CONNECTIONS IN CONSTRUCTIONS- light structural elements in the form of separate rods or systems (trusses); designed to ensure the spatial stability of the main bearing systems (trusses, beams, frames, etc.) and individual rods; spatial work of the structure by distributing the load applied to one or more elements to the entire structure; giving the structure the rigidity required for normal operating conditions; for the perception in some cases of wind and inertial (for example, from cranes, trains, etc.) loads acting on structures. Communication systems are arranged so that each of them performs several of the listed functions.
To create spatial rigidity and stability of structures consisting of flat elements (trusses, beams), which easily lose stability from their plane, they are connected along the upper and lower chords by horizontal ties. In addition, at the ends, and for large spans and in intermediate sections, vertical connections are placed - diaphragms. As a result, a spatial system is formed, which has high rigidity in torsion and bending in the transverse direction. This principle of providing spatial rigidity is used in the design of many structures.
In the span structures of beam or arch bridges, the two main trusses are connected by horizontal bracing systems along the lower and upper chords of the trusses. These communication systems form horizontal trusses, which, in addition to providing rigidity, take part in the transfer of wind loads to the supports. To obtain the necessary torsional rigidity, cross-links are placed to ensure the invariability of the cross-section of the bridge beam. In towers of square or polygonal section, horizontal diaphragms are arranged for the same purpose. In the roofs of industrial and public buildings, with the help of horizontal and vertical ties, two roof trusses are connected into a rigid spatial block, with which the rest of the roof trusses are connected by girders or strands (ties). Such a block ensures the rigidity and stability of the entire coating system. The most developed system of connections has steel frames of one-story industrial buildings.
The systems of horizontal and vertical connections of lattice crossbars of frames (trusses) and lanterns provide the overall rigidity of the tent, secure compressed structural elements from loss of stability (for example, the upper chords of trusses), ensure the stability of flat elements during installation and operation. Accounting for the spatial work provided by the connection of the main load-bearing structures by systems of connections, when calculating structures, it gives a reduction in the weight of structures. So, for example, taking into account the spatial work of the transverse frames of the frames of one-story industrial buildings reduces the calculated values of the moments in the columns by 25-30%. A method for calculating the spatial systems of span structures of girder bridges has been developed. In normal cases, bonds are not calculated, and their sections are assigned according to the maximum flexibility established by the norms.
The transverse stability of the frame of wooden buildings is achieved by pinching the main pillars in the foundations when the roof structure is hinged to these pillars; the use of frame or arched structures with hinged support; creating a hard disk cover, which is used in small buildings. The longitudinal stability of the building is ensured by setting (after about 20 m) a special connection in the plane of the frame walls and the middle row of racks. Wall panels (panels) can also be used as connections, properly fastened to the frame elements.
To ensure the spatial stability of planar load-bearing wooden structures, appropriate connections are placed, which are fundamentally similar to connections in metal or reinforced concrete structures. In arched and frame structures, in addition to the usual (as in beam trusses) unfastening of the compressed upper chord, it is provided for unfastening the lower chord, which, as a rule, with unilateral loads, compressed areas. This fastening is carried out by vertical ties connecting the structures in pairs. In the same way, stability is ensured from the plane of the lower chords in trussed structures. As horizontal ties, strips of slanting flooring and roof shields can be used. Spatial wooden structures do not need special connections.
The metal frame of an industrial building consists of a number of "flat" elements that are rigid and well accepting loads in their plane, but flexible in the perpendicular direction (frames, under-rafter and intermediate truss trusses, etc.). The main purpose of the connections is to unite flat elements into a spatial system capable of absorbing the loads acting on the building in any direction.
Secondly, the connections serve to ensure the stability of the compressed and compressed-curved rods of the upper chords of trusses, columns, etc. The danger of buckling of such elements is explained by the fact that the rods of the metal frame have large lengths and relatively small compact transverse dimensions. The braces release the compressed elements at intermediate points, reducing the calculated lengths of the elements in the direction of these releases.
There are the following main types of connections used in the metal frame of an industrial building
1) transverse connections between the upper chords of trusses (through beams of frames will be referred to as "trusses" in the future) (Fig. 1) 2) vertical connections between trusses (Fig. 9); 3) longitudinal and transverse ties located in the plane of the lower chords of trusses (Fig. II); 4) vertical connections between columns (Fig. 22). Consider the layout, purpose and design solutions of communication nodes using examples of buildings with different coatings.I. TRANSVERSAL RELATIONS BETWEEN THE UPPER BELTS OF TRUSSES
1.1. The upper chord of the truss, like any compressed rod, may lose stability if the force in it reaches a critical value. The loss of stability in this case will occur in one of two planes:
Fig.1. Cross connections between the upper chords of trusses, 2-2 each - vertical connections a) in the plane of the truss - the bar that has lost stability will remain in the plane of the truss. This means that when looking at the farm from above, the loss of stability will not be noticeable. As can be seen from Fig. 2, the calculated length when checking the stability of the upper chord "and the plane" of the truss corresponds to the distance - between the nodes, that is, the length of one panel;
Fig.2. Estimated length of the upper chord in the truss plane, (dotted line)
b) the loss of stability of the upper belt with its exit from the plane of the farm should be shown only in plan. Let's assume that links are not set. Then the loss of stability will occur according to the scheme shown in Fig. 3a. The girders, which are usually attached to the upper chord of the truss articulated (using bolts), by themselves, without ties, will not prevent the buckling of the trusses, since after the loss of stability, the upper chords of the trusses will bulge, and the girders will freely move to a new position. At the same time, the distance between trusses (span of runs) will remain.
