2.3.2. Connections between columns
Purpose of connections: 1) creation of longitudinal rigidity of the frame necessary for its normal operation; 2) ensuring the stability of columns from the plane of the transverse frames; 3) perception of wind load acting on end walls buildings, and longitudinal inertial effects of overhead cranes.
Connections are installed along all longitudinal rows of columns of the building. Scheme vertical connections between the columns are given in Fig. 2.34. Schemes (Fig. 2.34, c, d, f) refer to buildings without cranes or with suspended crane equipment, all others - to buildings equipped with overhead support cranes.
In buildings equipped with overhead support cranes, the main ones are the lower vertical connections. They are combined with two columns, crane beams and foundations (Fig. 2.34 d, f...l) form geometrically unchangeable disks fixed in the longitudinal direction. The freedom or constraint of deformation of other frame elements attached to such disks significantly depends on the number of rigid blocks and their location along the frame. If you place the connection blocks at the ends of the temperature compartment (Fig. 2.35, A), then with increasing temperature and the absence of freedom of deformation ( t 0) possible loss of stability compressed elements. That is why it is better to place vertical connections in the middle of the temperature block (Fig. 2.34, a...c, rice. 2.35, b), ensuring freedom of temperature movements on both sides of the connection block (Δ t 0) and excluding the appearance of additional stresses in the longitudinal elements of the frame. In this case, the distance from the end of the building (compartment) to the axis of the nearest vertical connection and the distance between the connections in one compartment should not exceed the values given in Table. 1.2.
In the overhead part of the columns, vertical connections should be provided at the ends of the temperature blocks and at the locations of the lower vertical connections (see Fig. 2.34 a, c). The feasibility of installing top ties at the ends of the building is determined, first of all, by the need to create the shortest path for transmitting wind loads R w to the end of the building along longitudinal tie elements or crane beams to the foundations (Fig. 2.36). This load is equal to the support reaction of a horizontal braced truss (see Fig. 2.30) or two trusses in multi-span
Rice. 2.35. The influence of the layout of bonded blocks on the development of temperature deformations:
a- when connecting blocks are located at the ends; b- the same, in the middle of the building
buildings. Forces from the longitudinal braking of cranes are transmitted to the foundations in a similar way. F cr(Fig. 2.36). The calculated longitudinal braking force is taken from two cranes of the same or adjacent spans. In long buildings, these forces are distributed equally across all vertical braced trusses between columns within the temperature block.
Structural diagram connections depends on the pitch of the columns and the height of the building. Various options solutions of connections are shown in Fig. 2.34. The most common is the cross pattern (Fig. 2.34, Mr.), since it provides the simplest and most rigid connection of the building columns. The number of panels in height is assigned in accordance with the recommended angle of inclination of the braces to the horizontal (α = 35°...55°). If it is necessary to use the space between the columns, which is often due to technological process, connections of the lower tier are designed as portal ones (Fig. 2.34 To) or semi-portal (see Fig. 2.34, l).
Vertical connections between columns are also used to secure spacers in the nodes (Fig. 2.34 e...i), if they are provided to reduce the estimated lengths of columns from frame planes.
In columns having a constant section height h≤ 600 mm, connections are located in the plane of the column axes; in stepped communication columns above
Rice. 2.36. Schemes for transmitting wind (from the end of the building) and longitudinal crane loads:
a, b- buildings with overhead support cranes; c, d- buildings with overhead cranes
brake structure (upper vertical connections) with h≤ 600 mm are installed along the axes of the columns, below the crane beam (lower vertical connections) with h> 600 mm - in the plane of each flange or column branch. The connections between the columns are shown in Fig. 2.37.
The connections are fastened with bolts of rough or normal precision and, after alignment of the columns, they can be welded to the packaging. In buildings with overhead cranes of operating mode groups 6K...8K, tie gussets should be welded or connections should be made with high-strength bolts.
When calculating connections, you can use the recommendations in paragraph 6.5.1.
Steel structures 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 taken to be the same as the upper part extreme 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-bay buildings with reinforced concrete or steel columns 18.24.30.36 m long, 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 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.
