Vertical braces, as the most economical structures, in most cases reliably provide the rigidity of buildings with a steel frame.

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 ties located in the end walls continue within the first hidden floor between the columns with the transfer of horizontal forces from the upper tie to the lower tie along the horizontal tie in the lower intermediate floor. 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 ties located in front of the facade. Each floor has six connections. 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.

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.

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 that 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, the lower chord is unfastened, 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 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 it is 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 truss 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 connections, 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 connection nodes made of angle and bend-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 links are also called mounting ones, 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, because. 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. Trusses 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 adjacent frames that are less loaded (Fig. 12b). Thus, the spatiality 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 step length of the frames.

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.

Transverse braces, as a rule, are placed under the braces along the upper chords, creating with them spatial transverse blocks, to which intermediate trusses (crossbars) are attached with the help of girders, vertical braces and longitudinal braces.

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 heavy-duty frames of 7K, 8K cranes and at high crane loads, ties are attached to trusses by welding (i.e., bolted 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 between 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 - the stability of the columns "from the plane" of the frames. Thus, the calculated 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.).

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 ties is usually located along the axis of the over-crane part of the column, and the lower ties 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.

1. SNiP II-23-81*. Steel structures, - M., Stroyizdat, 1988, - 96 p.
2. Belenya E.I. and others. Metal constructions.- M., Stroyizdat, 1989.- P.272-279.
3. SNiP 2.01.07.-85. Loads and influences. - M., Stroyizdat, 1989.
4. 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.
5. Benefit on the design of steel structures (to SNiP 23-81 *) - M., Central Institute for Standard Design, 1989 -148s.

The system of connections in the coatings of industrial buildings

The connections in the coatings are designed to ensure the spatial rigidity, stability and immutability of the building frame, to absorb horizontal wind loads acting on the ends of the building and skylights, horizontal braking forces from overhead support and overhead cranes and transfer them to the frame elements.

Relationships are divided into horizontal(longitudinal and transverse) and vertical. The connection system depends on the height of the building, the span, the pitch of the columns, the presence of overhead cranes and their lifting capacity. In addition, the design of all types of connections, the need for their installation, the location in the coating is determined by the calculation in each case and depends on the type of load-bearing structures of the coating.

In this section, examples of the arrangement of a bonding system in coatings with planar load-bearing structures made of metal, reinforced concrete and wood are considered.

Connections in coatings with metal planar supporting structures

The system of connections in the coatings of buildings with metal farms depends on the type of trusses, the pitch of the truss structures, the conditions of the construction area and other factors. It consists of horizontal ties in the plane of the upper and lower chords of roof trusses and vertical ties between trusses.

Horizontal connections along the upper chords truss trusses are most often provided only in the presence of lanterns and are located in the under-lantern space.

Horizontal connections in the plane of the lower chords There are two types of truss trusses. Connections first type consist of transverse and longitudinal braced trusses, struts and stretch marks. Connections second type consist only of transverse truss trusses, struts and stretch marks.

Cross-link trusses located at the ends of the temperature compartment of the building. With a temperature compartment length of more than 96 m, intermediate cross-braced trusses are installed every 42-60 m.

Longitudinal horizontal braced trusses along the lower belts of truss trusses for ties of the first type, they are located in one-, two- and three-span buildings along the extreme rows of columns. In buildings with more than three spans, longitudinal braced trusses are also located along the middle rows of columns so that the distance between adjacent braced trusses does not exceed two or three spans.

Connections first type are mandatory in buildings:

a) with overhead cranes that require the installation of galleries for passage along the crane tracks;

b) with truss trusses;

c) with an estimated seismicity of 7 - 9 points;

d) with a mark of the bottom of the truss structures of more than 24 m, (for single-span buildings - more than 18 m);

e) in buildings with a roof on reinforced concrete slabs, equipped with general-purpose bridge support cranes with a lifting capacity of more than 50 tons at a truss step of 6 m and a lifting capacity of more than 20 tons at a truss step of 12 m;

f) in buildings with a roof on a steel profiled flooring -

in one- and two-span buildings equipped with overhead cranes with a lifting capacity of more than 16 tons and in buildings with more than two spans with overhead cranes with a lifting capacity of more than 20 tons.

