Cross vertical ties on steel covering trusses. Vertical braces to provide rigidity to buildings. Communication systems for industrial building frames

The metal frame consists of many load-bearing elements(truss, frame, columns, beams, crossbars), which must be “connected” with each other to maintain the stability of the compressed elements, rigidity and geometric immutability of the structure of the entire building. For connection structural elements frame serve metal connections. They perceive the main longitudinal and transverse loads and transfer them to the foundation. Metal ties 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.

The Saratov Reservoir Plant produces connections from hot-rolled sectional angles, bent angles, bent profile pipes, hot-rolled profile pipes, round pipes, hot-rolled and bent channels and I-beams. The total mass of metal used should be approximately 10% of total mass metal structures of the building.

The main elements that connect the links are trusses and columns.

Metal column connections

Column connections ensure lateral stability of the metal structure of the building and its spatial immutability. The connections between columns and racks are vertical metal structures and are structurally struts or disks that form a system of longitudinal frames. The purpose of hard drives is to attach columns to the foundation of a building. Spacers connect the columns in a horizontal plane. Spacers are longitudinal beam elements, e.g. interfloor ceilings, crane beams.

Within the column connections there are connections of the upper tier and 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.

Scheme of vertical connections between columns

Metal truss connections

To impart spatial rigidity to the structure of a building or structure metal trusses are also connected by bonds. A truss connection is a spatial block with adjacent trusses attached to it. Adjacent trusses along the upper and lower chords are connected horizontal truss connections, and along the grille posts - vertical truss connections.

Horizontal connections of trusses along the lower and upper chords

Horizontal truss connections are also longitudinal and transverse.

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. 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 trusses/braces prevent the spacers from shifting.

Vertical truss connections are necessary during the construction of a building or structure. They are often called installation connections. Vertical connections help maintain the stability of trusses due to the displacement of their center of gravity above the supports. Together with intermediate trusses, they form a spatially rigid block at the ends of the building. Structurally, vertical truss connections are disks consisting of spacers and trusses, which are located between the racks roof trusses along the entire length of the building.

Vertical connections of columns and trusses

Metal bracing structures of steel frame

By design, metal connections can also be:

cross connections, when elements of connections intersect and connect together in the middle

corner connections, which are arranged in several parts in a row; mainly used for the construction of short-span frames

portal connections for frames U-shaped(with openings) have large area surfaces

Main connection type metal bonds- this is a bolted one, since this type of fastening is most effective, reliable and convenient during the installation process.

Specialists of the Saratov Reservoir Plant will design and manufacture metal connections from any profile in accordance with the mechanical requirements for physical and chemical properties material depending on technical and operational conditions.

Reliability, stability and rigidity metal frame Your building or structure largely depends on high quality workmanship metal bonds.

How to order the production of metal connections at the Saratov Reservoir Plant?

To calculate the cost of our metal structures, you can:

• contact us by phone 8-800-555-9480
• write to email technical requirements to metal structures
• use the form " ", provide contact information, and our specialist will contact you

The Plant’s specialists offer comprehensive services:

• engineering surveys at the operation site
• design of oil and gas complex facilities
• production and installation of various metal structures

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
	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.

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 symmetrical arrangement traverse 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.

· Determine the bending moments on separate areas slabs:

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).

Effort 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-design height, the distance between the axes of the belts is accepted (2250-180 = 2.07 m)

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 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 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 specified 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.

Structural diagram 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.

Ties of 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. Calculation scheme cross 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

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 beams at the ends of the building 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. A roof made of reinforced concrete panels is considered rigid. 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 machine rooms of power plants, longitudinal braces are placed only in the first panels of the lower chords of trusses adjacent to the columns of row A. C opposite side Trusses do not install longitudinal connections, 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 made in the form of independent mounting elements (trusses) and are installed together with transverse 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.

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.

