Ultra-High Performance Concrete (UHPC) beams simulation in Abaqus

Workshop 3: UHPC beam with CFRP pipe core static bending simulation

This tutorial focuses on examining the simulation of static bending in a UHPC beam with a CFRP pipe core using Abaqus. The concrete beam is represented as a three-dimensional solid part, while the CFRP pipe core is modeled as a three-dimensional shell part. A rigid body part is employed to act as a force body.

Composite structures are widely recognized as a means to enhance the effectiveness and efficiency of structural systems. In recent years, fiber reinforced polymer (FRP) composite structures have gained significant traction in civil engineering applications. The appealing characteristics of FRP include its high strength-to-weight ratio, excellent durability (especially in terms of corrosion resistance), and ease of installation. While concrete remains the most commonly used construction material, it still has limitations such as low tensile strength and brittleness. Ultra-High Performance Concrete (UHPC), an advanced form of concrete, has the potential to overcome these limitations.

To model the behavior of Ultra-High Performance Concrete, the Concrete Damage Plasticity model is employed, allowing for the consideration of both tensile and compression behaviors. For modeling CFRP composite material, the lamina elasticity approach and Hashin’s damage criterion are utilized to predict damage during bending. The simulation employs a general static step with modifications made to the convergence model to prevent premature convergence issues. Instead of surface-to-surface contact, perfect contact is assumed between the CFRP pipe and the inner surface of the concrete. A general contact algorithm with friction properties is utilized for all other contacts within the contact domain. Fixed boundary conditions are assigned to the two surfaces of the UHPC, while displacement boundaries are applied to the rigid body, serving as a load control model. It is important to utilize a fine mesh in order to obtain accurate results.

Upon completion of the simulation, various results such as stress, strain, damage assessment, failure analysis, and force-displacement diagrams become available for analysis.

Workshop 4: UHPC beam reinforced with GFRP bars dynamic bending simulation

This tutorial focuses on exploring the dynamic bending simulation of a UHPC beam reinforced with GFRP bars using Abaqus. The UHPC beam is represented as a three-dimensional solid part, while the cohesive layer acting as an interface between the UHPC and GFRP bars is modeled as another three-dimensional solid part. The GFRP bars themselves are modeled as three-dimensional solid parts. Additionally, two rigid parts are employed to apply the load to the structure.

To model the behavior of UHPC material, the Concrete Damaged Plasticity model is employed. This model takes into account both compression and tension data to simulate the response of UHPC under dynamic bending loads. For modeling the cohesive layer, elastic data types such as traction and traction-separation laws are utilized to consider failure. The behavior of GFRP is modeled using elastic data represented as engineering constants.

Given the large deformations and separation that occur during bending between the UHPC and GFRP bars, the dynamic explicit step is deemed suitable for this type of analysis. The general contact algorithm with friction as a contact property is chosen to consider all contacts within the simulation. Perfect or ideal contact is assumed for the surfaces of the concrete and cohesive layer, as well as between the GFRP and cohesive layer. Fixed boundary conditions are assigned to the two bottom surfaces of the beam, while displacement with amplitude is applied to the two top rigid bodies to introduce the desired load. It is important to use a fine mesh to achieve accurate results.

Upon completion of the simulation, various results including stress, strain, plastic strain, displacement, force-displacement diagrams, and more become available for analysis.

Workshop 5: UHPC beam reinforced with Jute-Epoxy lamina three-point bending test

This tutorial focuses on examining the simulation of a three-point bending test for a UHPC beam reinforced with Jute-Epoxy lamina using Abaqus. The UHPC beam is represented as a three-dimensional solid part, while the Jute-Epoxy lamina is represented as a three-dimensional shell part consisting of four layers. To apply displacement in the load section, a rigid body shell part is utilized as a means of loading.

