bounding RC frame. The dynamic material models with explicit dependency on strain rate were incorporated in the finite element (FE) models and validated against the experimental test data. The developed FE models of bare RC and MIRC frames were subjected to surface blasts with variable scaled distances representing the far-field, near-field, and close-in blasts. The effect of masonry infill on the response of RC frames subject to in-plane blast loading was investigated using the general-purpose FE software ABAQUS without employing user-defined subroutines. The blast response was characterized using displacements, energy dissipation, strain localization and accumulation, stiffness degradation, and damage modes. Results highlight the beneficial influence of masonry infill in reducing the local deformation and altering the failure modes of RC frames subject to in-plane blasts. However, results suggest that the effects of infill on the overall structural response, including axial, flexural, and shear demands, must be considered during the design of bounding RC frames. Furthermore, parametric studies were carried out based on varying masonry bonding patterns and wall thickness, number of bays and stories, and masonry infill heights, and provided conclusive remarks.

T-STUB COMPONENT BEHAVIOR OF THE BEAM TO COLUMN BOLTED FLANGE CONNECTION BASED ON A NUMERICAL ANALYSIS AND EN 1993-1-8 DESIGN CODES

Nodal joints uniting separate elements of steel structures are the most important parts of the whole structure. For the tensile zone of a connection, the study of its stress-strain state up to the limit of exhaustion of its bearing capacity is of greatest interest. There exist different design approaches to obtain the ultimate capacity of a tension-zone of a steel joint, both numerical and analytical methods. In the presented paper this has been realized using a general-purpose finite element analysis package. The application of numerical methods for modelling the tensile performance of the T-component makes it possible to compensate for the lack of data on full-scale experimental studies. Despite the widespread use of finite element analysis packages, there are still no clear guidelines for creating numerical models of such connections. Numerical analysis has taken into account important effects such as the nonlinear behavior of the material and the contact interaction of its individual elements. Finite element analyses should represent the reality in an accurate way while not being too time consuming to be set up and run. That means appropriate parameters and phenomena, such as element types or loading procedure, should be compiled in a way suitable to the problem at hand, so that the discrepancy between reality and model is sufficiently small. A FE-model with wrong representation of reality can be solved correctly with FEA, but will thereby provide inaccurate results. Therefore, one needs understanding about FE parameters and their influence on time to execute the procedure effectively. When these conditions are met, the possibility to analyze larger number of T-stubs with less user modification opens up. The analytical method for the calculation of the properties of a bolted joint established by the structural Eurocodes proposes the T-stub as a component for the characterization of the tension and compression zones in moment joints. Using the component method, which is the basis for the calculation of joints according to the EN 1993-1-8 design codes, the value of the ultimate tensile force for the T-shaped component of the dimensions adopted in the work was obtained; the obtained values of the ultimate forces were further used in the numerical experiment. Keywords: end-plate connection, numerical model, T-stub component, bolt connection.

Finite Element 3D Simulation Experiment on Shield Excavation

Shield technology is widely used in subway excavation projects, and the excavation of soil causes surface settlement, which affects the normal use and safety of the tunnel itself and surface buildings. Using Abaqus, a large general-purpose finite element software, a three-dimensional excavation finite element model of the shield tunnel is established, and the dynamic excavation process of the shield tunnel is finely simulated to derive the soil displacement settlement law during the shield excavation, and to discuss the influence of the change of the simulated values of the post-shield grouting pressure and support pressure on the maximum settlement (uplift) of the ground surface. The conclusions of the study have important theoretical and practical engineering significance.

The collapse mechanism of steel framed structure exposed to parametric design fire and travelling fire scenarios

The structural steel elements exposed to fire is susceptible to collapse owing to the temperature sensitivity of steel sections. The technical advances in the field of fire dynamics have enabled to simulate realistic fire scenarios to determine the performance of structural elements. However, a detailed parametric study is necessary to increase the knowledge on the performance of structural steel elements to various design fires. In this study, the behaviour of three-dimensional steel framed structures subjected to the action of standard fire and parametric fire as well as the travelling fire scenarios are analysed. In this work, the general-purpose finite element software ABAQUS is used to perform the analytical study. The material models calibrated with experiments were adopted for conducting parametric study. The results of the analytical study show, the uniform exposure of temperature to compartment is the most critical scenario as the compartments exposed to uniform fire is causing total collapse of structure. Uniform exposure of parametric fire to compartments is found to be less critical as the cooling phase of fire enabling more resistance against total collapse of the structure. Also, the uniform exposure of standard fire, a small resistance is observed from the unexposed columns. However, the structure exposed to parametric fire was sustained large deflections. The structure exposed to travelling fire is found to receive greater resistance before collapse. However, the structure found to collapse as the fire reaches final compartment.

