AU8231187A

AU8231187A - A beam

Info

Publication number: AU8231187A
Application number: AU82311/87A
Authority: AU
Inventors: Lars Stalin
Original assignee: STALIN KONSULTER AB
Current assignee: Stalin Konsulter AB
Priority date: 1986-10-30
Filing date: 1987-10-29
Publication date: 1988-05-25
Also published as: AU8231287A; WO1988003210A1; AU8231087A; EP0328544A1; WO1988003209A1; WO1988003211A1; DK358588D0; DK157205C; DK157205B; DK358588A

Description

A BEAM

TECHNICAL FIELD

The present invention relates to a beam with flanges manufactured of wood and a beam web connected to the flanges and consisting of rods manufactured from metallic tube or rod material, the rods extending reciprocally between the flanges and being accommodated, with etid portions or bent end regions, in recesses in the flanges.

BACKGROUND ART

A Beam of the type mentioned by way of introduction is previously known from SE 7610600-4. The beam according to this publication has both of the beam flanges divided in two longitudinal wooden laths or battens, grooves arranged in V-shape formation in relation to one another being disposed preferably in one, but possibly in both of the laths, the grooves being intended for accommodating the bent portions of the beam web arranged in zigzag formation. In this instance, the grooves are of substantially the same form as the bent portions of the beam web. After placement of the bent portions of the beam web, i.e. their turns or elbows, in the V-shaped disposed grooves, the two laths which each constitute the beam flange, are glued together.

A beam of the above-outlined prior art type has but limited carrying capacity and, moreover, suffers from a relatively large sagging before breakage. The cause of the problems inherent in the prior art beam is primarily to be found in the different strength properties in the wood material on the one hand, and in the steel material of the beam web on the other. Thus, with the above-described construction, it is impossible to avoid very severe point loadings from the steel material of the web against the wood material in the beam flanges. As a result, the wood material in the beam flanges will suffer from extreme deformations - and even breakage - before the the strength of the beam web has by any means been utilised to the full. SE 7901795-0 discloses a similar beam. According to this publication, attempts have been made to improve the inherent properties of the beam by the use of glue joints for anchoring the beam web in recesses in the beam flanges, in other words, the joint union is based on the employment of adhesion between the applied glue and adjacent wood material in the beam flanges.

The problem concerning the prior art beams resides primarily in the fact that the elasticity modulus of the steel included in the beam web is considerably greater than the elasticity modulus in the wood material used in the beam flanges, and the prior art constructions have not been designed in such a manner to take into account these different material properties. Nor does the gluing in any way compensate for these differences in material properties; instead - and despite the gluing - major local loading peaks occur which are disastrous for the glue joint proper and the softer material connected therewith. Furthermore, it is hardly possible in practice to obtain a satisfactory glue filling-out in a beam of the previously known type, for which reason alone loading peaks areunavoidable.

When a beam of the above-outlined type is placed under load, every other rod included in the beam web will be exposed to a compressive load, while every second rod included in the beam web will be exposed to tensile stress. In particular in beams of larger dimensions, at least those rods in the beam web which are exposed to compressive loading must be made of more robust dimensions in order to withstand the buckling to which they would otherwise be subjected. Naturally, a beam web of upgraded dimensions and increased rigidity in this way entails even more serious loading problems in the transitional region between the beam web and the beam flange.

PROBLEM STRUCTURE

The present invention has for its object to realise a beam of the type disclosed by way of introduction, the beam being designed in such a manner that, even if it is given large dimensions, it will possess large load carrying capacity and suffer from minor saggings before breakage. In particular, the present invention has for its object to propose a beam constructed in such a manner that the differences in material properties between the beam web and the flanges will have no negative effect. The invention further has for its object to realise a beam whose function may also be maintained without the adhesion effects which characterise glue joints, as regards the connection of the beam web to the beam flanges. Finally, the invention also has for its object to realise a beam which may be manufactured simply and economically in varying sizes and lengths.