A different picture of stability will be observed if links are placed. Relations can be cross - with two diagonals (Fig. 3.6) and lightweight, triangular (Fig. 3, c), i.e. with one diagonal. Compressed diagonals, obviously, are switched off from work, having lost stability, and stretched ones will prevent the rectangles from being distorted, will not allow them to turn into parallelograms. Consequently, at the attachment points of the diagonals, the truss belt will retain its original position and its estimated length "out of the plane" will be equal to the "L-B" section (Fig. 3, c), i.e. two panels. The top chords of all trusses connected to these points by girders (or braces by lanterns) will have the same effective lengths as the chords of two trusses directly fixed with ties, i.e. sections A "-B", A ""-B"" have a calculated length equal to two panels. 
Fig.3. Loss of stability of the upper chords of trusses; a) in a cover without bonds; b) the scheme of tensioning and switching off the braces of the ties; c) ensuring the stability of believing belts with the help of rod connections
Let us pay attention to the error that can be made when determining the estimated length of the upper chord from the truss plane. In Fig. 3c, the run intersects the bonds diagonal at point "f". It seems that the run is attached to the diagonal of the ties, and the estimated length of the upper chord from the truss plane, it would seem, can be taken equal to the panel. However, this is not true: runs and connections are located at different levels, there is a gap between them "f" (Fig. 7)
1.2.
In buildings with a lantern (Fig. 4), the upper belt is not unfastened from the truss plane over a large area, because there are no runs under the lantern. If we consider that the structures of the wall fencing of the lantern, together with the run, fix the point "B", then the estimated length of the upper chord is from the plane "B~B". The introduction of a spacer in the middle of the lantern span reduces the estimated length from the truss plane (Fig. 4b) to three panels. 
Fig.4. Estimated lengths of the upper belt under the lantern:
a) without spacers - 6 panels;
b) with one spacer - 3 panels;
c) with a truss spacing of 12 m, an intermediate communication belt PP is introduced
The upper belt of vertical ties (section 2) is used as a spacer, but paired corners or other profiles specially designed for this purpose can be used,
1.3.
Recently, in order to save metal, it has been customary to assign the functions of connections along the upper chords to the roofing, which, when securely attached to the trusses, can ensure the stability of the upper chords from the plane of the trusses.
So in non-purlin roofs with reinforced concrete flooring, the stability of the upper chords from the plane of the trusses is ensured by welding the embedded parts of the flooring to the upper chords. In this case, the estimated length of the upper belt from. truss plane can be taken equal to the length of one truss panel. 0 welding of the flooring to the chords of the trusses should be indicated in the note on the drawing.
During the erection of the building, these attachments of plates to chords must be controlled. In this case, it is required to draw up an act for hidden work. Profiled flooring can also act as ties along the upper chords if it is attached to the girders with dowels.
The best design solution when using profiled decking as bracing would be to attach the purlins to the truss so that the top flange of the purlin is flush with the top flange of the truss chord. In this case, the flooring is shot with dowels on its four sides - to the girders and upper chords of the trusses. For the convenience of attaching the girders to the trusses, in this case, it is possible to use roof trusses not with a triangular lattice, but with descending braces (Fig. 5). 
Fig.5. Use of profiled flooring as top chord ties:
a) roof truss with descending braces;
b) a variant of solving the support node of the run at the same level with the upper chord of the truss
With the economic advantages of replacing the ties with decking attached to the belts, the coatings are deprived of one important function performed by the ties. Connections along the upper chords, in addition to ensuring the stability of the trusses, are also fixers of the correct relative position of the trusses during installation. Therefore, when installing a coating without ties, it is recommended to provide for the use of temporary (removable) inventory ties, i.e. installation conductors.
If there are lanterns in the coatings, where the flooring serves as ties along the upper belt, under the lantern, to ensure the stability of the belt, ties are arranged in the form of diagonals with a truss step of 6 m or in the form of incomplete diagonals with a truss step of 12 m (Fig. 6). In this case, the estimated length of the upper chord of the trusses, when checking the stability from the plane, is taken equal to two panels. 
Fig.6. Ensuring the stability of the upper belts of trusses under the lanterns in the coatings, where it performs the functions of connections; flooring t a) truss spacing b m, b) truss spacing 12 m
1.4. In roofs with a truss spacing of 12 m and spans of 12 m, the braced truss is assumed to be 6 m wide. 6 m
1.5. The distance along the length of the building between the rod connections along the upper belt of the trusses should not exceed 144 m. Therefore, in long buildings, connections are placed not only in the extreme panels of the frame block, but also in the middle or thirds of the block length (Fig. I).
These requirements are explained by the fact that the stability of trusses located far away from o,t ties cannot always be reliably ensured, because the girders or spacers that attach the trusses to the tie blocks allow a certain displacement in the nodes due to the difference in the diameters of the bolts and holes . With an increase in the number of nodes, i.e. with distant connections, this miscibility is added and increased, which reduces the reliability of the stability of farms located far from the connections.
The designs of some tie units made of angle and bent welded profiles and their attachment to trusses are shown in Fig. 7, 8.
