Types of connections of frame buildings. Connections for covering industrial buildings Location of vertical connections
1. horizontal cross braces along the lower chords of the trusses are placed at the ends of the temperature block with a column spacing of the outer and middle rows of 12 m. If the block length is more than 144 m, they are additionally installed in the middle of the block. They are formed by combining the lower chords of 2 adjacent trusses using a lattice. As a result, they perform joint functions: they absorb the wind load from the end fencing posts and transfer it to the connections between the columns and further to the foundation, and also prevent the movement of vertical connections and braces between the lower chords of the trusses. Spacers between the lower chords of the trusses secure these chords from displacement, thereby reducing the estimated length from the plane of the truss, and reduces vibrations of the lower chords of the trusses.
2. horizontal longitudinal connections along the lower chords of the trusses serve as supports for the upper ends of the posts of the longitudinal half-timbering; under the action of crane loads, adjacent frames are involved in the work, reducing transverse deformations and avoiding jamming of overhead cranes. These connections are required in single-span buildings of great height, with heavy overhead cranes, and in the presence of longitudinal half-timbering. Spacers ensure the design position of the trusses during the installation process and limit the flexibility of the trusses from their plane. The role of spacers is performed by purlins that are secured against displacement.
3. horizontal cross braces along the upper chords of the trusses the designs and placement patterns are similar to the connections along the lower chords. They serve to displace the spacers along the upper chords of the trusses. They can be abandoned if vertical connections are installed between adjacent trusses of the block and through them the spacers are secured to the transverse connections along the lower chords of the trusses.
4. 4. vertical connections between the supports of trusses or beams They are placed only in buildings with a flat roof, and in buildings without rafter structures they are placed in each row of columns, and with rafter structures - only in the outer rows of columns at a step of 6 m. They are placed no more often than after one step. With a temperature block length of 60-72 m, for each row of columns there should be no more than 5 of them at a pitch of 6 m and no more than 3 at a pitch of 12 m. If these connections are present, spacers are placed on the top of the columns.
Unified modular system in construction
Typification in construction is carried out on the basis of the Unified Modular System. These are the rules by which the sizes of buildings and structures are assigned and agreed upon.
According to EMC rules, dimensions are assigned according to the module base. The main module (M) is 100 mm. When choosing dimensions for buildings and structures, an enlarged module is used: 6000 mm = 60M; 7200 mm = 72M. The fractional module is used to assign sections of structures: 50 mm = ½M.
EMC is a unified modular system, which is a set of rules that coordinate the dimensions of the space-planning and structural parts of construction projects and the dimensions of prefabricated modules and equipment.
MKRS - modular size coordination in construction. A standard, the use of which in the design of buildings makes it possible to unify the dimensions of building structures and the space-planning dimensions of buildings. This standard involves the unification of the following parameters: floor heights (H0), steps (B0) and spans (L0).
EMC is based on the principle of multiple sizes. The size of any building element must be a multiple of a value called a module. The EMC system adopts a module of 100 millimeters, which is designated in the technical documentation by the letter M. Accordingly, the dimensions of large structural elements will be designated as derivatives of the module. For example, 6000 mm - 60 M, 3000 mm - 30 M and so on. Small elements are designated as fractional from the module: 50 mm - ½ M, 20 mm - 1/5 M.
15 basis for planning industrial buildings
Industrial buildings are divided into two types of layout:
separate (detached) buildings, the layout of which, although it provides structural simplicity and a high level of industrialism in the production of buildings, is characterized by such disadvantages as a large building area, a large length of engineering and transport networks, the impossibility of organizing continuous production, and significant energy costs for heating premises;
solid (interlocked) buildings, which represent
multi-span buildings with a large area (up to 30...35 thousand sq.m). Solid layout provides a multi-variant arrangement of technological equipment, reducing the plant area by 30...40%, reducing construction costs by 10...15%, reducing the length of engineering and transport communications , reducing the perimeter of external walls by 50% with a reduction in operating costs. However, the disadvantages of solid buildings are the increased cost of natural lighting, difficult drainage from coatings, and the complication of routes for transport and personnel. It is advisable to block workshops in cases where adjacent production does not need to be separated by capital walls and the conditions of production technology and labor of workers do not deteriorate.
The layout of industrial buildings is accompanied by zoning within the volume of industrial buildings, premises, areas and zones, allocated according to the characteristics of the same type of technology, the level of industrial hazards, the level of fire and explosion hazard, the direction of transport and human flows, and the prospects for expansion and re-equipment.
The choice of number of storeys for an industrial building is influenced by:
production technology;
climatic conditions of the area;
requirements for development (urban, peripheral);
the nature of the allocated area (free, constrained terrain);
advantages and disadvantages.
One-story buildings have the following advantages:
simple space-planning solution;
tendency to unify and block;
reduction in the cost of 1 sq. m by 10% compared to the cost of multi-storey buildings;
facilitating the installation of technological equipment;
simplification of freight flow routes and the use of horizontal transport;
uniform illumination of workplaces with natural light through lanterns;
ensuring natural air exchange.
