Context
The glass spiral staircase by architect Eva Jiricna has long been admired as a masterclass in lightweight design, a quiet demonstration of how minimal a load-bearing element can become when geometry takes over from mass. While the architectural vision is uniquely hers, translating it into reality required exceptional engineering (a collaborative effort that involved my former colleague, Ing. Karel Kosek).
This article does not present my own design. Rather, it outlines a rigorous student exercise: my 2016 diploma thesis for the Civil Engineering programme at the Faculty of Civil Engineering, CTU in Prague. It was an in-depth structural and dynamic re-analysis of the staircase, undertaken to reverse-engineer its behavior and understand exactly why the original solution is correct.
The Approach and the Model
The thesis asked a narrow but complex question: given the published geometry and extreme slenderness, how does the steel actually behave under real-world conditions?
To answer this, I built a highly complex finite-element model using Dlubal Software. This model served as the foundation for two critical phases of evaluation: a static analysis and a dynamic assessment.
For the static analysis, I modeled the central spine and the cantilevered treads under various precise load cases. Rather than just applying a uniform live load, I simulated realistic occupancy scenarios: the staircase fully loaded, loaded only on specific segments, two people walking in sequence, three people in a row, and two people passing each other in opposite directions. The goal was to map the shifting force paths and compare them against the visible cross-sections of the realized structure.
The Dynamic Reality
Crucially, a structure this slender and lightweight cannot be evaluated by static forces alone. A significant portion of my thesis was dedicated to a dynamic assessment. I analyzed the natural frequencies of the staircase and its response to human-induced vibrations. In glass and steel structures of this type, ensuring dynamic comfort—so the stairs don't feel "bouncy" or unsafe underfoot—is often the governing factor in the engineering design.
Beyond the calculations and software simulations, the final thesis also included the production of comprehensive structural drawings, detailing the most critical connections and joints that make the structure viable.
What I Learned
Two major takeaways stayed with me.
First, from a purely mechanical standpoint, the dominant story is torsion. Each tread cantilevers from the central spine, and the spine carries the moments of every tread above and below it as a stack of small twists. Bending plays a smaller role than the visual appearance suggests; the spine is, for most of its height, a highly stressed torsion tube with a stair attached to it.
Second, and most profoundly, this project is a textbook example of absolute symbiosis between architecture and structural engineering. The architectural form is the structural form. One cannot exist without the other; there is no decorative envelope hiding the working steel. This is the discipline that Jiricna's practice is built on, and it can only be truly appreciated by working through the equations, one element at a time.
Recognition
In 2016, this comprehensive model and analysis received the 2nd prize in the Dlubal Software competition for the best diploma thesis carried out using their structural engineering programs.
Reflection
Re-analyzing someone else's design, when that design is a masterpiece, is one of the most useful exercises a young engineer can undertake. You learn far more from dissecting and reconstructing a correct answer than from generating a new, average one. Authorship here sits exactly where it belongs: with Eva Jiricna and her engineering team. What I took home was a profound education in how structural logic can become architectural poetry.