The connections that form HDD, are located in the middle of the building or temperature compartment, taking into account the possibility of columns moving due to thermal deformations of the longitudinal elements.

If you install connections (hard drives) at the ends of the building, then large thermal forces F t arise in all longitudinal elements (crane structures, rafter trusses, brace struts)

When the length of a building or temperature block is more than 120 m, two systems of tie blocks are usually installed between the columns.

Limit dimensions between vertical connections in meters

Dimensions in brackets are given for buildings operated at design outdoor temperatures t= –40° ¸ –65 °С.

Most simple circuit cross braces, it is used for column spacing up to 12 m. Rational angle of inclination of the braces, therefore, when not big step, But high altitude columns, two cross connections are installed along the height of the lower part of the column.

In the same cases, sometimes additional decoupling of columns from the plane of the frame with spacers is designed.

Vertical connections are installed along all rows of the building. With a large pitch of columns in the middle rows, and also in order not to interfere with the transfer of products from bay to bay, connections of portal and semi-portal schemes are designed.

The vertical connections between the columns receive forces from the wind W 1 and W 2 acting on the end of the building and the longitudinal braking of the cranes T pr.

Elements of cross and portal connections work in tension. Due to their high flexibility, compressed rods are excluded from work and are not taken into account in the calculation. The flexibility of tensile tie elements located below the level of crane beams should not exceed 300 for ordinary buildings and 200 for buildings with “special” crane operating modes; for connections above crane beams - 400 and 300, respectively.

Coverage connections.

Connections along the roof (tent) structures or connections between the trusses create the overall spatial rigidity of the frame and provide: stability of the compressed chords of the trusses from their plane, redistribution of local crane loads applied to one of the frames to adjacent frames; ease of installation; specified frame geometry; perception and transmission of some loads to the columns.

Coverage connections are located:

1) in the plane of the upper chords of the trusses - longitudinal elements between them;

2) in the plane of the lower chords of trusses - transverse and longitudinal braced trusses, as well as sometimes longitudinal braces between transverse braced trusses;

3) vertical connections between trusses;

4) communications via lanterns.

Connections in the plane of the upper chords of the trusses.

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.

Reinforced concrete roofing slabs and purlins can be considered as supports that prevent the upper nodes from moving out of the plane of the truss, provided that they are secured against longitudinal movements by connections located in the plane of the roof. It is advisable to place such ties (transverse trusses) at the ends of the workshop so that they, together with transverse trusses along the lower chords and vertical ties between the trusses, create a spatial block that ensures the rigidity of the coating.

If the building or temperature block is longer, intermediate transverse braced trusses are installed, the distance between which should not exceed 60 m.

To ensure the stability of the upper chord of the truss from its plane within the lantern, where there is no roofing, special spacers are provided, and trusses are required in the ridge assembly. During the installation process (before installing the covering slabs or purlins), the flexibility of the upper chord from the plane of the truss should be no more than 220. Therefore, if the ridge spacer does not provide this condition, an additional spacer is placed between it and the spacer on the truss support (in the plane of the columns).

Connections in the plane of the lower chords of 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.

If the lateral rigidity of the frame is insufficient, the cranes may jam during movement and normal operation will be disrupted. Excessive frame vibrations create unfavourable conditions for the operation of cranes and the safety of enclosing structures. Therefore, in single-span buildings of great height (H>18 m), in buildings with overhead cranes Q>100 kN, with cranes of heavy and very heavy operating modes with any load capacity, a system of connections along the lower chords of the trusses is required.

Horizontal forces F from overhead cranes act transversely on one flat frame or two or three adjacent ones.

Longitudinal braced trusses provide working together systems of flat frames, as a result of which the transverse deformations of the frame from the action of concentrated force are significantly reduced.

The end frame posts transmit wind load F W in the nodes of the transverse braced truss.

