My Master's thesis, titled "Calculation of Reinforced Concrete with Non-Linear Element Methods," explored the application of non-linear finite element analysis (FEA) for the design of reinforced concrete structures. This research, completed in 1992 under the supervision of Assistant Professor Dr. Erik Thorenfeldt at the Norwegian University of Science and Technology (NTNU), delved into the growing trend of using advanced computational methods to analyse and predict the behaviour of complex concrete structures.

The Challenge:

Traditionally, the design of large concrete structures relied on linear elastic analysis, often overlooking the non-linear behaviour of reinforced concrete under load. This approach could lead to inaccurate predictions of local stresses and deformations, particularly in areas experiencing cracking, yielding, or other non-linear phenomena.

The Focus:

My thesis focused on investigating the potential of non-linear FEA software like ABACUS and DIANA to improve the analysis of reinforced concrete structures.

The Approach:

The research involved the following key steps:

1. Comparative Analysis of Material Models: I explored the specific non-linear material models and calculation routines offered by both ABACUS and DIANA for reinforced concrete analysis.

2. Selection of Test Case: A simplified yet representative reinforced concrete section was chosen as the test case. This section could be a thick plate subjected to combined in-plane forces, bending moments, and shear forces.

3. Parametric Variations: Power combinations and analysis assumptions were systematically varied within the chosen software packages to assess their capabilities.

4. Example Calculations & Result Comparison: Example calculations were conducted using both ABACUS and DIANA. The results were then compared and evaluated to identify strengths and limitations of each software.

The Outcome:

The thesis evaluated the feasibility and effectiveness of non-linear FEA for analysing reinforced concrete structures. The findings provided valuable insights into:

• The accuracy and efficiency of the chosen software packages for non-linear analysis of concrete.

• The impact of parameter variations on the predicted behaviour of the concrete section.

• The potential of non-linear FEA for achieving a more realistic understanding of load distribution and crack formation in complex structures.

The Legacy:

This research laid the groundwork for my continued interest in utilizing advanced computational methods for the design and analysis of civil engineering structures. It has also informed my teaching philosophy, as I strive to equip students with the knowledge and skills necessary to embrace modern engineering tools for optimal design solutions.

Further Discussion:

The thesis also highlighted the need for further studies to address challenges associated with non-linear FEA, such as:

• Selection of appropriate element types and meshing strategies.

• Refining material models for specific concrete types and behaviours.

• Developing efficient computational techniques for complex structures.

I believe there is ongoing potential for non-linear FEA to revolutionize the design of reinforced concrete structures. My research serves as a stepping stone for further exploration in this exciting field.

I hope that by sharing this work, I can inspire students and colleagues to explore the vast possibilities that non-linear analysis methods offer in the design and evaluation of complex structures. If you share an interest in this topic or wish to discuss potential collaborations, please feel free to reach out to me through my contact page.