EP0401401B1 - Elastic control system for bridging joints in roadways with intermediate beams - Google Patents

Abstract

In a resilient control system for carriageway bridging structures using the segmental method, in which the cantilever segments 7, 8 are supported on supporting beams 3, 4 which are displaceably mounted by means of sliding springs/sliding bearings in supporting beam boxes 1, 2 and connected by control springs 16, 17, the control springs being formed by spring elements which are mounted on pins 15 extending parallel to the supporting beams and bear, with their end surfaces, against stops 10', 11, 12, 18, 18', 19, 19', 20, 20' attached to the supporting beams or to the supporting beam boxes, provision is made, according to the invention, for at least two spring elements 16, 17 to be arranged on each pin 15 and for the stops to be assigned to the supporting beams or to the supporting beam boxes so that at least one spring element is always under compressive stress, irrespective of the direction of loading and the magnitude of loading. <IMAGE>

Description

The invention relates to an elastic control system for lane bridging constructions in girder grate construction, wherein at least one girder is mounted on trusses, the trusses of each bearing point are connected to one another or to the joint edge by control springs, and the control springs are formed by spring elements which are parallel to the trusses extending thorns are stored and their end faces bear against stops attached to the trusses or the truss boxes.

In bridge construction in particular, expansion joints are provided to take into account temperature-related and / or load-related relative movements of two adjacent roadway parts between the roadway parts. The joints are elastic and gliding in truss boxes Bridges trusses that carry beams running parallel to the edge of the road.

• 1. Eine Steuerungsfunktion: Die gesamte Fugenbewegung muß gleichmäßig auf die einzelnen zwischen den Trägern bzw. zwischen den Trägern und den Fugenrändern vorhandenen, durch Dichtprofile abgedeckten Spalte aufgeteilt werden.
• 2. Abtragung von horizontalen Kräften, die durch Beschleunigung beim Anfahren bzw. Bremsen eines über die Fuge fahrenden Fahrzeuges entstehen, in die Fugenränder.

The elastic control system used for joint constructions based on the girder grating principle must basically perform two functions:

• 1. A control function: The entire joint movement must be divided equally between the individual gaps between the beams or between the beams and the joint edges, which are covered by sealing profiles.
• 2. Transfer of horizontal forces, which arise from acceleration when starting or braking a vehicle traveling over the joint, into the joint edges.

Function 2 is largely taken over by the friction that is generated between the crossbeams and the preloaded sliding springs / plain bearings as a crossbeam support. Because of the relatively large scatter of such frictional forces, which is caused, among other things, by the reduction of the spring preload over time, the effect of the frictional forces is not taken into account in the static verifications. The control springs used in the elastic control system have to take up a very long working path (70 to 80 mm) for the control. The control springs used so far inevitably have a very low spring constant c (kN / m). At the high braking forces of z. B. 39 kN / wheel thus result in large displacements of the beams or the cross beams coupled to the beams, which go so far that the cross beams abut end stops and then, instead of the elastic support by the control springs, there is a rigid support at the end stops . Frequent repetition can destroy or damage the transition structure.

A transition construction is known, as can be seen from FIG. 1. The opposite truss boxes 1 and 2 are shown there. The opposite end faces of boxes 1 and 2 are open. In the boxes, two trusses 3 and 4 are slidably mounted on plain bearings, not shown. On the cross members 3 and 4, a support 5 and 6 is arranged for each of a merely indicated support 7 and 8, respectively. The carriers 7 and 8 are connected to one another or to the edge profiles, not shown, by means of sealing profiles. As can be seen from the illustration in FIG. 1, stops 9 and 10 or 9 'and 10' are welded to one another on each traverse side, but offset from one another. Likewise, a stop 11 and 12 are screwed to each side wall of the boxes 1 and 2 on the open end face, in such a way that a stop 11 on the lower side wall of the box 1 on the left in the drawing and the other stop 12 are arranged on the upper side wall of the box 2 shown on the right in the drawing. Thus, the stops 9'and 11, 10 and 10'are 9 and 12 opposite each other. In the attacks 9 ', 11; 10, 10 'and 9, 12 are each aligned holes, in each of which a mandrel 13 is slidably mounted. In the present example, the mandrel 13 is provided in the middle with a groove into which a protruding ring arranged in the bore of the control spring engages to fix the control spring on the mandrel. Between each opposing stops 9 ', 11; 10, 10 'and 9, 12, a spring element 14 is arranged on the mandrels 13.

