The span of the bridge "pipe prokhorov - flexion"

 

The invention relates to a special construction and can be widely used in bridge building, as well as in the construction of trestle monorail roads. The span of the bridge, trestle or other overlying structures made from a single length of span of thin elastic sheet, pre-stressed by a smooth profiling relative to the vertical plane of symmetry. What's new is that the edges of the original sheet is combined, and formed by a sheet of a closed surface - pipe equipped with periodically mounted inside the transverse elements, with the resulting surface profile is determined from the mathematical dependencies. The technical result of the invention is the design of pre-stressed beams of elastic sheet material to ensure maximum rigidity of the product with minimum weight. 2 C.p. f-crystals, 4 Il.

The invention relates to a special construction and can be widely used in bridge building, as well as in the construction of trestle monorail roads.

Shaped structural element beam - is the simplest and most tranny object with connectivity 0 (solid material) or 1 (trumpet different profile). Unlike beam construction farm has great connectivity.

theory of strength of materials determines the beam as a structural member, working mainly on the curve”. Widely known classical formula for determining the amount of deflection of the freely lying on poles “weightless” beams under the action of a concentrated load

hereh - deflection; P is concentrated in the center of the span load; E is the modulus of elasticity of the material (young's modulus); J is the moment of inertia of the profile relative to the horizontal axis of symmetry; l is the length of the beam. In particular, for a rectangular profile (ribs) and round tubes

here b is the width of the ribs; h - the height of the ribs; R is the radius of the pipe.

For the edges of the original formula can lead to a “dimensionless” mind

here F is the factor loading (betram.);the form parameter of the beam.

The classical theory is in good agreement with the real data only within the<10. When>10 theory explicitly gives overestimated results. When~50 beam profile �232D/img_data/77/776631.gif">

The function of the cubic root mean that even under its own weight long rod sags noticeably, however, additional loading does not lead to a proportional increase in deflection. The real test of fully confirm this model. If100, under its own weight long rod forms a “chain line” described by the function of the hyperbolic cosine.

So, region 10<<50 is the most difficult for theoretical analysis, however, to practice this field of interest. For example, “classic” span with a length l~50 m height shall be h~5 m, which means a huge amount of material.

In the transverse horizontal direction of the thin-walled pipe sustainable, and thin vertical edge is unstable, it compressed the top edge under concentrated loading gives a “wave”. To stabilize the upper edge, the edge provide horizontal “shelves” - thus, there is a basic T-shaped profile (“brands”), is widely used today in the construction of bridges and overpasses from concrete.

In the literature so far are of the opinion that the ideal professionsal model deformation, not taking into account the General (span) stretching of the beam. Actually the bottom “shelf” does not give a significant increase rigidity, since the upper and lower edges of the support ribs (base) work in fundamentally different terms. For example, it makes little sense to strengthen the lower edge of steel “brand” - quality steel has a yield strength of about 100 kg/mm2and more. In the case of concrete brand bottom edge enhance, because the strength of this material in the gap is relatively small. However, reinforced concrete profile is still “brand” - the top “shelf” wider than the bottom, and sometimes the bottom “shelf” are absent (replace reinforcement).

Compared with the pipe “brands” easier to manufacture and more convenient since it does not require intermediate flooring. However, the “brand” has a serious drawback: the lines connecting the edges and “shelves” are local voltage. To eliminate these stresses corners round to a greater or lesser extent, which inevitably requires additional consumption of material. Thus, superior “brands” gets a curved surface and further modernization goes into a profile resembling zodiacus turns in the pipe.with. The USSR №1488503, IPC E 21 D 11/14, bull. No. 23 of 1989).

On the other hand, a round pipe when optimizing first becomes elliptical, and then becomes asymmetric about the horizontal plane (“egg-shaped” profile). The trend is easily visible, however, there is the eternal problem of the material.

In the patent literature there are many solutions to this problem. Most often hollow “optimal beam” trying to run from a sheet material, bent in various ways. (example - the design and.with. The USSR № 1698394, IPC E 04 3/10, bull. No. 46 for 1989).

