Horizontal connections to the upper chords of trusses. Vertical braces to provide rigidity to buildings. Unified modular system in construction

The design of the connections installed in the covering depends on the design and material of the frame, the type of covering, the height of the building, the type of crane, its load capacity and operating mode.
Vertical connections between the supports of reinforced concrete trusses or beams, coverings are placed only in buildings with flat roof, and in buildings without under truss structures connections are located in each row of columns, and with such structures - only in the outer rows of columns at a pitch of 6 m.

Vertical connections between the supports of trusses or beams are placed no more often than one step apart. Their number for a temperature block length of 60–72 At for each row of columns can be no more than 5 at a pitch of 6 m and no more than 3 at a pitch of 12 m. In Fig. 69, and four such connections are shown.

If there are vertical connections between the supports of trusses or roof beams or connections between columns (in buildings without cranes), there is a spacer at the top of the columns (Fig. 69, a, c).

In buildings with a column spacing of 12 m in the middle and outer rows, horizontal trusses are provided at the ends - two in each span per temperature block. These trusses are placed at the level of the lower belt of the trusses (Fig. 69, c). In buildings with rafter structures, horizontal struts are installed in the middle rows of columns in the amount of 2-4 per row of columns of the temperature block (Fig. 69, b).

Rice. 69. Ties in coatings for reinforced concrete trusses

In buildings with heavy-duty overhead cranes or equipment that causes structural vibrations, lower belt trusses or beams in the middle of each span, spacers (ties) and vertical connections are installed in the two outermost steps of the temperature block. Role horizontal connections Large-panel covering slabs are made along the upper chord of trusses or beams.

In spans with lanterns, to ensure the stability of the upper chord of the trusses, spacers (ties) are installed along the ridge of the trusses and horizontal connections along their upper chord within the width of the lantern in the extreme (or second) steps of the temperature block.

In coatings with purlins in the extreme steps of temperature blocks, horizontal connections of a cross pattern are arranged under the purlins along their entire width.
Vertical and horizontal connections are made in most cases from corners and attached to reinforced concrete structures using scarves (Fig. 69, d, e). The tie rods are made of round steel, and the compression struts are made of reinforced concrete.

The roof bracing system in buildings with a steel frame consists of horizontal bracing in the plane of the lower and upper chords of the trusses and vertical bracing between the trusses.

Horizontal connections along the lower chords of trusses are placed both across the building (transverse horizontal) and along it (longitudinal horizontal). Transverse horizontal connections along the lower chords are installed at the ends and expansion joints of the building. For temperature blocks 120–150 m long and for heavy-duty cranes, intermediate tie trusses are also provided every 60 m.
Longitudinal horizontal connections are located on the outer panels of the lower chords of trusses and are installed in buildings with Q>10T cranes and in buildings with sub-rafter trusses.

In single-span buildings, such connections are located along both rows of columns, and in multi-span buildings - along the outer rows of columns and through the row along the middle rows (for cranes with a lifting capacity of up to 50 7) or more often (for cranes with a lifting capacity of more than 50 T).
Along the middle rows of columns with the same height of adjacent spans, it is recommended to place longitudinal braces on one side of the columns, and in dreams, height adjustments - on both sides of the row of columns.

The lateral rigidity of the lower chords of the trusses located in the gap between two transverse braced trusses is supported by special braces from the corners, attached to the nodes of the braced trusses. The layout of transverse and longitudinal connections along the lower chords of the trusses is shown in Fig. 70, a.

Horizontal cross braces along the upper chords of the trusses ensure the stability of the upper chords of the trusses from their plane, and place them in coverings with purlins. In panel coverings, these connections are provided only at the ends of the building and at expansion joints. In the spaces between the transverse braced trusses, the lateral stability of the upper chords of the trusses is ensured by purlins, and in the areas under the lanterns - by braces from the corners. It is recommended to combine the transverse connections along the upper and lower chords of the trusses in plan.

