RU1838531C - Joint of beams with one or more uprights - Google Patents

Abstract

Usage: in lattice metal frame joints formed of uprights and beams that can be reinforced with diagnostic ties. SUMMARY OF THE INVENTION: the joining of beams with a pillar or pillars includes upper and lower axial horizontal plates spaced apart vertically from one another and fasteners. The connection is provided with additional upper and lower horizontal plates, tongues and vertical longitudinal and transverse plates and additional fasteners, additional upper and lower plates are spaced from each other, joined by transverse vertical plates, fixed to the main upper and lower plates, joined by tongues of longitudinal vertical plates and additional fasteners. Embodiments of plates, dowels, and fasteners of the joint are provided. 11 e.p.fl., 9 ill. w Ј

Description

The present invention relates to the connection of struts and beams in space frames and / or only beams in metal structures.

Fig. 1 is an elevational view, partially in cross-section of an embodiment of a connection; figure 2 is a section aa in figure 1; in Fig.Z - section bB in Fig.1; figure 4 is a section bb in fig.Z; Fig. 5 is a vertical view, partially in cross section, of a second embodiment of the connection; in Fig.6 is a section GG in Fig.5; Fig. 7 is an elevational view, partially in cross section, of a third embodiment; in Fig.Z - section DD in Fig.7; Fig.9 is a section EE in Fig.7.

Turning from the beginning to FIG. 1 to 4, they show a compound according to the invention for beams and interrupted posts.

In the connection design shown in FIG. 1 to 4, two parallel plates 1 and 2 are provided, located respectively at the upper end of the strut 3 and at the lower end of the strut 4, forming the first connection element.

Four holes 5 are provided in each of the two plates, suitable for fastening to corresponding holes provided on the second bolt connection member 6.

Thus, the four elements 6, each of which is attached to the metal beam 7, will be mounted on the plates 1 and 2, in a preferred embodiment

with

00

ate

00

with

Ante implementation shown in the figures.

On each of the two plates 1 and 2 there are two tongues 8 opposite each other, on their inner surface facing the other plate, so that when the two plates are fastened, they stand at an angle of 90 ° to each other, as possible notice on fig.Z.

Each of the elements 6 is made of two parallel horizontal plates 9,10, provided with a hole that corresponds to the hole 5 of the plates 1 and 2, of a vertical plate 11 placed longitudinally between said plates 9 and 10, which extends beyond them so as to correspond through a corresponding hole corresponding to the tongue 1 and 2, and from a vertical plate 12 transverse between the two plates 9 and 10, which corresponds to the size and part of the entire joint for the beam 7, in addition to anti-twisting reinforcement.

Further, a third element may be provided on the plates 1 and 2, having one or more tongues 13 with holes for attaching inclined connections (not shown) and holes 14 for attaching horizontal connections 15.

Two plates 1 and 2 must be connected to the uprights 4 and 3, while the elements b must be welded to the beams 7.

In the solution shown in Figs. 5 and 6, the first connection element according to the invention is made of two plates 1 and 2 parallel to each other using vertical tongues 8.

The plates 1 and 2 have a central opening for passing the strut 3, which in this case is a through strut.

The upper plate 2 in this case is narrower than the lower plate 1. Both plates 1 and 2 are provided with holes 5.

Elements 6 are essentially the same as elements 6 shown in FIG. 1 to 4, in the sense that they also have two parallel horizontal plates 9 and 10, a vertical longitudinal plate 11 and a vertical transverse plate 12.

However, in this case, since the plate 1 is narrower than the plate 2, the plate 9 of the element 6 must be longer than the plate 10, so that it can be fastened to the hole 5,

The vertical tongues 8 that connect the plates 1 and 2 represent the groove 16 into which the plate 11 of the element 6 enters.

Furthermore, in this embodiment of the joint structure, holes 14 for horizontal ties 15 and tongues 13 with holes for oblique vertical ties may be present.

Openings 17 are also provided for the passage of aggregates.

A compound of this type is administered via

a rack 3 with a length of, for example, 12 m, is positioned at the desired height, ensuring that the axes of the nodes coincide with the axes of the rack 3 and at a right angle to it, or if inclined scaffolds are used, they must be fixed by welding in the workshop

The usual error in centering and fixing the strut 3 of the joint does not prejudice the connection of the struts with beams 7, since the dimensions are removed from the axes

joints that do not reflect the eccentricity of the positioning of the stand in the joint structure. This type of connection is suitable for any type of construction. Anchor fastening of the first connection element to the rack 3 will be carried out by welding in the workshop, and if it is assumed that the rack has rolling tolerances, then changing the positioning gap and the thickness of the possible plates to strengthen the connection rack 3 can overcome this tolerance.