So, the connections located in the plane of the upper truss chords have the following main purpose: when loading, the coatings prevent the loss of stability of these chords from the truss plane, that is, they reduce the estimated length of the upper chords when checking their stability from the truss plane.
2. VERTICAL LINKS BETWEEN FARMS
These ties are also called assembly ties, since their main purpose is to hold the trusses put on supports in the design position, to prevent single trusses from tipping over during installation from wind and accidental influences, tk. the center of gravity of the farm is above the level of the supports (Fig. 9, a).
Vertical connections in the form of a chain of struts and trusses are placed along the length of the building between the racks of the truss trusses. To save metal, tie trusses are interconnected by upper and lower struts (Fig. 10). Thus, the trusses of vertical ties are disks, and the spacer rods attached to them provide intermediate truss trusses or frame crossbars from tipping over (Fig. 9b). The lattice of braced trusses, as a rule, can be arbitrary (Fig. 9c) and is made from single corners or from rectangular bent-welded pipes. In pavements with a truss spacing of 12 m, with trussed girders or decking reinforced with trussed trusses, the upper chord of the vertical truss truss may look as shown in Fig. 9d.
Vertical connections along the width of the span are located on the supports (between the columns) and in the span between the racks. Farms at least every 15 m, i.e. with a building span of 36 m, they will be located in the planes of two racks.
Fig.7. Attaching ties to the top truss chords
Fig.8. Nodes of coverage and connections at a truss spacing of 12 m (see Fig. 6);
a) Attaching connections made of closed profiles to trusses with belts from wide-shelf I-beams
b) Node B
Fig.9. Vertical links between farms:
a) the position of the center of gravity,
b) trusses-disks and spacers,
c) truss lattice schemes,
d) connections in coverings with a truss step of 12 m and with trussed runs
Trusses - disks of vertical connections are placed in increments of 30-36 m along the length of the building. Racks of corner trusses, to which connections are attached in the upper and lower nodes, are made of a cross section (Fig. 10).
Ties can also be attached to vertical gussets specially provided for this purpose. As part of a block in large-block installation, vertical connections are necessary elements that ensure the immutability of the block. 
Fig.10. Knot for attaching the upper belt of the vertical truss truss to the rack of the truss truss. The bottom node is done in the same way.
LONGITUDINAL HORIZONTAL LINKS ALONG THE LOWER BELTS OF THE RIGEL
The contour of the ties located in the plane of the lower through crossbars can be divided into longitudinal and transverse ties (Fig. 11). The purpose of the longitudinal links is as follows:
3.1. Longitudinal connections perceive transverse horizontal crane actions, i.e. they perceive the eccentric application of the vertical pressure of the crane on the column, causing horizontal displacement of the frame, as well as the transverse braking of the crane applied to one frame (Fig. 12a) and transfers these effects to neighboring frames that are less loaded (Fig. 12b). Thus, the space of the frame is ensured when it is working on local loads that cause horizontal displacements of the frame crossbar.
Fig.11. Connections on the lower chords of the crossbars of the frames
Fig.12. Scheme perceived by transverse horizontal loads by longitudinal braces along the lower chords:
a) mixing of frames from vertical eccentric application of the crane load and from braking;
b) transfer of transverse loads to connections
3.2. Note that the side load from the wind is transferred equally to all frames, causing the same mixing of them. In this case, there are no transverse forces between the frames, and therefore, in frames with a frame spacing of 6 m, longitudinal ties do not perceive wind loads,
With a column spacing of 12 m or more in frames with half-timbered (wall frame) racks, longitudinal ties work for this load; They are the upper horizontal supports of the half-timbered racks. Thus, in this case, the longitudinal ties transfer forces from wind loads from the half-timbered racks to adjacent frames (Fig. 13) and the ties are loaded with forces from the wind load along the length of the frame step. 
Fig.13. Transfer of wind load from half-timbered racks to longitudinal ties
3.3. In the extreme panels of the crossbar, due to the fact that the rigidly clamped crossbar on the support experiences bending moments of the opposite sign with respect to the sign of the moment in the span, compression of the lower chord is given (Fig. 14).
Fig.14. Compression in the lower chord of the crossbar near the supports
It is possible to fix the lower chord from the loss of stability from the plane of the crossbar here only with the help of longitudinal ties (point "f" Fig. 14). The stability of the lower chord in the plane of the crossbar is ensured either by the development of the moment of inertia of the chord section (in this panel it can be taken from two unequal angles made up of large shelves), or by introducing an additional suspension.
3.4. In multi-span buildings with heavy-duty cranes (7K, 8K), longitudinal connections in the form of horizontal trusses are placed from each other at a distance of no more than two spans (Fig. 15) 
Fig.15. Connections along the lower chords of crossbars in a multi-span frame with heavy-duty cranes (7K, 8K)
In multi-span buildings with medium-duty cranes with a lifting capacity of up to 50 tons, with spans of not more than 36 m and with a height of up to 25 m, as well as with a frame pitch of 6 m, it is allowed not to make longitudinal connections along the lower chord. However, struts and tie rods, which ensure the stability of the lower chords from the plane of the trusses, must be placed in each span (Fig. 16). 
Fig.16. Connections on the lower chords in the frame with medium-duty cranes (4K - 6K)
4. TRANSVERSAL LINKS IN THE PLANE OF THE LOWER CHORNS OF THE CAM
4.1. These connections serve to transfer forces from wind loads directed to the end of the building, from the racks of the end fachwerk to the vertical connections between the columns (Fig. 17) (pressure transfer is shown by arrows). 