Rice. 70. Bonds in coatings with steel trusses

If there are sub-trusses in single-span coverings without purlins and in multi-span coverings located at the same level, longitudinal horizontal connections are provided in the plane of the upper chords in one of the outer panels of the trusses. In case of differences in heights of adjacent spans, one longitudinal system is provided at each level.

Vertical connections of the covering are located in the planes of the support posts of rafter trusses, in the plane of the ridge posts, for trusses with a span of up to 30 m, as well as in the plane of the posts located under the attachment point for the outer legs of the lantern for trusses with a span of more than 30 m. Vertical connections are made in the form of trusses with parallel belts having a height equal to the height of the racks to which the connections are attached.

Connections along the purlins in the form of stiffening trusses, spacers and ties ensure the design position of the purlins, increase stability and facilitate the operation of the purlins on the slope component of vertical loads and absorb wind forces.

All types of braced trusses are made from angles with a cross lattice, spacers are also made from angles, and ties are made from round steel. The ties are fastened with black bolts; in buildings with heavy-duty cranes and heavy-duty work, and also in the case of significant forces in the elements of the ties - with assembly welding and less often - with rivets or clean bolts. Some details of fastening the connections are shown in Fig. 70, b - d.

Covering connections include vertical connections between trusses, horizontal connections along the upper and lower chords of the trusses. We arrange connections along the upper chords in order to absorb part of the wind load and prevent the compressed rods of the upper chords from bulging. We install transverse braced trusses at the ends and in the middle of the building. We install connections along the lower chords to absorb wind and crane loads in the longitudinal and transverse directions. A truss connection is a spatial block with adjacent trusses attached to it. Adjacent trusses along the upper and lower chords are connected by horizontal truss connections, and along the lattice posts - by vertical truss connections.

The lower chords of the trusses are connected by transverse and longitudinal horizontal connections: the first fix the vertical connections and braces, thereby reducing the level of vibration of the truss belts; the latter serve as supports for the upper ends of the posts of the longitudinal half-timbering and evenly distribute the loads on adjacent frames. The upper chords of the trusses are connected by horizontal transverse links in the form of struts or girders to maintain the designed position of the trusses.

Connections between columns of industrial buildings

Column connections ensure lateral stability of the metal structure of the building and its spatial immutability. Column and rack connections are vertical metal structures and are structurally represented by spacers or disks that form a system of longitudinal frames. Spacers connect the columns in horizontal plane. Spacers are longitudinal beam elements. Within the column connections, a distinction is made between the connections of the upper tier and the connections of the lower tier of columns. The connections of the upper tier are located above the crane beams, the connections of the lower tier, respectively, below the beams. Main functional purposes loads of two tiers are the ability to transfer wind load to the end of the building from the upper tier through the transverse connections of the lower tier to the crane beams. The upper and lower braces also help keep the structure from tipping over during installation. The connections of the lower tier also transfer the loads from the longitudinal braking of the cranes to the crane beams, which ensures the stability of the crane part of the columns. Basically, in the process of erecting metal structures of a building, the connections of the lower tiers are used.

Communication systems for industrial building frames

For connection structural elements The frame is formed by metal connections. They perceive the main longitudinal and transverse loads and transfer them to the foundation. Metal connections also distribute loads evenly between the trusses and frame frames to maintain overall stability. Their important purpose is to resist horizontal loads, i.e. wind loads. Column connections ensure lateral stability of the metal structure of the building and its spatial immutability. Within the column connections, a distinction is made between the connections of the upper tier and the connections of the lower tier of columns. The connections of the upper tier are located above the crane beams, the connections of the lower tier, respectively, below the beams. The main functional purposes of the loads of the two tiers are the ability to transfer wind load to the end of the building from the upper tier through the transverse connections of the lower tier to the crane beams. The upper and lower braces also help keep the structure from tipping over during installation. The connections of the lower tier also transfer the loads from the longitudinal braking of the cranes to the crane beams, which ensures the stability of the crane part of the columns. Basically, in the process of erecting metal structures of a building, the connections of the lower tiers are used. To impart spatial rigidity to the structure of a building or structure metal trusses are also connected by bonds. Adjacent trusses along the upper and lower chords are connected by horizontal truss connections, and along the lattice posts - by vertical truss connections. The lower chords of the trusses are connected by transverse and longitudinal horizontal connections: the first fix the vertical connections and braces, thereby reducing the level of vibration of the truss belts; the latter serve as supports for the upper ends of the posts of the longitudinal half-timbering and evenly distribute the loads on adjacent frames. Cross braces connect the upper chords of the truss into unified system and become the “closing edge”. The spacers prevent the trusses from shifting, and the transverse horizontal tie trusses prevent the spacers from shifting.

