EP0693600B1 - Vibration reduced composite girder - Google Patents

Abstract

The horizontal support beam (4) is normally under tension when loaded and has the load bearing surface (2) attached to its upper edge by special fittings (6) which allow some relative movement between the surface and the beam. The load bearing surface is under compression. The maximum amount of relative movement is 10 mm and can be backed by elastic padding. A construction has fastening bolts located in an elastic padding. The elastic padding can be an intermediate layer between the beam and the surface, with the friction providing damping. The fastenings can be at selected points along the structure. <IMAGE>

Description

The present invention relates to a composite beam as used in construction, and which essentially consists of a first element that can withstand tensile loads and one with the first element firmly connected second, pressure-resistant element. Such a Composite beams have been known for a long time. He is e.g. B. described in DE 2 206 140.

Bridges and, for example, the ceilings of large halls are often covered with such Composite beams stretched, the component loaded on train in general Steel beam with double T-profile is on the corresponding in the area of its two ends Bearing surfaces. Such steel beams withstand very high tensile forces. You are too already, relative to the use of material, relatively rigid, whereby in the case of a uniform, A deflection occurs over the length between the load points and wherein the bending moment increases continuously from the ends towards the center and essentially forms the shape of a parabola with a vertex in the middle of the beam. According to usual According to conventions, such a bending moment is referred to and taken into account as a positive bending moment.

The bending stiffness of the steel girder can, however, be combined with one that can withstand pressure or pressure-resistant element considerably increase. This composite is generally produced with a layer of concrete or concrete slab on the top or top flange of the steel girder rests and which is firmly connected to the steel girder in several places. In general So-called stud bolts are used for this connection, that is, with a head Provided steel pins that are welded to the top chord and protrude upwards from it. After the formwork for a ceiling slab, in which the steel beam is integrated then poured the concrete and also flows around the headed studs, so that a firm connection between the concrete slab and the underlying steel beam.

That the bending stiffness of such a composite beam compared to that considered in isolation Steel beam is significantly improved, follows from the following consideration. Will the steel beam laid on both ends and evenly loaded over its length, so results As already mentioned, there is a deflection with a maximum bending moment in the middle. At Equilibrium of forces means that the upper flange (the upper flange) of the steel girder is compressed while the lower chord is stretched. The upsets and strains are maximum in each case in the central area of the beam, because the greatest bending moment occurs here. At symmetrical formation of the double-T beam runs a neutral line, that is, a line inside the steel beam, along which the material is neither a compression nor an expansion experiences, exactly along the middle of the connecting the upper chord and the lower chord of the wearer Web. The concrete slab, which is firmly cast with the top flange of a double-T beam, has in this the deflection area absorbing pressure forces has a substantially larger cross section than the upper chord of the steel girder and therefore sets a much larger pressure force Resistance to the steel girder's upper chord alone. The one with the top chord tight connected concrete slab allows only a slight compression of the top chord, the neutral one Line moves in the web in the direction of the top chord and for absorbing the tensile forces there is a larger cross section of the steel beam available, due to the displacement resistance to the neutral line even with a given stretch of the lower flange deflection is increased. In other words, the deflection is given Load significantly reduced, the system as a whole more rigid.

Such a composite beam, which at its two ends on corresponding support surfaces rests at the same time as a structure capable of vibration. The resonance frequency decreases of such a vibrating structure with the increase in the total mass of the System and the increase in the distance between the support points more and more thereby into a frequency range, within which also typical human loads, Vehicles and other machines occur. This resonance phenomenon is from bridges also known to laypeople, for example, marching columns are not in step May cross bridges, because under certain circumstances the step frequency with the resonance frequency of the bridge match, causing them to collapse could.

Also halls that are used by vehicles, for example fork lifts, or in which If there are large crowds and move around, there should be no carrying ones if possible Have elements whose resonance frequency in the range between half and z. B. three Hertz lie.

On the other hand, with the given spans, masses and material properties (at least of the common materials such as steel and concrete) Natural frequencies in the Do not always exclude the mentioned area. The steel beams and possibly also the Concrete ceilings for such composite beams are therefore often oversized to be given Loads to reduce the vibration amplitudes and possibly also in the resonance range to withstand occurring loads.