To avoid vibration of the lower chord of the truss due to the dynamic impact of overhead cranes, the flexibility of the stretched part of the lower chord from the plane of the frame is limited: for cranes with a number of loading cycles of 2 × 10 6 or more - by a value of 250, for other buildings - by a value of 400. To reduce the length of the stretched part of the lower In some cases, belts are equipped with stretchers that secure the lower belt in the lateral direction.

Vertical connections between farms.

These ties connect the trusses together and prevent them from tipping over. They are installed, as a rule, in axes where connections are established along the lower and upper chords of the trusses, forming together with them a rigid block.

In buildings with suspended transport, vertical connections contribute to the redistribution between the trusses of the crane load applied directly to the covering structures. In these cases, as well as to the trusses, an electric crane is attached - beams of significant lifting capacity; vertical connections between the trusses are located in the suspension planes continuously along the entire length of the building.

The structural diagram of the connections depends mainly on the pitch of the trusses.

Ties along the upper chords of trusses

Ties along the lower chords of trusses

For horizontal connections with a truss pitch of 6 m, a cross lattice can be used, the braces of which work only in tension (Fig. a).

Recently, braced trusses with a triangular lattice have been mainly used (Fig. b). Here the braces work in both tension and compression, so it is advisable to design them from pipes or bent profiles, allowing to reduce metal consumption by 30-40%.

With a pitch of trusses of 12 m, the diagonal elements of the ties, even those working only in tension, turn out to be too heavy. Therefore, the bracing system is designed so that the longest element is no more than 12 m, and the diagonals are supported by this element (Fig. c, d).

It is possible to ensure fastening of longitudinal braces without a grid of braces along the upper chord of the trusses, which does not make it possible to use through purlins. In this case, the rigid block includes covering elements (purlins, panels), trusses and often located vertical braces (Fig. e). This solution is currently standard. The connection elements of the tent (covering) are calculated, as a rule, based on flexibility. The maximum flexibility for compressed elements of these connections is 200, for stretched elements - 400, (for cranes with a number of cycles of 2 × 10 6 or more - 300).

A system of structural elements that serve to support the wall fence and absorb wind loads called half-timbered.

Half-timbered structures are installed for loaded walls, as well as for interior walls and partitions.

With self-supporting walls, as well as with panel walls with panel lengths equal to the column spacing, there is no need for half-timbered structures.

With a pitch of external columns of 12 m and wall panels 6 m long intermediate half-timbered posts are installed.

Half-timbering installed in the plane of the longitudinal walls of a building is called longitudinal half-timbering. A half-timbering installed in the plane of the walls at the end of a building is called an end half-timbering.

The end timber frame consists of vertical posts, which are installed every 6 or 12 m. The upper ends of the posts in the horizontal direction rest on a transverse braced truss at the level of the lower chords of the trusses.

In order not to prevent the deflection of trusses from temporary loads, the support of the half-timbered posts is carried out using sheet hinges, which are a thin sheet t = (8 10 mm) with a width of 150-200 mm, which easily bends in the vertical direction without interfering with the deflection of the truss; in the horizontal direction it transmits force. Crossbars are attached to the half-timbered posts for window openings; when the height of the racks is high, spacers are placed in the plane of the end wall to reduce their free length.

Walls made of bricks or concrete blocks are designed to be self-supporting, i.e. taking up their entire weight, and only the lateral load from the wind is transferred by the wall to the column or half-timbered post.

Walls made of large-panel reinforced concrete slabs are installed (hung) on ​​tables of columns or half-timbered posts (one table every 3 - 5 slabs in height). In this case, the half-timbered post works in eccentric compression.

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 links (one or two along the length of the block) is determined by their 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 support posts roof 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. At long length elements that perceive small forces, connections are taken to the utmost 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 groups of operating modes 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 overhead support cranes general purpose with a load 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 in 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.

In the presence of hard drive On the roof, at the level of the upper chords of the trusses, inventory removable connections should be provided to verify the design position of the structures and ensure their stability during the installation process.