Fig.17. Scheme of transmission of wind loads from the end of the building in communication
4.2. Together with the longitudinal ties, they form a closed loop that increases the overall rigidity of the building frame.
Cross ties, as a rule, are placed under the ties along the upper chords, creating with them spatial transverse blocks, to which intermediate trusses (crossbars) are attached with the help of girders, struts of vertical ties and longitudinal ties.
Figures 18, 19 show the attachment points of horizontal ties made of angles and rectangular bent-welded pipes to truss chords. It should be noted that in the heavy-duty frames of 7K, 8K cranes and at high crane loads, the ties are attached to the trusses by welding (i.e., the bolt assemblies must be welded) or using high-strength bolts. 
Fig.18. Designs of corner ties along the lower chords
5. VERTICAL LINKS BETWEEN COLUMNS
Distinguish the upper tier of vertical connections between the columns (connections located above the crane beams) and the lower one below the beams (Fig. 20).
Fig.19. Knot of connections along the lower belt from rectangular bent-welded profiles
Fig.20. Scheme of vertical connections between columns
5.1. The connections of the upper tier have the following purpose:
a) the forces from the wind directed to the end of the building are transferred to the connections of the upper tier from the end cross-braces located in the plane of the lower chords, and then, along the stretched struts, these forces are transferred to the crane beams",
b) connections of the upper tier provide - stability of the columns "from the plane" of the frames. Thus, the estimated length of the over-crane part of the column (Fig. 20, dotted line) from the plane of the frame is equal to the height of this part of the column;
c) together with the lower tier of connections during installation, they keep the columns fastened with anchors from tipping over.
5.2. Vertical connections of the lower tier
The following functions are assigned to the connections of the lower tier:
a) transfer wind forces from the connections of the upper tier and from the longitudinal braking of cranes (Fig. 20);
b) ensure the stability of the crane part of the colony from the plane of the frame;
c) serve as mounting connections when installing columns. In high-rise buildings, the connections of the lower tier have an additional spacer between the columns - (Fig. 21,
a). Its purpose is to reduce the estimated length of the crane part of the column from the plane of the frame. This layout technique is resorted to when, during the calculation, I check the stability of the column "from the plane" does not give satisfactory results due to the high flexibility of the column (from the plane of the frame.).
The schemes of vertical connections can be different depending on the pitch of the columns, on the need to use an opening between the columns, etc. (Fig. 21b). 
Fig.21. Schemes of vertical connections of the lower tier:
a) additional spacer to reduce the estimated length of the column from the plane of the frame;
b) options for connections between columns
It is not necessary to attach the ties of the lower tier to the crane beams in the span, since when the crane moves, compression of the braces of the ties may occur, and, consequently, they can be turned off. Upper tier braces can be attached to the brake beams with oval bolts in a vertical direction. 
Fig.22. Structures of vertical connections between columns with a column spacing of 6 m
Rice. 23. Vertical connections between columns with a column spacing of 12 m: C - oval holes in node B, allowing deflections of the crane beam without loading the connections of the upper tier; t - brake beam
In the vertical plane, the upper tier of connections is usually located along the axis of the over-crane part of the column, and the lower connections should be double and should be located in the planes of both the outer and inner branches of the crane part of the column (Fig. 22). If there is a fachwerk, then the connections are established in the plane of the fachwerk and are joined to the fachwerk post in the middle node. Along the length of the building, the connections of the lower tier are placed in the middle of the temperature block (Fig. 22), but not in the cream case at the ends. Placing the connections in the middle of the building ensures free deformation of the longitudinal elements with temperature fluctuations (elongation or shortening of crane beams, longitudinal connections, etc. .). 
Fig.24. Middle knot of vertical connections (see fig. 23):
Г - fastening of connections and fachwerk rack f on assembly welding, D - on high-strength bolts, Q - stiffeners, 4-4 - calculated section of the gusset. Bolts are calculated for the axial force in the diagonal of the ties and the moment from the eccentricity "a"
6. CALCULATION OF RELATIONSHIPS
In most types of connections, it is difficult to accurately determine the magnitude of the efforts that will be perceived by them. Therefore, the sections of the connection elements, as a rule, are selected according to the ultimate flexibility. For elements that are known in advance that they will experience compression, it is recommended to take an ultimate flexibility of 200.
According to the known forces, vertical connections between columns, as well as transverse connections along the lower chord of the crossbar and longitudinal horizontal connections (in the case of taking into account the spatial work of the frame) are calculated.
- SNiP II-23-81*. Steel structures, - M., Stroyizdat, 1988, - 96 p.
- Belenya E.I. and others. Metal constructions.- M., Stroyizdat, 1989.- P.272-279.
- SNiP 2.01.07.-85. Loads and influences. - M., Stroyizdat, 1989.
- Central Research Institute Projectstalkonstruktsiya im. Melnikova, Typical building structures, products and components. Series 2.440-2, Units of structures of industrial buildings of industrial enterprises: Issue 4. Units of brake structures and vertical connections. KM drawings. Moscow, 1989. 49 p.
- Benefit on the design of steel structures (to SNiP 23-81 *) - M., Central Institute for Standard Design, 1989 -148s.