DE-A 2 241 327 describes a composite beam with a first element opposite a second element can be moved to a limited extent. The reinforced beam described therein made of steel and / or concrete is designed as a pressure element and only serves to reinforce the Carrier and not the vibration damping.

BE-A-795 916 and FR-A-2 128 569 also show composite beams with one another moving elements. With the BE-A-795 916 this flexibility is due to the assembly of the Composite beam limited. When assembled, there is no longer any mobility. At the FR-A-2 128 569 does indeed have a little play against a second element Element. Rather, this serves to compensate for non-adapted expansion coefficients and not the vibration absorption or transmission.

The present invention lies in relation to the prior art described above therefore the task is based on a composite beam with the features mentioned create that is improved in terms of its vibration behavior.

This object is achieved in that at least a section of the first or second Element compared to the other element or a third, with the first or second element connected element is limited movement, and that a Energy absorbing damping material between the moving elements or sections of the elements is arranged, in which with a relative movement of the relevant Sections generate frictional heat and thus kinetic energy is consumed.

The element that can be loaded under pressure and the element that can be loaded under tension are still solid connected with each other, but according to the invention it is nevertheless ensured that the occurring Loads of at least portions of the first and second elements are relative move towards each other, creating friction and every movement and especially Vibrations in the resonance range are damped.

However, it is not absolutely necessary that the first and second elements (sections) move relative to each other, but you get the same effect, if a third (or further) element with the first or second element essentially is firmly connected and the mentioned section-wise relative movement and thus a corresponding friction allows. In both cases, every movement of the composite beam dampened by this friction. It is sufficient if the movement play against each other movable sections is on the order of a few tenths of a millimeter and for example at least 0.1 mm. However, the maximum shift should preferably be used of the elements against each other at a permissible maximum static load 0.5 mm, this play being the difference between the positions without and with load understand is.

Even with very large spans, however, it should generally be sufficient if that maximum movement clearance does not exceed 10 mm.

It is understood that for effective damping the mutually movable sections of the elements mentioned must be in frictional engagement with one another, this frictional engagement can be present directly between the surfaces of the elements, but also an indirect one Rubbing engagement can be provided, for example by any suitable intermediate layer between the sections of the elements that can be moved relative to one another.

An embodiment of the invention is preferred in which the frictional engagement is performed by Clamping screws are ensured, which in each case in at least one of the connected thereby Elements are included in a mounting hole with play as these clamping screws do not create a firm, immovable connection between the two elements should, but only the parts should be pressed so tightly together that one occurring relative movement between them considerable frictional forces are to be overcome.

In order to achieve appropriate friction effects, it is useful if the first element and the second element at at least two clearly spaced apart points are rigidly connected to each other and have no rigid connection between these points. In the system of double T beams described at the beginning as prior art and concrete slab should have appropriate connections between these two elements, that means head bolts on the double-T beam, only in the end sections of the double-T beam be present so that in the rest of the area, ie over more than 70% of the length of the T-beam away, no fixed connection between the beam and concrete slab is provided. That when such a composite beam is loaded, relative movements between the top chord and the concrete ceiling on top of it, is still associated with the Figures are explained and described.

However, it can also be expedient if, in particular when connecting to a third element, the distance of the points of the elements to be rigidly connected is selectable. This distance can then be chosen so that the natural frequency of the third Element differs significantly from the typically occurring loading frequency and the natural frequency of the basic element differs. In addition, the natural frequency of the Basic element also to any harmonics of the fundamental frequency of the third element be spaced. With the additional arrangement of damping material between them different frequency, usually with a lower frequency, vibrating structures and the first and / or the second element, the movements that occur are dampened even better, all in all a very rigid and only little vibrating composite leads, which also makes it possible, for example, to lower both the beam and the concrete slab dimension, which in turn has beneficial effects in terms of increasing the resonant frequency has, but above all leads to considerable cost savings.

It has proven to be advantageous if the mass of the vibration damper (= third Element) is about 3% of the mass of the overall system and is significantly slower than that Basic system (without vibration damper) vibrates.

Even if the present invention here in connection with the specific embodiment of a Composite beam, consisting of a double-T beam and a and with this connected concrete slab has been described, it is understood that the Invention is generally applicable to all types of composite beams, in which one on train resilient or a tensile load and a resilient or compressive load receiving element are interconnected, regardless of the specific design of these two elements. It is therefore understood that the element resilient to tension can also be a (rectangular) tube or a truss, or a double T-beam, whose bridge is designed as a truss. However, the description continues to be based on the embodiment with a composite of double T-beam with an overlying Concrete slab.

