View Single Post
  #4  
Old Posted Feb 19, 2010, 9:54 PM
seismic's Avatar
seismic seismic is offline
Registered User
 
Join Date: Feb 2010
Location: ISLAND OF IOS CYCLADES
Posts: 126
placed in the hole opening (109) of the piston terminal ring (6) and hammered down in order to get the steel cable (2) anchored. Then, once the commercial traction equipment is removed, the pressure chamber is set to the desired pressure level by connecting the internally threaded inlet (10) through a piping system to an automated air (or other fluid) pressure system, "electrical pump with controlled pressure chamber". This pressure (90) within the pressure chamber (1) is exerted in all directions i.e. forces the pressure chamber downwards and the pressure piston (7) upwards; however, because the pressure piston (7) is tied to the steel cable (2) through the cone-shaped wedge (14) it cannot rise but exerts a pulling force (42) on the steel cable (2) while the base of the pressure chamber (1) exerts compressive force (45) on the slab originating from the reaction created by the pressure (90) of the piston bottom (12) towards the bottom of the pressure chamber (1). Moreover, to absorb the vibrations a rubber insert (13) is placed between the pressure chamber (1) and the top slab (33). This compressive force of the hydraulic tie rod for construction projects is different from the compression generated by the weight of the floors. In a multi-storey building the weight of each floor is the same when all floors are of the same dimensions and is accumulated generating the compressive force. However, the oscillating motion of each floor during an earthquake is different, the higher the floor and the longer the duration of the earthquake is, the larger the amplitude of the oscillation, increasing gradually and causing the first, the middle and the top slabs to oscillate deforming their vertical axis into an S shape changing the relationship of the horizontal and the vertical axis of the building by 90° leading eventually to the collapse of the building.

In contrast, the compression generated artificially by the tie rod for construction projects (108) is an active compressive force without the oscillations that the slabs are subjected to and which are generated as a result of the inertia of the slabs to the lateral forces caused by an earthquake. This artificial compressive force exerted by the tie rod prevents buckling of the columns, unless the steel cable breaks, thus, giving us the possibility to utilise its full strength at 100%. In case the drilling walls (31) collapse due to ground fluidization on account of an earthquake, the steel cable (2) will remain under tension, while the anchor diameter (17) on the horizontal plane will increase providing compaction of the soil on the drilling walls (31). This is because of the continuous pressure the steel cable (2) is being subjected to by the air (or other fluid) pressure exerted on the pressure chamber piston (7) and the pressure chamber (1) forcing the anchor (17) to open and automatically improve the soil on the drilling walls (31). In the event of the soil subsiding under the base (36), the building framework will not tilt because its weight is "taken up" by the metal resistance pipe (15) and then transferred to the side walls of the drilling (31) through the upper rods (27) of the anchor (17) which are pyramidal in shape, and are linked to the lower rods (27), which are pulled by the rising motion of the steel cable (2), through connecting rotary pins (29), (28). Moreover, this mechanism generates only compression (45) and tension (42) forces on the concrete column and prevents the generation of shear forces (46), which the concrete cannot withstand (see example of Figure 4). Moreover, anti-vibration rubber inserts (Figure 2, (35)) are placed in order to absorb the vibrations generated by the vertical earthquake forces. These rubber inserts (35) are placed between the individual bases (36) and the continuous base (37) which is constructed in order to prevent ramming the trusses and the slab (33) caused by the up-down movement of the individual bases during the waveform motion of the ground generated by the earthquake. In this way, the continuous base (37) is converted into a rigid boat keel lifting the columns on the same horizontal axis of the continuous base (37), in other words, the horizontal axis of the continuous base does not change shape during the earthquake and there is no ramming by the columns. In conclusion, the greater the width of the columns the more effective the hydraulic tie rod for construction projects is.