1.1. From a static point of view, they are bending cantilever beams fixed in the ground.
1.2. Significant forces arise in narrow vertical ties, and the rods themselves undergo large deformations along the length, which contributes to large deformations of the facade with a small column spacing.
1.4. The rigidity of narrow wind braces can be increased by combining them with external columns.
1.5. A high horizontal beam has the same effect (for example, in the technical floor of a high-rise building). It reduces the skew of the upper half-timber beam and the deviation of the building from the vertical.
The location of the vertical connections in the plan
In terms of vertical connections are needed in two directions. Solid or lattice vertical connections inside the building prevent the free use of the premises; they are located inside walls or partitions with a small number of openings.2.1. Vertical braces surround the stairwell.
2.2. A building with three cross braces and one longitudinal bracing. With a narrow core of stiffness in tall buildings, it is advisable to provide stiffness according to schemes 1.4 or 1.5.
2.3. Cross ties in windowless end walls are economical and efficient; longitudinal connection in one span between two internal columns.
2.4. Vertical connections are located in the outer walls. Thus, the appearance of the building is directly dependent on the structures.
2.5. A high-rise building with a square plan and vertical connections between four internal columns. The necessary rigidity in both directions is provided by using schemes 1.4 or 1.5.
2.6. In high-rise buildings with a square or near-square plan, the arrangement of ties in the outer walls allows for particularly cost-effective building structures.
Location of links in the frame
3.1. All connections are located one above the other.3.2. The vertical connections of the individual floors do not lie on top of each other, but are mutually displaced. Floor slabs transfer horizontal forces from one vertical bracing to another. The rigidity of each floor must be provided in accordance with the calculation.
3.3. Lattice connections along the outer walls involved in the transmission of vertical and horizontal loads.
The influence of vertical bonds on the base
The columns of a building, as a rule, are at the same time elements of vertical connections. They experience forces from the wind and from the load on the floors. The wind load causes tensile or compression forces in the columns. Forces in columns from vertical loads are always compressive. For the stability of the building, it is necessary that compressive forces prevail in the sole of all foundations, however, in some cases, the tensile forces in the columns may be greater than the compressive forces. In this case, the weight of the foundations is taken into account as ballast.4.1. Corner columns perceive insignificant vertical loads, however, with a large step of connections, the forces arising in these columns from the wind are also insignificant, and therefore artificial loading of corner foundations is usually not required.
4.2. Internal columns perceive large vertical loads, and due to the small width of the wind ties and large forces from the wind.
4.3. Wind forces are the same as in diagram 4.2, but are balanced by small vertical loads due to the outer columns. In this case, foundation loading is necessary.
4.4. It is not necessary to load the foundations if the outer columns are on a high basement wall, which is able to balance the tensile forces from the action of the wind.
5. The rigidity of buildings in the transverse direction is provided with the help of lattice ties in the windowless end walls. The connections are hidden between the outer wall and the inner fire-resistant cladding. In the longitudinal direction, the building has vertical connections in the corridor wall, but they are not located one above the other, but are displaced in different floors. - Faculty of Veterinary Medicine in West Berlin. Architects: Dr. Luckhardt and Wandelt.
6. The rigidity of the frame is provided in the transverse direction by lattice discs that pass through both shells of the building, going out in the gaps between the buildings. The rigidity of the building in the longitudinal direction is provided by connections between the inner rows of columns. - High-rise building "Phoenix-Rainror" in Düsseldorf. Architects: Hentrich and Petschnig.
7. Three-span building with a step of columns in the transverse direction 7; 3.5; 7 m. There are narrow transverse ties between four inner columns located in pairs, and a longitudinal tie between two inner columns of the same row. Due to the small width of the cross-links, the calculated horizontal deformations from the action of the wind are very large. Therefore, in the second and fifth floors, stressed braces to the outer columns are installed in four bracing planes.
Prestressed rods are made in the form of steel strips placed on the edge. They are pre-stressed (the stress is controlled by strain gauges) to such an extent that under the action of the wind the stress of the stretched brace in one direction doubles, and in the other direction becomes almost zero. - The building of the main administration of the company "Bevag" in West Berlin. Architect prof. Baumgarten.
8. The building has only outer columns. The beams cover a span of 12.5 m, the pitch of the outer columns is 7.5 m. In the high part, the wind braces are located over the entire width of the building between the outer columns. The outer columns take on heavy loads, which compensates for the tensile forces from the wind. The pediment of the high part of the building protrudes 2.5 m in front of the columns. The connections located in the end walls continue within the first hidden floor between the columns with the transfer of horizontal forces from the upper connection to the bottom along the horizontal connection in the lower interfloor overlap. To transfer the total support forces, a solid beam of steel sheets is used to the height of the floor, located in the technical floor between the penultimate and last columns. This beam forms a cantilever to the gable wall. - The high-rise building of the television center in West Berlin. Architect Tepets. Diploma constructor. eng. Treptow.
9. Ensuring the rigidity of the building with the help of external ties, transferring part of the vertical loads to the intermediate columns. Details - Alcoa Administration Building in San Francisco. Architects: Skidmore, Owings, Merrill.
10. Ensuring the rigidity of the building in the transverse direction: in the lower part thanks to a heavy reinforced concrete wall, in the upper part with the help of staggered staggered braces located in front of the facade. Each floor has six links. Tie rods are made of tubular profiles. Rigidity in the longitudinal direction is provided by the installation of half-timbered ties in the middle rows of columns. Details - Residential high-rise building on Rue Krulebarbe in Paris. Architects: Albert Boileau and Labourdette.