Optimal Domain-Partitioning Algorithm for Real-Life Transportation Networks and Finite Element Meshes

For large-scale engineering problems, it has been generally accepted that domain-partitioning algorithms are highly desirable for general-purpose finite element analysis (FEA). This paper presents a heuristic numerical algorithm that can efficiently partition any transportation network (or any finite element mesh) into a specified number of subdomains (usually depending on the number of parallel processors available on a computer), which will result in “minimising the total number of system BOUNDARY nodes” (as a primary criterion) and achieve “balancing work loads” amongst the subdomains (as a secondary criterion). The proposed seven-step heuristic algorithm (with enhancement features) is based on engineering common sense and observation. This current work has the following novelty features: (i) complicated graph theories that are NOT needed and (ii) unified treatments of transportation networks (using line elements) and finite element (FE) meshes (using triangular, tetrahedral, and brick elements) that can be performed through transforming the original network (or FE mesh) into a pseudo-transportation network which only uses line elements. Several examples, including real-life transportation networks and finite element meshes (using triangular/brick/tetrahedral elements) are used (under MATLAB computer environments) to explain, validate and compare the proposed algorithm’s performance with the popular METIS software.

Experimental and Numerical Behavior of Encased Pultruded GFRP Beams under Elevated and Ambient Temperatures

In this research, experimental and numerical studies were carried out to investigate the performance of encased glass-fiber-reinforced polymer (GFRP) beams under fire. The test specimens were divided into two peer groups to be tested under the effect of ambient and elevated temperatures. The first group was statically tested to investigate the monotonic behavior of the specimens. The second group was exposed to fire loading first and then statically tested to explore the residual behavior of the burned specimens. Adding shear connectors and web stiffeners to the GFRP beam was the main parameter in this investigation. Moreover, service loads were applied to the tested beams during the fire. Utilizing shear connectors, web stiffeners, and both enhanced the load-carrying capacities of the encased beams by 100.6%, 97.3%, and 130.8%, respectively. Comparisons between the burned and unburned peer beams were presented with losses in the load-carrying capacity of the burned beams. These losses were the highest in the cases of shear connectors and web stiffeners due to the obtained severe damage, which led to more reductions in the residual behavior of the burned beams. Numerical analyses were performed using the general-purpose finite element (FE) ABAQUS package to conduct a parametric study. The investigated parameters included the effect of the exposure duration and the temperature level. The results of the FE analysis showed good agreement with the experimental results. Additional reductions in the residual capacities of the fire-damaged beams were observed due to exposure to longer fire durations. The improvements in the beam capacities due to using shear connectors and web stiffeners relative to the reference beams under the same exposure time decreased as the exposure duration increased. Furthermore, increasing the temperature to 700 °C, 800 °C, 900 °C, and 950 °C caused reductions in the residual capacities by about 25%, 45%, 70%, and 80%, respectively, for the encased beams in comparison to their peers at ambient temperature.

Design of a typical aerospace interstage structure using orthogrid/waffle configuration

The term interstage refers to a primary structure housed between two stages of a launch vehicle. It is configured to withstand the varying magnitudes of loads during the flight. In this study, an interstage cylindrical shell structure of a Launch Vehicle is designed with isogrid and orthogrid configurations, which are integral-rib-stiffened-skin configurations to have mass-optimised aerospace structures. Design based on closed form solutions, parametric optimisation and numerical analyses to validate the design are carried out for both the configurations and results are compared. Static - linear, static - nonlinear, linear eigen value buckling analysis and non-linear static riks analysis are the different kinds of numerical analyses carried out for estimating the load carrying capacity of the structural configuration under study. The objectives of this work include understanding different aerospace structural configurations, studying grided structures in depth, and using these two to model Orthogrid structures mathematically and design a typical launch vehicle interstage structure using this Orthogrid configuration. Abaqus, a general-purpose Finite Element software is used for the numerical validation. Study compares the results of both the configurations and concludes that orthogrid configuration can be designed with lesser mass for the interstage configuration, loads and kinematic conditions considered for the design problem. The least mass configurations corresponding to each configuration are obtained through parametric design iterations. Various numerical calculations are used to validate these results. The study's findings show that for the geometry, loads, and boundary conditions taken into account, orthogrid design provided superior mass optimisation than isogrid configuration.