Figures 7 through 9 show a solution for a through pillar of reinforced concrete and a metal box acting as an elastically deformable temporary pillar.

Essentially, the connection is implemented with the same characteristics as the embodiment of FIGS. 5 and b, wherein

matching elements are denoted by the same reference numerals. This connection design allows for the construction of metal boxes from load-bearing posts and their design as welded rods

frames - mandrels to introduce reinforced concrete uprights into the joint structure.

A reinforced concrete metal cage made of longitudinal rods 18 and brackets 19 will occupy half the lower floor and half the upper floor and will be introduced at each level of the scaffold. The metal box 20 may have any section, for example, square, round, octagonal, etc.,

and you can also be the outer end of the rack 3 and act as a frame for the rack itself, leaving a metal cage made of reinforced concrete The task of connecting the lower and upper

Racks and the task of hardening a limited connection,

i Naturally, making the hole 21 in the upper plate 1 smaller, | it is easy to achieve narrowing of the uprights. It should be noted that according to the theory and: in contrast to the practical techniques for working with reinforced concrete, the scaffold is covered in the center of the post 3, and not at its base, with the possibility of reducing the number of scaffolds departing from the connection.

, The connection according to the present invention can ensure the absence of elastic deformation of the metal box; 20 strut 3 of reinforced concrete. This,; again returns to the solution shown in Fig. 1-4, on which instead of The dowel grooves 8 make a central hole 21, as in Fig. 8, for positioning the metal cage 18, 19 of reinforced concrete. In this case, the longitudinal rods 18 and brackets 19. serve as a replacement for fasteners, which was completely possible with the help of dowels. In this embodiment, the iron the felling is interrupted at the junction and welded to the plates 1 and 2, as in Figs. 1 and 2, while the reinforced concrete stand in Figs. 7 and 8 passes through the assembly and the metal box in Fig. 9 does not undergo elastic deformation. since it is welded, as shown in Figs. 1-3, and forms the outer end of the stand made of mixed sections of reinforced concrete. The use of these joints makes it possible to make a metallic embodiment of reinforced concrete.

When using the compounds according to the invention, the metal skeleton of the structure, when assembled, will: be a spatial structure consisting of various vertical flat frames with or without connections and various horizontal and / or inclined and / or curved flat frames with or without connections.

The production and sale of this new element in series - the bolted connection, which will be reported in the directories, as is done for all products of the steel industry, will achieve the following advantages: even the smallest workshops, due to the simplicity of operations, will be able to create their own structures using in advance manufactured connection, and they will come to the use of wind coupled circuits, most suitable for metal structures, since the only work that should be performed NENA - this is unscrewing bolts, preparing components from the elements and welding in the workshop

the first element to the uprights or racks, and the second element to the extremities of the beams. The only operation required with respect to the rods is to trim them to the required size.

0 all structural defects can be avoided by starting with a theoretical design scheme, which allows you to get the right shape design, and this is the first requirement for earthquake-resistant

5 designs. In addition, the welding of the rods to the creation in the workshop is directed in advance, since for the beams a fully restored welded joint is also provided by welding of poor quality and in any case to be checked in the workshop before use. And the workshop can also be mobile and operate on the construction site itself with the resulting savings on

5 transportation of structural elements. With prefabricated joints, any design can be designed, designed and built in a very limited time, and can also

0 to be programmed on the computer. The method does not depend on the rolling tolerance, since the rolled rod is introduced into the connection through the tip of the strut or beam and connected to it by welding using also transitional parts if necessary. The accuracy of the assembly will be guaranteed by a prefabricated bolted joint made specifically for this purpose.

0 by workers, as well as by positioning the axes of the nodes.

Brackets can be easily made.

As for the bar frames, in addition to the maximum configuration that the connection is able to accept, you can use any other rods of a smaller size, and to adapt to the connection it takes only 0 s to weld the beams 7 with only the plate 12, which limits the lengths of the plates 9 and 10 plate 12, and increasing the size of the plate 12, it is possible to introduce a rod of any size at any angle. If to the first

5, fewer rods come together, it is enough to cut off the part of the connection that is not relevant. By changing the size of the joint, more stable profiles on the lower floors and less rigid profiles on the upper floors can be used, which leads to a better distribution of materials in accordance with theoretical calculations. Similarly, a steel structure using these joints can be competitive with reinforced concrete, since thanks to them, in contrast to reinforced concrete, it is possible to make reinforcing connections with hoses at a low cost. These bonds largely absorb the stress arising from seismic events, mitigating the impact on the rest of the structure. The use of the joint will expand the construction of steel structures, which will have a beneficial effect on the steel industry, and will provide society with more seismically reliable structures.