In other cases, links should be applied second type, while with a pitch of truss trusses of 12 m and the presence of longitudinal half-timbered racks along the columns of the extreme rows, longitudinal truss trusses should be provided.

Vertical links are located at the locations of transverse truss trusses along the lower chords of truss trusses at a distance of 6 (12) m from each other.

The mounting fastenings of the ties to the coating structures are taken on bolts or on welding, depending on the magnitude of the force effects. Link elements are designed from hot-rolled and bent-welded profiles.

Figures 5.2.1 - 5.2.10 show the layout of the bonds in the roof with trusses from paired corners. Connections in coatings using wide-shelf tees, wide-shelf I-beams and round pipes are solved similarly. Structural solution of vertical ties with a span of 6 and 12 m is shown in Figure 5.2.11, 5.2.12

Connections in the roof with trusses from closed bent-welded profiles of the Molodechno type are shown in Figures 5.2.13 - 5.2.16.

The basis for the invariability of the coating in the horizontal plane is a solid disk formed by a profiled decking fixed along the upper chords of the trusses. The flooring unties the upper chords of the trusses from the plane along the entire length and perceives all horizontal forces transmitted to the floor.

The lower chords of the trusses are untied from the plane by vertical braces and spacers, which transfer all forces from the lower chord of the trusses to the upper disk of the cover. Vertical connections are established through 42 - 60 m along the length of the temperature compartment.

In buildings with roof structures of the "Molodechno" type with a slope of the upper chord of 10%, the arrangement of vertical braces and struts is similar to that shown in Figures 5.2.14 - 5.2.16. The vertical connection in this case is performed by a V-shaped span of 6 m (Fig. 5.2.11).

Fig.5.2.5. Schemes of arrangement of vertical bonds in coatings

using profiled flooring

(sections are marked in Fig. 5.2.1, 5.2.2)

Fig.5.2.8. Scheme of arrangement of vertical ties in coatings using reinforced concrete slabs

Steel structures of one-storey industrial buildings

The steel frame of an industrial building consists of the same elements as the reinforced concrete, only the material of the frame is steel.

The use of steel structures is advisable for:

1. for columns: with a step of 12 m or more, a building height of more than 14.4 m, a two-tier arrangement of overhead cranes, with a crane lifting capacity of 50 tons or more, for heavy duty operations;

2. for roof structures: in heated buildings with a span of 30 m or more; in unheated buildings 24 m and more; over hot shops, in buildings with high dynamic loads; with steel columns.

3. for crane beams, lanterns, crossbars and half-timbered racks

columns

Columns designed:

· single-branched solid-walled with a constant section at a building height of 6 - 9.6 m, a span of 18, 24 m (series 1.524-4, issue 2),

· two-branch with a building height of 10.8-18 m, a span of 18.24.30.36 m (series 1.424-4, issue 1 and 4),

· separate type used in buildings with a large load capacity and a height of more than 15 m.

Hanging equipment

With a building height of up to 7.2, overhead cranes are not provided, only suspended equipment with a lifting capacity of up to 3.2 tons; in buildings 8.4-9.6 overhead cranes with a lifting capacity of up to 20 tons can be used.

The columns are designed in two versions: with passages and without passages. For columns without passages, the distance from the center axis to the axis of the crane rail is 750 mm, for columns with passages - 1000 mm. The upper part of the column is an I-beam, the lower part is made up of two branches connected by a lattice of rolled corners, which are welded to the branches of the branches.

