Cable systems: device, advantages, features and disadvantages

How many varieties of bridges in the world? Dozens! Arch, cantilever, movable, ice, pontoon, pushes flooded, lifting, turning, hanging, beam, stolopodobnye and many others. But in this article we will talk with you about an aesthetically validated and reliable variation - with hanging cable structures of coatings, as well as about such systems themselves.

Cable and hanging systems

Hanging constructions are steel structures, the bearing components of which are directed to tension. They are here:

• steel wire ropes;
• strip or round steel;
• membranes (special steel sheets);
• rolling profiles (for representation - rigid metal threads), capable not only of tension, but also of bending.

Cable structures, in contrast to the previous ones, inCoverings have not only stretched threads, but also rigid elements. The latter work just like a bend, they can be fenced, including roofing and flooring.

Both hanging and cable-stayed systems are able to cover a span of up to 200 m. However, their average length in practice varies between 50-150 m.

Advantages of constructions

Let's list the advantages of hanging and cable-stayed structures:

• Creating an enabling basis for visibility, acoustics, lighting.
• You can use a variety of design forms of cable-stayed suspension structures, which leads to a variety of variations of architectural designs.
• Bridges of this type are capable of overlapping an impressive span length.
• When constructing an object, one should not fail to note the good transportability of the structures used - flexible ribbons and ropes can be rolled up into coils or bays.
• The process of erecting a bridge is simplified by the fact that it is not necessary to install scaffolds or scaffolding.
• When the load is perceived in an elongated structurecarrying the whole cross-sectional area. When using high-strength steel in their production, this expense can significantly reduce the consumption of this metal.

Disadvantages of constructions

We touch the shortcomings of hanging and cable-stayed coatings:

• There is an increased degree of deformation of the structure - especially this is characteristic of dangling varieties, because there is a need for preliminary tension to stabilize the filaments.
• For the perception of the spread of stretched load-bearing components, a number of supporting circuits are required.
• In some cases, there is a difficulty in constructing a drainage system.

Features of cable systems

The composition of cable suspension structures isBearing straight stretched ropes or cables, as well as rigid components - racks, beams and so on. Taking into account the fact that the cables are straight, they can consist of strip profiles or rods. It is important to note that the angle of inclination of the guys should not reach 25-30 degrees.

The simplest scheme of cable systems iscable-beam. For it is characteristic that the guy in one or several places maintain a beam of rigidity. In this case, they themselves either diverge from the peaks of the pylons, or resemble the outlines of the harp, when they run parallel to each other.

Hanging systems

After cable-stayed systems, let's look at the types of hanging:

• Single-sided. Performed above the premises both round andrectangular shape. The perception of the spread of metal threads is provided by pylons, braces, extensions to the building and so on. It is typical to use flexible threads or arches as intermediate supports. The coating is stabilized by roofing reinforced concrete panels, by embedding the seams.
• Two-point. In addition to carrying ropes, they also haveStabilizing, which are connected with bearing extensions or spacers. The least deficiencies of suspension systems are found when using a convex-concave combined coating scheme.
• Wire ropes (a kind of two-point). Their indisputable advantages are the variety of form-building and architectural merits, achieved with qualified design.
• Membrane coatings. This consists of sheets or strips solidsingle-layer coatings that are cut and joined in such a way that they form a pre-planned surface of double or single curvature. They distinguish, on the background of other hanging designs, the fulfillment of the enclosing and bearing task. But significant shortcomings of the membrane coating are low fire resistance due to large surfaces of open metal, corrosion resistance, so that the minimum thickness of the steel sheet should be within 4-5 mm with an allowable 1-2 mm. The membranes can be cylindrical, circular, tent-shaped.

Let's pass directly to the suspension and cable-stayed bridges.

Cable-stayed bridge

This species is characterized by a special typebearing systems - cable-stayed trusses, which are formed by stretched flexible rods (ropes). Sometimes there are combined variations in which the lower parts of these trusses are replaced by beams of rigidity. The work of the latter is aimed at bending, and the function is to support the platform of the roadway. The guys here are high-strength wire, formed into bundles, or steel ropes.

Both cable farms and combined systems inThis structure is supported by pylons. From the places of suspending the guys on the pylon, the horizontal component of their reference pressure is transferred to the anchors by the system of braces. If there is a beam of stiffness, then the ends of the braces are fixed on it, which makes the system seemingly out of place. The construction of the carriageway is already attached to the nodes of cable-stayed farms.

The first cable-stayed bridge in the Soviet Union was builtin 1932 - across the river Magan (modern Georgia). However, the first bridge of the modern cable system appeared only in 1956 - this is the Swedish Stomsund. The pioneer cable-stayed railway building was built in 1979 in Belgrade.

The first cable-stayed bridge in the territory of the modernRussia is Oktyabrsky through the Sheksna River (Cherepovets). Its construction was completed in 1979. In Russia there is also a cable-stayed construction-record holder. This is the Russian bridge in Vladivostok, overlapping the Eastern Bosporus Strait. It stands out as the longest span - 1104 m (the total length is 1886 m), which is supported by two pylons.

Advantages and disadvantages of the cable bridge

Consider the pros and cons of such bridges. For better perception, we decided to present them to you in the form of a table below.

In conclusion, we will also consider the suspension bridges.

Suspension bridge

Hanging (otherwise - suspended) bridge - a structure,whose main supporting structure is flexible elements (ropes, chains, cables, etc.) working on tension, and the carriageway is suspended. Such bridges are a real find in cases where a large cover is required, and it is dangerous or impossible to establish intermediate supports (for example, on a navigable river).

Bearing structures are suspended betweenbuilt on both sides by pylons. To these cables vertical beams are already attached, to which the road part of the main span is directly suspended. The concentrated load allows the bearing structure to change its shape, which reduces the rigidity of the bridge. In order not to happen, the roadway is strengthened by longitudinal beams.

The first suspension bridges were built by the ancientEgyptians, Incas, other peoples of Central and South America, Southeast Asia. Constructions of the modern species began to appear in the XVII-XVIII centuries. in Spain, France, Great Britain, and later in the United States. In Russia, the first suspension bridge was built in 1823 in the park Ekateringof in St. Petersburg. One of the most famous for today's domestic suspension bridges can be called the Crimean in Moscow, built in 1938.

Advantages and disadvantages of suspension bridges

Consider the pros and cons of these suspension structures, which are presented in the table below.

That's all we wanted to tell you aboutcables, cable-stayed structures, bridges. Suspended and cable-stayed coverings are light in construction, able to cover large spans, harmoniously looking, providing space for design solutions. However, they also have their own shortcomings, erecting restrictions, for example, for the construction of a certain type of bridges.