Thanks to the use of the joint, under the same conditions, a reduction in the weight of the structures, uniformity of the height of the beams with subsequent higher productivity will be achieved; isolated connections will not exist and, consequently, there will be no concentration of stresses, with subsequent savings on ground work and the connections themselves, an increase in assembly speed, and finally, the structure will look more elegant. The burdensome step of calculating the connection of the frame rods with the consequent elimination of the possibility of error is eliminated, since this step is carried out in a specific way during the development of the prototype of the compound to be mass-produced.

As you could see, with the current level of technology, frame steel structures are only completed when it is caused by architectural or structural requirements, for example, in the construction of skyscrapers, and it is usually completed entirely in the workshop that the welded joint is used because known bolted joints cannot be implemented and with difficulty provide a connection with the complete restoration of a weaker structural element.

For example, a flanged fixed joint, the most widely used in practice and considered the most effective from a static point of view, as indicated in the 1979 Italsider publication I collegamentl nella Carpentaria metallica p. 58. The disadvantage is that it is necessary to drill the column and thus weaken it at the point of maximum moment, i.e. at the point where hardening is needed. According to the present joint construction, on the contrary, it is envisaged to make a welded joint in the workshop on a hardened column. It should be emphasized that the hardening of conventional metal rods is timely, because when it comes to frame structures, the moment has a zero value in the center of the rack and a maximum value of

0 at the junction, and also because usually each post refers to two flat frames at right angles to each other, and therefore it is necessary to give the post sufficient bending strength also in the weakest direction. This hardening should be such that, as soon as the seismic forces caused the deflection of the vertical links and thus the displacement of the forests, and at the same time caused moments

0 begin to be significant ..plastic hinges are created at the tip of the beams, and not at the tip of the posts, which would lead to the destruction of the entire structure.

Strengthening the stand at the junction

5 is useful, in addition to this, for reasons related to structural design, also for correcting defects in rolling of the through post, which, by definition, should pass through the hole and should be welded along its contour. The hole can be precisely defined for each rod: in fact, by changing the gap between the plates and the stand, for example: according to Italian designs between

5 0 and 3 mm for plates greater than or equal to 10 mm, it is possible to limit the rolling tolerance for racks according to the formula 3 mm x 4 mm welding 12 mm, i.e. it is possible to overcome the rolling tolerance for all NOT racks, except for the HEM 500 racks. In this case, it will also be necessary to change the thickness of the reinforcing plates and this makes sense, because if the rolled rod is less than theoretical, i.e. estimated then

5, hardening of the section with plates of increased thickness and vice versa in the opposite case is timely.

Plastic deformation from the beginning of the vertical ties and then the ends of the beam should dissipate the kinetic energy transmitted by the earthquake structure, prevent its destruction or, if necessary, provide an opportunity to evacuate

5 design before its destruction. Returning to the drawbacks of flange connections, another drawback is the fact that the connecting bolts are placed at increasing intervals from the point where the beam transfers tensile stress to the strut and, therefore, since not all bolts are applied in the same way, breaking a series of bolts in one times may happen. Deformation of the bolts before breaking creates a positive effect from point 3, the plasticity of the joint, but cannot be said to be plastic resistant Joints, because the energy dissipation in the bolts before breaking is very low.

The bolt, on the other hand, allows both inelastic deformation in the bolt connection when the holes are oval (elastic deformation in the connecting plates) and the creation of the actual plastic joint. In contrast to the solution with a flange connection, when making the holes oval, all the bolts work simultaneously in the same way and energy dissipation takes place in the plates, and not in the bolts.

It is appropriate to refer to the following Note in the monograph 5 Indagine Sperimentale sulla Resistenza e Duttilita di Collegameml Strutturali, study ftalsider-Comunlta Europea July 1981, Gena. On page 42/43, in the conclusion to the experiment with a connection in a lattice structure, you can read with vertical connections: The behavior of bolted connections is determined by slides, which, however, do not seem random and which in any case have a positive effect, since they greatly contribute to the ductility of the joint and, consequently, improve the dynamic response of the System, and again: The structural ductility of the bolted joint under these conditions is no less than that of the whole welded solution, i.e. it has been concluded that the connecting plates are completely restored.

