Kirsanov N.M. Lecture text

CONNECTIONS IN CONSTRUCTIONS- light structural elements in the form of separate rods or systems (trusses); designed to ensure the spatial stability of the main bearing systems (trusses, beams, frames, etc.) and individual rods; spatial work of the structure by distributing the load applied to one or more elements to the entire structure; giving the structure the rigidity required for normal operating conditions; for the perception in some cases of wind and inertial (for example, from cranes, trains, etc.) loads acting on structures. Communication systems are arranged so that each of them performs several of the listed functions.

To create spatial rigidity and stability of structures consisting of flat elements (trusses, beams), which easily lose stability from their plane, they are connected along the upper and lower chords by horizontal ties. In addition, at the ends, and for large spans and in intermediate sections, vertical connections are placed - diaphragms. As a result, a spatial system is formed, which has high rigidity in torsion and bending in the transverse direction. This principle of providing spatial rigidity is used in the design of many structures.

In the span structures of beam or arch bridges, the two main trusses are connected by horizontal bracing systems along the lower and upper chords of the trusses. These communication systems form horizontal trusses, which, in addition to providing rigidity, take part in the transfer of wind loads to the supports. To obtain the necessary torsional rigidity, cross-links are placed to ensure the invariability of the cross-section of the bridge beam. In towers of square or polygonal section, horizontal diaphragms are arranged for the same purpose. In the roofs of industrial and public buildings, with the help of horizontal and vertical ties, two roof trusses are connected into a rigid spatial block, with which the rest of the roof trusses are connected by girders or strands (ties). Such a block ensures the rigidity and stability of the entire coating system. The most developed system of connections has steel frames of one-story industrial buildings.

The systems of horizontal and vertical connections of lattice crossbars of frames (trusses) and lanterns provide the overall rigidity of the tent, secure compressed structural elements from loss of stability (for example, the upper chords of trusses), ensure the stability of flat elements during installation and operation. Accounting for the spatial work provided by the connection of the main load-bearing structures by systems of connections, when calculating structures, it gives a reduction in the weight of structures. So, for example, taking into account the spatial work of the transverse frames of the frames of one-story industrial buildings reduces the calculated values ​​of the moments in the columns by 25-30%. A method for calculating the spatial systems of span structures of girder bridges has been developed. In normal cases, bonds are not calculated, and their sections are assigned according to the maximum flexibility established by the norms.

The transverse stability of the frame of wooden buildings is achieved by pinching the main pillars in the foundations when the roof structure is hinged to these pillars; the use of frame or arched structures with hinged support; creating a hard disk cover, which is used in small buildings. The longitudinal stability of the building is ensured by setting (after about 20 m) a special connection in the plane of the frame walls and the middle row of racks. Wall panels (panels) can also be used as connections, properly fastened to the frame elements.

To ensure the spatial stability of planar load-bearing wooden structures, appropriate connections are placed, which are fundamentally similar to connections in metal or reinforced concrete structures. In arched and frame structures, in addition to the usual (as in beam trusses) unfastening of the compressed upper chord, it is provided for unfastening the lower chord, which, as a rule, with unilateral loads, compressed areas. This fastening is carried out by vertical ties connecting the structures in pairs. In the same way, stability is ensured from the plane of the lower chords in trussed structures. As horizontal ties, strips of slanting flooring and roof shields can be used. Spatial wooden structures do not need special connections.

To ensure the spatial stability of metal structures, special steel elements are used - vertical connections between columns. Production Association "Remstroymash" offers metal structures of its own production for various manufacturing and construction enterprises.

In the assortment of the enterprise:

• Rods.
• Beams.
• Farms.
• Frames and other connection systems.

The main purpose of the connections of metal structures

With the help of light structural elements, spatial systems are formed that have unique properties:

• stiffness in bending and transverse twisting;
• resistance against wind loads, inertial influences.