SOLUTION

The objects forming the basis of the present invention are attained if this beam is characterised in that there are provided, in the recesses, substantially rigid anchorage bodies containing a plastic material, the rods extending thereinto; and that there are provided, in the anchorage bodies, members connected to the rods and having portions extending outside a cross-section of an adjacent portion of a rod.

In one embodiment of the present invention, which is particularly favourable from the viewpoint of strength properties, it suitably applies that the portions of the members located outside the cross-section of the rods are provided with surfaces which are transversely directed in relation to the longitudinal direction of the flanges.

In one embodiment of the present invention which is particularly advantageous in large beams, it suitably applies that the beam web is composed of a number of rods which are united with one another interiorly in the anchorage bodies. The preferred embodiment of the present invention is also suitably characterised in that the members are disposed between mutually adjacent end portions on the rods.

As a result of these novel features, the major advantage will be afforded that the member, or pressure plate, may readily be joined together with the rods; and that the member is located in such a manner that the transfer of forces will be the most favourable.

In one alternative embodiment, it also suitably applies according to the invention that rods accommodated in an anchorage body are interconnected with one another exclusively by the intermediary of the anchorage bodies.

Further advantages will be gained according to the present invention if the subject matter of the invention is also given one or more of the features as set forth in claim 4.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The nature of the present invention and its aspects will be more readily understood from the following brief description of the accompanying Drawings, and discussion relating thereto. In the accompanying Drawings:

Fig. 1 is a plan view of a beam according to the invention; Fig. 2 is an end elevation of the beam of Fig. 1; Fig. 3 is a detail view of one of the flanges included in the beam in an anchorage region for the beam web;

Fig. 4 is a section taken along the line A-A in Fig. 3; Fig. 5 is a view approximately corresponding to that of Fig. 4, from which will be apparent the tension distribution in the anchorage body on loading of the beam; Fig. 6 shows a modified embodiment in section approximately corresponding to that of Fig. 4; and

Figs. 7-10 show further modified embodiments in section approximately corresponding to that of Fig. 4.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the Drawings, it is apparent from Fig. 1 that a beam according to the present invention has two beam flanges 1 and 2 and beam web extending therebetween. The beam flanges are manufactured of wood, while the beam web is manufactured or metal, preferably steel. In this Figure, the beam is shown as being of uniform height, but of course the beam may taper along its length. In such an embodiment, the beam flanges may be of thicker cross-section at the major end of the beam.

Suitably, the beam web 3 is manufactured of tube or rod material and may be bent in one piece from a longer continuous length of this material, or be composed of shorter pieces, so that there will thereby be formed, between the beam flanges 1 and 2, reciprocally extending rods 4. If the beam web 3 is produced by bending of long continuous length, closely adjacent rods 4 will have bent conjunction regions which may be V-shaped, U-shaped or be bent in any other suitable manner. As will be apparent from Fig. 1, these bent conjunction regions between closely adjacent rods 4 are interiorly accommodated in recesses in the two beam flanges 1 and 2.

In Fig. 1, the rods forming the beam web 3 have been shown as straight rods which run in zigzag formation at an angle of approximately 60° in relation to the longitudinal direction of the beam flanges. Naturally, the rods 4 need not be arranged in this manner, but the angle between the rods and the beam flanges may vary within broad limits. In practice, a range of between 45° and 65° has proved to be usable, in which instance 45° provides the best transfer of forces between the flanges and the rods. This entails that if the rods are viewed as rigid, an optimum strength will be obtained for this angle. However, employing this angle, the rods placed under compressive loading will have a relatively large free buckling length, for which reason relatively high demands will, naturally, be placed on the material dimensions in the rods. On the other hand, a larger angle will give poorer transfer of forces, but it should be set against this factor the very fact that the free buckling length of the rods reduces when the angle increases, for which reason, and given that the rods cannot be prefectly rigid, it is probable that the optimum will be reached with an angle which is slightly greater than 45°. Further according to the invention, neither do the rods 4 need be arranged in a regular pattern, but, for example, every other rod may be at right angles to the longitudinal direction of the beam flanges, while every second rod is obliquely inclined. As an important subalternative, the rods 4 exposed to compressive loading when the beam is placed under load may be at a larger angle to the beam flanges 1 and 2 than those exposed to tensile stress (see further below). A further alternative may reside in the fact that the rods 4 are reciprocally bent in wave formation, between the flanges, for example following the form of a sine curve of the like.