In the state of the control system shown in FIG. 1, the spring elements are very strongly compressed. The restoring force of the spring elements is therefore greatest. At the end of a load, the preloaded springs relax to the position that is determined by the joint width that is present and is dependent on the bridge temperature.

In the known bridging construction described above, for example, the spring element 14c in the right-hand crossbar box 2 is subjected to tension when the braking force is directed to the crossbar 3 from left to right. The disadvantage here is that neither the stiffening of the spring due to the high rate of deformation nor the stiffening with increasing spring travel c = c (s) occur.

The invention is therefore based on the object of designing the elastic control system of the type mentioned in such a way that, regardless of the direction and the size of the horizontal forces introduced, there is always elastic support by the control springs, so that damage to the roadway bridging construction is avoided.

This object is achieved according to the invention in that at least two spring elements are arranged on each mandrel and the stops are assigned to the trusses or the truss boxes such that at least one spring element is always subjected to pressure. It can be provided in an advantageous manner that two stops including the spring elements are provided on a crossmember and that two spring elements with their mutually facing end faces rest on the opposite side faces of stops attached to the respectively adjacent crossbar or the crossbar boxes. The spring elements are mounted on mandrels, the ends of which are fixedly connected to a respective stop, the mandrels each penetrating an opening which is provided coaxially with the mandrel axis in the stop attached to the adjacent crossmember or the crossbar box. This has the advantage that, regardless of the direction of loading, a spring element is always subjected to pressure. If the spring elements are additionally biased to pressure, this leads to the fact that the spring, which is subjected to tension, also contributes by reducing its preload, and thus the two springs are connected in parallel Springs of the resulting spring stiffness can be treated c₁ + c₂. However, the spring stiffness c₂ of the spring-loaded spring is considerably less than the spring stiffness c₁ of the spring-loaded spring. The pressure preload is advantageously chosen such that all spring elements are always subjected to pressure regardless of the direction and the size of the relative movement of the stops. In the case of those spring elements into which tensile forces are introduced, there is therefore a reduction in the compressive preload as a function of the magnitude of the tensile force introduced.

, wobei f die Prüffrequenz der pulsierenden Federbelastung darstellt und w den Federweg angibt, d.h., c_dyn wächst linear mit dem Verschiebeweg w. Diese Verhältnisse ergeben sich allerdings nur bei dem erfindungsgemäßen ausgestaltenen Steuersystem, bei welchem sämtliche elastomeren Federelemente nur auf Druck beansprucht werden. Da bei auf Zug beanspruchten Federelementen dieser Effekt nicht auftritt, wird eine Mitwirkung der im Zugbeanspruchungsbereich liegenden Federelemente durch das oben beschriebene Aufbringen einer Druckvorspannung erreicht, die bei Zugbeanspruchung entsprechend abgebaut wird und damit in der Wirkung einer zugbeanspruchten Feder gleichkommt.It is advantageously provided that the spring elements consist of an elastomeric, foamed material with a spring constant which is a linear function of the spring travel. Experiments with elastomeric spring elements made of foamed material have shown that under very sudden loads (high loading speed) the spring stiffens significantly and that the spring constant c is a function of the spring travel, $\text{c = k. f. w}$

, where f represents the test frequency of the pulsating spring load and w indicates the spring travel, ie, c _{dyn increases} linearly with the displacement w. However, these relationships only arise in the control system designed according to the invention, in which all the elastomeric spring elements are only subjected to pressure. Since this effect does not occur in the case of spring elements subjected to tension, the spring elements located in the area of tensile stress cooperate by applying a compressive pretension as described above, which is correspondingly reduced under tensile stress and thus has the same effect as a spring subject to tensile stress.

Since the spring constant also increases linearly with increasing stress, ie with increasing spring travel, the stiffness of the horizontal elastic support of the carrier increases, so that it does not increase even with high horizontal forces the disadvantageous approach of the trusses against the rigid end stops.

The invention achieves an improvement in the "horizontal force transmission" function of the control system. As a side effect of the arrangement of double springs, there is also an improvement for "carrier control". Due to the parallel connection of the two springs of a control element described above, when a beam is deflected from the central position, the difference between the spring forces acting on the left and right of a crossbar will be twice as high as when only one spring is arranged within one control element. This differential force is calculated from the static spring constant c _stat , while the dynamic spring constant c _{dyn is} decisive for the absorption of the horizontal forces from vehicle _brakes . At the end of the horizontal load, the beam is pushed back into its central position by the occurrence of this differential force, which is dependent on the respective total joint opening. In order to limit the opening of the joint bridging construction to a maximum value, it is provided in a further advantageous embodiment of the invention that rigid end stops are provided between the individual cross members and the cross members and cross member boxes, the interacting end stops being arranged alternately on the cross members or cross member boxes, that they come into contact with each other before one of the spring elements assigned to them comes on block. This also prevents damage to the spring elements and thus premature wear.