During assembly, the binding systems perform the listed functions aimed at increasing the resistance against external influences. Wind connections of metal structures give finished structures additional sailing stability during operation. Spatial rigidity and stability of buildings, columns, bridges, trusses, etc. is ensured due to connections installed in horizontal planes in the form of upper and lower chords.

At the same time, at the ends and in the intervals between spans, special connections are established for metal structures of a vertical arrangement - diaphragms. The resulting system of connections provides the required spatial rigidity of the finished structure.


Transverse links of superstructures
a - the design of the main communication nodes; b - diagram of cross-links

Types of connections of metal structures

Products differ in manufacturing and assembly methods:

• Welded products.
• Prefabricated (bolted, screw).
• Riveted.
• Combined.

The materials for the manufacture of binding metal structures are black and stainless steel. Due to the unique technical characteristics, stainless steel products do not require additional anti-corrosion treatment.

Vertical connection schemes:
A cross; B two-tiered cross, C - diagonal inclined, G - multi-tiered diagonal inclined

Relationship examples

Farm Links are designed to:

- creation (associatively with the connections along the columns) of the overall spatial rigidity and geometric invariability of the frame of the BHT;

- ensuring the stability of the compressed elements of the trusses from the plane of the crossbar by reducing their estimated length;

– perception of horizontal loads on individual frames ( transverse braking of crane trucks) and their redistribution to the entire system of flat frame frames;

- perception and (ashamed of the connections along the columns) transmission to the foundations of some longitudinal horizontal loads on the structures of the turbine hall (wind acting on the end of the building and crane loads);

– ensuring ease of installation of trusses.

Farm links are divided into:

─ horizontal;

─ vertical.

Horizontal connections are placed in the plane of the upper and lower truss chords.

Horizontal links located across the building are called transverse, and along - longitudinal.

Connections along the upper belts of farms

Links along the lower belts of trusses

Vertical ties across trusses

Cross horizontal connections in the plane of the upper and lower chords of the trusses, together with the vertical connections between the trusses, they are installed along the ends of the building and in its middle part, where the vertical connections along the columns are located.

They create rigid spatial bars at the ends of the building and in its middle part.

Spatial beams at the ends of the building serve to perceive the wind load acting on the end fachwerk and transfer it to connections along the columns, crane beams and further to the foundation.

Otherwise they are called wind connections.

2. The elements of the upper chord of the truss trusses are compressed and may lose stability out of the plane of the trusses.

The transverse braces along the upper truss chords, together with the spacers, secure the truss nodes from moving in the direction of the longitudinal axis of the building and ensure the stability of the upper truss chord out of the truss plane.

Longitudinal connection elements (struts) reduce the estimated length of the upper chord of the trusses, if they themselves are secured from displacement by a rigid spatial tie bar.

In non-purlin coatings, the edges of the panels secure the truss nodes from displacement. In purlin coverages, truss nodes from displacement secure the purlins themselves, if they are fixed in a horizontal braced truss.

During installation, the upper chords of the trusses are fixed with spacers at three or more points. It 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 placed more often.

In a non-purlin coating, this fastening is carried out with the help of additional spacers, and in coatings with purlins, the purlins themselves are the spacers.

Spacers are also placed in the lower chord to reduce the calculated length of the elements of the lower chord.

Longitudinal horizontal ties along the lower chords trusses are designed to redistribute the horizontal transverse crane load from the braking of the trolley on the crane bridge. This load acts on a separate frame and, in the absence of ties, causes significant transverse movements.

Transverse displacement of the frame from the action of the crane load:

a) in the absence of longitudinal ties along the lower chords of trusses;

b) in the presence of longitudinal ties along the lower chords of 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 design of the roof. Roofing made of reinforced concrete panels is considered rigid. Roofing from profiled flooring along the runs, then it cannot take horizontal loads to a large extent. Such a roof is considered not rigid.

Longitudinal ties along the lower chords of trusses are placed in the extreme panels of trusses along the entire building. In the machine rooms of power plants, longitudinal ties are placed only in the first panels of the lower chords of trusses adjacent to the columns of row A. On the opposite side of the trusses, longitudinal ties are not installed, because the force of transverse braking of the crane is taken up by a rigid deaerator stack.