In Fig. 2, the beam flanges 1 and 2 are shown as being approximately square in cross-section, but, of course, this is not a critical requirement according to the present invention, instead the cross-sectional configuration of the beam flanges may be completely different and may, for instance, be rectangular or be of any other form which proves to be practical in view of the use to which the beam is put or in view of the manner of its manufacture. As was intimated above, the cross-section may also vary along the length of the beam. Figs. 3 and 4 show a first embodiment of the invention and, more closely, a detail view of one of the beam flanges 1 and 2 and the manner in which the rods 4 included in the beam web 3 are fixed in the flange. If it is assumed, in Figs. 3 and 4, that the illustrated beam flange is the lower beam flange 2, Fig. 3 will show a section of this beam flange 2 seen straight from above.

For anchoring the rods 4 in the beam flange 2, use is made of an anchorage body 9 which is accommodated in and completely fills the recess 5 in the flange and which is formed of a plastic composition with a thermosetting plastic and a suitable filler. As thermosetting plastic, use may, for example, be made of polyesters, epoxy or vinyl and the proportion of filler in the plastic composition should be at least 50%. In the manufacture of the beam, the plastic composition is poured as a liquid or viscous paste into each recess 5 around the portions of the rods 4 accommodated in the recesses, so that the recesses will be completely filled with the plastic composition. Once this has set, a form-permanent, anchorage body will be obtained which is well connected to the rods, by surrounding them, and which has the same form as the recess 5. The anchorage body also has good surface abutment against substantially all of the defining surface of the recess 5. It will be apparent from Fig. 3 that the recesses 5 are composed of two recesss, an outer recess 14 and an inner recess 15 in association therewith. These two recesses have outer end walls 16 and end walls 17 which are transversely directed, at right angles, or possibly slightly undercut, in relation to the longitudinal direction of the beam flange. The end walls are, furthermore, somewhat transverse of, or possibly at right angles to the horizontal resultant H (see Fig. 5) which is formed under the action of the loadings of the rods 4 on loading of the beam. Moreover, the recesses 5 in this embodiment have outer and inner bottom walls 18 and 19, respectively, which are suitably approximately parallel to the longitudinal direction of the beam flange. The transitional regions between the different end walls and the bottom walls are gently curved, while the inner end walls 17 are in guiding cooperation, at the edge regions 11, with the rods 4. According to the present invention, both the end walls 16 and 17 and the bottom walls 18 and 19 are suitably arched, so that, thereby, sharp corners and loading concentrations are avoided, and the width of the recesses 5 is approximately twice the diameter of the rods 4. The width which the recesses 5 must have (at right angles to the plane of the Drawing in Fig. 4) is critical in at least two respects. First, the width must, by a suitable margin, exceed the diameter or transverse dimension of the rods 4 of the beam web 3, such that indications of fracture in the anchorage bodies in register with the rods 4 will be avoided. Secondly, the total end surface 16 and 17 of the recess 5 must be of such an area that the normal tension caused by the resultant H (see Fig. 5) and acting via the anchorage body on the wood material will not be beyond the capacity of the wood material to absorb. It will further be apparent from Fig. 4 that there is a space 13 between the top portion 12 of the meeting rods 4 and the bottom wall 7 in the recess 5, this space being, in the finished state of the beam, filled with a part of the anchorage body 9. This space is essential, as regards the strength and 'continuity' in the joint between the rods 4 and the flanges 1 and 2. By use of the space 13, a part of the anchorage body 9 will lie between the top portion 12 and the bottom wall 19 of the recess 5.