It is useful if the formed between the web and the upper or lower flange Free spaces of a double-T beam are filled with chamber concrete, for example for Fire protection purposes, around the bridge and the top chord depending on the fire department Provisions a sufficiently long time before heating in the event of a fire protect. An additional reinforcement absorbing tensile forces can be placed in the chamber concrete be inserted and here too the connection between chamber concrete and reinforcement be designed that a relative movement in sections, be it between chamber concrete and web or straps, whether between chamber concrete and reinforcement or opposite both, is possible.

A further embodiment of the invention thereby contributes to a further improvement and Optimization of the vibration behavior in that a third element is provided, the Mass is at least 3% of the mass of the first element that can withstand tensile loads and that this third element via at least partially loaded elastomer springs on the first or second element is suspended or mounted on one of these elements.

In addition to the previously described embodiments, in which a third element over elastomer blocks on the lower flange of a Steel beam is suspended, it has proven to be advantageous if such elastomer blocks and the corresponding third elements are arranged so that the elastomer elements be at least partially pressurized. Furthermore, it has proven to be beneficial if the mass of such a third element is at least 3% and preferably between 4 and 10% of the mass of the first element loaded under tension, the latter is in generally a double-T steel beam with a reinforced concrete slab on the upper or lower flange lies on.

In a preferred embodiment of the invention, the third element is a compact, block-shaped absorber mass is formed, whereby the term "absorber mass" express should be that vibrations are absorbed or "eradicated" by this mass.

In a preferred embodiment of the invention, this absorber mass is in a recess provided in the chamber concrete of a double-T beam, which is the first element that can withstand tensile loads represents. This block can be moved and opened relative to the chamber concrete in its recess Elastomer springs stored in the recess. It is understood that the block in question Recess must have some play to be relative to the wearer and the to be able to move other chamber concrete to absorb vibrations. Apart from corresponding joints between absorber mass and the walls of the recess in the Chamber concrete, however, is the absorber mass or the block of absorber mass trained that he the web of a corresponding double-T beam in the area of The cutout is almost completely covered and thus acts as fire protection for the steel girder keeps. The inserted block, which forms the absorber mass, preferably also consists of Concrete. In another embodiment, fire protection is not provided by the chamber concrete formed and the absorber mass made of concrete only serves to reduce the vibrations.

According to another embodiment of the invention, one is on the lower flange of a double T steel beam suspended undervoltage provided, which forms or carries the absorber mass. In a preferred embodiment, this undervoltage has a tension band, which trapezoidal and thus partially stretched parallel to the lower flange, two Rod-shaped, attached to the ends of the short parallel trapezoidal side and under pressure Resilient parts keep the drawstring at a distance from the lower flange. The relevant rod-shaped Parts can be strips, bars, rods or even plate-shaped elements.

The tension band expediently consists of a steel part, preferably one Flat steel element or round steel element. On the undervoltage or on the parallel to the A tension mass is arranged in the lower chord of the tension band, and this too The drawstring itself can be designed to be correspondingly massive and can serve as an absorber mass. This Absorber mass is also attached to rod-shaped or strip-shaped elements that become the Lower flange of the double-T beam and, if necessary, through holes in it extend so that the absorber mass with the help of these rods and via intermediate Elastomer springs are suspended from the double T-beam. The suspension can also a chamber concrete that may be provided on the double-T beam. For example, the chamber concrete can be sectioned into an upper and a lower section Bearing block to be divided, the tensile rods which are the absorber mass wear, are attached to the upper bracket, the lower bracket z. B. on the lower flange of the double-T support and elastomer springs in a gap or space are arranged between the upper and the lower bearing block. There is an embodiment the invention particularly preferred in which two sections of a gap between the upper and lower bracket V-shaped relative to each other run, the in these relatively inclined sections Elastomer spring elements are arranged. This leads to a in the stress situation combined pressure and shear stress of the elastomer spring elements, whereby in the case of Relative movements in the longitudinal direction of the column the additionally impressed shear deformation the elastomer springs have a strong energy absorption and dampening effect.