· Farms from round pipes (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, lanternless, unheated storage facilities 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. Support stand 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 they are arranged: 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 brick walls, in prefabricated buildings, for temporary portable end walls during the construction of a building in several stages. 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 paths are suspended from the lower belts load-bearing 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, easy to manufacture and install, but compared to continuous ones they are larger and complicate operating conditions. crane tracks and require more 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. Beams are middle and extreme (located at the ends and at expansion joint, one of the supports is moved back 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, permitted with easy mode The operation of cranes with a lifting capacity of up to 30 tons and an average 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.
Fastening 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 ensure the spatial stability of metal structures, special steel elements are used - vertical connections between columns. Production Association"Remstroymash" offers metal structures self-made for various manufacturing and construction enterprises.
The company's assortment includes:
- Rods.
- Beams.
- Farms.
- Frames and other connection systems.
The main purpose of connections of metal structures
With the help of the lungs structural elements spatial systems are formed that have unique properties:
- bending and lateral torsional rigidity;
- resistance against wind loads and inertial influences.
When assembled, the connecting systems perform the listed functions aimed at increasing resistance against external influences. Wind connections of metal structures give the finished structures additional sail stability during operation. The spatial rigidity and stability of buildings, columns, bridges, trusses, etc. is ensured thanks to connections installed in horizontal planes in the form of upper and lower chords.
At the same time, special connections of vertical metal structures - diaphragms - are installed at the ends and in the spaces between spans. The resulting system of connections provides the required spatial rigidity of the finished structure. 
Transverse connections of spans
a - design of the main connection points; b - cross-link diagram
Types of connections of metal structures
Products differ in manufacturing and assembly methods:
- Welded products.
- Prefabricated (bolt, screw).
- Riveted.
- Combined.
The materials used for the manufacture of connecting metal structures are ferrous and stainless steel. Thanks to the unique technical specifications, stainless steel products do not require additional treatment against corrosion. 
Vertical connection diagrams:
A cross; B two-tier cross, C - diagonal inclined, D - multi-tiered diagonal inclined
Examples of connections
Farm links are for:
– creation (in conjunction with column connections) of general spatial rigidity and geometric immutability of the OPC frame;
– ensuring the stability of compressed truss elements from the beam plane by reducing their design length;
– perception of horizontal loads on individual frames ( transverse braking of crane trolleys) and their redistribution to the entire system of flat frame frames;
– perception and (in conjunction with connections along the columns) transmission to the foundations of some longitudinal horizontal loads on the turbine hall structures (wind loads acting on the end of the building and crane loads);
– ensuring ease of installation of trusses.
Farm connections are divided into:
─ horizontal;
─ vertical.
Horizontal connections are located in the plane of the upper and lower chords of the trusses.
Horizontal connections located across the building are called transverse, and along - longitudinal.
Connections along the upper chords of trusses
Connections along the lower chords of trusses
Vertical connections across farms
Transverse horizontal connections in the plane of the upper and lower chords of the trusses, together with the vertical connections between the trusses, are installed at the ends of the building and in its middle part, where the vertical connections along the columns are located.
They create rigid spatial beams at the ends of the building and in its middle part.
Spatial bars at the ends of the building they serve to absorb the wind load acting on the end timber frame and transfer it to the connections along the columns, crane beams and then to the foundation.
Otherwise they are called wind connections.
2. The elements of the upper chord of the trusses are compressed and may lose stability from the plane of the trusses.
Transverse braces along the upper chords of the trusses, together with spacers, secure the truss nodes from moving in the direction of the longitudinal axis of the building and ensure the stability of the upper chord from the plane of the trusses.
Longitudinal tie elements (spacers) reduce the design length of the upper chord of trusses if they themselves are secured against displacement by a rigid spatial tie beam.
In non-girder coatings, the ribs of the panels secure the truss units from displacement. In girder coverings, truss nodes secure the girders themselves from displacement if they are secured in a horizontal braced truss.
During installation, the upper chords of the trusses are secured with spacers at three or more points. This depends on the flexibility of the truss during installation. If the flexibility of the elements of the upper chord of the truss does not exceed 220 , spacers are placed along the edges and in the middle of the span. If 220 , then spacers are installed more often.
In a non-purlin coating, this fastening is done with the help of additional spacers, and in coatings with purlins, the struts are the purlins themselves.
Spacers are also placed in the lower chord to reduce the estimated length of the elements of the lower chord.