Column design

The step of the columns is recommended for craneless buildings and with suspended equipment along the outer rows - 6 m, middle rows - 6, 12 m; with overhead cranes along the extreme and middle rows - 12 m. In order to unify the columns, their lower ends must be placed at a mark of - 0.6 m. To protect against corrosion, the underground part of the columns, together with the base, is covered with a layer of concrete.

The main parameters of the column in height:

H in - the height of the upper part,

· H n - the height of the lower part, the mark of the head of the crane rail, the height of the section of the branch h.

In the middle rows with a height difference in the frames, one row of columns can be installed, but along the drop line it is necessary to provide two center axles with an insert between them. The upper part of such columns is assumed to be the same as the upper part of the outermost columns, i.e. has a binding of 250 mm. The second center axis is aligned with the outer edge of the upper part of the columns.

Farms

Coating trusses are used in single and multi-span buildings with reinforced concrete or steel columns 18.24.30.36 m long, the column spacing is assumed to be 6.12 m. They consist of the truss itself and support posts. The support of the truss on columns or truss trusses is taken to be hinged.

Three types are made: with parallel belts, polygonal, triangular.

Truss structures:

· Farms with parallel belts with a span of 18 m. have slopes of 1.5% only of the upper belt, the rest of both the upper and lower belts. The height of the truss on the support is 3150 mm - along the edges, and 3300 mm - the total height with the stand, the nominal length is less than the span by 400 mm. (for 200 mm of extreme compartments). Reinforced concrete slabs directly rest on the upper belt of the truss truss, reinforced with overlays in the places of support and are welded. In coatings with prof. flooring, 6 m long girders are used, which are installed on the upper chord and fastened with bolts, lattice girders 12 m long are welded.

· Trusses from round pipes(more economical by 20%, less prone to corrosion due to the absence of cracks and sinuses) series 1,460-5. intended only for prof. flooring, the lower chord is horizontal, the upper one with a slope of 1.5%, the height on the support is 2900 mm., the total height is 3300, 3380 mm., the nominal length is also 400 mm. shorter.

· Farms with a slope of the upper belt 1:3.5 ( triangular), designed for single-span roofless, unheated warehouses with external drainage, series PK-01-130/66 for covering with purlins.

· Roof trusses are designed with parallel chords, the height of the rims is 3130 mm., the total height is 3250 mm. The supporting post of the truss truss is made of a welded I-beam with a table in the lower part for supporting the truss trusses. Rafter structures with a span of 12 m are installed on reinforced concrete or steel trusses. With a span of 18.24 m only on steel.

· Fachwerk in a steel frame suit: with walls made of sheet material or panels, in buildings with a height of more than 30 m, regardless of the wall structure, in buildings with heavy duty cranes with brick walls, in prefabricated buildings, for temporary portable end walls during the construction of a building in multiple queues. Fachwerk consists of their racks and crossbars. Their number and location is determined by the pitch of the columns, the height of the building, the design of the wall filling, the nature and magnitude of the load, and the location of the openings. The upper ends of the half-timbered racks are attached to roof trusses or ties using curved plates.

Link system:

The system of connections in the covering consists of upper and lower chords of roof trusses, horizontal in the plane, and vertical between trusses.

The system is designed to provide spatial work and impart spatial rigidity to the frame, absorb horizontal loads, ensure stability during installation, if the building consists of several blocks, each block has an independent system.

If the building is covered with reinforced concrete slabs, then the connections along the upper belt consist of spacers and stretch marks, horizontal connections are provided only in lantern buildings and are located in the under-lantern space. Attached with bolts.

Horizontal connections along the lower chords

Horizontal connections along the lower belts are of two types:

The first type of transverse braced trusses is used with a spacing of the outer columns of 6 m and is located at the ends of the temperature compartment, with a compartment length of more than 96 m, additional trusses are installed with a step of 42-60 m. In addition, longitudinal horizontal trusses are used, which are located along the outer columns, as needed and average.