In recent times, researchers and engineers have been exploring the application of ultra-high performance concrete (UHPC) for rehabilitating and strengthening reinforced concrete (RC) beams. The exceptional material properties of UHPC, including its high tensile and compressive strengths, ductility, and durability, make it an appealing choice for various engineering structures, particularly in bridge engineering. To model the nonlinear behavior of UHPC in compression and tension, the widely used Concrete Damaged Plasticity (CDP) model available in ABAQUS was employed. This model enables the prediction of tensile and compressive damage during the analysis. Jute-based green composites have gained attention due to their favorable properties, such as a suitable strength-to-weight ratio, high damping ratio, low cost, and corrosion resistance. There is a growing interest in natural and environmentally friendly materials, as well as a desire to reduce the cost of synthetic fibers commonly used in polymer composite synthesis. Many researchers have started focusing on natural fiber composites, also known as bio composites, which have found widespread use in the automotive industry and in various interior and exterior car parts. To model the Jute-epoxy lamina, a conventional shell with four layers is employed. The analysis is performed using the general static step, with some modifications made to the convergence model to prevent premature non-convergence. The surface-to-surface contact approach with friction as the contact property is used to define the contact between the rigid body and the concrete part. Ideal contact is selected to define the interaction between the UHPC beam and the Jute-epoxy lamina. Fixed boundary conditions are applied to both ends of the beam, and displacement is imposed on the rigid body. To obtain accurate results, a fine mesh is recommended. After the simulation, a wide range of results, including stress, strain, tensile and compressive damage, force-displacement diagrams, and more, are available for analysis.

Workshop 6: Interior voided RC UHPC beam dynamic bending simulation

This tutorial focuses on investigating the simulation of a dynamic bending test for an interior voided RC UHPC beam using Abaqus. The UHPC beam, made of Ultra-High-Performance Concrete, is represented as a three-dimensional solid part that includes interior sphere voids. The steel bars and strips are represented as three-dimensional wire parts. To apply the load on the top surface of the UHPC beam, rigid bodies are employed as hydraulic jacks.

The voided beam exhibits significantly lower weight compared to a solid beam with the same flexural strength. In this example, the Concrete Damage Plasticity material model is utilized to account for the nonlinear behavior of the UHPC beam during the bending test. The compression and tension data, along with their associated damage, are considered to capture crack propagation and stiffness degradation. For the steel elements such as bars and strips, a material model with elastic-plastic behavior is chosen. Both the static and dynamic solvers can be employed, but due to convergence issues in the static procedure, the analysis time becomes excessively long. Therefore, in this tutorial, the dynamic explicit step is selected as it offers a more efficient approach. Surface-to-surface contact with frictional properties is utilized between the rigid bodies and the top surface of the beam. The bars and strips are embedded within the concrete beam. Fixed boundary conditions are applied to the two sides of the beam, while displacement is imposed on the two top rigid bodies. To ensure accurate results, a fine mesh is recommended. Following the simulation, various results such as stress, strain, tensile and compressive damage, force-displacement diagrams, and more become available for analysis.

Ultra-High Performance Concrete Abaqus

It would be helpful to see Abaqus Documentation to understand how it would be hard to start an Abaqus simulation without any Abaqus tutorial. Moreover, if you need to get some info about the FEM, visit this article: “Introduction to Finite Element Method | Finite Element Analysis”. You don’t know which Abaqus software editions are suitable for you, Do not worry! This article would give you info about Abaqus editions: “How to download Abaqus? | Abaqus student & commercial edition” . One note, when you are simulating in Abaqus, be careful with the units of values you insert in Abaqus. Yes! Abaqus don’t have units but the values you enter must have consistent units. You can learn more about the system of units in Abaqus.

If you need to find the reaction forces of the components or the structures, I think this article could help you out: “Getting total reaction force in Abaqus | Complete guide”.

If you are keep getting Negative Eigenvalue warnings, read this article to understand how to deal with it: “Causes and Solutions for Abaqus Negative Eigenvalues warning”.