Longitudinal horizontal connections along the lower chords trusses are designed to redistribute the horizontal transverse crane load from trolley braking on the crane bridge. This load acts on a separate frame and, in the absence of connections, causes significant lateral movements.
Transverse displacement of the frame due to the action of the crane load:
a) in the absence of longitudinal connections along the lower chords of the trusses;
b) in the presence of longitudinal connections along the lower chords of the trusses
Longitudinal horizontal connections involve adjacent frames in spatial work, as a result of which the transverse displacement of the frame is significantly reduced.
The transverse displacement of the frame also depends on the roof structure. Roofing from reinforced concrete panels considered tough. A roof made of profiled decking along purlins means it cannot significantly absorb horizontal loads. Such a roof is not considered rigid.
Longitudinal connections along the lower chords of the trusses are placed in the outer panels of the trusses along the entire building. In the turbine rooms of power plants, longitudinal braces are placed only in the first panels of the lower chords of the trusses adjacent to the columns of row A. On the opposite side of the trusses, longitudinal braces are not installed, because The lateral braking force of the crane is absorbed by a rigid deaerator shelf.
In the buildings 30 m To secure the lower chord from longitudinal movements, spacers are installed in the middle part of the span. These spacers reduce the effective length and, consequently, the flexibility of the lower chord of the trusses.
Vertical connections across farms located between farms. They are performed as independent mounting elements(trusses) and are installed together with cross braces along the upper and lower chords of the trusses.
Along the width of the span, vertical braced trusses are located along the supporting nodes of the trusses and in the plane of the vertical posts of the trusses. The distance between the vertical connections along the trusses from 6 before 15 m.
Vertical connections between the trusses serve to eliminate shear deformations of the coating elements in the longitudinal direction.
Vertical dimensions
H o ≥ H 1 + H 2 ;
N 2 ≥ N k + f + d;
d = 100 mm;
Full Column Height
Lantern dimensions:
· H f = 3150 mm.
Horizontal dimensions
< 30 м, то назначаем привязку а = 250 мм.
< h в = 450 мм.
where B 1 = 300 mm according to adj. 1
· 
< h н = 1000 мм.
-
- lantern connections;
- half-timbered connections.
3. 
Collection of loads on the frame.
3.1.1.
Loads on the crane beam.
Crane beam with a span of 12 m for two cranes with a lifting capacity of Q = 32/5 tons. The operating mode of the cranes is 5K. The span of the building is 30 m. Beam material C255: R y = 250 MPa = 24 kN/cm 2 (with thickness t≤ 20 mm); R s = 14 kN/cm 2.
For a crane Q = 32/5 t medium operating mode according to adj. 1 greatest vertical force on the wheel F k n = 280 kN; cart weight G T = 85 kN; type of crane rail - KR-70.
For medium-duty cranes, the transverse horizontal force on the wheel, for cranes with flexible crane suspension:
T n = 0.05*(Q + G T)/n o = 0.05(314+ 85)/2= 9.97 kN,
where Q is the rated load capacity of the crane, kN; G t – cart weight, kN; n o – number of wheels on one side of the crane.
Calculated values of forces on the crane wheel:
F k = γ f * k 1* F k n =1.1*1*280= 308 kN;
T k = γ f *k 2 *T n = 1.1*1*9.97 = 10.97 kN,
where γ f = 1.1 - reliability coefficient for crane load;
k 1 , k 2 =1 - dynamic coefficients, taking into account the shock nature of the load when the crane moves along uneven tracks and at rail joints, table. 15.1.
