When tendons and prestressing are used along the sides of walls and are anchored to the ground (or rock), the ground does not merely function as a static substrate but becomes actively integrated into the structure. In this case, the center of gravity is lowered, as is the overturning moment, because the energy from the tendons is transferred to the ground, making it part of the system.

The key difference here is that the ground is not considered just a static base but an active element of the system that interacts with the structure, reducing overturning and aiding in the better distribution of loads. If this is achieved, it represents a revolutionary advancement in seismic technology as it reduces seismic loads.

Dear Dr. Samy Elhadi Oussadou

Thank you for your response. It fully satisfies me!

Best regards,

Ioannis Lymperis

Dear Dr. Samy Elhadi Oussadou

I asked ChatGPT: Are the basements and foundations calculated at the center of mass of the structure? ChatGPT replied: No, basements and foundations of a structure are typically not calculated at the center of mass when conducting static or dynamic analysis. The center of mass (or center of gravity) of a structure refers to the upper part of the structure, i.e., the section above the foundation.

I responded to ChatGPT: There is an error in the above analysis. The walls, like the entire structure, are subjected to upward forces on one side and downward forces on the other. The ground reacts to the downward forces, causing compression, while the upward forces lift the beams and structure upward. This leads to partial loss of support from the ground, and the combination of unanchored downward loads with upward forces on the walls creates tension.

On one side, the foundation is subjected to compression, transferring the loads to the ground, while on the other side, the foundation is recalled due to the upward loads. In the case of upward loads, the foundation reacts with its own weight, but also with the help of the underground or connecting beams. Therefore, foundations and basements play an active role in addressing the overturning moment.

These factors should be considered, at least in dynamic analysis, as they affect the overturning moment (mass × height), responding to the upward forces.

If the basements and foundations provide stability and rigidity, this is even more true when prestressing is applied to the walls, and the tendons are strongly anchored to the foundation ground (e.g., tendons Φ/70, with a strength of 1560 MPa). In this case:

• The nodes are relieved of moments.
• Prestressing the walls drastically reduces or eliminates the moments at the nodes, as:The distribution of forces in the wall becomes more uniform. The tendons transfer a significant portion of the forces to the ground, reducing internal stress concentrations at the nodes. The static function of the structure becomes more efficient, as the nodes primarily serve as connection points without taking on high moments. The cross-section of the walls gains greater resistance to the shear force from the foundation.
• Prestressing strengthens the wall sections, allowing:Greater resistance to shear: The tendons act as "mechanical connectors" preventing the separation of the section under high shear stresses. Resistance to combined loads: Compressive prestressing in the vertical sections reduces cracking, making the walls more resistant to shear forces developed at the foundation. Reduced stress on the ground: The better distribution of forces reduces local loads on the foundation ground.
• The ground is strengthened, making it stronger.
• The anchoring of tendons in the ground acts as reinforcement for the foundation, making the ground:Stronger and more stable: The tendons ensure that the forces transferred from the structure do not exceed the bearing capacity of the ground, distributing the stresses over a larger area. Increased bearing capacity: The vertical connection of the structure with the ground through the tendons increases the active mass of the system, improving the overall resistance to seismic forces.
• The bearing capacity of the structure increases significantly.
• Increased bearing capacity of the structure

The overall bearing capacity of the structure increases significantly due to:

• Reduction of tensile stresses: Prestressing eliminates tensile stresses at critical points, reducing the likelihood of failure.
• Increased compressive strength: The walls function more efficiently as compressive forces are already prestressed, preventing overloading.
• Improved rigidity: The connection of the tendons to the ground and the absorption of dynamic loads makes the structure more "resistant" to deformations.
• The bending moment is significantly reduced, strengthening the structure's resistance.

With this methodology, the structure achieves higher stability, rigidity, and resistance to seismic stresses, ensuring long-term performance and safety.