Prestressed abutting joints and the manner of making thereof

Abstract

 Prestressed joints are characterized by that between the facing plates /2/ there are spacing elements /10, 11, 12, 13/ located on the peripheries of the plates, and the stressing bolts /3/ connecting the facing plates are situated in the stretched zone between the spacing elements and the contour of the cross-section of the joined elements. Preferably, the spacing elements are flat bars.
The manner of the making of a prestressed abutting joint as in the invention is characterized by that elements of the structure are so positioned that a distance between the facing plates is kept and then spacing elements are placed on the edges of the plates, preferably in the shape of flat bars, after which the facing plates of the joint are stressed by the bolts. Preferably, the spacing elements are bonded or welded to one of the facing plates.

Description

[0001] The subject of the invention is prestressed abutting joints and the manner of making thereof The invention can be applied in metal construction to manufacture and assemble steel structures with abutting bolted joints as well as in construction of machines and industrial devices made of other metals and structural materials.

[0002] The commonly known abutting bolted joints of metal structures require narrow working tolerances of the coupled elements and components of the joint in order to keep coplanarity of the facing sheets of the joint. The difficulty of keeping such working requirements result in very high level of randomness of the load capacity and rigidity of the joint. It is also a cause of random effort and rupture of bolts as early as at the stage of construction. Another inconvenience is non-linearity of the dependence of the angle of rotation of the joint on the bending moment of the joint. This makes theoretical static analysis of a structure characterized by random and non-linear rigidity of joints more difficult. Another inconvenience is the introducing of random assembly forces and displacements hindering the assembly of subsequent elements and keeping the designed geometry of the structure.

[0003] In known solutions, steel washers or other filling of chinks in the joint are used in order to better fit the facing sheets. The correction of deviations and chinks takes place during prestressing. The rupture of high-resistance bolts demonstrates non-linearity of transmission of stresses in the joint.

[0004] The patent description PL 190817 discloses a solution where the space between the planes of the facing plates is filled with quick-hardening elastic substance or elastic spacers of low coefficient of elasticity which easily fit in the chinks between the plates. The applied elastically deformable spacing layer ensures the right distribution of stresses in the joint in spite of special geometrical imperfections of the planes of the abutting planes. The essential result of this solution is the elimination of additional torsion and bending of the joined girders which occurs when using conventional methods of fitting contacting elements of metal structures. Another result is prevention against appearance of corrosion in the place of contact.

[0005] The drawback of the known solutions is relatively small, random and hardly controllable rotational rigidity of the joint as well as mom-linear dependence of the bending moment on the angle of rotation of the joint.

[0006] The patent description PL 188508 discloses a prestressed abutting joint where between the facing plates there are spacers in the form of plates of surface smaller than the surface of the facing plates. This solution is characterized by consistency of effort of bolts and effort of the cross-section of the joined elements, where the effort of the bolts and the effort of the beam cross-section results from the intended introduction of bending moment. This solution enables regulation of bending moments in abutting joints, especially of continuous beams.

[0007] In known joints removal of chinks by additional tensioning of bolts leads to rupture thereof due to their random effort, even in spite of their double overdimensioning.

[0008] In the invention, prestressed abutting joints containing facing plates with stressing bolts are characterized by that between the facing plates they have spacing elements situated on the peripheries of the plates, while the stressing bolts which join the facing plates are located in the tensioned zone between the spacing elements and the contour of the cross-section of the joined elements. Preferably, the spacing elements are flat bars or bent rims of one of the facing plates. The spacing elements can also be welds made on the peripheries of the facing plates during the assembly of the structural elements.

[0009] The manner of making of the prestressed abutting joint, of the elements of metal structures where facing plates and stressing bolts are used, in the invention consists in such positioning of the elements of the structure that a distance is kept between the facing plates, then the spacing elements, preferably in the form of flat bars, are placed on the peripheries of the plates, and then the facing plates of the joint are stressed with bolts.

[0010] Spacing elements in the form of flat bars should preferably be secured by bonding or welding to one of the facing plates.

[0011] The invention also provides for such a solution that after situating the elements of the structure with keeping a distance between the facing plates, a weld is made on a part or the whole of their periphery and next the stressing of the facing plates is regulated with bolts. Inthis case, the weld plays the role of the spacing element.

[0012] The essential feature of the solution as in the invention is obtaining practically linear rotational rigidity of such joints.

[0013] In the case of application of the stressing of the facing plates, rotational rigidity of the joint is increased even 8 times. This rigidity is substantial in increasing the critical and the boundary load capacity of structural systems, in particular of tilting metal frames.

[0014] The result of the invention is also about twice increased load capacity of the facing plates of the joint and obtaining linear rotational rigidity of the joint, lower random stresses during assembly, easier and more accurate fitting of elements during assembly.

[0015] Additional benefits of using joints as in the invention are increased preciseness of estimation of intersection forces in the elements as well as of displacements and load capacity of steel structures with existing professional computer programs.