Table
| Load number | Loads and force combinations | Ψ 2 | Rack sections | ||||||||||||||||||||||
| 1 - 1 | 2 - 2 | 3 - 3 | 4 - 4 | ||||||||||||||||||||||
| M | N | Q | M | N | M | N | M | N | Q | ||||||||||||||||
| Constant | -64,2 | -53,5 | -1,4 | -56,55 | -177 | -6 | -177 | +28,9 | -368 | -1,4 | |||||||||||||||
| Snow | -67,7 | -129,9 | -3,7 | -48,4 | -129,6 | -16 | -129,6 | +41,5 | -129,6 | -3,7 | |||||||||||||||
| 0,9 | -60,9 | -116,6 | -3,3 | -43,6 | -116,6 | -14,4 | -116,6 | +37,4 | -116,6 | -3,3 | |||||||||||||||
| Dmax | to the left pillar | +29,5 | -34,1 | +208,8 | -464,2 | -897 | +75,2 | -897 | -33,4 | ||||||||||||||||
| 0,9 | +26,5 | -30,7 | +188 | -417,8 | -807,3 | +67,7 | -807,3 | -30,1 | |||||||||||||||||
| 3 * | to the right pillar | -99,8 | -31,2 | +63,8 | -100,4 | -219 | +253,8 | -219 | -21,9 | ||||||||||||||||
| 0,9 | -90 | -28,1 | +57,4 | -90,4 | -197,1 | +228,4 | -197,1 | -19,7 | |||||||||||||||||
| T | to the left pillar | ±8.7 | ±16.2 | ±76.4 | ±76.4 | ±186 | ±16.2 | ||||||||||||||||||
| 0,9 | ±7.8 | ±14.6 | ±68.8 | ±68.8 | ±167.4 | ±14.6 | |||||||||||||||||||
| 4 * | to the right pillar | ±60.5 | ±9.2 | ±12 | ±12 | ±133.3 | ±9 | ||||||||||||||||||
| 0,9 | ±54.5 | ±8.3 | ±10.8 | ±10.8 | ±120 | ±8.1 | |||||||||||||||||||
| Wind | left | ±94.2 | +5,8 | +43,5 | +43,5 | -344 | +35,1 | ||||||||||||||||||
| 0,9 | ±84.8 | +5,2 | +39,1 | +39,1 | -309,6 | +31,6 | |||||||||||||||||||
| 5 * | on right | -102,5 | -5,5 | -39 | -39 | +328 | -34,8 | ||||||||||||||||||
| 0,9 | -92,2 | -5 | -35,1 | -35,1 | +295,2 | -31,3 | |||||||||||||||||||
| +M max N resp. | Ψ 2 = 1 | No. of loads | - | 1,3,4 | - | 1, 5 * | |||||||||||||||||||
 efforts | - | - | - | +229 | -177 | - | - | +787 | -1760 | ||||||||||||||||
| Ψ 2 = 0.9 | No. of loads | - | 1, 3, 4, 5 | - | 1, 2, 3 * , 4, 5 * | ||||||||||||||||||||
| efforts | - | - | - | +239 | -177 | - | - | +757 | -682 | ||||||||||||||||
| -M ma N resp. | Ψ 2 = 1 | No. of loads | 1, 2 | 1, 2 | 1, 3, 4 | 1, 5 | |||||||||||||||||||
| efforts | -131,9 | -183,1 | -105 | -306,6 | -547 | -1074 | -315 | -368 | |||||||||||||||||
| Ψ 2 = 0.9 | No. of loads | 1, 2, 3 * , 4, 5 * | 1, 2, 5 * | 1, 2, 3, 4, 5 * | 1, 3, 4 (-), 5 | ||||||||||||||||||||
| efforts | -315,1 | -170,1 | -52,3 | -135 | -294 | -542 | -1101 | -380 | -1175 | ||||||||||||||||
| N ma +M resp. | Ψ 2 = 1 | No. of loads | - | - | - | 1, 3, 4 | |||||||||||||||||||
| efforts | - | - | - | - | - | - | - | +264 | -1265 | ||||||||||||||||
| Ψ 2 = 0.9 | No. of loads | - | - | - | 1, 2, 3, 4, 5 * | ||||||||||||||||||||
| efforts | - | - | - | - | - | - | - | +597 | -1292 | ||||||||||||||||
| N mi -M resp. | Ψ 2 = 1 | No. of loads | 1, 2 | 1, 2 | 1, 3, 4 | - | |||||||||||||||||||
| efforts | -131,9 | -183,1 | -105 | -306,6 | -547 | -1074 | - | - | |||||||||||||||||
| Ψ 2 = 0.9 | No. of loads | 1, 2, 3 * , 4, 5 * | 1, 2, 5 * | 1, 2, 3, 4, 5 * | - | ||||||||||||||||||||
| efforts | -315,1 | -170,1 | -52,3 | -135 | -294 | -472 | -1101 | - | - | ||||||||||||||||