The disadvantages of one-story buildings are:
large building area;
large extent of engineering and transport networks;
increased costs for landscaping;
large area of external enclosing structures and, as a result, significant heating costs.
Multi-storey buildings do not have most of the disadvantages of single-storey buildings and are rational in use, especially with loads up to 10 kN/sq. m.
The main disadvantages of multi-story buildings include:
need for vertical transport;
increased cost;
width limitation if natural lighting is necessary (width no more than 24 m);
high proportion of utility rooms.
Temperature block.
To limit the forces arising in structures from temperature changes, the building is cut with temperature expansion joints into compartments (temperature blocks), the dimensions of which depend on the frame material, the thermal regime of the building and the climatic conditions of the construction area. These dimensions are determined by calculation.
Longitudinal and transverse temperature-deformation joints are indicated in blue and red colors, respectively.
For reinforced concrete and mixed frames, the length of the temperature block A ≤ 72 m - if the building contains continuous elements along its length (for example, crane beams). For craneless buildings, the standards allow A to be increased to 144 m. However, if the building has suspended equipment (monorail, etc.), the length of the temperature block should not exceed 72 m. A is allowed to be increased to 280 m, but the height of the building should not exceed 8.4 m.
The width of temperature block B should not be more than 90-96 m.
In special climatic regions and for unheated rooms, the length of temperature block A is assigned according to instructions related to local climatic conditions.
In steel frame buildings with overhead cranes A ≤ 120 m, in craneless buildings A ≤ 240 m, and B ≤ 210 m. In buildings with heavy-duty cranes (Q up to 4500 kN) or in heavy or especially heavy duty modes of their operation, A should not exceed 96 m.
Temperature seam
First of all, it is necessary to understand the concept of an expansion joint and the function it performs. A temperature joint is a through cut in the wall of a building or its roof slab. For each building, several such cuts are made, as a result of which it is divided into several independent blocks. As a result, each of these blocks can be freely deformed, which does not lead to the formation of cracks in the slabs. The fact is that expansion joints are a kind of artificial cracks that are designed in such a way as not to create any problems during the operation of the building. The width of the expansion joint determines the value within which it is possible to change the linear dimensions of each block. It would be more accurate to say the opposite: the width of the expansion joint should be selected based on the possible magnitude of deformations.
Design of expansion joints is one of the most important stages of building construction. In this case, it is necessary, first of all, to determine the length of each of the blocks into which the walls are divided by expansion joints, as well as the width of the joints. Any expansion joints, including expansion joints, are installed in those areas where the stresses caused by the corresponding deformations are concentrated. In this case, the length of the blocks must be such that each of them can be subjected to thermal deformations without loss of structural rigidity and without destruction. Therefore, to determine this parameter, a number of factors are taken into account, including the type of wall material, design features, average temperatures in summer and winter, characteristic of the construction region.
An important feature of expansion joints is that they are installed only to the height of the above-ground part of the building, while some other expansion joints, such as sedimentary ones, are installed to the entire height of the building to the base of the foundation. This is due to the fact that the foundation of the building is much less susceptible to temperature changes and does not require special protection
Ties are important elements of a steel frame that are necessary for:
1. ensuring the immutability of the spatial system of the frame and the stability of its compressed elements.
2.perception and transmission of some loads to the foundations (wind, horizontal from cranes).
3. ensuring the joint operation of transverse frames under local loads (for example, crane loads).
4. creating the rigidity of the frame necessary to ensure normal operating conditions.
The connections are divided into connections between columns and connections between trusses (tent connections).
The system of connections between the columns ensures during operation and installation the geometric immutability of the frame and its load-bearing capacity in the longitudinal direction, as well as the stability of the columns from the plane of the transverse frames.
To perform these functions, you need at least one vertical hard drive along the length of the temperature block and a system of longitudinal elements attaching columns that are not part of the hard drive to the latter. The hard disks include two columns, a crane beam, horizontal struts and a lattice, which ensures geometric immutability when all elements of the disk are hinged. The lattice is most often designed as a cross lattice, the elements of which work in tension in any direction of forces transmitted to the disk, and triangular, the elements of which work in tension and compression. The lattice design 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°). For large column spacing, it is advisable to construct a disk in the form of a double-hinged lattice frame in the lower part of the column, and to use a rafter truss in the upper part. The spacers and lattice at low heights of the column sections are located in one plane, and at high heights - in two planes. Torques are transmitted to the tie disks, and therefore, when vertical bonds are located in two planes, they are connected by horizontal lattice connections.
When placing hard drives along the building, it is necessary to take into account the possibility of columns moving due to thermal deformations of the longitudinal elements (Fig. 11.6, a). If you place disks at the ends of the building (Fig. 11.6, b), then excessive thermal forces arise in all longitudinal elements (crane structures, rafter trusses, brace braces).