These connections are used in buildings: single-span, double-span with cargo cranes. 10 tons or more; in buildings with three or more spans with a total load. 30 tons and more.

In other cases, type 2 connections are used - the second type is used with a step of the outermost columns of 12 m and are located similarly to the first type.

Connections are fastened with bolts, in case of heavy duty welding.

Vertical links

Vertical ties are located along the spans, at the locations of transverse horizontal trusses every 6 m, fastened with bolts or welding, depending on the effort.

When used in the coating prof. flooring, runs are used, which are located in increments of 3 m, in the presence of height differences, 1.5 m is allowed. prof. the flooring is attached to the girders with self-tapping screws.

Vertical connections between steel columns, provided in each longitudinal row of columns, are divided into main and upper.

The main ones ensure the invariability of the frame in the longitudinal direction, they are located along the height of the crane part of the column in the middle of the building or the temperature compartment. Cross, portal or semi-portal are designed.

The top ties, which ensure the correct installation of the column heads during installation and the transfer of longitudinal forces from the upper sections of the end walls to the main ties, are placed within the overhead part of the column along the edges of the temperature compartment. In addition, these connections are arranged in those panels where vertical and transverse horizontal connections between the roof trusses are located. They are designed in the form of struts, crosses, struts and trusses.

They make connections from channels and angles, fasten to columns with black bolts, in buildings with a heavy load capacity of heavy duty - site welding, clean bolts or rivets.

Crane structures

overhead tracks they are usually made of rolled I-beams of type M with joints outside the supports. These tracks are suspended from the lower chords of the supporting structures with the help of bolts, followed by welding.

Crane structures for overhead cranes consist of crane beams, perceiving vertical and local forces from crane rollers; brake beams or trusses, perceiving horizontal impacts of cranes; vertical and horizontal connections, providing rigidity and immutability of structures.

Crane steel beams, depending on the static scheme, are divided into split and continuous. Mostly used cut. They are structurally simple, less sensitive to support settlements, easy to manufacture and install, but compared to continuous ones they have a greater height and complicate the operating conditions of crane tracks and require more steel consumption.

According to the type of section, crane beams can be solid and through (lattice) section

Crane beams series 1,426-1 in the form of a welded I-beam with symmetrical belts or not, span 6, 12, 24 m, height: with a length of 6 m - 800, 1300 mm .; with a length of 12 m - 1100.1600 mm. The section height of solid beams is 650-2050 mm with a gradation of 200 mm. The beams are provided ribs stiffness to ensure the stability of the walls, located after 1.5 m. Beams are medium and extreme (located at the ends and at the expansion joint, one of the supports is moved back by 500 mm). The support of the beams on the console of the columns is assumed to be hinged: to the ordinary ones - on bolts, to the bonded ones - on bolts and field welding.

Brake structures represent connections along the upper chords of crane beams, which are selected depending on the presence of passages and the span of the beam.

At the level of crane runways, spans with heavy-duty overhead cranes are provided for walk-through platforms. Platforms are accepted with a width of at least 0.5 m with railings and stairs. At the locations of the columns, passages are arranged on the side or through openings in them.

Depending on the lifting capacity of the cranes and the type of running wheels for crane runways railway rails, rails of the KR profile or bar profile are used. Fastening rails to beams can be fixed and movable.

Fixed fastening, which is allowed for light duty operation of cranes with a lifting capacity of up to 30 tons and medium duty with a lifting capacity of up to 15 tons, is provided by welding the rail to the beam. In most cases, the rails are attached to the beams in a movable way, allowing the rails to be straightened. At the ends of the crane runways, shock absorber stops are arranged to prevent impacts on the end walls of the building.

Used in industrial buildings mixed frames(reinforced concrete columns and metal trusses) under the conditions:

the need to create large spans;

· to reduce the weight of the coating elements.

Fastening of steel trusses to reinforced concrete columns is carried out using bolted joints, followed by welding. To do this, anchor bolts are provided in the column head.