I is shown in Fig.2 design analog edges visible similarity elliptical pipe, but in the center of the span, there are two independent edges. With this in mind, under concentrated load will occur “wave” and beam “lead”. The design of Fig.5 is formed from the joined bottom edges (inverted U-shaped profile). However, the bottom shelf is not able to prevent the development of lateral instability on the upper edges of the ribs.

In addition, the U-shaped profile can only be done from a soft sheet type roofing tin). On the strength qualities of such a sheet can not speak Above already Yelena to say, any attempt to generate the “optimal beam from the traditional plastic (cold rolled) or fragile (concrete) materials obviously doomed to failure. You must use the new, non-traditional construction materials.

The closest in technical essence and the achieved result to the claimed technical solution designs are described in and.with. The USSR №1483028 IPC E 04 7/08, bull. No. 20 of 1989, although they belong to different areas of construction. The authors clearly indicate the use of Providermessage sheet material, which is stated in the claims. Respectively, on the accompanying drawings depicts some curved surfaces (fabric overlap). These very elegant form can be classified as “natural” - they are formed, if the external deforming force is applied only to the edges of the elastic sheet.

But “natural” form is insufficient, if the goal is the formation of “optimal beams”. At small angles of bending of the elastic sheet takes approximately parabolic shape, but in the course of further bending the top of the profile passes in the circle. Finally, if bent 360° (until it touches the edges of whether the profile. The problem arises edges of the sheet, so as to weld along the line of maximum tension is undesirable (lost strength quality).

In addition, all pipe still does not have sufficient local stiffness at the top. Better - pipe elliptical, but the optimal profile of the top of the arc shape of the “catenary” (function hyperbolic cosine, approximately represented by the parabola). For the formation of beams of the original elastic sheet to compress the edges, as above.

The objective of the invention is the design of pre-stressed beams of elastic sheet material to ensure maximum rigidity of the product with minimum weight.

In addition, the implementation of the transit portion of the sheet material allows installation works directly at the site of erection of the bridge (overpass) and deliver the source material in compact form (on the drum).

The problem is solved by the characteristics specified in paragraph 1 of the claims, and in common with the prototype, such as the span of the bridge, trestle or other overlying structures, made from a single length of span of thin elastic sheet, prestressed p is Reznikov - edge of the original sheet is combined, and formed by a sheet of a closed surface - pipe equipped with periodically mounted inside the transverse elements, with the resulting surface profile is determined by the formula

where y is the current distance from the vertical line of symmetry of the profile, x=h/2h0; h - current distance from the highest point of the profile; (h0- the distance from the highest point of the profile to its maximum width.

It should be noted that theoretically the curve y(x) is open (goes to infinity). However, when x=2 y(x)=4% of the maximum value, i.e., practically4h0.

In paragraph 2 of the claims reflected the possibility of improvement of the claimed design, namely in the middle of the span inside the closed surface of the pipe is an additional element stiffness type frame, for example, a triangular profile, the length of the additional element is at least twice the height of the main profile and the width of the additional element corresponds to the maximum width of the main profile.

P. 3 reflects the possibility of further improvement, namely under dopolicies blocks skipped tension wire so the Central block ulibaetsa rope bottom, and end blocks from above.

The above distinguishing features - individually and collectively - is aimed at solving the problem and are significant. The proposed use of the combination of essential features of the prior art was not found, therefore the proposed solution meets the patentability criteria of “novelty.”

One set of new essential features with common, well-known provides a solution to the problem is obvious to experts in the field of technology and demonstrates compliance of the claimed technical solution to the patentability criterion of “inventive step”.

The invention is illustrated by the following drawings: Fig.1 shows the calculated profile of the beam-pipe, and Fig.2 - General view of the ready passage part from the installation of the supports of Fig.3 separately shows the approximate form of the element stiffness, Fig.4 schematically shows the construction of the transit portion of the tensioning cable.