[0016] The subject of the invention is shown in embodiments in the drawings, where Fig. 1 and Fig. 2 present an abutting joint of a double-tee bar subject to bending, Fig. 3 - a joint of a girder with an undulated web, Fig. 4 and Fig. 5 - a joint of a girder with a column used in tilting frames, where the joints are alternately loaded with positive and negative bending moment, Fig. 6 - a joint of high girders, where the spacing elements take the form of flat bars, Fig. 7 and Fig. 8 - a joint where welds are the spacing elements, and Fig. 9 - a joint where the distance which allows the stressing of the facing plate is obtained by an arched shape thereof.

[0017] Spacing element can be composed of a few layers, obtained as continuous or discontinuous welds, or welded to the facing plates.

[0018] Fig. 1 represents a section across a joint along double-tee girders subject to bending 1, to which facing plates 2 are welded. Located between the facing plates 2 are spacing elements 10 and 11 in the stretched zone of the joint and 12 and 13 in the compressed zone of the joint. The bolts 3 in the stretched zone of the joint are located between the spacing element and the profile of the joined girder. The bolts 3 tighten the facing plates which press the spacing elements causing the stressing of the facing plates which increases several times rotational rigidity and load capacity of the joint.

[0019] Fig. 3 represents a section across a girder 1 with a view on a facing plate 2, location of spacing elements 10, 11 in the stretched zone of the joint and spacing elements 12, 13 in the compressed zone of the joint. The bolts 3 are located in the stretched zone between the spacing elements 10, 11 and the profile 1 of the joined girder.

[0020] Fig. 3 represents a section across a girder 5 with an undulated web with a view on location of spacing elements 14, 15. The reason of the location of the spacing elements is that the web of the girder does not carry normal forces, and the stressing of the facing plate 21 has a beneficial influence on the joint in the stretched zone.

[0021] Fig. 4 represents a section across a joint of a girder 102 with a column 105. Between the facing plate 23 of the girder 102 and the plate 22 of the column 105 are located spacing elements 16 and 17. The facing plates 22 and 23 are tightened with bolts 3 and they press the spacing elements 16 and 17 thus causing the stressing of the facing plates 22 and 23. In this case, the stressing reduces the effort of the plate 22 of the column 105, and increases rotational rigidity and load capacity of the joint.

[0022] Fig. 5 represents a section across a girder 102 with a view on location of spacing elements 16 and 17 and on location of bolts 3. The symmetrical location of the spacing elements and of the bolts is conditioned by alternate bending of the joint with a positive and negative moment.

[0023] Fig. 6 represents a section of a joint subject to alternate bending of a high plate girder 103 with the plate 22 of a column 105. Spacing elements 18 in the form of flat bars are located on the periphery of the facing plate 24. Bolts 3 are located between the spacing elements 18 and the contour of the cross-section of the plate girder 103. The facing plates tightened with the bolts 3 press the spacing elements thus causing the stressing of the facing plates 22 and 24. In the examples in Fig. 7, Fig. 8 and Fig. 9. the facing plate 25 is welded with a weld 19 to the plate 22 of the column 105 and stressed with the bolts 3. In this embodiment, the distance allowing the stressing of the facing plate 25 was obtained due to its arched shape. The facing plate 25 is rested on a bracket 106 fastened to the column 105.

[0024] In all the examples shown in Fig. 1 to Fig. 6 the role of spacing elements can be played by welds.

Claims

1. Prestressed abutting joints containing facing plates connected with stressing bolts, characterized by that between the facing plates /2, 21, 22, 23, 24, 25/there are spacing elements /10, 11, 12, 13, 14, 15, 16, 17, 18, 19/ located on the peripheries of the plates, and stressing bolts '/ located on the peripheries of the plates, and stressing bolts /3/ connecting the facing plates are located in the stretched zone between the spacing elements and the contour of the cross-section of the connected elements /1, 101, 102, 103, 104/.

2. Abutting joints as claimed in 1, characterized by that the spacing elements are formed by bent rims of one of the facing plates.

3. Abutting joints as claimed in 1, characterized by that the spacing elements are formed by flat bars.

4. Abutting joints as claimed in 1, characterized by that the spacing elements are formed by welds.

5. A manner of making of a prestressed abutting joint of elements of metal structures, where facing plates and stressing bolts are used, characterized by that the elements of the structure are so positioned that a distance is kept between the facing plates /2, 21, 22, 23, 24, 25/ and then spacing elements /10, 11, 12, 13, 14, 15, 16, 17, 18, 19/ are located on the peripheries of the plates, preferably in the form of flat bars, after which the facing plates of the joint are stressed with the bolts /3/.

6. The manner as claimed in 5, characterized by that the spacing elements are bonded or welded to one of the facing plates.

7. The manner as claimed in 5, characterized by that the facing plates /2, 21, 22, 23, 24/ are welded to each other over a part or the whole of their periphery, and then they are stressed with the bolts /3/.

Drawing