On loading of a beam designed according to the present invention, every other rod 4 will be exposed to tensile stress, while every second rod will be exposed to compressive loading. In the embodiment according to Fig. 1, these loadings will be of equal magnitude, for which reason there is formed a resultant force H (see Fig. 5) directed along the flanges. In this case, there will be no vertical resultant, since the vertical components of the rod loadings will be equal but counterdirected. On the other hand, a torque will be exercised against the anchorage body 9, such that this will have a tendency, under the action of the loading forces of the beam, to twist about an imaginary axis 10 which is approximately at right angles to the plane of the beam web 3 and which extends somewhere through the anchorage body 9 or which, depending upon the geometric conditions which apply and the loading conditions which prevail, may even be located outside the anchorage body. If, in Fig. 4, the left-hand rod 4 is exposed to tensile stress, as intimated by the arrow, while the right-hand rod is exposed to compressive loading, this would have as a consequence that a moment of torque would be generated on the anchorage body 9 clockwise about the above-mentioned axis 10. As a result of the shape of the recess 5 and because the anchorage body is configurationally permanent, such a torque cannot take effect unless either the material in the beam flange 2 or in the anchorage body 9, or possibly in both, be considerably deformed. It should be emphasised that, to prevent the rods 4 from being detached from the beam flanges, no direct adhesion between the material in the anchorage body 9 and the material in the beam flanges is necessary; instead anchorage of the rods is effected in. that the anchorage body is form-permanently locked by friction in its recess by the applied loading. A manifest adhesion between the anchorage body 9 and the material in the beam flange might possibly increase overall strength in that the friction is increased, but such adhesion is not a critical requirement. For good function, it is further presupposed that the connection between the rods 4 and the anchorage body 9 is satisfactory, such that the loadings placed on the rods are transferred to the anchorage body without any deformation or breakage in the body. One of the major problems inherent in prior art technology resides in the fact that the material properties in the steel material of the rods 4 and the wood material in the beam flanges 1 and 2 differ greatly from one another. According to the present invention, it therefore applies that the anchorage body 9 must be given material properties which, as far as is possible, approach the properties of both the steel and of the wood material. In this context, it might well be mentioned that the elasticity modulus in the wood material may vary between the order of magnitude of 10 000 and twice that level, depending upon the type of wood employed. The elasticity modulus for steel lies beyond 20 000, for which reason considerable differences may be present in the size of the deformations which the different materials undergo on being placed under load.

One method of realising a more or less 'continuous' transition, in terms of strength, between the different material properties resides in the fact that the anchorage body is given, in its central regions, a greater elasticity modulus than in the peripheral areas. Such a variation of the elasticity modulus can be achieved in that the plastic material included in the anchorage body is given a lower degree of setting and final curing in the interface regions to the wood than applies in towards the centre. In such a manner, the anchorage body will be harder in towards its centre than in its peripheral parts. However, in cases involving larger beams, the forces which the rods 4 are to transfer to the beam flanges are so great that not even the strength properties in the plastic material of the anchorage bodies will be sufficient. This implies that, in larger beams, it is not the conjunction between the anchorage body and the wood mateiral which is critical, but rather the conjunction between the rods 4 and the anchorage body. Hence, in large beams, there is a certain risk that failure may occur in the anchorage body itself.

Theoretical calculations have established the pattern of the tension distribution in the anchorage body 9 on loading of the beam according to Figs. 3 and 4.

In most practical situations, forces are transferred between plastic and wood in such a manner that the adhesion between the materials is of major importance. This said, the adhesion between plastic and wood is difficult to document and quantify in terms of 'strength properties', for which reason the calculations which have been conducted are made without regard to the adhesion forces which may also occur. As a result, the strength values which have been calculated hereby are on the safe side. Thus, the calculations show that it is the permanent form engagement between the anchorage bodies and the recesses which substantially impart the load bearing capacity to the beam.

Fig. 5 shows the appearance of the tension distribution in the anchorage body 9 on loading of the beam in the embodiment according to Figs. 3 and 4. It should be observed that the loading direction for the rods 4 of the beam web is shown opposite to that which applies in the remaining Figures.