In buildings span 30 m to secure the lower belt from longitudinal movements, spacers are installed in the middle part of the span. These braces reduce the effective length and hence the flexibility of the lower chord of the trusses.

Vertical ties across trusses located between farms. They are made in the form of independent mounting elements (trusses) and are installed together with cross braces along the upper and lower chords of the trusses.

According to the width of the span, vertical truss trusses are located along the supporting nodes of the trusses and in the plane of the vertical racks of the trusses. The distance between vertical ties on trusses from 6 before 15 m.

Vertical connections between trusses serve to eliminate shear deformations of pavement elements in the longitudinal direction.

The metal frame consists of many load-bearing elements (truss, frame, columns, beams, girders), which must be “linked” to each other to maintain the stability of the compressed elements, the rigidity and the geometric invariability of the entire building structure. To connect the structural elements of the frame are used metal ties. They perceive the main longitudinal and transverse loads and transfer them to the foundation. The metal ties also distribute loads evenly between the trusses and frame frames to maintain overall stability. Their important purpose is to counteract horizontal loads, i.e. wind loads.

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

The main elements that connect links are trusses and columns.

Metal connections of columns

Column connections provide transverse stability of the metal structure of the building and its spatial immutability. Connections of columns and racks are vertical metal structures and structurally represent struts or disks that form a system of longitudinal frames. The purpose of hard drives is to fasten columns to the foundation of a building. Spacers connect columns in a horizontal plane. Spacers are longitudinal beam elements, for example, interfloor ceilings, crane beams.

Inside the connections of the columns are distinguished ties of the upper tier and ties 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 two tiers are the ability to transfer the wind load to the end of the building from the upper tier through the cross braces of the lower tier to the crane beams. Top and bottom ties also help keep the structure from tipping over during installation. The connections of the lower tier also transfer loads from the longitudinal braking of cranes to the crane beams, which ensures the stability of the crane part of the columns. Basically, in the process of erecting the metal structures of the building, the connections of the lower tiers are used.

Scheme of vertical connections between columns

Metal truss ties

To give spatial rigidity to the structure of a building or structure, metal trusses are also connected by ties. A truss connection is a spatial block with adjacent truss trusses attached to it. Adjacent farms along the upper and lower belts are connected horizontal truss ties, and along the racks of the lattice - vertical truss ties.

Horizontal truss ties along the lower and upper chords

Horizontal truss ties are also longitudinal and transverse.

The lower truss belts are connected by transverse and longitudinal horizontal ties: the first ones fix vertical ties and stretch marks, thereby reducing the vibration level of the truss belts; the latter serve as supports for the upper ends of the racks of the longitudinal fachwerk and evenly distribute the load on adjacent frames.

The upper chords of the trusses are connected by horizontal cross braces in the form of spacers or girders to maintain the designed position of the trusses. Cross ties unite the upper chords of the truss into a single system and become the “closing edge”. The struts just prevent the trusses from moving, and the transverse horizontal trusses / ties prevent the struts from moving.

Vertical connections of farms are necessary in the process of erecting a building or structure. They are often referred to as mounting links. Vertical connections contribute to maintaining 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 ties are disks consisting of spacers and trusses, which are located between the racks of truss trusses along the entire length of the building.

Vertical connections of columns and trusses

Structures of metal ties of a steel frame

By design, metal bonds are also:

cross-links, when the elements of the links intersect and connect to each other in the middle

angular bonds, which are located in several parts in a row; are mainly used for the construction of low-span frames

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

The main type of connection of metal ties is bolted, since this type of fastening is the most effective, reliable and convenient during installation.

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

Reliability, stability and rigidity of the metal frame of your building or structure largely depends on the quality of the production of metal ties.

