General Purpose Finite Element Software 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.

Behavior of container berth structure under the influence of environmental and operational loads

Abstract Container docks, which are an essential component of the marine berth, are exposed to loads from various sources, such as self-weight, operation, and environment. In this study, four sets of combined loads to which the container berth is exposed were selected at the Um-Qaser Port in southern Iraq. The berth was constructed more than 40 years ago, which has to be verified according to latest specifications, and each set of combined loads was analyzed in three cases. In the first case, the piles were assumed to be fixed at the seabed, and in the second and third cases the piles were modeled as embedded in elastic and elasto-plastic sandy soil, respectively. The general-purpose finite-element software ABAQUS was used to model the various components to determine the maximum stresses, displacements, axial forces, shear forces, and bending moments due to dead, live, operate, berthing, mooring, waves, and seismic loads. It has been demonstrated that the impact loads of ships have a more significant impact on the structure compared to other loads. The calculated displacement when the piles are assumed to be fixed at the seabed level may be reduced by 50–94% of that calculated when the soil is modeled, meaning that assuming fixed piles yields inaccurate results, especially for deck displacements. However, this assumption was verified to yield reasonable results for shear forces at the pile head. It could also be noted that the elasto-plastic model of soil was more sensitive than the elastic model in displacement by 0.4–8% and bending moment by 0.3–34%, while it is less sensitive in axial force by 3–8%. The aim of this study is to obtain knowledge on the behavior and efficiency of container berth under the influence of different loads and the environmental conditions surrounding it.

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.

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.

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.

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.

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.

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.

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.

Discrete shear projection method for mechanical buckling analysis of FGM sandwich plates

This paper deals with the mechanical buckling analysis of functionally graded material (FGM) sandwich plates using quadrilateral element Q4γs based on the discrete shear projection method (DSPM) to avoid shear locking. The element has four-node and five degrees of freedom per node. It allows modelling two types of FGM sandwich plates, i.e. type A with a homogeneous core and FGM face sheets, and type B with homogeneous top and bottom layers and an FGM core. Different thickness schemes have been considered leading to symmetrical or unsymmetrical geometrical stacking. The paper focuses on the buckling in simply supported square plates under uniaxial or biaxial loads. The linear classical buckling theory (LCBT) is retained to evaluate the critical loads. The results obtained by the Q4γs element are compared with those reported by Zenkour (2005) and using another in-house finite element based on DKMQ and DKQ elements. All results are in good agreement when the LCBT is used to define critical loads, but the paper includes selected non-linear analysis based on the general-purpose finite element software ABAQUS. The results show the limit of validity of the LCBT for unsymmetrical stacking in the sandwich of type A and all sandwich of type B.

Response Analysis of a Ballasted Rail Track Constructed on Soft Soil by 3D Modeling

The displacement, stress, and strain distributions of railway embankments on the soft deltaic deposit of the Ganges–Brahmaputra floodplain are investigated. A numerical model developed in general-purpose finite element software is used to simulate the design train load on a deltaic deposit for a 100 km/hr rail speed. The numerical analysis analogy is grounded in the spring model, where a beam under the unit load is modeled based on the Winkler foundation model concept. In the moving load simulation on soil, the static point load relating to the axle load is assigned in the form of a dynamic multiplier, determined using auxiliary software. The calculated shear force in terms of the influence line is applied as a dynamic multiplier. The numerical results demonstrate that under a dynamic train load, the loose ballast undergoes larger and more erratic displacement than the subballast. Comparative analysis between varying subballast stiffnesses shows that stiffer subballast yields smaller displacements. Moreover, a high subballast stiffness can counterbalance the potential of forming permanent deformation by generating lower strains. However, a stiffer subballast does not play a prominent role in reducing the displacement of ballast or vertical stresses. The subgrade is found to carry the maximum load, withstanding the maximum vertical stress; thus, the importance of using an improved subgrade with higher stiffness is also observed. A greater subgrade stiffness improves its load-carrying capacity but fails to reduce the tension responsible for the lateral spreading of the soft subsoil. To reduce the high radial strain, the effects of improving the stiffness properties of two immediately adjacent soft soil layers are numerically investigated. The improvement of subsoil alone is effective in reducing the radial strain, whereas the improvement of both subgrade and subsoil produces further reductions. The critical train speed generating the maximum displacement is identified as 120 km/hr, and the dynamic velocity amplitude decreases with depth. Finally, an allowable limit of rail embankment settlement on a soft deltaic deposit is observed.