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Ties are important elements of the steel frame, which are necessary to fulfill the following requirements: – ensuring the immutability of the frame spatial system and the stability of its compressed elements; - perception and transfer to the foundations of some loads (wind, horizontal from cranes); - ensuring the joint operation of transverse frames under local loads (for example, crane); - creation of frame rigidity necessary to ensure normal operating conditions; – providing conditions for high-quality and convenient installation. Links are divided into links between columns and links between trusses (cover links). |
Links between columns.
The system of connections between columns (9.8) provides during operation and installation:
– geometric immutability of the frame;
- the bearing capacity of the frame and its rigidity in the longitudinal direction;
- the perception of longitudinal loads from the wind in the end of the building and braking of the crane bridge;
– stability of columns from the plane of transverse frames.
To perform these functions, at least one vertical hard disk is required along the length of the temperature block and a system of longitudinal elements attaching columns that are not included in the hard disk to the latter. The hard disks (Fig. 11.5) include two columns, a crane beam, horizontal braces and a lattice, which ensures geometric invariability when all elements of the disk are hinged.
The lattice is designed cross (Fig. 9.13, a), the elements of which are accepted as flexible [] = 220 and work in tension in any direction of forces transmitted to the disk (the compressed brace loses stability) and triangular (Fig. 9.13, b), the elements of which work in tension and compression. The lattice scheme is chosen so that its elements can be conveniently attached to the columns (the angles between the vertical and the lattice elements are close to 45 °). With large column pitches in the lower part of the column, it is advisable to arrange a disk in the form of a double-hinged lattice frame, and in the upper part - the use of a truss truss (Fig. 9.13, c). Spacers and grating at low heights of the column section (for example, in the upper part) are located in one plane, and at high heights (lower part of the column) - in two planes.
Rice. 9.13. Schemes of designs of hard disks of connections between columns:
a - while ensuring the stability of the lower part of the columns from the plane of the frame; b - if necessary, install intermediate struts; c - if it is necessary to use a crane gauge.
Rice. 9.14. Schemes of temperature movements and forces:
a - at the location of vertical bonds
in the middle of the frame; b - the same, at the ends of the frame
When placing hard disks (connection blocks) along the building, it is necessary to take into account the possibility of column movements during thermal deformations of the longitudinal elements (Fig. 9.14, a). If you put the disks on the ends of the building (Fig. 9.14, b), then in all longitudinal elements (crane structures, truss trusses, bracing braces) and in the braces, significant temperature forces arise.
Therefore, with a small length of the building (temperature block), a vertical connection is placed in one panel (Fig. 9.15, a). With a long building length, vertical connections are placed in two panels (Fig. 9.15, b), and the distance between their axes should be such that the forces F t are small. The limiting distances between the disks depend on possible temperature differences and are established by the standards (Table 9.3).
At the ends of the building, the extreme columns are interconnected by flexible upper connections (see Fig. 9.15, a). Due to the relatively low rigidity of the overhead part of the column, the location of the upper connections in the end panels has little effect on thermal stresses.
Vertical connections between columns are placed along all rows of columns of the building; they should be placed between the same axes.
Rice. 9.15. Location of connections between columns in buildings:
a - short (or temperature compartments); b - long; 1 - columns; 2 - spacers; 3 - axis of expansion joint; 4- crane beams; 5 - communication block; 6- temperature block; 7 - bottom farms; 8 - shoe bottom
Table9.3. Maximum dimensions between vertical ties, m
When designing connections along the middle rows of columns in the crane runway, it should be borne in mind that quite often, according to the conditions of technology, it is necessary to have free space between the columns. In these cases, portal connections are constructed (see Fig. 11.5, c).
The connections installed within the height of the crossbars in the connection and end blocks are designed in the form of independent trusses (mounting element), spacers are placed in other places.
The longitudinal elements of the connections at the points of attachment to the columns ensure that these points are not displaced from the plane of the transverse frame. These points in the calculation scheme of the column can be taken by hinged supports. When the height of the lower part of the column is high, it may be advisable to install an additional spacer, which fixes the lower part of the column in the middle of its height and reduces the estimated length of the column.
Rice. 9.16. The work of connections between columns under the influence of: a - wind load on the end of the building; b - overhead cranes.
Load transfer. At point A (Fig. 9.16, a), the flexible bond element 1 cannot perceive the compressive force, therefore F w is transmitted by a shorter and rather rigid spacer 2 to point B. Here, the force through element 3 is transmitted to point C. At this point, the force is perceived by crane beams 4, transmitting the force F w to the connection block at point G. The connections work similarly on the forces of the longitudinal effects of cranes F (Fig. 9.16, b).
Connection elements are made of angles, channels, rectangular and round pipes. With a large length of connection elements that perceive small forces, they are calculated according to the ultimate flexibility, which for compressed connection elements below the crane beam is 210 - 60 ( is the ratio of the actual force in the connection element to its bearing capacity), above - 200; for stretched ones, these values are 200 and 300, respectively.
Coverage Links (9.9).
Horizontal links are located in the planes of the lower and upper chords of the trusses and the upper chord of the lantern. Horizontal connections consist of transverse and longitudinal (Fig. 9.17 and 9.18).
