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Tie Rod Summary


A Greek engineer developed a Tension Tie for building structures, which can be used to provide protection against the origination and development of failings in building structures, caused by earthquake and wind forces, and also to anchor any large structures, such as damns, houses, wind generators, bridges etc, into the ground (like a huge screw). This is achieved by a continuous prestressing (pulling) of both the structure towards the ground and of the ground towards the structure, making them into one body. The prestressing force is applied by means of a mechanical tension tie for construction.

The inventor is seeking

a) Funding to register an international patent

b) A manufacturer for the invention

c) Further tests

Funding for the above or any of those three

Description of the offer or R&D result:

It comprises of a tension tie for building structures (
Figure 1
) and an effective anti-vibration system to distribute evenly damage-causing earthquake and wind forces. To understand the invention, just visualise how earthquake forces are being transmitted in a wavelike fashion and also how an earthquake sways a structure left and right and knocks it up and down, twisting the horizontal or vertical axis of the structure. So said engineer developed a continuous double base (
Figure 2
, (12)(13)) for the building frame, whose dimensions are equal to the basement area, with rubber in between said base (14) to prevent the wavy motion of the ground, caused by the earthquake, from turning each single base (13) (base for each column) into a column-fracturing ram. Understandably, column reinforcement is joined only to the upper continuous base, preferably by means of additional reinforcement and prestressing. Thus, the horizontal axis of the structure is kept rigid. To prevent the vertical axis from being twisted by an earthquake as it moves the structure either left or right, said engineer developed a tension tie for building structures (
Figure 1
), acting like a screw, and tied said tension tie (11) with the ground, preferably in the centre of the building frame and making it rigid through prestressing. Care is taken to leave a gap (9) between the slab and the tension tie and also between the continuous base (12) and the single base of the tension tie. This combined structure exhibits the following behaviour during an earthquake: the rest of the framework (10) sways around the tension tie well (11) touching on it at various points along the gap (9), which is lined with anti-vibration rubbers, just before the frame exceeds its fracture point; and so before breaking and collapsing, it touches on a rigid structure (tension tie); thus, besides preventing the vertical axis of the frame from exceeding its fracture point, it does not allow it to take an "S" shape due to the inactivity of the plates to the lateral forces generated during an earthquake. Said tension tie consists of a steel cable (
Figure 2
, (18)), passing freely through the four corners of a tension tie (Figure), (7)(5)(6)(8)). Its lower end is tied by means of an anchor mechanism (
Figure 2
, (20)) that is driven into the walls of a drill hole (17), preventing it from being uplifted. The steel cable's top end is tied to a screw mechanism at the top of the tension tie, on all four corners of it. The pulling force applied to steel cable (18) by the screw and the resistance to such pulling from the fixed anchor at the other end create the desired compression in tension tie. In structures with a small surface area, tension ties are placed on every frame column (
Figure 2
, (10)) since the wavelike motion of the ground generated by an earthquake does not affect small structures; this because it moves up and down within the seismic wave range.


Innovative aspects

This is the first time that an anti-seismic patent connects the ground to the structure at appropriate points, independently (using an empty space, gap) of the rest of the structure, to develop flexible and rigid areas and by means of an anti-vibration slab to distribute evenly damage-causing earthquake and wind forces. There are areas where what's required is only rigidity and clamping/anchoring of structures such as dams, pylons, bridges, windmills, timber structures vulnerable to cyclones, and these requirements are satisfied by the tension tie for building structures.

This tension tie may be installed on existing structures as well as in structures under construction. It is as if we have just discovered a screw and are trying to work out how it can be used. The tension tie does exactly what a tree does: it has roots into the ground and flexible branches. On two sides of anti-seismic slabs, scaffolds are screwed together with the base to protect the tested structure from collapsing by the latter touching on them. The patent of this tension tie does just that, the only difference being that the (tension tie) scaffolding is screwed at the centre of the tested structure, providing a corresponding gap over and inside the ground.

Main advantages

a) During earthquakes and high winds, it keeps the horizontal and vertical axes of building structures in a straight line to prevent them from breaking and collapsing.

b) It increases the strength of concrete to tensile forces generated by an earthquake.

c) The steel cable uses % of its tensile strength, whereas in the normal, inactive reinforcement, the tensile ability of steel is cancelled out due to the inability of concrete to hold it and resist to the pulling force generated during an earthquake at its vertical elements.

d) It protects houses from hurricanes and cyclones

e) It provides a way of anchoring large structures into the ground (for various reasons) horizontally, vertically and under an angle.