Therefore, when the length of the building (temperature block) is short, a vertical connection is installed in one panel (Figure 11.7, a). With a large building (or block) length, inelastic displacements at the ends of the columns increase due to the compliance of the fastenings of the longitudinal elements to the columns. The distance from the end to the disk is limited in order to secure the columns located close to the end from loss of stability. Under these conditions, vertical connections are placed in two panels (Figure 11.7, b), and the distance between the axes should be such that the force is not very large.
At the ends of the building, the outer columns are sometimes connected to each other by flexible upper connections (Fig. 11.7, a). The upper end connections are also made in the form of crosses (Figure 11.7, b).
Upper vertical braces should be placed not only in the end panels of the building, but also in the panels adjacent to the expansion joints, as this increases the longitudinal rigidity of the upper part of the frame; In addition, during the construction of a workshop, each temperature block can for some time constitute an independent structural complex.
Vertical connections between columns are installed along all rows of columns of the building; they should be located between the same axes.
The connections installed within the height of the crossbars in the connection block and end steps are designed in the form of independent trusses; spacers are installed in other places.
Longitudinal tie elements at the points of attachment to the columns ensure that these points are not displaced from the plane of the transverse frame (Figure 11.8, a). These points in the design diagram of the column (Figure 11.8, b) can be accepted by hinged supports. If the height of the lower part of the column is large, it may be advisable to install an additional spacer (Fig. 11.8, c), which secures the lower part of the column in the middle of its height and reduces the estimated length of the column (Fig. 11.8, d).
For large lengths of connection elements, which absorb small forces, are calculated according to their maximum flexibility.
Coverage connections.
The connections between the trusses, creating the overall spatial rigidity of the frame, ensure: the stability of the compressed elements of the crossbar from the plane of the trusses; redistribution of local loads applied to one of the frames; ease of installation: specified frame geometry; perception and transmission of some loads to the columns.
The coating connection system consists of horizontal and vertical connections. Horizontal connections 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. 11.10, 11.11)
The elements of the upper chord of the trusses are compressed, so it is necessary to ensure their stability from the plane of the trusses.
To secure the slabs and girders against longitudinal displacements, transverse connections are arranged along the upper chords of the trusses, which are advisable to be located at the ends of the workshop so that they ensure spatial rigidity of the coating. If the building or temperature block is long (more than 144 m), additional transverse braced trusses are installed. This reduces the lateral movements of the truss chords resulting from the compliance of the ties.
Particular attention is paid to tying the knots of the trusses within the lantern, where there is no roofing. Here, to unfasten the nodes of the upper chord of the trusses from their plane, spacers are provided, and such spacers are required in the ridge node of the truss. Spacers are attached to the end braces in the plane of the upper chords of the trusses.
In buildings with overhead cranes, it is necessary to ensure horizontal rigidity of the frame both across and along the building. When operating overhead cranes, forces arise that cause transverse and longitudinal deformations of the workshop frame. Therefore, in single-span buildings of great height (), in buildings with overhead cranes and very heavy operating conditions for any load capacity, a system of connections along the lower chords of the trusses is required.
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 braces absorb a conditional lateral force Q.
In long buildings consisting of several temperature blocks, transverse braced trusses along the upper and lower chords are placed at each expansion joint, keeping in mind that each temperature block is a complete spatial frame. Rafter trusses have insignificant lateral rigidity, so it is necessary to arrange vertical connections between the trusses, located in the plane of the vertical posts of the trusses (Fig. 11.10, c).
When resting the supporting lower assembly of the rafters on the head of the column from above, the vertical connections must also be placed along the supporting posts of the trusses.
In multi-span workshops, connections along the upper chords of trusses and vertical ones are installed in all spans, and horizontal ones along the lower chords - along the contour of the building and some middle rows of columns through 60-90 m along the width of the building (Fig. 11.13). In buildings with differences in height, longitudinal braced trusses are placed along these differences.
The structural diagram of the connections depends mainly on the pitch of the trusses. For horizontal connections at a truss pitch of 6 m, a cross lattice is usually used, the braces of which work only in tension (Fig. 11.14, a), and trusses with a triangular lattice can also be used (Fig. 11.14, b) - here the braces work in both compression and stretching With a pitch of 12 m, the diagonal elements of the ties, even those working only in tension, are too heavy, so the system of ties is designed so that the longest element is no more than 12 m, and these elements support the diagonals.
Connections between columns.