Concerning the welded solution: However, in addition to the significant difficulties associated with the obligatory execution of welding in the workshop, it provides low energy dissipation, does not significantly contribute to the ductility of the joint, and the reaction during seismic events is less favorable than for the bolted joint. I / I finally: Tests with oversized bolts, M20, show in general how oversizing bolts have positive aspects at the level of strength, although it does not reduce the characteristics; si with regard to ductility; in fact, 10% greater moments are achieved than those observed with the M 14 bolts, with significantly higher rotations from the point of view of failure.

It is also evident that the dissipation of energy in the hysteresis cycle is substantially increased.

The joint favors the creation of plastic joints where there is a passage between the cross section of the rod and the joint. Actually at the point where. the beam must be dimensioned to withstand a moment that is almost equal to the moment along the center line, but much lower than the maximum to which the fixed joint is subjected, a sudden decrease in strength corresponds to a continuous change in stress,

Another advantage of the bolted joint is that it facilitates assembly in the workshop with lowering the beam from above. This means that the beam is lowered by a crane and is guided in its place, so that it automatically takes its position and cannot fall, since besides the fact that it rests on a part of the connection near the uprights, the second connection element cannot be displaced in the horizontal direction.

A final advantage with respect to the flange solution is the absence of welded plates inside the rack to restore the continuity of the beam that passes through the connection, since this continuity is achieved by the connection itself outside the rack.

From an analysis of the bonding technique applied to the report by the engineers of Besio, Korban, Cremonini and De Martino, it follows that it includes brackets bolted near the rack, bolting profiles of unstrengthened rods near the brackets and sealing with butt plates. This assembly, in addition to drilling beams and racks, does not provide hardening of beams and racks in the joint, does not provide communication, does not provide fastening with large bolts, and consists of too many elements.

In order to make the assembly using the connection, on the contrary, the worker in the workshop on the floor (s) should have only bolts, nuts, gaskets and tools for centering the holes and tighten the bolts and should not also have brackets, plates and butt plates, which are heavy and bulky.

The most commonly used joint configuration assumes that the lower and upper legs, four beams at right angles to each other, four or eight inclined vertical links and four horizontal connections converge into it, however, using the same type of assembly, compounds which suggest that the beams converge into it in different numbers or at different angles, as well as different heights). Various horizontal and vertical inclinations can also be obtained by welding the first element to the strut obliquely and welding the beams obliquely to the second element,

Claims (12)

1. The connection of the beams with the rack or racks, including the upper and lower coaxial horizontal plates spaced one relative to the other vertically, and fasteners, characterized in that it is equipped with additional upper and lower horizontal plates, tongues and vertical longitudinal and transverse plates and additional fasteners, the additional upper and lower plates are spaced one relative to another, combined by transverse vertical plates, fixed to the main upper and izhney plates obedinennum vertikalnymi- longitudinal tongue plates and additional fasteners. 2. The joint according to claim 1, wherein the tongues joining each main upper and lower plate having equal dimensions are paired and mounted centrally along the symmetry axis of the joint. 3. The compound of claim 1, wherein each upper and lower plate is provided with a central hole for passing a reinforced concrete stand. 4. The connection according to claims 2 and 3, characterized in that the additional horizontal plates are made with equal dimensions. 5. The connection according to claim 1, with the exception that the horizontal bottom plate is made with a central hole to pass the rack, has a size larger than the top, and vertical tongues are installed outside the hole, their number is at least equal to the number of connected beams. 6. The compound according to claim 5, characterized in that the number of dowels is four. 7. A joint according to claim 5, characterized in that the upper plate is made with grooves for introducing a longitudinal vertical plate. 8. Connection PP. 5 and b, with the exception that each of the tongues is made in the form of vertical elements parallel spaced from each other to insert a longitudinal vertical plate. 9. The connection according to claim 5, from l and h more - so that the additional lower horizontal, the plate is larger than the upper .. 10. The connection according to claim 1, on the basis of the fact that part of the fasteners are made in the form of bolts. 11. The connection according to claim 1, characterized in that the upper and lower plates are provided with fasteners for horizontal and inclined connections. 12. The connection according to claim 11, wherein the fasteners are made in the form of bolts. B Bj 1 . thirteen 9K Aa Fig. G Ј /.& fi & .5 G - G t ty with CO ate Oj fi & 9