In those cases where all rods 4 do not make equally large angles with the flanges 1 and 2, or when the beam tapers, a vertical resultant may also occur in addition to the horizontal resultant H. Such a vertical resultant also occurs at the outermost anchorage body at the ends of the beam. However, these vertical resultants have but marginal effect on the strength of the beam.

One of the prerequisites on which the calculations are based is: that the anchorage body 9, on breakage in the beam, moves as a rigid body. It is further assumed that this rigid body is connected to the rods 4 and that no breakage between these components has occurred.

It will be apparent from Fig. 5 that both compressive stresses and shearing stresses occur in the interface between the anchorage body 9 and the material of the beam flanges 2. In addition, a major horizontal force H arises in the so-called interstice 21, which is the line of intersection between the centre lines of both of the rods 4 meeting in the anchorage body 9. In particular in powerfully dimensioned beams in which the rods 4 are manufactured as tubular profiles which are capable of withstanding buckling, this resultant force H will be considerable. The risk is then imminent that the prerequisite for the calculation will not be met, namely that the influence of forces impressed by the rods 4 on the anchorage body will be so great that the anchorage body is either deformed or fractured.

Fig. 6 shows one embodiment of the present invention which is particularly well-suited for large beams in which the rods 4 are designed as tubular profiles. In such beams, considerable forces occur in the rods and, for this reason, the fixed retention of the rods in the anchorage bodies will pose serious problems.

In the embodiment according to Fig. 6, the rods are bevelled in their mutually facing ends and, between these ends, there is disposed a pressure plate 22, which may be considered as a retention member which, in a direction transversal of the longitudinal direction of the beam flange 2, extends outside that cross-section which the closely adjacent portions of the rods 4 define in the joint region. This implies that the pressure plate 22 is of a width at right angles to the plane of the Drawing of Fig. 6 which is preferably greater than the diameter of the two rods 4, so that it will have surfaces which are transversely directed not only in relation to the resultant H, but also to the longitudinal direction of the beam, and to the rods 4. In Fig. 6, the pressure plate 22 is shown as being fixedly welded with symmetric welding seams in both of the rods 4, and it is presupposed that these welding seams are circumferential, such that they run about the entire periphery of the rods. As a result, the rods are interconnected with one another via the pressure plate 22. It will be apparent from Fig. 6 that the left-hand rod 4 is exposed to tensile stress while the right-hand rod is exposed to compressive loading. This entails that the right-hand rod 4, on loading, will influence the pressure plate 22 with a compressive force, for which reason it could possibly be conceivable to reduce the welding between the pressure plate and the right-hand rod 4 to bond welding only. The relationship is the reverse as regards the left-hand rod 4, since this is exposed to tensile stress. In this case, the anchorage between the pressure plate and the rod must be complete.

In the illustrated embodiment, the pressure plate 22 is fully embedded in the anchorage body 9 and thereby effectively contributes to the transfer, by the anchorage body 9, of the resultant H to those foreces which act in the rods 4. In one alternative, use is made of two pressure plates 22 which are each connected to their rod 4 and are placed against one another. In this case, the pressure plates, and also the rods 4 are united with one another via the anchorage body 9. In yet a further alternative, the inclination of the rods in relation to the beam flange 2 may be different, for which reason there may be a wedgeshaped space which is filled with the material of the anchorage body, between the pressure plates, or the rods may be cut at different angles.

In the embodiment according to Figs. 3 and 4, the recess 5 has been shown as being of uniform width, i.e. both the outer recess 14 and the inner recess 15 are of substantially the same width. In the embodiment according to Fig. 6, the same dimensioning of the recess 5 may be employed, but it may conceivably be possible to render the inner recess 15 wider transversely of the longitudinal direction of the flange 2 than is the case for the outer recess 14 which is intimated by the broken, lines 23. In such a case, the pressure plate 22 may be allowed to extend laterally a considerable distance outside the rods 4. However, the pressure plate 22 must be embedded in the anchorage body in a dependable manner, such that no fracture indications are formed in the anchorage body along the edges of the pressure plate 22. As a result of the broadening 23 of the inner recess 15, there will also be attained larger total end surfaces on the recess 5, whereby that surface on the anchorage body 9 which is to transfer the resultant H to the wood material of the flange will be correspondingly greater.

