TENSIONED CONSTRUCTION BEAM AND METHOD THEREFOR

Abstract

A tensioned construction beam comprises a main longitudinal body defining a beam length and opposite longitudinal ends. The main longitudinal body includes a tubular part extending along the beam length and defining a cavity therein that is circumscribed by an inner wall of this tubular part. One or more steel cables extend within the cavity along the beam length and are embedded therein via grout filling the cavity. The one or more steel cables have been submitted to a tension force prior to being embedded and released from this tension force such that the tension force is applied to the main longitudinal body.

Claims

1. A tensioned construction beam comprising: a main longitudinal body defining a beam length and opposite longitudinal ends thereof, the main longitudinal body comprising a tubular part thereof extending along the beam length and defining a cavity therein circumscribed by an inner wall of the tubular part; and one or more steel cables extending within the cavity along the beam length and embedded therein via grout, the one or more steel having been submitted to a tension force prior to being embedded and released from the tension force such that the tension force is applied to the main longitudinal body.

2. A tensioned construction beam according to claim 1, wherein the tubular part defines open front and rear ends thereof, the one or more steel cables having an initial length exceeding the open front and rear ends and having been cut at the open front and rear ends for being released from the tension force when embedded in the tubular part of the beam.

3. A tensioned construction beam according to claim 1, further comprising deviator elements positioned within the cavity and mounted to the inner wall for deviating the one or more steel cables at predetermined positions along the beam length.

4. A tensioned construction beam according to claim 3, wherein the deviator elements are positioned above and/or below the one or more steel cables for engaging the one or more steel cables to respectively deviate them upwardly and/or downwardly at the predetermined positions along the beam length.

5. A tensioned construction beam according to claim 3, wherein the deviator elements comprise plates having a width and length with holes defined therein along the width thereof, each of the holes receiving a respective one of the one of more steel cables therethrough, the holes being positioned along a predetermined height position of the plate to deviate the one or more steel cables upwardly or downwardly at the predetermined positions along the beam length.

6. A method of making a tensioned construction beam comprising: providing a main longitudinal beam body defining a beam length and opposite longitudinal beam ends thereof, the main longitudinal body comprising a tubular part thereof extending along the beam length and defining a cavity therein circumscribed by an inner wall of the tubular part and respective open tube ends thereof; positioning one or more steel cables within the cavity defining respective opposite cable ends thereof, the one or more steel cables extending along the beam length with the opposite cable end portions protruding outwardly of the cavity via respective ones of the open tube ends; anchoring the one or more steel cables outside of the cavity; stretching the one or more anchored steel cables against the anchoring thereof further outwardly of the cavity thereby applying a tension force to each of the one or more steel cables; filling the cavity with grout thereby embedding the one or more steel cables under the tension force therein; and cutting the two opposite cable end portions protruding outwardly of the one or more steel cables thereby releasing the embedded cable from the anchoring and from the stretching and thereby providing for the tension force applied to each of the one or more steel cables to be applied to the main longitudinal body.

7. A method according to claim 6, wherein the anchoring of the one or more steel cables comprises anchoring at least one end portions protruding outwardly of the cavity at an anchoring point thereof.

8. A method according to claim 6, wherein the anchoring of the one or more steel cables comprises anchoring the end portions protruding outwardly of the cavity at respective anchoring points thereof.

9. A method according to claim 8, wherein one of the anchored end portions defines a free end thereof extending beyond the anchoring point, wherein the stretching comprises moving the free end further away from the cavity.

10. A method according to claim 6, wherein the tension force applied to the main longitudinal body defines a camber at a position along the beam length, the method further comprising modulating the position of camber along the beam length.

11. A method according to claim 10, wherein modulating comprises: positioning deviator elements in the cavity above and/or below of the one or more steel cables for engagement thereof at predetermined positions along the beam length prior to grouting to deviate the one or more steel cables upwardly and/or downwardly; and mounting the deviator elements to the inner wall prior to grouting.

12. A method according to claim 10, wherein modulating comprises; positioning deviator elements in the cavity, the deviator elements having holed to receive the one or more steel cables therethrough at predetermined positions along the beam length prior to grouting to deviate the one or more steel cables upwardly and/or downwardly; and mounting the deviator elements to the inner wall prior to grouting.