Fig. 1

ein elastisches Steuersystem für eine bekannte Fahrbahnüberbrückungskonstruktion in Trägerbauweise, und

Fig.2a - c

im Prinzip Darstellungen in Draufsicht einer Fahrbahnüberbrückungskonstruktion mit dem erfindungsgemäßen elastischen Steuersystem in drei verschiedenen Öffnungszuständen der Dehnungsfuge.

Further features, advantages and details of the invention result from the following description of a preferred exemplary embodiment with reference to the drawing. In it show:

Fig. 1

a resilient control system for a known carrier bridging structure, and

Fig.2a - c

in principle representations in top view of a road bridging construction with the elastic control system according to the invention in three different opening states of the expansion joint.

In the exemplary embodiments shown in FIGS. 1 and 2, corresponding parts are designated with the same reference symbols. In contrast to the embodiment of FIG. 1 described above, in the embodiment of FIG. 2, two spring elements 16 and 17 are arranged one behind the other on each mandrel 15. The spring elements with their outwardly facing end faces against stops 18, 18 '; 19, 19 '; 20, 20 'abut while they rest with their mutually facing end faces against the screwed to the truss boxes 1 and 2 stops 11 and 12 or against the welded to the crossbar 4 stop 10'. The ends of the respective mandrels 15 are fixedly connected to the corresponding stop pairs 18, 18 'and 19, 19' and 20, 20 '. The spring elements are preferably prestressed under pressure. If, for example, the crossbeam 4 is now loaded from left to right in relation to the drawing - for example by a braking force acting on the crossbeam - then the crossbeam 4 is pushed into the right crossbeam box 2 (as shown, for example, in FIGS. 2b and 2c is), the spring element 16 is increasingly loaded under pressure, while the spring element 17 is stressed in tension. In contrast, if the crossmember was loaded from right to left, the spring element 17 would be subjected to pressure, while the spring element 16 would be subjected to tension. In any case, however, care is taken to ensure that the springs 16, 17 arranged one behind the other are always subjected to pressure regardless of the direction of loading, since the tensile forces introduced merely lead to a reduction in the pretension.

An example is intended to further illustrate the difference between the control system according to the invention and the prior art.

daraus c_res = $\frac{\text{1}}{\text{2}}$

. c.Applies to a conventional control system acc. Fig. 1a a left to right horizontal force on the welded to the cross member 3 at point 6, the control springs 14a and 14b are subjected to pressure, while control spring 14c would be tensile. The control springs 14a and 14b are connected in series, their resulting spring stiffness c _{res is} calculated

from it c _res = $\frac{\text{1}}{\text{2nd}}$

. c.

bzw. wenn keine Zugfeder vorhanden ist $${\text{c}}_{\text{ges}}\text{=}\frac{\text{c }}{\text{2.}}$$

Since the spring 14c cannot absorb any tension, it does not cooperate in absorbing the horizontal braking force. If a tension spring with the spring stiffness c _{z were} arranged in the place of the spring 14c, this spring would be connected in parallel with the two pressure springs of the resulting spring stiffness c _{res connected in series} . The total rigidity of the horizontal bearing would then be $${\text{c}}_{\text{total}}{\text{= c}}_{\text{res}}{\text{+ c}}_{\text{e.g.}}\text{=}\frac{\text{c}}{\text{2nd}}{\text{+ c}}_{\text{e.g.}}$$

or if there is no tension spring $${\text{c}}_{\text{total}}\text{=}\frac{\text{c}}{\text{2nd}}$$

Now the control system according to the invention. 2a to 2c considered. The horizontal force acts again from left to right on the center beam welded to the crossbar 3 via point 5. The springs 16a and 16b are subjected to pressure, the springs 17a and 17b assigned in the double spring package to tension. In contrast to the conventional control system, however, the spring 16c is also subjected to pressure here, the associated double spring 17c is subjected to tension. The double spring systems 16a / 17a, 16b / 17b are connected in series, while 16c / 17c is connected in parallel.