Fig. 7 shows a modified embodiment in which the most crucial difference in relation to the embodiment according to Fig 6 is the employment of a transversely directed foot 24 in the lower end of the pressure plate 22 as shown in the Figure. This foot is of particuluar importance in such cases where a vertical resultant is created, in addition to the horizontal resultant, by the force influence from the rods 4, this taking place at different angles of inclination of the rods 4 or at the ends of the beam. If the pressure plate 22 in the embodiment according to Fig. 6 may be produced by cutting of a strip or band shaped profile, the pressure plate 22 in the embodiment according to Fig. 7 may be produced by cutting of a T-profile.

In the right-hand rod 4 in the Figure, a compressive force prevails, as intimated by the arrow. In the joint region with the pressure plate 22, this rod supports against the foot 24, for which reason there is no reason to fear (not even in the case of a very slightly dimensioned weld between the rod 4 and the pressure plate 22) that the rod would slide towards the pressure plate 22 in a downward direction on loading of the rod.

On the other hand, also in this embodiment, the connection between the left-hand rod 4 and the pressure plate 22 must be adequate, such that the mutual union therebetween is capable of absorbing large tensile stresses. Also in this embodiment, the inner recess 15 may be wider than the outer recess 14, as is intimated by the broken lines 23. The pressure plate 22 is, in this embodiment, also suitably dimensioned in such a manner that it also extends laterally (at right angles to the plane of the Drawing) outside the cross-section defined by the rods 4 in the joint region. In the embodiment according to Fig. 8, the direction of load in the rods 4 is reversed. In this embodiment, the pressure plate 22 is provided with a side shank 25 which has the same function as the one half of the foot 24 in the embodiment according to Fig. 7, as regards facilitating absorption of a vertical resultant or compressive loading between the pressure plate 22 and the rod 4, subjected to pressure. Also in this embodiment, the rod 4 subjected to tensile stress (the right-hand rod on the Drawing) must be fixedly retained in the pressure plate 22 in a dependable manner. In analogy with that mentioned above with reference to Fig. 6, it is also possible, in the embodiments according to Figs. 7 and 8, to fix a retention member or pressure plate 22 on each rod 4, without connecting these, or the rods mutually, by any other manner than embedding in the material of the anchorage body 9. According to Fig. 7, one foot 24 lies, in this alternative, turned to face upwardly and one foot turned to face downwardly, while, according to Fig. 8, the side shanks 25 lie against one another such that the retention member 22 placed under pressure through the rod 4 will be located interiorly in the other. In the above-described embodiment according to Figs. 3 and 4, no pressure plate 22 is shown on the Drawings. In the embodiment in which the beam web is produced of one-piece bent web rods 4, the pressure .plate may be in the form of a plate with an aperture through which the bent portion 12 of the rods 4 extends. This plate or washer is, naturally, anchored in the rods by suitable means, for example by welding. In the operational position, the washer should be oriented in such a manner that its plane will be at right angles to, or at least approximately transvere of the longitudinal direction of the beam flange 2. In one alternative, or as a supplement to the above-described washer, use may be made of two or more washers which are placed not directly in the top portion or curvature region 12 of the rods 4, but higher up along the rods 4 so that one washer may possibly be placed in the outer recess 14 of either rod, while a further washer may be placed in the inner recess 15 of either rod. In this alternative, the plane of extent of the washers may be at right angles to the longitudinal direction of the rods 4 in question. In analogy with that mentioned above with reference to Figs. 3 and 4, the embodiments according to Figs. 6 to 8 may, naturally, be provided in this way with washers or plates through which the rods 4 extend. These washers or plates may substitute the pressure plate 22 shown on the Drawing, but may also possibly act as supplement to the pressure plate.