The system of connections between the columns ensures during operation and installation the geometric immutability of the frame and its load-bearing capacity in the longitudinal direction, as well as the stability of the columns from the plane of the transverse frames. To perform these functions, at least one vertical hard drive is required along the length of the temperature block and a system of longitudinal elements attaching columns that are not part of the hard drive to the latter. The hard disks include two columns, a crane beam, horizontal struts and a lattice, which ensures geometric immutability when all elements of the disk are hinged. The lattice is often designed as cross (its elements work in tension in any direction of forces) and triangular (elements work in tension, compression). For large column spacing, it is advisable to construct a disk in the form of a double-hinged lattice frame in the lower part of the column, and a rafter truss in the upper part. At low heights, the cross-sections of the columns are located in one plane, and at high heights - in two planes. Torques are transmitted to the tie disks, and therefore, when vertical bonds are located in two planes, they are connected by horizontal lattice connections. When placing hard drives (connection blocks) along the building, it is necessary to take into account the possibility of columns moving due to thermal deformations of the longitudinal elements. If you place disks at the ends of the building, significant temperature forces arise in all longitudinal elements (crane structures, truss trusses and bracing struts). Therefore, with a short building length, a vertical connection is installed in one panel. With a large building length, inelastic movements for columns at the ends increase due to the compliance of the attachments of longitudinal elements to the columns. The distance from the end to the disk is limited in order to secure the columns located close to the end from loss of stability. In these cases, the connections are placed in two panels, and the distance between their axes should be such that the forces are not very great. The maximum distances for using disks are based on possible differences in t and are established by standards. At the ends of the building, the outer columns are sometimes connected to each other by flexible upper connections. They are made in the form of crosses, which is advisable from the point of view of installation conditions and uniformity of solutions. Upper vertical braces should be placed not only in the end panels of the building, but also in the panels adjacent to the expansion joints, because this increases the longitudinal rigidity of the upper part of the frame. Vertical connections are installed along all rows of columns of the building, located along the same axes. When designing connections along the middle rows of columns in the crane section, you should keep in mind that sometimes you need to have free space between the columns, then portal connections are designed. In hot shops with continuous crane beams or heavy crane-sub-rafter trusses, it is advisable to provide special design measures: reducing the length of temperature blocks. The connections, in addition to conditional transverse forces, perceive wind loads directed at the end of the building and from the longitudinal effects of overhead cranes. The wind load on the end of the building is perceived by the uprights of the end timber frame and is partially transmitted to the connections along the lower chord of the trusses. The tent's ties transmit this force into the rows of columns.
Steel structures of one-story industrial buildings
The steel frame of an industrial building consists of the same elements as reinforced concrete, only the frame material is steel.
The use of steel structures is advisable when:
1. for columns: with a pitch of 12 m or more, a building height of more than 14.4 m, a two-tier arrangement of overhead cranes, with a lifting capacity of the cranes of 50 tons or more, under heavy operating conditions;
2. for truss structures: in heated buildings with a span of 30 m or more; in unheated buildings 24 m or more; above hot shops, in buildings with high dynamic loads; in the presence of steel columns.
3. for crane beams, lanterns, crossbars and half-timbered posts
Columns
Columns are designed:
· single-branch solid-walled of constant cross-section with a building height of 6 - 9.6 m, span 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, issues 1 and 4),
· separate type, used in buildings with a large load capacity and a height of more than 15 m.
Hanging equipment
For building heights 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.
Columns are designed in two versions: with passages and without passages. For columns without passages, the distance from the centering axis to the axis of the crane rail is 750 mm, for columns with passages - 1000 mm. The upper part of the column is I-beam, the lower of two branches connected by a lattice of rolled angles, which are welded to the flanges of the branches.
Column design
The column spacing is recommended for craneless buildings and with suspended equipment in the outer rows - 6 m, in the middle - 6, 12 m; with overhead cranes in the outer and middle rows - 12 m. In order to unify the columns, their lower ends should be located at a level 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.
Main column height parameters:
H in - the height of the upper part,
· H n - height of the lower part, mark of the head of the crane rail, height of the branch section h.
In the middle rows with a difference in height, one row of columns can be installed in the frames, but along the line of the difference it is necessary to provide two alignment axes 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 reference of 250 mm. The second alignment axis is aligned with the outer edge of the top of the columns.
Farms
Cover trusses are used in single and multi-span buildings with reinforced concrete or steel columns with a length of 18, 24, 30, 36 m, the column spacing is 6.12 m. They consist of the truss itself and support posts. The support of the truss on columns or rafter trusses is assumed to be hinged.
They are manufactured in three types: with parallel belts, polygonal, triangular.
Truss structures:
· Trusses with parallel chords with a span of 18 m, the slopes are 1.5% only in the upper zone, the rest of both the upper and lower zones. The height of the truss on the support is 3150 mm - along the edges, and 3300 mm - the full height with the stand, the nominal length is 400 mm less than the span. (200 mm of outer compartments). Reinforced concrete slabs are directly supported on the upper chord of the truss, reinforced with overlays at the points of support and are welded. Covered with Prof. The flooring uses purlins 6 m long, which are installed on the upper chord and fastened with bolts; lattice purlins 12 m long are welded.
· Round tube trusses(20% more economical, less susceptible to corrosion due to the absence of cracks and sinuses) series 1,460-5. are intended only for professional use. flooring, the lower belt is horizontal, the upper one with a slope of 1.5%, the height on the support is 2900 mm, the full height is 3300, 3380 mm, the nominal length is also 400 mm. Briefly speaking.
· Farms with an upper chord slope of 1:3.5 ( triangular), designed for single-span, skylight-free, unheated warehouses with external drainage, series PK-01-130/66 for covering with purlins.