Solid purlins

Continuous purlins are used with truss spacing of no more than 6 m and, depending on the purpose, they have different design cross-sections. Continuous purlins are manufactured according to split and continuous patterns. Most often, split patterns are used because of their ability to simplify installation, however, the continuous pattern also has positive benefits. distinctive properties, for example, with a continuous design, less steel is spent on the purlins themselves.

Purlins located on the slope, taking into account the roof with large slope always work on bending in two planes. The stability of the purlins is achieved by fastening roofing slabs or by attaching the flooring to the purlins, taking into account all the friction forces between them. It is customary to attach purlins to truss chords using short corner pieces and bent elements made of sheet steel.

Lattice purlins

Rolled or cold-formed channels are used as purlins; when the truss spacing is more than 6 m, lattice purlins are used. Simple and most lightweight design The lattice girder is a rod-truss girder with a lattice and a lower chord made of round steel. The disadvantage of such a run is the complexity of control welds in the interface between the grating rods and the lower chord, as well as the need for careful transportation and installation.

The upper chord of lattice girders, in the case of its high rigidity from the plane of the purlin, should be calculated for the combined action of axial force and bending only in the plane of the purlin, and in the case of low rigidity of the upper chord from the plane of the purlin, it is necessary to calculate the upper chord for the combined action of axial force and bending both in the plane run, and in a plane perpendicular to it. The flexibility of the upper belt of lattice purlins should not exceed 120, and the flexibility of lattice elements should not exceed 150. The upper chord of this purlin consists of two channels, and the lattice elements are made of a single bent channel. Typically, the braces are fixed to the upper chord using arc or resistance welding.

Lattice girders are designed as trusses with a continuous upper chord, which always works in compression with bending in one or two planes, while other elements experience longitudinal forces.

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 assumed to be the same as top 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-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.

· 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. 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 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. Top ends half-timbered posts are attached to roof trusses or ties 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 beams depending on static schema divided into cut and uncut. 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 sectional 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.

IN industrial buildings use 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.

Vertical dimensions

H o ≥ H 1 + H 2 ;

N 2 ≥ N k + f + d;

d = 100 mm;

Full Height columns

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
	Q ma	Ψ 2 = 0.9	No. of loads								1, 2, 3, 4, 5 *
efforts			-89

3.4. Calculation of a stepped column of an 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.

The ratio of the 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;

section 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 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.

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 By course projects“Metal structures” 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 bottom construction farm But:

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 Hk is the height of the 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

Connections are important elements steel frame, which are necessary for:

1. ensuring the immutability of the spatial system of the frame and its stability 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 bearing capacity in the longitudinal direction, as well as the stability of columns from the plane of the transverse frames.

To perform these functions, at least one vertical HDD along the length of the temperature block and a system of longitudinal elements attaching columns that are not included in 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.

Special attention pay attention 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 workshop frame. Therefore, in single-span buildings of great height (), in buildings with overhead cranes and very heavy duty operation 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 support posts farms

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 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, it should be borne in mind that sometimes it is necessary to have free space between the columns, then portal connections are constructed. 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. Relationships other than conditional ones shear forces, perceive the wind load directed at the end of the building and from the longitudinal effects of overhead cranes. Wind load at 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.