Figs. 9 and 10 illustrate further modified embodiments of the present invention. In these two embodiments, the recess 5 has been formed in a different manner than is the case for the abovediscussed embodiments and, thus, the recess is here intimated as being rectangular or slightly undercut in configuration. That which was disclosed above regarding the rounded contours of the recess also applies in both of these embodiments.

In the embodiment according to Fig. 9, both of the rods have angled portions 20 which are laid over one another so that, in this instance, the left-hand rod 4, which is exposed to tensile stress, lies outside the right-hand rod, which is exposed to compressive loading. As a result of this arrangement of the rods, the best mutual transfer of forces between the rods will be attained. It will be further apparent from the Drawing that the rod exposed to compressive loading (the right-hand rod on the Drawing) is of more robust dimensions than the rod exposed to tensile stress. In this embodiment, the end surfaces 27 of the rods will have a function which partly assumes the function of the above-described pressure plate 22.

If yet a further improvement to strength properties is desired in the embodiment according to Fig. 9, it is possible to place, in the joint region between these rods, a pressure plate (not shown) which may have a U-shaped recess for accommodating the joint regions of the rods, or which may be provided with an aperture through which one or both of the rods extend. In the alternative in which only the one rod is provided with a pressure plate, a considerable improvement of the strength properties will be achieved if the rods are not only laid together as intimated on the Drawing, but are also interconnected with one another, for example by welding. In the embodiment according to Fig. 10, the central portion of the recess 5 is wider than the remaining portions. This is intimated at the broken lines 23. In the wider portion of the recess 5, the angled portions 20 of the rods 4 lie in side-by-side relationship and may possibly be interconnected by welding. Also in this embodiment, the end surfaces 27 of the rods - and in addition to a certain extent the surfaces indicated by reference numeral 28 on the Drawing - will replace or supplement the action of the above-described pressure plate. Moreover, in this embodiment, the pressure plate may be provided with an aperture through which the rods 4 extend, or have an open recess such that it may be passed in over the joint region of the rods and be fixedly retained in the rods.

It is also possible according to the embodiments of Figs. 9 and 10 to make use of supplementary washers or plates which are connected with the rods 4 in the manner as described above with particular reference to Figs. 3 and 4.

The present invention should not be considered as restricted to that described above and shown on the Drawings, many modifications being conceivable without departing from the spirit and scope of the appended Claims.

Claims

1. A beam with flanges (1, 2) manufactured of wood, and a beam web (3) connected to the flanges and essentially comprising rods (4) manufactured of metallic tube or rod material, the rods extending reciprocally between the flanges and being, with end portions or bent portions, accommodated in recesses (5, 14, 15) in the flanges, characterised in that there are disposed, in the recesses (5, 14, 15), substantially rigid anchorage bodies (9) containing a plastic material, the rods (4) extending thereinto; and that there are provided, in the anchorage bodies, members (22, 27, 28) connected to the rods and having portions which extend outside a cross-section of an adjacent portion of a rod.

2. The beam as claimed in claim 1, characterised in that the portions of the members (22) located outside the cross-section of the rods have surfaces which are transversely directed in relation to the longitudinal direction of the flanges (1, 2).

3. The beam as claimed in claim 1 or 2, characterised in that the beam web (3) is composed of a number of rods (4) which are united with one another interiorly in the anchorage bodies (9).

4. The beam as claimed in claim 2, characterised in that the members (22) are disposed between mutually adjacent end portions of the rods (4).

5. The beam as claimed in anyone of claim 3 or 4, characterised in that rods (4) accommodated in the anchorage bodies (9) are united with one another exclusively by the intermediary of the anchorage body.

6. The beam as claimed in anyone of claim 3 or 4, characterised in that rods (4) accommodated in the anchorage bodies (9) are united with one another by the intermediary of the members (22).

7. The beam as claimed in anyone of claims 1 to 3, characterised in that the members (22) are provided with apertures through which the rods (4) extend.