Furthermore, it has proven to be advantageous to move between parts of the Composite carrier and / or the third element intermediate layers with defined friction in To be combined with slide films or the like.

The rubbing intermediate layers are e.g. formed from two stainless steel plates, the neighboring surfaces are roughened and with a certain contact pressure on each other rub. The contact pressure can be adjusted by a pre-tensioned screw connection in each Application can be set exactly, the screw length and the screw diameter be determined so that in the horizontal displacement generated in the screw permissible bending stresses occur.

The rubbing layers can also be made of plastic sheets, the surfaces of which are roughened are exist.

In another embodiment, the friction surfaces are made of synthetic resin paints, in which fine quartz sand is sprinkled.

Between the contact surfaces with increased friction there are sliding surfaces with very low friction, which are formed from slide films or lubricious paints.

Figur 1

einen Längs- und einen Querschnitt durch einen Verbundträger ,

Figur 2a bis g,

schematisch die Kräfte, Momente und Relativbewegungen, die Druck- und Zugelement gemäß der vorliegenden Erfindung erfahren,

Figur 3

einen Längsschnitt durch eine weitere Ausführungsform mit einem zusätzlichen dritten Element,

Figur 4

eine Abwandlung der Ausführungsform gemäß Figur 3,

Figur 5

ein Beispiel eines Dämpfungselementes,

Figur 6

eine Seitenansicht eines Verbundträgers mit Unterspannung

Figur 7

einen Querschnitt durch den unteren Bereich eines Verbundträgers nach Figur 6,

Figur 8

im linken Teilbild eine Längsansicht und im rechten Teilbild eine Querschnittsansicht eines Verbundträgers, der als Tilgermasse einen Block aus Beton aufweist, und

Figur 9

einen Teilquerschnitt durch einen Verbundträger mit speziellen Reibungselementen.

The essence of the invention and further advantages, features and possible uses thereof will become even clearer from the following description of preferred embodiments and the associated figures.

Figure 1

a longitudinal and a cross section through a composite beam,

2a to g,

schematically the forces, moments and relative movements experienced by the push and pull element according to the present invention,

Figure 3

2 shows a longitudinal section through a further embodiment with an additional third element,

Figure 4

3 shows a modification of the embodiment according to FIG. 3,

Figure 5

an example of a damping element,

Figure 6

a side view of a composite beam with undervoltage

Figure 7

6 shows a cross section through the lower region of a composite carrier according to FIG. 6,

Figure 8

in the left partial image a longitudinal view and in the right partial image a cross-sectional view of a composite beam, which has a block made of concrete as the absorber mass, and

Figure 9

a partial cross section through a composite beam with special friction elements.

A longitudinal section can be seen in FIG. 1 and a longitudinal section in the right partial image Cross section through a composite beam, which essentially consists of a double-T beam 1 Steel and a concrete plate 2 lying thereon, firmly connected to the upper flange 3. An energy-absorbing damping element is designated by 13.

The double-T beam 1 consists of an upper flange 3 (also called an upper flange), one Web 4 and a lower flange 5 (lower flange). As can be seen in the longitudinal section, are the two end sections of the upper flange 3 are provided with a plurality of head bolts 6, which are fixed Ensure that the concrete slab 2 is anchored to the top chord 3 or to the double-T beam should.

At the two ends of the double-T beam 1 there are support points 7 in The shape of triangles is indicated schematically. FIG. 2 shows forces a and f in the partial images Torque distributions and horizontal shifts between areas of the double-T beam 1 and the concrete slab 2. In Figure 2a, the normal force curve is in the vertical direction Concrete pressure plate recorded over the length of the beam. As you can see, the concrete slab is standing 2 under a constant compressive stress, which by convention with a negative Sign is marked. The torque line of the Double-T beam, initially without considering the coupling to the concrete slab, however with an assumed uniform load from above. The bending moment that occurs is positive according to the usual conventions, but is applied downwards. This essentially results in a parabolic shape with a for the moment line Vertex in the middle between the two support points 7.