The author of the invention provides for the calculation of the profile (Fig.1) the name “pipe Prokhorov, and for the finished product (Fig.2) the name of the coy, and is somewhat reminiscent of the farm.

Positions in Fig.1-4 are marked: 1 - the curved surface of the elastic sheet; 2 - line forming couplers according to the points of inflection of the generatrix curve; 3 - line strengthening ties in the area of maximum width; 4 - installation concrete pads-cushions with the inverse profile; 5 - an additional element stiffness; 6 - Central pulley-block; 7 and 8 - terminal blocks; 9 - tension wire.

The curve y(x) is the product of two “optimal” function: ln(1+...) - inverse hyperbolic cosine (areabusiness”), and exp(-x2) - curve “maximum coverage”, better known as a function of the normal distribution of the random variable.

The inflection point forming the profile of the function y(x) occur at x=1. The points of inflection allows you to perform beam-pipe 1 of the three longitudinal elastic sheets, riveted “overlap”. At the inflection point should be the main (formative) tie 2 with a period, not a lower height profile. Also required screed 3 line maximum width that prevents the “flattening” of the pipe under the local (i.e., “concentrated in the point load. Even closer to the optimal design profile allows you to approach the third system couplers slightly above the line the soup special cross “patterns” (continuous curvilinear elements), however, almost enough couplers 2 and 3, shown in Fig.1.

Stiffness stated asymmetric pipe-beams exceeds the rigidity of the conventional round pipe and “brand,” but it had “danger zone”. The first zone is the area of maximum compression around the top center point of the span. It is at this point a round pipe gives a “break”, after which the cylindrical surface is flattened and the collapse of the beam. To prevent catastrophic (irreversible) deformation in the center of the passage introduces an additional element of rigidity 5, relieving the bending deformation with the top of the pipe and sends it to the sides.

After eliminating risk is the risk of the development of lateral instability (“waves”). The maximum strain of the “wave” is the distance from the center of the spanl‰h. Therefore, the length of the optional element stiffness exceed 2h.

For the construction of the pedestrian bridge just one flexion with additional flooring. There is also a variant with two suspended “corridors” on both sides of the beam.

To use flexion as a beam monorail must snanam surfaces “sevens” have move support rollers, and on the lateral surfaces with a negative slope of about 10° to the lateral stabilizing rollers. To implement the high-speed operation is desirable maximum straight path, which is provided by the crowning compensation system according to the point 3 of the present invention. Due to the blocks 6, 7, 8, and a tension cable 9 beam 1 receives the reverse deflection taking into account the average weight of the crew. When passing by the crew of flight both deformations are mutually compensated.

Road bridge can be created on the basis of two or three parallel flexional similarly used parallel “brands”. The main thing is to efficiently reallocate local pressure from the wheels through the intermediary hard flooring.

Formed on the shore flexion can be transported by water, it is enough to provide their side “plugs”. To flexione not twisted afloat and well passed through the shallow water, they must be connected in pairs or in groups larger number of ribs up like a raft.

Claims

1. The span of the bridge, trestle or other overlying structures, made from a single length of span of thin elastic sheet, pre-n is that the edges of the original sheet is combined, and formed by a sheet of a closed surface of the pipe is provided with periodically mounted inside the transverse elements, with the resulting surface profile is determined by the formula

,

where y is the current distance from the vertical line of symmetry of the profile, x=h/2h0;

h - current distance from the highest point of the profile.

h0- the distance from the highest point of the profile to the maximum line width.

2. The span of the bridge under item 1, characterized in that in the middle of the span inside the closed surface of the pipe is an additional element stiffness type frame, for example, a triangular profile, the length of the additional element is at least twice as good as the full height of the main profile and the width of the additional element corresponds to the maximum width of the main profile.

3. The span of the bridge under item 1 or 2, characterized in that extra element stiffness installed the pulley - block, and two other blocks are installed at the ends of the passage, through the blocks skipped tension wire so that the Central unit ulibaetsa the bottom rope, and terminal blocks at the top.

 

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