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

Workshop 5:  Encased steel-UHPC composite column compression test simulation

This tutorial focuses on conducting the simulation of a compression test on an encased steel-UHPC composite column using Abaqus. The UHPC column is represented as a three-dimensional solid part, while the I-shaped steel column is also modeled as a three-dimensional solid part. The steel bars and strips, on the other hand, are modeled as three-dimensional wire parts.

Composite columns are structural elements that combine structural steel and concrete, either with steel inside concrete or concrete inside steel. These columns are designed to resist axial compressive loads or a combination of axial and bending moments. The interaction between the concrete and steel sections in these composite columns allows them to withstand external loads through contact and friction. Compared to control columns, composite columns offer economic benefits and can handle larger loads with smaller cross-sections. They also provide advantages such as resistance to fire and corrosion, which are not typically found in standard steel columns. Structural steel exhibits characteristics such as high strength, ductility, and stiffness, which contribute to its excellent load carrying capacity. However, concrete, despite being widely used in construction, has limitations such as low tensile strength and brittleness. Ultra-High Performance Concrete (UHPC), an advanced form of concrete, has the potential to address these limitations. To model UHPC material, the Concrete Damaged Plasticity model is selected. This model allows for the definition of UHPC behavior considering its elastic-plastic properties. For the steel material, an elastic-plastic material model coupled with a ductile damage criterion is utilized. The simulation employs a general static step with modifications made to the convergence model for improved accuracy. The general contact algorithm with friction behavior is employed to consider all contacts within the contact zones. The bars and strips within the UHPC host are assigned an embedded region constraint. Perfect or ideal contact is used to define the interaction between the UHPC and steel columns. Fixed boundary conditions are assigned to the bottom of the column, and the load is applied to the top rigid body. A fine mesh is necessary to obtain accurate results.

After the simulation, various results including stress, strain, damage assessment, force-displacement diagrams, and more become available for analysis.

Workshop 6: Air blast simulation over the composite RC slab( UHPC and NSC)

This tutorial focuses on examining the simulation of an air blast explosion over a composite RC slab consisting of UHPC and NSC using Abaqus. The UHPC and NSC materials are represented as three-dimensional solid parts, with UHPC forming the upper face and NSC forming the bottom part of the slab. The steel bars within the slab are modeled as three-dimensional wire parts.

Researchers and engineers are increasingly exploring the use of ultra-high performance concrete (UHPC) for rehabilitating and strengthening reinforced concrete (RC) beams. UHPC possesses exceptional material properties, including high tensile and compressive strengths, ductility, and excellent durability, making it an attractive option for various engineering structures, particularly in bridge engineering applications. To model the behavior of Ultra-High Performance Concrete Structures under blast loads, the Concrete Damaged Plasticity approach is selected. This model effectively simulates the tensile and compressive behaviors of the UHPC, allowing for the analysis of damage in both tension and compression. Material data for UHPC and normal strength concrete (NSC) are obtained from the reference paper. Elastic-plastic data is used to define the behavior of the steel reinforcement. Given the nature of the analysis, the dynamic explicit step is chosen as the appropriate approach. The steel bars are embedded within the UHPC and NSC host materials. The interface zone between the UHPC and NSC is modeled using cohesive behavior, employing stiffness and damage parameters. The CONWEP air blast load procedure is considered, with the detonation point and the amount of TNT specified. Pinned boundary conditions are applied to two sides of the slab. To obtain accurate results, a fine mesh is required.

Upon completion of the simulation, various results including stress, strain, tensile and compressive damage, displacement, and more become available for analysis.

Workshop 7: Composite panel ( UHPC-NSC) dynamic bending simulation in Abaqus

This tutorial focuses on examining the dynamic bending test simulation of a composite panel consisting of UHPC and NSC using Abaqus. The Ultra-High-Performance Concrete (UHPC) and Normal Strength Concrete (NSC) materials are represented as three-dimensional solid parts, while the steel bars within the panel are modeled as three-dimensional wire parts. To apply the displacement in the load section, a shell rigid body is utilized as a hydraulic jack.

Researchers and engineers have recently been exploring the application of ultra-high performance concrete (UHPC) for the rehabilitation and strengthening of reinforced concrete (RC) beams. UHPC’s exceptional material properties, including high tensile and compressive strengths, ductility, and excellent durability, make it an attractive choice for various engineering structures, particularly in bridge engineering.

