“PARSANT” Method

The PARSANT method (Additional Pin Connected Antiseismic Frames), with a patent in the name of Mr. John Marneris, refers to the strengthening of existing buildings and is applied to the external perimeter of the buildings, without damage and without interrupting their operation. Based on this method, additional “walls” made of strong metal frames with diagonal members having their own foundation, are placed on the perimeter of the buildings (on each side or at least on three sides), pinned connected to the existing framing system. The cross-sections of the metal frames are hollow sections, and those of the columns and beams are often filled with small aggregate concrete (compsite members).

The pin-connection is achieved using steel rods, which go through existing and new beams and are bolted at both sides. The existing beams sides in contact with the new ones, are previously reinforced using steel plates attached to them by epoxy glue and steel anchors (beton plaque).

During an earthquake the major part of horizontal forces are transferred to the rigid additional panels, relieving the existing columns, which that way have sufficient strength for the reduced forces they receive. The same applies for the rest of the structural elements avoiding that way their strengthening with conventional destructive methods, like concrete mantles etc, while it makes it possible to add one or more additional floors even if this was not foreseen in the original design.

The method often is applied in combination with high technology systems of absorbing seismic energy (dampers), installed directly to the buildings framing system or inserted to the diagonal members of the PARSANT additional panels. They are very sophisticated devices, usually “fluid viscous” or “friction” type, that can absorb about 40% of the seismic energy, relieving that way proportionally the existing structure. The structural analysis of such structures requires non linear methods and needs special software. Lately we use the most advanced and less expensive damper named “buckling restrained braces” which are “metallic yielding” devices replacing the total diagonal bracing system of the upper floors.

Foundation
The PARSANT frames have their own foundation system, which can be έχουν το δικό τους σύστημα θεμελίωσης, που μπορεί να είναι:

• Conventional long footings, made by cast in place concrete, which usually extend over two consecutive footings of the existing building. The new footings cover the existing ones, acting like concrete mantles, with steel dowels at the common surface.
• Piles of small diameter 0.25-0.30m with a slab on top, at the level of ground floor, which contains the anchors for the positioning of the PARSANT panels. The length of the piles comes out of soil/structural calculations and guarantees the full fixity of the panels. That way no excavation at all is required, whereas the small diameter piles machinery is quite small and versatile, being able to approach the building closely and work even under balconies.

The structural analysis considers a model of two separate structures (the existing building and the PARSANT panels) very close to each other, connected by steel members, which represent the connecting rods. Each rod is described in the model as a structural element and its adequacy is checked by the program, taking into account a higher safety factor. If seismic dampers are included in the PARSANT frames, the seismic analysis becomes more complex, and the use of “non-linear analysis” using accelerograms instead of response spectra is often needed.

The PARSANT method can be applied to ground floor “soft floors”, like pilotis.

Application
The application time depends on case by case, depending on accessibility, the existence of balconies, etc. In general, however, the time is very short, due to the fact that the metal structure is being prepared, during the construction of the foundation. Indicative for a 5-story building, approximately 600 m2 per floor, the construction time is approximately 2 months.

Application Cases
The method applies to the following cases:

• Buildings already damaged by earthquake.
• Buildings needing upgrading on their anti-seismic behavior, according to the latest Codes of practice.
• Buildings expecting additional floors, when their framing system has not adequate strength.
• Buildings with new higher live loads than the initial ones, due to change of their use, like houses or offices to be transformed to educational buildings, gyms etc.
• Buildings with heavily oxidized reinforcements, in which case after restoring them it is not necessary to provide additional reinforcement bars to cover the reduction of their cross-section.
• Buildings damaged by fire, in which case the method is used after the restoration of the structural elements with the appropriate light methods. In this case also is not necessary to provide additional reinforcement bars to cover the reduction of their cross-section.

The PARSANT method is included in the “Greek Code for repairing and strengthening of existing buildings” (ΚΑΝΕΠΕ).

Conferences
The method is presented by John Marneris in many Conferences as follows:

• The “14th International Conference on earthquake engineering” in Beijing China in October 2008.
• The “3rd Conference in structural engineering” in Tel Aviv, Israel, in June 2013.
• The “3rd National Conference on Seismic Engineering and Technical Seismology”, in Athens, in November 2008.
• The “16th European Conference on Earthquake Engineering” in Thessaloniki, in June 2018.
• The “5th National Conference of Steel Structures”, in Xanthi, in October 2005.

The method has been published in over 30 magazines and newspapers in Greece and abroad, while it is the subject of a diploma thesis of a serious number of students in Greece and abroad.

Application of the method in projects of the public and private sectors
The method has been successfully applied to many public and private projects in Greece (hospitals, universities, commercial buildings, residences), such as:

1) The General Public Hospital of Preveza
2) The Law School of the University of Athens
3) The Municipal Theater of Lixouri, Kefalonia
4) The Town Hall of the “Aspropyrgos” Municipality
5) “GAP” pharmaceutical industry
6) General Chemistry Building in Athens
7) “Gerolymatos” pharmaceutical industry
8) LIDL Super Market in “Chaidary”, Athens
9) LIDL Super Market in “Dafni”, Athens
10) HONDOS CENTER Department Store, at Ippokratous Street
11) LADA HELLAS building in Athens Ave
12) Cultural building of the Onassis Foundation at Legaki Street

13) EUROBANK – Syngrou Ave branch
14) ARVANITI SA offices at Vass. Konstantinou Street
15) Office building and robotic parking area of AKTER SA, in Chania
16) Clinic at 10 Angilis Street, in Neos Kosmos
17) Filothei Nursery School
18) The Town Hall of the “Filothei – Psychiko” Municipality
19) Apartment building “ISV – A. Kariotis” in Filothei
20) Three-storey building at P. Faliro.
21) Four-storey building at Sofokleous Street, Voula
22) Three-storey building with pilotis at G. Stavrou Street, Filothei
23) Four-storey building at Patron Street, Kifissia
24) Four-storey Ginou building in Corfu

Conclusion
The application of the PARSANT method, in combination or not with passive seismic energy absorption systems (dampers, tuned mass dampers), ensures the strengthening of practically every building, without interfering with their interior and without interrupting their operation.