Moment Rotation behavior of Top and Seat Angle Connection with Angle Stiffeners

The design specifications for seven commonly used semi-rigid steel connections have been embodied in Indian Standard Code of Practice for General Construction in Steel (IS800:2007). Bolted connections are proved to be efficient by several researchers for its energy dissipating capability under reversal of loading; among them top and seat angle (TSA) connection has higher capacity. An attempt has been made to investigate the behaviour of stiffened TSA connection by finite element analysis in this research. Previously published experimental specimens of TSA connection (RAMAN 2005) semi-rigid TSA bolted connection and their results have been considered to develop 3D Non-linear Finite Element (FE) model and analyses have been executed using the general purpose FE software. The M-?r behavior of numerical analyses are compared with that of the experimental results and thus, the FE model is validated. Further studies are carried out on TSA with all angles stiffened and TSA with angles subjected to tension alone are stiffened. The FE analysis results showed that TSA connection with only tension angles stiffened behave similar to that of TSA connection with all angles stiffened i.e., the stiffeners provided in compression angles does not contribute to the stiffness and connection capacity. The plastic flexural resistance of stiffened TSA connection has enhanced by 30% to that of TSA connection and the ratio of initial stiffness of stiffened TSA to the unstiffened TSA is found to be 1.25. So, the stiffened TSA connection is proved to be efficient in terms of both capacity and failure. The further studies have been carried out to investigate the influence of stiffener properties on the M-?r mechanism of the connection and the results showed that thickness of stiffener equal to the beam web thickness is more efficient.

Numerical modeling and nonlinear analysis of semi-rigid jointed steel frames

This paper investigates the effect of semi-rigid connection, geometric nonlinearity and material nonlinearity in steel frame analysis. To study the independent and combined effects of different nonlinearities, elastic and inelastic analyses are carried out using general purpose finite element software SAP2000. Connections are modeled as rotational springs and frame as one dimensional beam element. Verification and application of the simplified numerical model developed in the present study is demonstrated by considering different examples and comparing the results of present study with those available in the published literature. Numerical alternatives, key features about modeling and necessary input parameters are discussed in detail. Rotational springs are characterized by linear, bilinear, multi-linear or nonlinear moment-rotation relationships of the connection. Results in terms of beam moment and nodal displacement are presented for both elastic and inelastic analyses. With the increase in connection flexibility, beam mid-span moments and displacements increase, but beam-end moments decrease. It is observed that the influence of connection nonlinearity dominates over material and geometric nonlinearities.

Elastic buckling of simply supported stiffened steel plates with circular opening

Steel plates are used as the main components of steel elements in many structures. Openings in steel elements may exist for maintenance or inspection purposes in addition to creating paths for different fixtures such as air conditioning, pipes, and facilities. The structural performance of plates with openings is different from that of solid plates when subjected to axial compressive load. Openings affect local buckling, lateral torsional buckling, and shear of plates. Adding stiffeners around openings is a common engineering practice to strengthen plates. However, different design codes and guides provide estimates of the flexural and shear capacity of beams with no clear formulas for the influence of such openings on axial buckling strength. In this study, a parametric study has been performed using general-purpose finite element software, ANSYS, in order to study the effect of using stiffeners around circular opening in simply supported axially loaded plates on the elastic buckling behavior. Different parameters were considered including the aspect ratio of the plate, opening diameter, opening position in both horizontal and vertical directions, and stiffener’s dimensions. The results of the extensive parametric study are used to propose an empirical design formula considering the different studied parameters.