· Rafter trusses designed with parallel belts, the height of the butts is 3130 mm, the total height is 3250 mm. The support post of the truss truss is made of a welded I-beam with a table in the lower part for supporting the trusses. Rafter structures with a span of 12 m are installed on reinforced concrete or steel trusses. Span 18.24 m only on steel.
· Half-timbered in a steel frame are used: 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 crane operation with brick walls, in prefabricated buildings, for temporary portable end walls during the construction of a building in several queues. A half-timbered structure consists of posts and crossbars. Their number and location are 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-timber posts are attached to the covering trusses or bracings using curved plates.
Communication system:
The system of connections in the covering consists of horizontal in the plane of the upper and lower chords of the trusses and vertical ones between the trusses.
The system is designed to ensure spatial operation and impart spatial rigidity to the frame, absorb horizontal loads, and ensure stability during installation; if the building consists of several blocks, each block has an independent system.
If the roof of the building is made of reinforced concrete slabs, then the connections along the upper chord consist of struts and braces; horizontal connections are provided only in lantern buildings and are located in the space under the lanterns. The connections are secured with bolts.
Horizontal connections along the lower chords
Horizontal connections along the lower chords are of two types:
The first type of transverse braced trusses is used when the pitch of the outer columns is 6 m and is located at the ends of the temperature compartment; when the length of the compartment is more than 96 m, additional trusses are installed with a pitch of 42-60 m. In addition, longitudinal horizontal trusses are used, which are located along the outer columns, as needed and on average.
These connections are used in buildings: one- and two-span with cargo cranes. 10 tons or more; in buildings of three or more spans with a general cargo load. 30 tons or more.
In other cases, connections of type 2 are used - the second type is used when the pitch of the outer columns is 12 m and are located similarly to the first type.
The connections are fastened with bolts for heavy-duty welding work.
Vertical connections
Vertical braces are located along the spans, at the locations of transverse horizontal trusses every 6 m, and are fastened with bolts or welding, depending on the effort.
When used in coating prof. for flooring, purlins 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 purlins using 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 and are located along the height of the crane part of the column in the middle of the building or temperature compartment. Cross, portal or semi-portal are designed.
The upper 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 crane 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 covering trusses are located. They are designed in the form of struts, crosses, struts and trusses.
Ties are made from channels and angles, fastened to columns with black bolts, in buildings with a large load-bearing capacity for heavy duty use - by installation welding, clean bolts or rivets.
Crane structures
Suspended tracks They are usually made from rolled I-beams of type M with joints arranged outside the supports. These tracks are suspended from the lower chords of the supporting structures using bolts, followed by welding.
Crane structures for overhead cranes consist of crane beams, receiving vertical and local forces from crane rollers; brake beams or trusses, cranes that perceive horizontal impacts; vertical and horizontal connections, ensuring rigidity and immutability of structures.
Crane steel Depending on the static design, beams are divided into split and continuous. Predominantly split ones are used. They are simple in design, less sensitive to support settlements, and easy to manufacture and install, but compared to continuous ones they have a greater height and complicate the operating conditions of crane runways and require greater steel consumption.
According to the type of section, crane beams can be of solid or 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, heights: 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 equipped ribs rigidity to ensure the stability of the walls, located every 1.5 m. The beams are middle and outer (located at the ends and at the expansion joint, one of the supports is moved back by 500 mm). The support of beams on the column consoles is hinged: for ordinary beams - on bolts, for braced beams - on bolts and installation welding.
Brake structures They are connections along the upper chords of crane beams, which are selected depending on the availability of passages and the span of the beam.
At the level of crane runways, spans with heavy-duty overhead cranes are provided with platforms for through passages. Platforms must be at least 0.5 m wide with railings and stairs. Where columns are located, 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 tracks Railway rails, KR profile rails or block profile rails are used. The fastening of rails to beams can be fixed or movable.
Fixed fastening, allowed for light operation of cranes with a lifting capacity of up to 30 tons and medium-duty operation with a lifting capacity of up to 15 tons, is ensured by welding the rail to the beam. In most cases, the rails are attached to the beams in a movable manner, which allows straightening of the rails. At the ends of the crane tracks, shock absorbers are installed 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 weight from coating elements.
The fastening of steel trusses to reinforced concrete columns is carried out using bolted connections followed by welding. For this purpose, anchor bolts are provided at the column head. 
To give the workshop spatial rigidity, as well as to ensure the stability of the frame elements, connections are arranged between the frames.
There are connections: horizontal - in the plane of the upper and lower chords of the trusses - and vertical - both between and between the columns.
The purpose of horizontal connections along the upper chords of trusses was discussed in section. These connections ensure the stability of the upper chord of the trusses from their plane. The figure shows an example of the arrangement of ties along the upper chords of trusses in a covering with purlins.
In non-girder roofs, in which large-panel reinforced concrete slabs are welded to the upper chords of the trusses, the rigidity of the roof is so great that it would seem that there is no need to install ties.
Taking into account, however, the need to ensure proper structural rigidity during the installation of the slabs, as well as the fact that the load from the slabs is not applied strictly vertically along the axis of the trusses and therefore can cause torsion, it is considered necessary to install ties along the upper chords of the trusses at the edges of the temperature compartments. Equally necessary are spacers at the ridge of the trusses, at the supports and under the lantern posts.