However, the deflection of the double-T girder is caused by the head bolts and the concrete pressure plate 2 1 a counterforce because the head bolts 6 due to the deflection tend to be moved towards each other from the two ends, this movement however, the extensive incompressibility of the concrete slab 2 stands in the way. Because in the concrete slab 2 there is a uniform pressure distribution in the longitudinal direction, are accordingly on the Head bolts 6 acting at the two opposite ends, the head bolts exerted forces away from each other with respect to the neutral line 17 of Effectively attack the double-T beam 1 using a lever. This causes a constant, in comparison bending moment opposite to the previously considered deflection, which in Figure 2c is reproduced. The total torque line resulting from the superimposition of the bending moment line 2b and by coupling to the concrete pressure plate 2nd is shown in Figure 2d. Figure 2e shows the normal force line of the steel beam of the is exposed to a tensile load for reasons of balance with the concrete compressive force.

From these moments and normal forces acting on the double-T beam, one can easily derive the horizontal movement of certain sections of the top chord. It is assumed that the distance between the support points 7 does not change and that the deflection or when the bending moments act according to FIG. 2d, the lower flange 5 is stretched and the upper chord 3 is tightened. This is illustrated in Figure 2f for three different points shown. On the far left you can see in Figure 2f that where the bending moment is 0, only one constant expansion of the steel beam occurs due to the normal force according to Figure 2e. In the In the middle of the beam, where the bending moment is greatest, a compression is made on the top chord 3 and on the lower chord 5 an elongation, as evidenced by the negative and the positive indicator can be seen in the right part of Figure 2f. However, this picture is asymmetrical, because of the effect of the concrete slab 2 in the steel beam an additional Elongation occurs.

In an intermediate position, the compression is even less because of the bending moment is smaller here.

If one looks at two arranged near the center of the double T-beam, but in Points spaced apart in the longitudinal direction, the spacing of which is small enough, however that the compression in the area between the two points is approximately constant be applied or replaced by an average of the compression at the two points can, it can be seen that due to the greater compression in the middle these two Points will move closer together than any two other points in the same Longitudinal distance at any other location on the surface of the top chord 3. In the vicinity of the zero point of the moment there are even stretches in the upper chord 3. On the other hand the concrete slab 2 is under a constant compressive stress over its entire length, so that along the entire length of the bottom by a certain distance points apart due to the compressive stress everywhere by the same fixed amount approach each other. Since the top flange 3 and the concrete slab 2 are in the area between the Head bolts are not rigidly connected to each other, results from the comparison of the movement of points on the top of the top chord 3 and the bottom of the concrete pressure plate 2 imperative that relative movements occur between these abutting surfaces which also cause friction. In Figure 2g is the schematic Amount of the relative displacement plotted over the length of the beam. One recognizes that only relatively slight relative movements occur at the edges and in the middle, while the curve of the relative movement runs over a maximum at points in between. This maximum should be at least in the order of a few tenths of a millimeter lie in order to be able to dissipate sufficient energy for effective damping.

Another embodiment of the invention is shown in FIG. 3. In this case there is a third element an additional lower base plate 10 is attached to the lower flange 5. A firm connection 11, for example by welding, is in turn only at the ends of the base plate 10 and the lower flange 5. Relative shifts are possible in the intermediate areas, clamping screws 12 ensure that the two elements 10, 5 in any case remain in frictional engagement with one another.

When considering the torque lines similar to the considerations for Figure 2, one also poses here a relative movement between the top of the base plate 10 and the bottom of the Upper belt 5 fixed when the entire composite beam is alternately loaded and unloaded.

A variant of this embodiment is shown in FIG. 4, with connection 11 between the base plate 10 and the lower flange 5 deliberately a distance between the base plate 10 and the lower flange 5 is produced so that a gap or a gap 15 is formed. Different attenuators can be inserted into this gap, for example one Hose filled with a viscous material, a gel or the like. At the Bending of the composite girder according to FIG. 5 again results in relative displacement and also deformations, in particular a narrowing of the gap 15, so that here again Deformation and friction work is done, which strongly dampens the movements and the occurrence of resonance vibrations at least largely resonance amplitudes prevented. If the base plate 10 is made wider than the lower flange 5, can elastomer blocks 18 fastened on both sides of the lower flange 5 to this and to the base plate 10 be in the event of a relative displacement between the lower flange 5 and the base plate 10 Absorb shear forces. It has been found that elastomer blocks act in this arrangement Particularly good cushioning, especially when subjected to shear forces. A corresponding Embodiment is shown in Figure 5a, which in the lower part of a composite beam Cut shows. One can still see the web 4 and the lower flange 5 from the double T-beam on the lower flange 5, two elastomer blocks 18 are fastened, which are attached to the lower flange 5 opposite sides are each firmly connected to a (steel) rail 19, which in turn are welded onto the base plate 10. In this case it is wider than the one above lying lower chord 5 and, such as. B. shown in Figure 3 or 4, at their end portions the lower chord 5 firmly connected. The elastomer blocks 18 and the rails 19 extend essentially over the entire length of the base plate, but at least along that length Areas where the strongest relative movements between base plate 10 and lower flange 5 occur.