In another especially preferred embodiment of the present invention, based on the above conclusion and on our attempt to achieve the greatest possible structural rigidity, four hydraulic tie rods (108) are placed at the four corners of a lift shaft (Figure 2, (32)) with sizable external side dimensions, as well as a separate individual base so that the resulting unit will be very rigid. Care is taken not to leave a joint-spacing (38) between the slab (33) and the lift (32) and between the continuous base (37) and the individual base of the lift (32). This combined structure exhibits the following behaviour during an earthquake: the rest of the framework is oscillating around the lift shaft touching on it at various points along the gap (38) just before the framework exceeds its fracture point and thus before it is subjected to fracture and collapse it touches on a rigid structure (lift shaft) or a cross-shaped rigid column and thus the vertical axis of the framework does not exceed its allowed fracture point and does not assume an S shape as a result of the inertia of the slabs mentioned above.

In yet another embodiment of the present invention, the hydraulic tie rod for construction projects may be used with reinforcement in the columns, particularly with pre-stressing which is usually applied to the trusses. This is a very innovative way of using the hydraulic tie rod of the present invention adding improved strength mainly to large structures wherein simply covering the external columns of the building structure may not be sufficient to give the structure full structural rigidity and protection. In order to achieve this and have a vertical pre-stressing of the steel, it must not be anchored within the concrete and for that reason the steel is guided (Figure 6, (44)) through pipes (65) which are fixed with a pipe holding hoop (64) comprising the central pipe (110) fastening, the steel passage pipes (72) fastening, and the pipe holding bars (73) bearing hole openings to allow the concrete to pass through (74). Pipes (65) and (66) are fastened into said fastening hole openings (72) and (110) once the steel (44) and the steel cable (2) have passed through the pipe and fastening hole openings. The same procedure is followed in fastening the remaining pipes one on top of the other. Figure 5 presents an illustration of a frame column (34) with an individual concrete base (36). It shows the method of installing hoops (64), tie rod-cable passage pipe (66), steel passage pipes (65), and metal plates (62) as well as the method of threading with the base tightening screw (70) and the tightening screw (69) for joining and extending the steel, it also shows steel cable (2) and steel reinforcement (44). There follows a description for the placement and the construction of column (34). Once the drilling (31) has been carried out, the anchor (17) is screwed on the metal resistance pipe (15) provided the steel cable (2) has been guided through its hole opening. The anchor is lowered inside the drilling (31) and then the metal base plate (62) is placed provided the steel cable (2) has been guided first through its central hole opening. Then we fasten all steel carrying pipes (65), as well as the main steel cable carrying pipe of the tie rod (66), to the metal plate (63) hole openings, provided the steel reinforcement (44) and the tie rod steel cable (2) have passed first through their hole (67) and then screwing steel (44) using tightening screws (70) on the bottom part of the metal plate (62) to prevent it from rising upwards. These pipes are held inside a partially finished formwork of the column by means of hoops (64) and when the pipes (65) and the steel (44) reach beyond the level of the slab, the column formwork is completed and the concrete is poured into the column formwork (34). When the concrete sets the pipes projecting from the slab are cut and metal plate (62) is placed on the projecting steel (44) with threading (68) taking care that the steel (44) and steel cable (2) get through the hole openings of the plate (63). The tightening and steel joining/extending screw (69) is then screwed to the steel (44) threading (68) on its internal half threading (71), while the extension of the other steel is screwed on the other half internal threading of screw (69). Tensional forces on steel (44) and compressive forces on column (34) are generated during the fastening of the tightening screw (69) on the metal plate (62). This way, the required additional and desirable result of column compression is obtained, thus preventing the generation of shearing forces when the classical reinforcement method is utilized, i.e. pre-stressed concrete is produced in the framework column (34) by means of both the steel and the steel cable of the tie rod.

Based on the foregoing description, the advantages of using the hydraulic tie rod for construction projects can be listed as follows:
1) The structure's centre of gravity is shifted and is now located into the ground, making the construction structurally rigid. This is achieved by means of tightening the structure to the ground thereby forcing it to act as an integral
Reply With Quote