Implementation and Validation of Casting Simulation Methodology for Diagnostics of Lamellar Graphite Iron

This paper describes and validates a methodology for implementation of full-scale sand-casting simulation in a general-purpose finite element software, including mold filling, heat transport, solidification kinetics, chemical microsegregation and prediction of microstructure and material properties. The solidification model, customized for gray cast iron, includes novel methods for handling interaction between parallel dendritic and eutectic solidification modes and its impact of their interaction on the final microstructure. The validation involves a previously published gray iron casting experiment and involves comparison of simulated and experimental cooling curves, microstructure parameters and tensile strength. We believe that this is valuable to researchers and engineers seeking to improve the state of the art of casting simulation tools.

Finite element solution of electro-magnetic-thermo-chemical problem in microwave assisted pultrusion processes

New finite element models and algorithms are developed for a solution of coupled electro-magnetic-thermo-chemical problem arising in microwave assisted pultrusion processes. In the first algorithm stage, the microwave set-up is predefined according to the requirements on energy-effectiveness and homogeneity of generated absorption field, in the second – an iterative procedure preserving the dependence of dielectric material properties on microwave frequency, temperature and degree of cure is applied to avoid resin overheating and flow from the die exit, and to guarantee a required profile quality. These holistic simulation tools are built by using the general-purpose finite element software ANSYS that makes available various modelling and analysis features of the finite element package and results in considerable savings in design time and costs. To demonstrate features and benefits of electromagnetic heating, the pultrusion process for a production of the rod profile with diameter of 16 mm and made of polyester resin POLRES 305 BV and glass fibers 4800 tex is developed. Based on the results of parametric study executed for the microwave assisted pultrusion set-ups with different ceramic dies, finite element modelling and coupled analysis aspects are discussed. • Coupled electro-magnetic-thermo-chemical problem has been formulated. • New finite element models and algorithms has been developed. • Finite element modelling and coupled analysis aspects have been discussed. • Microwave assisted pultrusion process has been developed.

Bending Stiffness of the Floor of the Assembled-Type Light Steel-Modular House

The assembled -type light steel (ATLS) modular house is an emerging type of eco-friendly modular building and has been widely used for buildings with repetitive units. This paper focused on the bending stiffness of the bottom frame of ATLS modular house. The bending stiffness of the full-scale ATLS modular house was tested. It was indicated that the stiffness of the cold-formed thin-walled beam of the bottom floor was weak and the vertical deformation of the beam was obvious. Furthermore, the finite-element (FE) model was developed based on the general purpose finite-element software ABAQUS. The results of the FE model were consistent approximately with the test results in terms of the load–displacement curves at the mid-span of the bottom frame beam, and center of the bottom floor. Based on the verified FE model, the influence of the calcium silicate board, opening of corner fitting, stiffness of bolt connection, and the constraint of corner fitting on the bending stiffness of the bottom frame beam was revealed. The opening of the corner fitting has little effect on the bending stiffness of the floor. The existence of the calcium silicate board can increase the bending stiffness of the floor by 23%. The increase of stiffness of the high-strength bolt connection has less influence on the bending stiffness of the floor. The bending stiffness of the floor decreases by 14.7% when constraining the inside edge of the corner fitting compared to other boundary conditions. The presented experimental and numerical studies will be useful to promote the design of ATLS modular house.

Buckling of Conventional and High-Strength Vanadium Steel Single- and Double-Angle Compression Members and Truss Subassemblies: Experimental and Computational Correlation Study

High-strength, low-alloy vanadium (HSLA-V) steel offers higher strength and toughness than conventional steel. The resulting lighter weight and more slender structural members are more susceptible to buckling in compression. This study establishes an understanding of buckling in this material and the ability to predict it analytically. A series of conventional ASTM A572 Grade 50 steel and HSLA-V (nominal Grade 80) steel angle compression members were tested at Lehigh University’s Advanced Technology for Large Structural Systems (ATLSS) laboratory. A general-purpose finite element (FE) software was used in this study to simulate the buckling and post-buckling behavior of the structural members. The objective of these simulations was to establish confidence in the ability to accurately predict buckling response. The influence of the following modeling parameters on the accuracy of the compression angle member simulation results was investigated: variation in material stress-strain relationship, residual stresses, and the shape and magnitude of geometric imperfections. For the truss subassembly simulations, the influence of the following parameters was also investigated: bracing and boundary element stiffness and design code assumptions of end conditions.