In both embodiments according to FIGS. 3 and 4, in addition to the fastening parts 11 Clamping screws 12 are provided, by means of which the base plate 10 is tightened according to FIG. 3 the lower flange 5 is to be pressed in order to make the frictional forces correspondingly large. These clamping screws are expediently arranged precisely where the strongest Relative movements between the lower flange 5 and the base plate 10 occur.

With regard to the embodiment according to FIG. 4, it should be noted that the base plate 10 is there is freely tensioned and can swing like a string. The clamping screws 14 are in this Case primarily intended for the natural frequency of the vibratable base plate 10 increase.

With the system according to the invention it is possible, among other things, for given spans increase the natural frequency of the system since lighter components can be used, which also offers price advantages.

This is possible due to the deliberately intended friction between individuals Any vibrations or vibrations that may occur in the elements of the composite beam be strongly damped, so that the wearer with all practically occurring loads never get into dangerous resonance vibrations that exceed the load limit. The carrier can therefore be chosen more easily and with a smaller profile cross section than this is possible due to the safety design based on conventional criteria.

A composite carrier can be seen in FIG. 6 in a side view or in a longitudinal section, which consists of a double-T steel beam 1 and a concrete slab 2 fastened thereon. The Both ends of the carrier 1 rest on supports 7. The connection between steel girders 1 and concrete slab 1 takes place, as in the previous embodiments, near the Support area by protruding into the concrete and on the upper chord of the steel girder welded head bolts.

On the lower flange 5 of the steel beam 1 is a trapezoidal tension band 21 with its attached both ends near the support points 7. Two rigid bars, plates or webs 22 tension the drawstring 21 downwards into the trapezoid shape mentioned. The drawstring can consist of a plate or band-shaped steel element. In the middle area, in which the drawstring 21 otherwise between the two end points of the short trapezoidal side would sag, it is via rods or plates 23 and intermediate elastomer springs 27 suspended from the lower flange 5 of the steel beam 1. With vibratory movements can the tension band 21 in the middle, between the rods 22 freely stretched relative movements run to the steel girder 1, with the design of the tension band 21st It is important to ensure that the natural frequency of the tension band thus arranged is clearly from the natural frequency of the composite girder consisting of steel girder 1 and concrete slab 2 deviates. This leads to vibrations on the concrete slab or the composite beam are transmitted to relative movements between the tension band 21 and the lower flange 5 of the steel beam 1 or with respect to the entire steel beam 1, with the intermediate Elastomer springs 27 absorb appropriate forces and absorb energy.

A preferred way of suspending the tension band 21 in the middle between the bars 22 can be seen in cross section according to FIG. 7. On the lower flange 5 of the double-T beam 1 there is a lower bearing block 25, this bearing block 25 consisting of two there may be separate sections, which are provided on each side of the web, on the other hand, however, recesses can also be provided in the web, through which at least in sections a connection between the two sides of the web 4th arranged bearing block parts 25 can be produced. The lower bracket 25 has two walls sloping relative to each other V-shaped, which is also characterized by a horizontal lower Section can be connected.

The upper bearing block 26 is complementary to this, that is to say it has a cross section Trapezoidal shape with two V-shaped outer walls running relative to each other, which are the same Have slope like the V-shaped inner walls of the lower bracket 25, where that both bearing blocks 25, 26 complement each other. The bearing block 26 is relative raised to the pedestal 25, so arise between the inclined External walls corresponding column, in which elastomeric springs 27 or elastomer blocks are arranged. The rods or are on rods 28 and possibly also cross struts Web plates 23, on which in turn the absorber mass or the drawstring 21 hang, with the upper bracket 26 connected. Accordingly, relative movements of the Tension band or the absorber mass 21 opposite the lower flange 5 of the composite beam 1 or compared to the entire composite beam 1 via the web plates 23, the rods 28, Cross struts and the upper bearing block 26 are caught by the elastomer springs 27. there the vibrational energy that occurs is absorbed and the vibrations become strong subdued. This applies to both relative movements in horizontal and vertical Direction, the angular orientation of the elastomer springs 27 relative to each other helps to dampen movements in any direction.