| N mi -M resp. | Ψ 2 = 1 | No. of loads | 1, 5 * | ||||||||||||||||||||||
| efforts | +324 | -368 | |||||||||||||||||||||||
| N mi +M resp. | Ψ 2 = 0.9 | No. of loads | 1, 5 | ||||||||||||||||||||||
| efforts | -315 | -368 | |||||||||||||||||||||||
| Qma | Ψ 2 = 0.9 | No. of loads | 1, 2, 3, 4, 5 * | ||||||||||||||||||||||
| efforts | -89 | ||||||||||||||||||||||||
3.4. Calculation of a stepped column industrial building.
3.4.1. Initial data:
The connection between the crossbar and the column is rigid;
The calculated forces are indicated in the table,
For the top of the column
in section 1-1 N = 170 kN, M = -315 kNm, Q = 52 kN;
in section 2-2: M = -147 kNm.
For the bottom of the column
N 1 = 1101 kN, M 1 = -542 kNm (bending moment adds additional load to the crane branch);
N 2 = 1292 kN, M 2 = +597 kNm (bending moment adds additional load to the outer branch);
Q max = 89 kN.
Ratio of rigidities of the upper and lower parts of the column I in /I n = 1/5;
column material – steel grade C235, foundation concrete class B10;
load reliability coefficient γ n =0.95.
Base of the outer branch.
Required slab area:
A pl.tr = N b2 / R f = 1205/0.54 = 2232 cm 2;
R f = γR b ≈ 1.2*0.45 = 0.54 kN/cm 2 ; R b = 0.45 kN/cm 2 (B7.5 concrete) table. 8.4..
For structural reasons, the overhang of the slab from 2 should be at least 4 cm.
Then B ≥ b k + 2c 2 = 45 + 2*4 = 53 cm, take B = 55 cm;
Ltr = A pl.tr /B = 2232/55 = 40.6 cm, take L = 45 cm;
A pl. = 45*55 = 2475 cm 2 > A pl.tr = 2232 cm 2.
Average stress in concrete under the slab:
σ f = N in2 /A pl. = 1205/2475 = 0.49 kN/cm2.
From the condition of the symmetrical arrangement of the traverses relative to the center of gravity of the branch, the distance between the traverses in the clear is equal to:
2(b f + t w – z o) = 2*(15 + 1.4 – 4.2) = 24.4 cm; with a traverse thickness of 12 mm with 1 = (45 – 24.4 – 2*1.2)/2 = 9.1 cm.
· We determine bending moments in individual sections of the slab:
plot 1(cantilever overhang c = c 1 = 9.1 cm):
M 1 = σ f s 1 2 /2 = 0.49 * 9.1 2 /2 = 20 kNcm;
area 2(cantilever overhang c = c 2 = 5 cm):
M 2 = 0.82*5 2 /2 = 10.3 kNcm;
section 3(slab supported on four sides): b/a = 52.3/18 = 2.9 > 2, α = 0.125):
M 3 = ασ f a 2 = 0.125*0.49*15 2 = 13.8 kNcm;
section 4(slab supported on four sides):
M 4 = ασ f a 2 = 0.125*0.82*8.9 2 = 8.12 kNcm.
For calculation we accept M max = M 1 = 20 kNcm.
· Required slab thickness:
t pl = √6M max γ n /R y = √6*20*0.95/20.5 = 2.4 cm,
where R y = 205 MPa = 20.5 kN/cm 2 for steel Vst3kp2 with a thickness of 21 - 40 mm.
We take tpl = 26 mm (2 mm is allowance for milling).
The height of the traverse is determined from the condition of placing the seam for attaching the traverse to the column branch. As a safety margin, we transfer all the force in the branch to the traverses through four fillet welds. Semi-automatic welding with Sv – 08G2S wire, d = 2 mm, k f = 8 mm. The required seam length is determined:
l w .tr = N in2 γ n /4k f (βR w γ w) min γ = 1205*0.95/4*0.8*17 = 21 cm;
l w< 85β f k f = 85*0,9*0,8 = 61 см.
We take htr = 30cm.
Checking the strength of the traverse is carried out in the same way as for a centrally compressed column.
Calculation of anchor bolts for fastening the crane branch (N min =368 kN; M=324 kNm).
Force in anchor bolts: F a = (M- N y 2) / h o = (32400-368 * 56) / 145.8 = 81 kN.