These spacers serve to tie the top chords of all intermediate trusses. The flexibility of the upper chord between the points secured during installation of the slabs should not exceed 200 - 220. The connections along the upper chords of the trusses are attached to the chords with black bolts.
When making ties, it is important to accurately weld the gusset to the corner, ensuring the appropriate angle of inclination, since with the help of ties the correctness of the geometric scheme of the mounted structure is partially controlled.
Therefore, it is recommended to weld the gussets to the tie elements in jigs. The figure shows the simplest type of conductor in the form of a channel, on which holes are precisely punched at the required angle.
Horizontal braces along the lower chords of the trusses are located both across the workshop (transverse bracing) and along the workshop (longitudinal bracing). Cross braces located at the ends of the workshop are used as wind farms.
They support the frame racks of the workshop's end wall, which absorbs wind pressure. The belts of the wind farm are the lower chords of the trusses. The same transverse connections along the lower chords of the trusses are arranged at the expansion joints (in order to form a hard disk).
With a large length of the temperature block, cross braces are also placed in the middle part of the block so that the distance between the transverse braces does not exceed 50 - 60 m. This has to be done because the connections of the braces are often made on black bolts, which allow large shifts, as a result of which the influence of the braces re spreads over long distances.
Transverse deformation of the frame from local (crane) load: a - when
lack of longitudinal connections; b - in the presence of longitudinal connections.
Horizontal longitudinal connections along the lower chords of trusses have their main purpose of involving neighboring frames in the spatial work under the action of local, for example crane, loads; thereby reducing frame deformations and increasing the lateral rigidity of the workshop.
Longitudinal connections are especially important for heavy cranes and workshops with heavy duty work, as well as for light and non-rigid roofs (made of corrugated steel, asbestos-cement sheets, etc.). In heavy duty buildings, connections should be welded to the bottom chord.
For braced trusses, as a rule, a cross lattice is adopted, considering that when loads are applied on any one side, only the system of elongated braces works, and the other part of the braces (compressed) is switched off from operation. This assumption is valid if the braces are flexible (λ > 200).
Therefore, elements of cross braces, as a rule, are designed from single corners. When checking the flexibility of cross-tensile braces made from single angles, the radius of inertia of the angle is taken relative to an axis parallel to the flange.
With a triangular lattice of braced trusses, compressive forces may occur in all braces, and therefore they must be designed with flexibility λ< 200, что менее экономично.
In spans of more than 18 m, due to the limited lateral flexibility of the lower chords of the trusses, in many cases it is necessary to install additional spacers in the middle of the span. This eliminates the trembling of the trusses when the cranes are operating.
Vertical connections between trusses are usually installed at the truss supports (between the columns) and in the middle of the span (or under the lantern posts), placing them along the length of the workshop in rigid panels, i.e., where the transverse connections along the chords of the trusses are located.
The main purpose of vertical braces is to bring a spatial structure consisting of two trusses and transverse braces along the upper and lower chords of the trusses into a rigid, unchangeable state.
In shops with light and sometimes medium-duty cranes in the presence of a rigid roof made of large-panel reinforced concrete slabs welded to roof trusses, a system of vertical bracing can replace a system of transverse bracing along the belts of the trusses (except for end wind trusses).
In this case, the intermediate trusses must be connected by spacers.
The design of vertical connections is taken in the form of a cross of single corners with a mandatory horizontal closing element or in the form of a truss with a triangular lattice. The vertical connection to the truss is secured with black bolts.
Due to the insignificance of the forces acting in the elements of the coating connections, when designing their fastenings, a slight deviation from centering can be allowed.
Vertical connections between columns are installed along the workshop to ensure stability of the workshop in the longitudinal direction, as well as to absorb longitudinal braking forces and wind pressure on the end of the building.
If in the transverse direction the frames clamped in the foundations are an immutable structure, then in the longitudinal direction a series of installed frames, hingedly connected by crane beams, is a variable system that, in the absence of vertical connections between the columns, can fold (the supports of the columns in the longitudinal direction should be considered hinged ).
Therefore, the compressed elements of the connections between columns (below the crane beams), and in buildings with heavy duty operation, the tensile elements of these connections, which are essential for the stability of the entire structure as a whole, are made sufficiently rigid to avoid their shaking. For this purpose, the maximum flexibility of such elements is limited to λ = 150.
For other stretched elements of connections between columns, the flexibility should not exceed λ = 300, and for compressed elements λ = 200. Elements of cross connections between columns are usually made from corners. Particularly powerful cross braces are made from paired channels connected by a lattice or slats.
When determining the flexibility of intersecting rods (in a cross lattice), their calculated length in the lattice plane is taken from the center of the node to the point of their intersection. The calculated length of the rods from the plane of the truss is taken according to the table.
