STKO ASDEA

26/06/2026

Thank you to Massimo Petracca, PhD., and everyone who joined our Handle with care webinar.

🔎 If you couldn’t make it or would like to revisit the session, you can catch all the insights on our YouTube at: https://youtube.com/live/qwVUCjXqRxI?feature=share

👉 Follow us to stay updated on future webinars, tutorials, and software insights.

Strain-softening materials, such as concrete, make a standard finit...

25/06/2026

A common misconception in nonlinear hashtag : applying loads and controlling displacements are not interchangeable.

They follow the same equilibrium path only up to the first peak. Beyond that point, the analysis strategy determines whether the response can be traced or not.

𝗟𝗼𝗮𝗱 𝗰𝗼𝗻𝘁𝗿𝗼𝗹: the load factor is prescribed and displacements result from the structure's ability to sustain the applied forces. At a limit point, no equilibrium may exist for a higher load, causing the analysis to fail and the post-peak response to be missed.

𝗗𝗶𝘀𝗽𝗹𝗮𝗰𝗲𝗺𝗲𝗻𝘁 𝗰𝗼𝗻𝘁𝗿𝗼𝗹: one or more response quantities are used to drive the analysis. This allows the equilibrium path to be followed beyond the peak and into the softening regime, where load control typically cannot proceed.

𝗔𝗿𝗰-𝗹𝗲𝗻𝗴𝘁𝗵 𝗺𝗲𝘁𝗵𝗼𝗱𝘀 (𝗥𝗶𝗸𝘀, 𝗖𝗿𝗶𝘀𝗳𝗶𝗲𝗹𝗱): the solution increment follows the equilibrium path itself, enabling the analysis of snap-through and snap-back behavior as well.

The rule is simple: choose the control strategy based on the instability mechanism you expect, not on habit.

25/06/2026

Refine Your Mesh - today 25/06/2026 at 6:00 PM CET
🔗 Register here: https://www.stko.net/webinar-registration

The full topic of the session will be:
𝗠𝗲𝘀𝗵-𝗼𝗯𝗷𝗲𝗰𝘁𝗶𝘃𝗲 𝗿𝗲𝘀𝘂𝗹𝘁𝘀 𝘄𝗶𝘁𝗵 𝗳𝗿𝗮𝗰𝘁𝘂𝗿𝗲-𝗲𝗻𝗲𝗿𝗴𝘆 𝗿𝗲𝗴𝘂𝗹𝗮𝗿𝗶𝘇𝗮𝘁𝗶𝗼𝗻
𝗦𝘁𝗿𝗮𝗶𝗻-𝘀𝗼𝗳𝘁𝗲𝗻𝗶𝗻𝗴, 𝗹𝗼𝗰𝗮𝗹𝗶𝘇𝗮𝘁𝗶𝗼𝗻, 𝗮𝗻𝗱 𝘁𝗵𝗲 𝗿𝗲𝗴𝘂𝗹𝗮𝗿𝗶𝘇𝗮𝘁𝗶𝗼𝗻 𝘄𝗲 𝘂𝘀𝗲 𝗶𝗻 𝗢𝗽𝗲𝗻𝗦𝗲𝗲𝘀.

We will cover the localization problem in strain-softening analyses, why results depend on the mesh, and how fracture-energy regularization addresses this - with examples applied directly in STKO.

If you are working with damage models and nonlinear analyses, join us at 6:00 PM CET.

24/06/2026

Only one day left!

Registration link: https://www.stko.net/webinar-registration
𝗥𝗘𝗙𝗜𝗡𝗘 𝗬𝗢𝗨𝗥 𝗠𝗘𝗦𝗛 - 𝗙𝗥𝗘𝗘 𝗪𝗘𝗕𝗜𝗡𝗔𝗥

This webinar reviews the problem and the techniques used to recover mesh-objective results

Thursday 25 June 2026, 18:00 CEST (09:00 PT / 12:00 ET / 17:00 BST).
Duration: 60 minutes.
Speaker: Massimo Petracca, PhD (ASDEA S.r.l.).