Required cross-sectional area of bolts made of steel Vst3kp2: R va = 18.5 kN/cm 2 ;
A v.tr = F a γ n / R va =81*0.95/18.5=4.2 cm 2 ;
We take 2 bolts d = 20 mm, A v.a = 2 * 3.14 = 6.28 cm 2. The force in the anchor bolts of the outer branch is less. For design reasons, we accept the same bolts.
3.5. Calculation and design of a truss truss.
Initial data.
The material of the truss rods is steel grade C245 R = 240 MPa = 24 kN/cm 2 (t ≤ 20 mm), the material of the gussets is C255 R = 240 MPa = 24 kN/cm 2 (t ≤ 20 mm);
The truss elements are made from angles.
Load from the weight of the coating (excluding the weight of the lantern):
g cr ’ = g cr – γ g g background ′ = 1.76 – 1.05*10 = 1.6 kN/m 2 .
The weight of the lantern, in contrast to the calculation of the frame, is taken into account in the places where the lantern actually rests on the truss.
The mass of the lantern frame per unit area of the horizontal projection of the lantern g background ’ = 0.1 kN/m 2 .
The mass of the side wall and glazing per unit length of the wall g b.st = 2 kN/m;
d-calculated height, the distance between the axes of the belts is taken (2250-180=2.07m)
Nodal forces(a):
F 1 = F 2 = g cr 'Bd = 1.6*6*2= 19.2 kN;
F 3 = g cr ' Bd + (g background ' 0.5d + g b.st) B = 1.6*6*2 + (0.1*0.5*2 + 2)*6 = 21.3 kN;
F 4 = g cr ' B(0.5d + d) + g background ' B(0.5d + d) = 1.6*6*(0.5*2 + 2) + 0.1*6*( 0.5*2 + 2) = 30.6 kN.
Support reactions: . F Ag = F 1 + F 2 + F 3 + F 4 /2 = 19.2 + 19.2 + 21.3 + 30.6/2 = 75 kN.
S = S g m= 1.8 m.
Nodal forces:
1st option of snow load (b)
F 1s = F 2s =1.8*6*2*1.13=24.4 kN;
F 3s = 1.8*6*2*(0.8+1.13)/2=20.8 kN;
F 4s = 1.8*6*(2*0.5+2)*0.8=25.9 kN.
Support reactions: . F As = F 1s + F 2s +F 3s +F 4s /2=2*24.2+20.8+25.9/2=82.5 kN.
2nd option of snow load (c)
F 1 s ’ = 1.8*6*2=21.6 kN;
F 2 s’ = 1.8*6*2*1.7=36.7 kN;
F 3 s ’ = 1.8*6*2/2*1.7=18.4 kN;
Support reactions: . F′ As = F 1 s ’ + F 2 s ’ + F 3 s ’ =21.6+36.7+18.4=76.7 kN.
Load from frame moments (see table) (d).
First combination
(combination 1, 2, 3*,4, 5*): M 1 max = -315 kNm; combination (1, 2, 3, 4*, 5):
M 2corresponding = -238 kNm.
Second combination (excluding snow load):
M 1 = -315-(-60.9) = -254 kNm; M 2corresponding = -238-(-60.9) = -177 kNm.
Calculation of seams.
| Rod no. | Section | [N], kN | Seam along the hem | Feather seam | ||||
| N rev, kN | Kf, cm | l w , cm | N p, kN | kf, cm | l w , cm | |||
| 1-2 2-3 3-4 4-5 5-6 | 125x80x8 50x5 50x5 50x5 50x5 | 282 198 56 129 56 | 0.75N = 211 0.7N = 139 39 90 39 | 0,6 0,6 0,6 0,6 0,6 | 11 8 3 6 9 | 0.25N = 71 0.3N = 60 17 39 17 | 0,4 0,4 0,4 0,4 0,4 | 6 6 3 4 3 |
LIST OF REFERENCES USED.
1. Metal structures. edited by Yu.I. Kudishina Moscow, ed. c. "Academy", 2008
2. Metal structures. Textbook for universities / Ed. E.I. Belenya. – 6th ed. M.: Stroyizdat, 1986. 560 p.
3. Calculation examples metal structures. Edited by A.P. Mandrikov. – 2nd ed. M.: Stroyizdat, 1991. 431 p.
4. SNiP II-23-81 * (1990). Steel structures. – M.; CITP of the USSR State Construction Committee, 1991. – 94 p.
5. SNiP 2.01.07-85. Loads and impacts. – M.; CITP of the USSR State Construction Committee, 1989. – 36 p.
6. SNiP 2.01.07-85 *. Additions, Section 10. Deflections and displacements. – M.; CITP of the USSR State Construction Committee, 1989. – 7 p.