Calculated length from the plane of the truss of the cross lattice bars
| Characteristics of the intersection of lattice rods | When stretched in the support rod | When the support rod is not working | When compressed in the support rod |
| Both rods are not interrupted | 0.5 l | 0.7 l | l |
| The supporting rod is interrupted and covered with a gusset | 0.7 l | l | l |
Calculation of cross braces is usually carried out under the assumption that only tensile elements are working (at full load). If the work of the elements of the cross lattice is also taken into account in compression, the load is distributed equally between the braces.
To ensure freedom of thermal longitudinal deformations of the frame, vertical connections between columns are best located in the middle of the temperature block or close to it.
But since the installation of a structure usually begins from the edges, it is advisable to tie the first two columns into a frame so that they are stable. This forces us to construct connections as shown in the figure Connections along the lower chords of the trusses and between columns b, i.e., in the outer panels, establish connections only within the upper part of the columns.
Such connections allow bending deformation of the lower parts of the columns with temperature changes. At the same time, one of the braces, working under the tensile load of the wind, transfers these forces to the crane beam.
The further path of wind forces is shown in the figure. Connections along the lower chords of the trusses and between the columns b; they are transmitted along rigid crane beams to the middle connections and are lowered into the ground along them. It is advisable to choose a connection scheme such that they adjoin the columns at an angle close to 4 - 5°. Otherwise, the resulting heavy gussets will be too elongated.
Frame vertical connections: a - with a column spacing of 6 m;
b - with a column spacing of at least 12 m.
If, due to technological conditions, it is impossible to completely occupy a single span for bracing, and also when the column spacing is large, frame braces are arranged; in this case, it is believed that from a one-sided load they work to stretch the connections of one corner, and the elements of the other corner, due to their great flexibility (λ = 200 / 250), are switched off from work. With this design of the structure, we get a “three-hinged arch.”
Vertical connections are installed below the crane beam in the plane of the crane branch of the column, and above the crane beam - along the cross-sectional axis of the column. In heavy-duty workshops, the connections below the crane beams are attached to the columns using rivets (mainly) or welding.
"Design of steel structures"
K.K. Mukhanov
The choice of the transverse profile of multi-bay workshops depends not only on the given useful dimensions of the workshop and the dimensions of the overhead cranes, but also on a number of general construction requirements, primarily on the organization of water drainage from the roof and on the lighting arrangement for the middle spans. Water drainage can be either external or internal. External drains are installed in narrow workshops, as well as…
Frame connections provide geometric immutability and stability of elements in the longitudinal direction, joint spatial work of frame structures, building rigidity and ease of installation and consist of two main systems: connections between columns and coating connections.
Connections between columns. The connections between the columns (Fig. 6.4) ensure during operation and installation the geometric immutability of the frame and its load-bearing capacity in the longitudinal direction, perceive and transmit to the foundation wind loads acting on the end of the building and the effects of longitudinal braking of bridge cranes, and also ensure stability columns from the plane of the transverse frames.
The column bracing system consists of over-crane single-plane V-shaped ties, located in the plane of the longitudinal axes of the building, and sub-crane two-plane cross-shaped ties, located in the planes of the column branches.
Crane connections in each row of columns are located closer to the middle of the building block to ensure freedom of temperature deformations in both directions and reduce thermal stresses in the frame elements. The number of ties (one or two along the length of the block) is determined by their load-bearing capacity, the length of the temperature compartment and the greatest distance L with from the end of the building (expansion joint) to the axis of the nearest vertical connection (see Table 6.1). If there are two vertical connections, the distance between them in the axes should not exceed 40 - 50 m.
Over-crane connections are installed at the outermost column spacings at the end of the building or temperature block, as well as in places where vertical connections are provided in the plane of the support posts of trusses.
Intermediate columns (outside the bracing blocks) at the level of the trusses are braced with spacers.
If the height of the crane part of the column is high, it is advisable to install additional horizontal spacers between the columns, reducing their estimated length from the plane of the frame (shown with dotted lines in Fig. 6.4).
Vertical connections along columns are calculated for crane and wind loads W, based on the assumption of tensile work on one of the braces of the crane cross braces. For large lengths of elements that accept small forces, the connections are taken to the limit of flexibility λ u = 200.
The tie elements are made from hot-rolled angles, the spacers are made from bent rectangular profiles.
Coverage connections. The coating bracing system consists of horizontal and vertical bracings that form rigid blocks at the ends of the building or temperature block and, if necessary, intermediate blocks along the length of the compartment (Fig. 6.5).
Horizontal connections in the plane of the lower chords of trusses are designed of two types. Ties of the first type consist of transverse and longitudinal braced trusses and braces (see Fig. 6.5, V G– at a step of 12 m). Ties of the second type consist of transverse braced trusses and braces (see Fig. 6.5, d– with a truss pitch of 6 m; see fig. 6.5, e– with a truss pitch of 12 m).