FIG. 8 shows another variant of a vibration damping system according to the presented present invention. In the left part of the picture you can see the composite beam in a longitudinal side view on two supports 7, while the right partial image one Cross section through the composite beam in the area of the springs 27 of a vibration damper block 30 shows.

The composite beam 1 according to Figure 8 consists of the upper concrete slab 2 and a double-T steel beam 1. The connection between these two elements is done in the same way as in the previously described embodiments. In the illustrated in Figure 8 Embodiment are defined between the upper flange 3, lower flange 5 and web 4 Gaps filled with so-called "chamber concrete" 32, the one with a Reinforcement 8 is provided. On the one hand, this chamber concrete 32 forms an optical cladding of the steel beam 1, but primarily serves to protect the steel beam 1, in particular when a possible fire. If steel girders in the event of fire are exposed to direct flame or generally exposed to intense heat, occurring, high temperatures quickly lose strength, so that the composite carrier then breaks altogether under the existing load. So that such a failure of Composite beams should not appear too early in the event of fire and therefore have enough time remains for rescue and protective measures, those defined by the carrier Clearances filled with the chamber concrete 32, which then for at least the web of the carrier protects against heat for a certain time, so that a composite carrier protected in this way withstands heat in the event of fire for a long time without to give in to the existing load.

In this further embodiment, which is based on such double-beam filled with chamber concrete relates, a recess is provided in the chamber concrete, in which a as Absorber mass serving block 30 is mounted on elastomer springs 27. The recess and the Block 30 are designed so that block 30 essentially fills the recess, wherein however, all around small joints remain, so that the block supported on the elastomer springs 27 30 can move relative to the rest of the chamber concrete 32 and the steel beam 1. Similar to the previously described embodiment, they may then occurring vibrations of the system through relative movements between the Block 30 and the rest of the system due to the coupling by the elastomer springs 27 subdued.

The fact that the block 30 is adapted to the shape of the corresponding recess takes over he function in this area of the chamber concrete 32 as flame or fire protection. It is particularly expedient if the block 30 is also made of concrete. To in this The area of the recess can improve the protection against heat even further can also be provided with gradations, and the block 30 then has corresponding projections on, so that block 30 and chamber concrete 32 overlap each other in the area of the joints, so that the joints 31 are completely covered.

As already mentioned, the springs 27 consist of plates or blocks made of an elastomer Material, of course, such elastomer springs can also by others damped spring system can be replaced, for example by a combination of normal Steel springs with shock absorbers, through hydraulic multi-chamber systems, in which by Relative movements forced a liquid to flow back and forth due to a bottleneck will etc.

FIG. 9 shows a section of a cross section through the steel beam 1 which can be subjected to tension and an adjacent pressure-resistant second or third element 3, which in one Area in which parts 1, 2 can in principle be displaced relative to one another by small distances are, but are held together by a clamping screw 12, which has a Load distribution plate 33 presses a pair of roughened steel plates 34 together one plate with the first element and the other plate with the second element connected is. By appropriately pretensioning the tensioning screw 12, that a relatively well definable frictional force is required to bear against each other to shift roughened friction surfaces of the steel plates 34, the Tensioning screw 12 is designed to occur during this displacement To record bending stress and in particular the screw 12 with play corresponding bores at least in the steel plates 34 and the load distribution plate 33 and / or an upper flange of the element 1 is received. Outside of that by the Clamping screw held together, a special sliding layer 35 is provided, e.g. consists of slide films or a good lubricious coating, so that to the force which is required in this area to move elements 1 and 2 against each other move, contribute almost exclusively to the roughened plates 34. These plates 34 can of course consist of a material other than steel and can especially plastic plates. The plates 34 can also by one Synthetic resin painting, which e.g. Quartz sand is added.