A proposed approach for Pin-Fuse connections strengthened with pre-tensioned cables

A Pin-Fuse connection dissipates energy through a friction-slip mechanism during powerful earthquakes. Pin-Fuse connections are an innovative system that can be replaced after earthquakes and can sustain seismic energy with less harm to beams and columns. Herein, the monotonic response of the Pin-Fuse connection system strengthened by pre-tensioned cables is investigated. The strength, force–displacement diagram, and moment-rotation curve of the connection have been examined with various friction coefficients of 0, 0.6, and 0.9 together with various pre-tensioned cable forces. The general-purpose finite element program ABAQUS has been utilized to model the behavior of Pin-Fuse connections. The available test is used to validate the ABAQUS model. The result shows that in the systems with a friction effect, the presence of the pre-tensioned cables reduces the beam’s deflection and increases the tolerable bending moment of the system. The more the value of the pre-tensioned force, the more the system’s bearing capacity.

Experimental and Numerical Study of the Behavior of RC Shear Wall with Opening Using Concealed Stiffeners

A shear wall becomes weak when an opening is provided in it. It is important to provide some arrangement in the shear wall having an opening for recovering strength loss due to the opening. It may be recovered by providing some steel profiles around the opening or at weaker sections in the shear wall having an opening. At first, the identification of weaker sections in the shear wall having an opening is important and then, the wall can be made stronger as the shear wall without an opening by strengthening weaker sections. In the present study, the performance of a shear wall having an opening subjected to horizontal cyclic loading along the plane of the shear wall in the presence of concealed stiffeners is investigated. The reduced models of shear walls with openings were tested under axial and lateral load conditions. Load-carrying capacity, deformation behavior and strain behavior of shear walls were studied with experiments and the validation of the results was made with general-purpose finite element software ANSYS. Significant improvements were observed in strength, deformation and strain behavior of a shear wall having a central opening using concealed reinforced concrete (RC) stiffeners and steel tube stiffeners. KEYWORDS: Shear wall, Strength, Stiffness, Strain, Openings, Stiffeners.

Numerical analysis of reinforced concrete beams subjected to impact loads

Abstract Numerical models for impact load assessment are becoming increasingly reliable and accurate in recent years. The processing time duration for such analysis has been decreased to an acceptable level when combined with modern computer hardware. The aim of this study was to represent a simulation technique and to verify the validity of modern software in measuring the response of reinforced concrete beam strengthened by carbon fiber-reinforced polymer (CFRP) sheet subjected to impact loads at the ultimate load ranges. In this investigation, ABAQUS/Explicit Software’s nonlinear finite element modeling had been used. The response of the impact force–time history and the displacement–time history graphs were compared to the existing experimental results. The adopted general-purpose finite element analysis is verified to be capable of simulating and accurately forecasting the impact behavior for structural systems. In addition, a parametric analysis was carried out to gain a better knowledge of the performance of reinforced concrete beams under impact loading. Four parameters had been changed among the analyzed beams such as impact velocity, impact mass, CFRP sheet thickness, and compressive strength of concrete. Generally, it has been found that using a CFRP sheet in strengthening reinforced concrete beams can greatly improve the members’ impact behavior by improving stiffness as well as increasing load-carrying capacities. The enhanced performance characteristics of strengthening beams under impact loads correlate with the applied kinetic energy and CFRP thicknesses. Finally, for beams with high compressive strength, the deflection values were reduced because of the increase in stiffness.

Design and Analysis of Automobile Disc Brake using ANSYS

The application of disc brake in the growing automotive world is considered a major automotive performance factor to be considered while designing any automobile class and variants. A disc brake is one of the essential components in any automobile as it is used to turn down the speed of the automobile. During braking operation, the braking pads and discs are undergoing severe conditions of wear and high temperature. To prevent harm to the disc brake or other components, the heat generated by this disc brake must then be released into the environment. Therefore, it is crucial to provide effective heat dissipation to the environment. Increasing the surface area where heat is dissipated into the environment is one potential solution. Comparison can be done for deformation, stresses, temperature etc. form the three materials to check which material is best. Catia is a 3d modeling software widely used in the design process. ANSYS is general-purpose finite element analysis (FEA) software package. Finite Element Analysis is a numerical method of deconstructing a complex system into very small pieces (of user-designated size) called elements. The project aims to model a disc brake. Structural and Thermal analysis is done on the disc brake A proper rotor design and superior heat-dissipating material provide better performance during the braking mechanism. In this project, the optimal arrangement of holes, slots, and cut sections curved are studied by using Ansys software.