. Aus den beiden hintereinander geschalteten Doppelfedersystemen 16a/17a und 16b/17b ergibt sich eine resultierende Federsteifigkeit

The tension and compression springs are connected in parallel within a double spring system. Disregarding the dynamic With the spring stiffness c of the single spring, the increase factor is calculated as the resulting spring stiffness of the double spring system $\text{c + c = 2c}$

. A spring stiffness results from the two double spring systems 16a / 17a and 16b / 17b connected in series

gegenüber dem herkömmlichen Steuersystem mit nur $\frac{\text{c }}{\text{2.}}$

In this case, the overall rigidity of the horizontal support is:

$${\text{c}}_{\text{total}}\text{=}\frac{\text{2c}}{\text{2nd}}\text{+ 2c = 3c}$$

compared to the conventional tax system with only $\frac{\text{c}}{\text{2nd}}$

For reasons of simplification, the difference between c _dyn and c _{stat has been} neglected. As already stated, only c _{stat can be} applied to the spring that is _subjected to tension. Because of the dependence of the spring stiffness c on the spring travel s, c = c (s), this stiffening has an effect when the spring 16 c is under pressure. 2a as a spring connected in parallel in the spring chain here in full, while the stiffening influence in the spring systems 16a / 17a and 16b / 17b is halved by connecting them in series.

From FIGS. 2a to 2c it can also be seen that rigid end stops 21, 22, 23 and 24 are provided between the individual trusses 3, 4 and the truss boxes 1, 2. The end stops 21 and 23 are welded to the cross member 3, while the end stops 22 and 24 are welded to the cross member 4. In the maximum opening position of the roadway bridging construction, in which the beams 7 and 8 are at a maximum distance D (see FIG. 2a), the end stops 21, 22 come to bear against one another in order to limit this maximum opening position. The spring element 16 assigned to the stops is not yet in a block state, so that it can wear out prematurely.

Claims (8)

1. Resilient control system for bridging joints in roadways with supporting beams, in which at least one beam (7, 8) is mounted on crossbars (3, 4) which are displaceably mounted in crossbar casings (1, 2) by sliding springs/sliding bearings and are connected by control springs, wherein the control springs are formed by spring elements which are mounted on spindles extending parallel to the crossbars and abut, with their end faces, abutment stops that are secured on the crossbars or the crossbar casings, characterised in that at least two spring elements (16, 17) are arranged on each spindle (15), and the abutment stops (10', 11, 12, 18, 18', 19, 19', 20, 20') are associated with the crossbars (3, 4) or the crossbar casings (1, 2) in such a manner that at least one spring element is always under compressive stress, independently of the direction of the size of the load.
2. Control system according to Claim 1, characterised in that at least two abutment stops (18, 18'; 19, 19'; 20, 20') enclosing the spring elements (16, 17) are provided on a crossbar (3, 4) in each case, and in that the end faces, which face one another, of two spring elements (16, 17) abut the opposite lateral faces of abutment stops (10', 11, 12) which are secured to the crossbars or crossbar casings which are adjacent in each case.
3. Control system according to Claim 2, characterised in that a spindle (15) is associated with each pair of abutment stops (18, 18'; 19, 19'; 20, 20'), the ends of which spindle are securely connected to an abutment stop in each case and which engages through an aperture that is provided, coaxial to the axis of the pin, in the abutment stop (10, 11, 12) secured on the adjacent crossbar or the crossbar casing.
4. Control system according to at least one of the preceding claims, characterised in that the spring elements (16, 17) are under precompressive stress.
5. Control system according to Claim 4, characterised in that the precompressive stress is selected in such a manner that all the spring elements (16, 17) are always under compressive stress, irrespective of the direction and extent of the relative movement of the abutment stops.
6. Control system according to at least one of the preceding claims, characterised in that the spring elements (16, 17) consist of an elastomer foamed material with a spring constant that is a linear function of the spring elongation.
7. Control system according to at least one of the preceding claims, characterised in that rigid end abutment stops (11, 12, 21, 22, 23, 24) which limit the opening of the gap bridging construction to a maximum value are provided between the individual crossbars (3, 4) and the crossbars and crossbar casings (1, 2).
8. Control system according to Claim 7, characterised in that the cooperating end abutment stops (21, 22; 11, 18; 12, 23) are disposed on the crossbars (3, 4) or crossbar casings (1, 2) on alternate sides such that they come to abut one another before one of the spring elements (16, 17) associated therewith is compressed into a block.

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