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

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

• contact us by phone 8-800-555-9480
• write technical requirements for metal structures by e-mail
• use the form "", specify contact information, and our specialist will contact you

Plant specialists offer complex services:

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

2.3.2. Links between columns

The purpose of the connections: 1) the creation of the longitudinal rigidity of the frame, necessary for its normal operation; 2) ensuring the stability of the columns from the plane of the transverse frames; 3) the perception of the wind load acting on the end walls of the building, and the longitudinal inertial effects of overhead cranes.

Connections are established along all longitudinal rows of building columns. Schemes of vertical connections between columns are given in Fig. 2.34. Schemes (Fig. 2.34, c, d, f) refer to buildings without cranes or with overhead crane equipment, all the rest - to buildings equipped with overhead cranes.

In buildings equipped with overhead cranes, the main ones are the lower vertical connections. They, together with two columns, crane beams and foundations (Fig. 2.34 d, f...l) form geometrically invariable discs fixed in the longitudinal direction. The freedom or constraint of deformation of other frame elements attached to such disks depends significantly on the number of rigid blocks and their location along the frame. If you place the communication blocks at the ends of the temperature compartment (Fig. 2.35, but), then with an increase in temperature and the absence of freedom of deformation ( t 0) loss of stability of the compressed elements is possible. That is why it is better to place vertical connections in the middle of the temperature block (Fig. 2.34, a...in, rice. 2.35 b), providing freedom of temperature movements on both sides of the connection block (Δ t 0) and eliminating the appearance of additional stresses in the longitudinal elements of the frame. At the same time, the distance from the end of the building (compartment) to the axis of the nearest vertical connection and the distance between the connections in one compartment should not exceed the values ​​\u200b\u200bgiven in Table. 1.2.

In the overhead part of the columns, vertical connections should be provided at the ends of the temperature blocks and at the locations of the lower vertical connections (see Fig. 2.34 a, in). The expediency of installing top connections at the ends of the building is due, first of all, to the need to create the shortest path for transferring the wind load Rw on the end of the building along the longitudinal tie elements or crane beams on the foundations (Fig. 2.36). This load is equal to the support reaction of a horizontal truss truss (see Fig. 2.30) or two trusses in multi-span

Rice. 2.35. Influence of layouts of connection blocks on the development of temperature deformations:
a- when the connection blocks are located at the ends; b- the same, in the middle of the building

buildings. Similarly, forces from longitudinal braking of cranes are transferred to the foundations F cr(Fig. 2.36). The calculated longitudinal braking force is taken from two cranes of one or adjacent spans. In long buildings, these force effects are distributed equally to all vertical braced trusses between columns within the temperature block.

The constructive scheme of connections depends on the pitch of the columns and the height of the building. Various options for solving links are shown in Fig. 2.34. The most common is the cross scheme (Fig. 2.34, Mrs.), as it provides the simplest and most rigid tying of building columns. The number of panels in height is assigned in accordance with the recommended angle of inclination of the braces to the horizontal (α = 35°...55°). If it is necessary to use the space between the columns, which is often due to the technological process, the connections of the lower tier are designed portal (Fig. 2.34 to) or semi-portal (see Fig. 2.34, l).

Vertical connections between columns are also used for fixing spacers in nodes (Fig. 2.34 e...and), if they are provided to reduce the effective lengths of the columns from the planes of the frames.

In columns with a constant section height h≤ 600 mm, connections are placed in the plane of the axes of the columns; in stepped communication columns above

Rice. 2.36. Schemes of transmission of wind (from the end of the building) and longitudinal crane loads:
a, b- buildings with overhead cranes; c, g- buildings with overhead cranes

brake structure (upper vertical connections) with h≤ 600 mm are installed along the axes of the columns, below the crane beam (lower vertical ties) when h> 600 mm - in the plane of each shelf or column branch. Connection nodes between columns are shown in fig. 2.37.

The connections are fastened on bolts of coarse or normal accuracy, and after the alignment of the columns, they can be welded to the packings. In buildings with overhead cranes of the 6K ... 8K operating mode groups, the gussets of the connections should be scalded or connections made on high-strength bolts.

When calculating links, you can use the recommendations of clause 6.5.1.