Rice. 9.17. Links between farms: a - along the upper belts of farms; b - along the lower belts of farms; c - vertical; / - spacer in the ridge; 2 - transverse braced trusses
Rice. 9.18. Connections between lanterns
The elements of the upper chord of the truss trusses are compressed, so it is necessary to ensure their stability from the plane of the trusses. Roof slab ribs and purlins can be considered as supports that prevent the upper nodes from moving out of the truss plane, provided that they are secured from longitudinal movements with braces.
It is necessary to pay special attention to the tying of truss knots within the lantern, where there is no roofing. Here, to unfasten the nodes of the upper belt of the trusses from their plane, struts are provided, and such struts are required in the ridge truss node (Fig. 9.19, b). Spacers are attached to the end connections in the plane of the upper chords of the trusses.
During installation (before the installation of roof slabs or girders), the flexibility of the upper chord from the plane of the truss should not be more than 220. If the ridge strut does not provide this condition, an additional strut is placed between it and the strut in the plane of the columns.
In buildings with overhead cranes, it is necessary to ensure the horizontal rigidity of the frame both across and along the building. During the operation of overhead cranes, forces arise that cause transverse and longitudinal deformations of the shop frame. If the transverse rigidity of the frame is insufficient, the cranes may jam during movement, and their normal operation is disrupted. Excessive vibrations of the frame create unfavorable conditions for the operation of cranes and the safety of enclosing structures. Therefore, in single-span buildings of great height ( H 0 > 18 m), in buildings with overhead cranes with a lifting capacity ( Q≥ 10 t, with cranes of heavy and very heavy duty at any load capacity, a system of longitudinal ties along the lower chords of trusses is required.
Rice. 9.19. Cover link work:
a - diagram of the operation of horizontal connections under the action of external loads; b and c "- the same, with conditional forces from the loss of stability of the truss belts; / - ties along the lower truss belts; 2 - the same, along the top; 3 - bracing of the ties; 4 - stretching of the ties; 5 - form of buckling or oscillation in the absence of spacers (stretch marks); 6 - the same, in the presence of spacers.
Horizontal forces from overhead cranes act in the transverse direction on one flat frame and two or three adjacent ones. Longitudinal connections ensure the joint operation of the system of flat frames, as a result of which the transverse deformations of the frame from the action of a concentrated force are significantly reduced (Fig. 9.19, a).
The rigidity of these links must be sufficient to involve adjacent frames in the work, and their width is assigned equal to the length of the first panel of the lower chord of the truss. Connections are usually installed on bolts. Welding of bonds increases their rigidity several times.
The panels of the lower chord of trusses adjacent to the supports, especially when the crossbar is rigidly connected to the column, can be compressed, in this case the longitudinal braces ensure the stability of the lower chord from the plane of the trusses. The transverse ties fix the longitudinal ones, and at the ends of the building they are also necessary for the perception of the wind load directed at the end of the building.
Fachwerk racks transmit the wind load F w to the nodes of the transverse horizontal end truss, the belts of which are the lower belts of the end and adjacent truss trusses (see Fig. 9.19, a). The support reactions of the end truss are perceived by vertical connections between the columns and are transferred to the foundation (see Fig. 9.19). In the plane of the lower chords, intermediate cross braces are also arranged, located in the same panels as the cross braces along the upper truss chords.
To avoid vibration of the lower chord of trusses due to the dynamic action of overhead cranes, it is necessary to limit the flexibility of the stretched part of the lower chord from the plane of the frame. In order to reduce the free length of the stretched part of the lower chord, in some cases it is necessary to provide braces that secure the lower chord in the lateral direction. These extensions perceive the conditional transverse force Q fic (Fig. 9.19, c).
In long buildings consisting of several temperature blocks, cross-braced trusses along the upper and lower chords are placed at each expansion joint (as at the ends), bearing in mind that each temperature block is a complete spatial complex.
Vertical connections between trusses are installed in the same axes in which horizontal cross braces are placed (see Fig. 9.20, c). Vertical connections are placed in the plane of the truss struts in the span and on the supports (when the trusses are supported at the level of the lower chord). In the span, one or two vertical connections are installed along the width of the span (in 12-15 m). Vertical ties give immutability to the spatial block, consisting of two truss trusses and horizontal cross ties along the upper and lower chords of the trusses. Rafter trusses have a slight lateral rigidity, therefore, during installation, they are fixed to a rigid spatial block with spacers.
In the absence of horizontal cross braces along the upper chords, to ensure the rigidity of the spatial block and fix the upper chords from the plane, vertical ties are installed after 6 m (Fig. 9.20, e).
Rice. 9.20. Schemes of communication systems by coverage:
a - cross connections with a 6-meter step of frames; b - connections with a triangular lattice; c and d - the same, with a 12-meter frame step; e - a combination of horizontal ties along the lower chords of trusses with vertical ties; I, II - connections, respectively, on the upper and lower chords of farms
The sections of the connection elements depend on their design scheme and the pitch of the truss trusses. For horizontal connections with a truss pitch of 6 m, a cross or triangular lattice is used (Fig. 9.20, a, b). The braces of the cross lattice work only in tension, and the posts work in compression. Therefore, racks are usually designed from two corners of the cross section, and braces - from single corners. The elements of a triangular lattice can be both compressed and stretched, so they are usually designed from bent profiles. Triangular ties are somewhat heavier than cross ties, but their installation is easier.