17/06/2026

Strain-softening materials, such as concrete, make a standard finite element model mesh-dependent: as the mesh is refined, the localization band narrows, the dissipated energy decreases, and the computed response does not converge.

This webinar reviews the problem and the techniques used to recover mesh-objective results:

• the origin of the pathology: strain localization and loss of ellipticity in a local continuum;
• an overview of regularization methods (nonlocal, gradient-enhanced, micropolar, higher-order continua, and fracture-energy regularization) and their implementation cost in general-purpose finite element codes;
• the fracture-energy (crack-band) approach as implemented in OpenSees with ASDConcrete, including the role of the element characteristic length and its limitations;
• a mesh-refinement study showing convergence of the load–displacement response for different element types.

The implementation is available in the public OpenSees repository.

Thursday 25 June 2026, 18:00 CEST (09:00 PT / 12:00 ET / 17:00 BST).
Duration: 60 minutes.
Speaker: Massimo Petracca, PhD (ASDEA S.r.l.).

Registration link in the comments.

12/06/2026

Thank you to Stefano Ercolessi, Ph.D. and Massimo Petracca, PhD., and everyone who joined our Handle with care webinar.

🔎 If you couldn’t make it or would like to revisit the session, you can catch all the insights on our YouTube at: https://www.youtube.com/live/GAb4LU0_8XA

👉 Follow us to stay updated on future webinars, tutorials, and software insights.

Some of the most common mistakes in STKO and OpenSees come down to ...

11/06/2026

Didn’t have time to register? Don’t worry we have got you covered!

You can watch the webinar “Handle with care.'' on our YouTube channel by clicking on the link:

Some of the most common mistakes in STKO and OpenSees come down to ...

10/06/2026

Only one day left! Click the link to Register: https://www.stko.net/webinar-registration

Handle with care.

🗓️ 11 June 2026 – 18:00 (CEST - UTC+2)
📍 Live on Zoom
Stefano Ercolessi, Ph.D. and Massimo Petracca, PhD.

Some of the most common mistakes in STKO and OpenSees come down to one thing we rarely think about: how constraints are enforced. Get it wrong and your model might crash on you, a solver that won't converge, an error you can't explain. Or, worse, it runs cleanly and hands you a converged, confident, completely wrong answer.

The good news? The Auto constraint handler, implemented by ASDEA in OpenSees, takes care of this for you, so most of the time things just work and never have to think about it. The point of this tip is to understand why SP and MP constraints really are, the classic ways they trip up a model, and exactly what that Auto handler is quietly protecting you from.

05/06/2026

ADVANCED NONLINEAR ANALYSIS

STKO was built to tackle complex nonlinear analyses, from material plasticity and contact interactions to unstable structural behavior. It is designed for researchers and engineers who need both flexibility and full control over their numerical models.

From highly accurate static and dynamic nonlinear analyses to the investigation of complex phenomena such as softening, snapping, and localization, STKO provides a robust environment for advanced structural simulation.

To learn more about STKO and its capabilities, visit 👉 www.stko.net.
To request a quotation, contact us at 👉 [email protected].

04/06/2026

Handle with care.

FREE WEBINAR
🗓️ 11 June 2026 – 18:00 (CEST - UTC+2)
📍 Live on Zoom
👉 Register here: https://www.stko.net/webinar-registration

Presenter: Stefano Ercolessi, PhD
Q&A: Massimo Petracca, PhD

Some of the most common mistakes in STKO and OpenSees come down to one thing we rarely think about: how constraints are enforced. Get it wrong and your model might crash on you, a solver that won't converge, an error you can't explain. Or, worse, it runs cleanly and hands you a converged, confident, completely wrong answer.

The good news? The Auto constraint handler, implemented by ASDEA in OpenSees, takes care of this for you, so most of the time things just work and never have to think about it. The point of this tip is to understand why SP and MP constraints really are, the classic ways they trip up a model, and exactly what that Auto handler is quietly protecting you from.