Rice. 6.4. Column connection diagram
6.5. Coverage connections
Rice. 6.5(continuation)
Transverse braced trusses along the lower chords of trusses are provided at the ends of the building or temperature (seismic) compartment (see Fig. 6.5, d, e). An additional horizontal braced truss is also provided in the middle of a building or compartment with a length of more than 144 m in buildings erected in areas with an estimated outside air temperature of -40 o C and above, and with a building length of more than 120 m in buildings erected in areas with design temperature below –40 o C (see Fig. 6.5, V, G). This reduces the transverse movements of the truss chord, which arise due to the compliance of the connections. Transverse horizontal connections at the level of the lower chords of the trusses absorb the wind load on the end of the building, transmitted by the upper parts of the half-timbered posts, and together with the transverse horizontal connections along the upper chords of the trusses and the vertical connections between the trusses provide spatial rigidity of the coating.
Longitudinal horizontal connections in the plane of the lower chords of trusses are provided along the outer rows of columns in buildings:
– with overhead support cranes of operating mode groups 7K and 8K, requiring the installation of galleries for passage along the crane tracks;
– with rafter trusses;
– with calculated seismicity 7, 8 and 9 points;
– with an elevation of the bottom of the trusses over 18 m, regardless of the lifting capacity of the cranes;
– in buildings with roofs on reinforced concrete slabs, equipped with general-purpose overhead support cranes with a lifting capacity of over 50 tons with a truss spacing of 6 m and over 20 tons with a truss spacing of 12 m;
– in single-span buildings with a roof on a steel profiled deck, equipped with cranes with a lifting capacity of over 16 tons;
– with a truss pitch of 12 m using longitudinal half-timbering posts.
Transverse horizontal connections at the level of the upper chords of trusses are provided to ensure the stability of the chords from the plane of the trusses. Due to the lattice of cross braces along the upper chords of the trusses, the use of lattice girders is difficult and therefore transverse braces, as a rule, are not used. In this case, the decoupling of the trusses is ensured by a system of vertical connections between the trusses.
In buildings with roofs on reinforced concrete slabs, spacers are provided at the level of the upper chords of the trusses (see Fig. 6.5, A). In buildings with a roof on a steel profiled flooring, the spacers are located only in the space under the lanterns; the trusses are fastened to each other by purlins (see Fig. 6.5, b); with a calculated seismicity of 7, 8 and 9 points, transverse braced trusses or stiffening diaphragms are also provided, installed at the ends of the seismic compartment (see Fig. 6.5, and– with a truss pitch of 6 m; see fig. 6.5, To- with a truss pitch of 12 m), and additionally at least one for a compartment length of more than 96 m in buildings with a calculated seismicity of 7 points and with a compartment length of more than 60 m in buildings with a calculated seismicity of 8 and 9 points.
In stiffening diaphragms, the profiled flooring, in addition to the main functions of enclosing structures, performs the function of horizontal connections along the upper chords of the trusses. Transverse stiffening diaphragms and horizontal braced trusses absorb longitudinal design horizontal loads from the coating.
In buildings with a lantern, if an intermediate stiffening diaphragm is installed, the lantern above the diaphragm must be interrupted. Rigidity diaphragms are made from profiled flooring grades H60-845-0.9 or H75-750-0.9 in accordance with GOST 24045-94 with reinforced fastening to the purlins.
Rafter trusses that are not directly adjacent to the transverse braces are secured in the plane of location of these braces with spacers and braces. Spacers provide the necessary lateral rigidity of the trusses during installation (ultimate flexibility of the upper chord of the truss from its plane during installation λ u= 220). Stretches are provided to reduce the flexibility of the lower belt in order to prevent vibration and accidental bending during transportation. The maximum flexibility of the lower chord from the plane of the truss is assumed to be: λ u= 400 – with static load and λ u= 250 – with cranes operating in 7K and 8K operating modes or when exposed to dynamic loads applied directly to the truss.
For horizontal bracing, a triangular lattice braced truss is usually adopted. With a truss pitch of 12 m, the truss struts are designed with sufficiently high vertical rigidity (as a rule, from bent rectangular profiles) to support long diagonal braces made from angles with insignificant vertical rigidity.
Vertical connections between trusses are provided along the length of the building or temperature compartment in the locations of transverse braced trusses along the lower chords of the trusses. In buildings with a calculated seismicity of 7, 8 and 9 points and a roof on a steel profiled flooring along rows of columns, vertical braces are installed at the locations of braced trusses or stiffening diaphragms along the upper chords of the trusses.
The main purpose of the vertical braces is to ensure the design position of the trusses during installation and to increase their lateral rigidity. Usually one or two vertical connections are installed along the width of the span (every 12 - 15 m).
When the lower assembly of the trusses is supported on the column head from above, the vertical connections are also located in the plane of the truss support posts. When the trusses are adjacent to the side of the column, these connections are located in a plane aligned with the plane of the vertical connections of the crane part of the column.
In the coatings of buildings operated in climatic regions with a design temperature below –40 o C, it is necessary, as a rule, to provide (in addition to the usually used braces) vertical braces located in the middle of each span along the entire building.
If there is a hard disk of the roof at the level of the upper chords of the trusses, inventory removable connections should be provided to align the design position of the structures and ensure their stability during the installation process.