7. Metal structures. Textbook for universities/Ed. V. K. Faibishenko. – M.: Stroyizdat, 1984. 336 p.
8. GOST 24379.0 – 80. Foundation bolts.
9. Guidelines on course projects “Metal structures” by Morozov 2007.
10. Design of metal structures of industrial buildings. Ed. A.I. Aktuganov 2005
Vertical dimensions
We begin designing the frame of a one-story industrial building with the selection of a structural diagram and its layout. Height of the building from floor level to the bottom of the construction truss H about:
H o ≥ H 1 + H 2 ;
where H 1 is the distance from the floor level to the head of the crane rail as specified by H 1 = 16 m;
H 2 – distance from the head of the crane rail to the bottom of the building structures of the coating, calculated by the formula:
N 2 ≥ N k + f + d;
where N k – height overhead crane; N k = 2750 mm adj. 1
f – size that takes into account the deflection of the coating structure depending on the span, f = 300 mm;
d - gap between the top point of the crane trolley and building structure,
d = 100 mm;
H 2 = 2750 +300 +100 = 3150 mm, accepted – 3200 mm (since H 2 is taken as a multiple of 200 mm)
H o ≥ H 1 + H 2 = 16000 + 3200 = 19200 mm, accepted – 19200 mm (since H 2 is taken as a multiple of 600 mm)
Height of the top of the column:
· Н в = (h b + h р) + Н 2 = 1500 + 120 + 3200 = 4820 mm., the final size will be determined after calculating the crane beam.
The height of the lower part of the column, when the column base is buried 1000 mm below the floor
· N n = H o - N in + 1000 = 19200 - 4820 + 1000 = 15380 mm.
Full Column Height
· H = N in + N n = 4820+ 15380 = 20200 mm.
Lantern dimensions:
We accept a lantern with a width of 12 m with glazing in one tier with a height of 1250 mm, a side height of 800 mm and a cornice height of 450 mm.
N fnl. = 1750 +800 +450 =3000 mm.
· H f = 3150 mm.
The structural diagram of the building frame is shown in the figure:
Horizontal dimensions
Since the column spacing is 12 m, the load capacity is 32/5 t, the building height< 30 м, то назначаем привязку а = 250 мм.
· h in = a + 200 = 250 + 200 = 450mm
h in min = N in /12 = 4820/12 = 402mm< h в = 450 мм.
Let us determine the value of l 1:
· l 1 ≥ B 1 + (h b - a) + 75 = 300 + (450-250) + 75 = 575 mm.
where B 1 = 300 mm according to adj. 1
We take l 1 = 750 mm (multiple of 250 mm).
Section width of the lower part of the column:
· h n = l 1 +a = 750 + 250 = 1000mm.
· h n min = N n /20 = 15380/20 = 769mm< h н = 1000 мм.
The cross-section of the upper part of the column is designated as a solid-walled I-beam, and the lower part as a solid one.
Connections steel frame industrial building
The spatial rigidity of the frame and the stability of the frame and its individual elements are ensured by setting up a system of connections:
Connections between columns (below and above the crane beam), necessary to ensure the stability of columns from the frame planes, the perception and transmission of loads acting along the building (wind, temperature) to the foundations and the fixation of columns during installation;
- connections between trusses: a) horizontal transverse connections along the lower chords of the trusses, taking the load from the wind acting on the end of the building; b) horizontal longitudinal connections along the lower chords of the trusses; c) horizontal transverse connections along the upper chords of the trusses; d) vertical connections between farms;
- lantern connections;
- half-timbered connections.
3. Calculation and design part.
Collection of loads on the frame.
3.1.1. Design diagram of the transverse frame.
The geometric axes of stepped columns are taken to be lines passing through the centers of gravity of the upper and lower parts of the column. The discrepancy between the centers of gravity gives the eccentricity “e 0”, which we calculate:
e 0 =0.5*(h n - h in)=0.5*(1000-450)=0.275m