With a truss pitch of 12 m, the diagonal elements of the connections, even in the cross lattice, are very heavy. Therefore, the system of connections is designed so that the longest element is no more than 12 m, diagonals support these elements (Fig. 9.20, c). On fig. 9.20, d shows the diagram of connections, where the diagonal elements fit into a square 6 m in size and rely on longitudinal elements 12 m long, which serve as belts of truss trusses. These elements have to be made of a composite section or from bent profiles.
Vertical connections between trusses and lanterns are best done in the form of separate transportable trusses, which is possible if their height is less than 3900 mm. Various schemes of vertical connections are shown in fig. 9.20, e.
On fig. 9.19 shows the signs of the forces arising in the elements of the pavement ties for a certain direction of the wind load, local horizontal forces and conditional transverse forces. Many link elements can be compressed or stretched. In this case, their section is selected according to the worst case - according to the flexibility for the compressed elements of the connections.
Spacers in the ridge of the upper chord of the trusses (element 3 in Fig. 9.19, b) ensure the stability of the upper chord from the plane of the trusses both during operation and during installation. In the latter case, they are attached to only one cross-link, their cross section is selected based on compression.
The metal frame consists of many load-bearing elements (truss, frame, columns, beams, girders), which must be “linked” to each other to maintain the stability of the compressed elements, the rigidity and the geometric invariability of the entire building structure. To connect the structural elements of the frame are used metal ties. They perceive the main longitudinal and transverse loads and transfer them to the foundation. The metal ties also distribute loads evenly between the trusses and frame frames to maintain overall stability. Their important purpose is to counteract horizontal loads, i.e. wind loads.
The Saratov Reservoir Plant produces connections from hot-rolled profiled angles, bent angles, bent profile pipes, hot-rolled profile pipes, round pipes, hot-rolled and bent channels and I-beams. The total mass of the metal used should be approximately 10% of the total mass of the steel structure of the building.
The main elements that connect links are trusses and columns.
Metal connections of columns
Column connections provide transverse stability of the metal structure of the building and its spatial immutability. Connections of columns and racks are vertical metal structures and structurally represent struts or disks that form a system of longitudinal frames. The purpose of hard drives is to fasten columns to the foundation of a building. Spacers connect columns in a horizontal plane. Spacers are longitudinal beam elements, for example, interfloor ceilings, crane beams.
Inside the connections of the columns are distinguished ties of the upper tier and ties of the lower tier of columns. The connections of the upper tier are located above the crane beams, the connections of the lower tier, respectively, below the beams. The main functional purposes of the loads of two tiers are the ability to transfer the wind load to the end of the building from the upper tier through the cross braces of the lower tier to the crane beams. Top and bottom ties also help keep the structure from tipping over during installation. The connections of the lower tier also transfer loads from the longitudinal braking of cranes to the crane beams, which ensures the stability of the crane part of the columns. Basically, in the process of erecting the metal structures of the building, the connections of the lower tiers are used.
Scheme of vertical connections between columns
Metal truss ties
To give spatial rigidity to the structure of a building or structure, metal trusses are also connected by ties. A truss connection is a spatial block with adjacent truss trusses attached to it. Adjacent farms along the upper and lower belts are connected horizontal truss ties, and along the racks of the lattice - vertical truss ties.
Horizontal truss ties along the lower and upper chords
Horizontal links of farms are also longitudinal and transverse.
The lower truss belts are connected by transverse and longitudinal horizontal ties: the first ones fix vertical ties and stretch marks, thereby reducing the vibration level of the truss belts; the latter serve as supports for the upper ends of the racks of the longitudinal fachwerk and evenly distribute the load on adjacent frames.
The upper chords of the trusses are connected by horizontal cross braces in the form of spacers or girders to maintain the designed position of the trusses. Cross ties unite the upper chords of the truss into a single system and become the “closing edge”. The struts just prevent the trusses from moving, and the transverse horizontal trusses / ties prevent the struts from moving.
Vertical connections of farms are necessary in the process of erecting a building or structure. They are often referred to as mounting links. Vertical connections contribute to maintaining the stability of trusses due to the displacement of their center of gravity above the supports. Together with intermediate trusses, they form a spatially rigid block at the ends of the building. Structurally, vertical truss ties are disks consisting of spacers and trusses, which are located between the racks of truss trusses along the entire length of the building.
Vertical connections of columns and trusses
Structures of metal ties of a steel frame
By design, metal bonds are also:
cross-links, when the elements of the links intersect and connect to each other in the middle
angular bonds, which are located in several parts in a row; are mainly used for the construction of low-span frames
portal connections for U-shaped frames (with openings) have a large surface area
The main type of connection of metal ties is bolted, since this type of fastening is the most effective, reliable and convenient during installation.
Specialists of the Saratov Reservoir Plant will design and manufacture metal connections from any profile in accordance with the mechanical requirements for the physical and chemical properties of the material, depending on the technical and operational conditions.
Reliability, stability and rigidity of the metal frame of your building or structure largely depends on the quality of the production of metal ties.
How to order the production of metal ties at the Saratov Reservoir Plant?
To calculate the cost of metal structures of our production, you can:
- contact us by phone 8-800-555-9480
- write technical requirements for metal structures by e-mail
- use the form "", specify contact information, and our specialist will contact you
Plant specialists offer complex services:
- engineering surveys at the operation site
- design of oil and gas facilities
- production and installation of various metal structures
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