Claims (22)

1. A composite beam comprising a first element (1) which can be loaded in tension and a second element (2) which is fixedly connected to the first element (1) and which can be loaded in compression, characterised in that at least one portion of the first or second element is limitedly movable relative to the respective other element, that is to say the second or the first element respectively, or relative to a third element connected to the first or second element, and that an energy-absorbing damping material (13, 18) is arranged between relatively mutually movable portions of the elements (1, 2, 10).
2. A composite beam according to claim 1 characterised in that the maximum clearance of motion of mutually movable portions of the elements is at least 0.1, preferably at least 0.5 mm.
3. A composite beam according to claim 1 or claim 2 characterised in that the maximum clearance of motion of mutually movable portions of the elements (1, 2, 8, 10) is at most 10 mm.
4. A composite beam according to one of claims 1 to 3 characterised in that the limitedly mutually movable portions are in direct or indirect frictional engagement with each other.
5. A composite beam according to claim 4 characterised in that the frictional engagement is provided by clamping screws (12) which are received with play in holes and which urge the mutually movable portions of the elements (1, 2, 10) against each other.
6. A composite beam according to one of claims 1 to 5 characterised in that the first and second elements are rigidly connected together at at least two points which are spaced relatively far from each other, preferably in the region of the ends of the composite beam.
7. A composite beam according to one of claims 1 to 6 characterised in that the third element has two or more connecting elements in the proximity of its ends or at different spacings so that the largest spacing between two connecting elements can be selected.
8. A composite beam according to one of claims 1 to 7 characterised in that the first element (1) which can be loaded in tension is a double-T-beam.
9. A composite beam according to claim 8 characterised in that the free spaces formed between the web (4) and the upper and lower flanges (3 and 5 respectively) are filled with aerated concrete (16).
10. A composite beam according to claim 9 characterised in that elements (8) which are loaded in tension are provided in the aerated concrete in the proximity of the lower flange (5).
11. A composite beam according to one of claims 1 to 10 characterised in that the element loaded in tension is a lattice beam.
12. A composite beam according to claim 11 and one of claims 8 to 10 characterised in that the web of a double-T-shaped beam is formed by a lattice.
13. A composite beam according to one of claims 1 to 12 characterised in that elastomer blocks (18) are fixed preferably laterally to the lower flange (5) and on a base plate (10) which is preferably wider than the lower flange (15), which elastomer blocks carry shearing forces upon relative displacement upon the lower flange (5) and the base plate (10).
14. A composite beam according to one of claims 1 to 13 characterised in that the third element is of at least 3% of the mass of the first element (1) and by way of elastomer springs (27) which are loaded in tension is suspended from the first or second element (1, 2) or mounted on one of said elements (1, 2).
15. A composite beam according to claim 14 characterised in that the mass of the third element is between 4 and 20% of the mass of the first element.
16. A composite beam according to one of claims 1 to 15 characterised in that the third element is in the form of a compact, block-shaped damping weight.
17. A composite beam according to claim 16 characterised in that an opening is provided in the aerated concrete of a first element (1) which is in the form of a double-T-steel beam, wherein the damping weight is supported in said opening on elastomer springs.
18. A composite beam according to claim 16 characterised in that the damping weight (30) also comprises concrete and in the opening provided therefor substantially covers over the web (4) of the steel beam.
19. A composite beam according to one of claims 1 to 18 characterised in that provided on the lower flange (5) (lower chord) of a double-T-steel beam which serves as the first element (1) is a trussing (20) suspended from the lower flange (5) of the steel beam.
20. A composite beam according to claim 19 characterised in that the trussing comprises a tensile band (21) which is trussed in parallel relationship away from the lower flange (5) and which together with the lower flange defines a trapezium shape, wherein two bar-shaped members which fit to the ends of the short ones of the parallel sides of the trapezium and which can be loaded in compression are held at a spacing relative to the lower flange (5).
21. A composite beam according to claim 19 or claim 20 characterised in that the trussing has a damping weight (21) which either comprises the tensile band itself or an additional element, wherein the damping weight is suspended to the steel beam or the aerated concrete thereof by way of bar-shaped or strip-shaped elements and interposed elastomer springs.
22. A composite beam according to one of claims 1 to 21 characterised in that one or more frictional surfaces and/or one or more sliding foils is or are arranged between parts which are movable relative to each other.

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