To model the behavior of both UHPC and normal strength concrete (NSC), the Concrete Damaged Plasticity model is employed. This model is a continuum-based, plasticity-driven, damage model specifically designed for concrete. It considers the primary failure mechanisms of tensile cracking and compressive crushing in concrete materials. For modeling the steel bars, an elastic-plastic model is selected to accurately represent their behavior. To reduce simulation time and minimize the inertia effect, the dynamic explicit step with mass scaling technique is used. The surface-to-surface contact approach with frictional contact properties is employed to define the contact interaction between the rigid body and NSC. To capture the interaction between UHPC and NSC at their interface, a cohesive behavior model with a damage criterion is considered. Embedded constraints are applied to represent the steel bars embedded within the concrete host. Fixed boundary conditions are assigned to the two sides of the bottom slab, while displacement is applied to the rigid body. To achieve accurate results, a fine mesh is recommended.

After the simulation, a range of results such as stress, strain, tensile and compressive damage for both concrete materials, force-displacement diagrams, and more are available for analysis.

Workshop 8: Bending simulation of curved steel–UHPC–steel double skin composite panel

This tutorial focuses on examining the simulation of a curved steel-UHPC-steel double skin composite panel under bending load using Abaqus. The UHPC panel is represented as a three-dimensional solid part, while the steel skins are represented as three-dimensional shell parts.

Steel-UHPC-steel double skin composite panels are structural elements composed of two external steel plates filled with a concrete core. To accurately model the behavior of the concrete, it is crucial to select an appropriate material model that defines its compressive and tensile characteristics. A variety of concrete models are available in the ABAQUS software for simulating the nonlinear behavior of concrete.

In this tutorial, the Concrete Damage Plasticity model is employed to define the behavior of the UHPC panel under compression and tension loads. This model also accounts for tensile and compressive damage to represent crack propagation. For the steel skins, an elastic-plastic model with a ductile damage criterion is chosen. The simulation is divided into two parts: one using the static solver and the other using the explicit solver. The differences between the static solver and explicit solver are minimal. In the static general model, the surface-to-surface contact algorithm with contact properties is assigned to the contact zone between the rigid body and the top steel skin. In the explicit model, the contact between the UHPC and steel skins is modeled as general contact with cohesive behavior. Fixed boundary conditions are applied to both ends of the panel, and displacement is imposed as a load on the top rigid body. To obtain accurate results, a fine mesh is recommended. After both simulations (static and explicit), various results such as stress, strain, tensile and compressive damage, force-displacement diagrams, and more become available for analysis.

Workshop 9: Composite Column (UHPC + Steel box) cyclic loading simulation

This tutorial focuses on investigating the simulation of cyclic loading on a composite column consisting of Ultra-High-Performance Concrete (UHPC) and a steel box cover using Abaqus. The UHPC column is represented as a three-dimensional solid part, while the steel box cover is represented as a three-dimensional shell part.

The concrete-filled steel box presents significant potential for use in the construction of bridges and buildings. While concrete is widely employed in construction, it has certain limitations, such as low tensile strength and brittleness. However, these concerns may be addressed by utilizing Ultra-High Performance Concrete (UHPC), an advanced form of concrete.

To model the behavior of the UHPC column under cyclic loading, the Concrete Damaged Plasticity model is used. This model is based on continuum plasticity and incorporates damage mechanisms specific to concrete, including tensile cracking and compressive crushing. The behavior of the steel box is defined using an elastic-plastic model with a ductile damage criterion, accounting for damage during cyclic loading. The general static step is employed, with adjustments made to the convergence model to prevent premature non-convergence.

Two types of interaction between the UHPC column and the steel box are considered. The first is cohesive surface interaction, where the stiffness, damage, and fracture energy are defined. The second is perfect contact, assuming idealized contact between the two materials. Fixed boundary conditions are assigned to the bottom surfaces of the composite column, while displacement with a cyclic protocol is applied to the top surface. To obtain accurate results, a fine mesh is recommended.

Following the simulation, a range of results such as stress, strain, displacement, damage, hysteresis diagrams, and more become available for analysis.

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”.