13. A system for tensioning a construction beam comprising a main longitudinal beam body defining a beam length and opposite longitudinal beam ends thereof, the main longitudinal body comprising a tubular part thereof extending along the beam length and defining a cavity therein circumscribed by an inner wall of the tubular part and respective open tube ends thereof, wherein one or more steel cables are positioned within the cavity defining respective opposite cable ends thereof, the one or more steel cables extending along the beam length with the opposite cable end portions protruding outwardly of the cavity via respective ones of the open tube ends; anchoring units for anchoring the cable end portions of the one or more steel cables and respective anchoring points thereof; an actuator for moving free ends of the one or more steel cables extending outwardly of the anchoring points further away from the anchoring points to apply a tension force to each of the one or more steel cables; and a cutter for cutting the two opposite cable end portions protruding outwardly of the one or more steel cables when embedded within the cavity via grout thereby releasing the embedded cable from the anchoring and from the stretching and thereby providing for the tension force applied to each of the one or more steel cables to be applied to the main longitudinal body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following drawings form part of the present specification and present disclosure. In the appended drawings:

[0024] FIG. 1 is a perspective view of a construction beam defining a tubular part thereof and including steel cables therein in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0025] FIG. 2 is a lateral end view of the construction beam of FIG. 1;

[0026] FIG. 3 is a photograph of a construction beam similar to the construction beam of FIG. 1 in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0027] FIG. 4 is another photograph of the construction beam of FIG. 3;

[0028] FIG. 5 is a schematic representation of three steel cables as positioned within a construction beam engaged by deviator elements positioned in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0029] FIG. 6 is a schematic representation of the steps (A to of making a pre-tensioned construction beam in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0030] FIG. 7 is a lateral end view of a construction beam in accordance with another non-restrictive illustrative embodiment of the present disclosure;

[0031] FIG. 8 is a lateral end view of a construction beam in accordance with a further non-restrictive illustrative embodiment of the present disclosure;

[0032] FIG. 9 is a lateral end view of a construction beam in accordance with yet another non-restrictive illustrative embodiment of the present disclosure;

[0033] FIG. 10 is a side schematic view of a system for tensioning strands positioned within tubular construction beams beam in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0034] FIG. 11 is an enlarged view of a front portion of the system of FIG. 10 showing an actuator and a front anchoring unit thereof in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0035] FIG. 12 is an enlarged view of a front portion of the system of FIG. 10 showing an actuator and a front anchoring unit thereof in accordance with another non-restrictive illustrative embodiment of the present disclosure;

[0036] FIG. 13 is a front view of the front anchoring thereof of the system of FIG. 10 in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0037] FIG. 14 is an enlarged view of a rear portion of the system of FIG. 10 showing a rear anchoring unit thereof in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0038] FIG. 15 is an enlarged view of a middle section of the system of FIG. 10 showing the tubular beam thereof in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0039] FIG. 16 is a front view of a plurality of deviators position within the tubular beam of the system of FIG. 10 in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0040] FIG. 17 is a side schematic view of a system for tensioning strands positioned within tubular construction beams beam in accordance with another non-restrictive illustrative embodiment of the present disclosure;

[0041] FIG. 18 is an enlarged view of a front portion of the system of FIG. 17 showing an anchoring and actuating assembly in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0042] FIG. 19 is a top plan view of the system of FIG. 17 in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0043] FIG. 20 is a side sectional view of beam with the pretensioned cables embedded therein and deviators in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0044] FIG. 21 shows front sectional view of the beam of FIG. 20 taken at each deviator position within the beam in accordance with a non-restrictive illustrative embodiment of the present disclosure;

[0045] FIG. 22 are diagrams showing the contribution of the prestressing of strands embedded within tubular beans in accordance with a non-restrictive illustrative embodiment of the present disclosure; and

[0046] FIG. 23 is a schematic representation of a tubular construction beam in accordance with a non-restrictive illustrative embodiment of the present disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0047] Generally stated and in accordance with an aspect of the present disclosure, there is a tensioned construction beam comprising a main longitudinal body defining a beam length and opposite longitudinal ends. The main longitudinal body includes a tubular part extending along the beam length and defining a cavity therein that is circumscribed by an inner wall of this tubular part. One or more steel cables extend within the cavity along the beam length and are embedded therein via grout filling the cavity. The one or more steel cables have been submitted to a tension force prior to being embedded and released from this tension force such that the tension force is applied to the main longitudinal body.

[0048] In an embodiment, the beams of the disclosure are I beams made of structural steel. In an embodiment, the structural steel is a lower grade steel combined with one or more higher grade steel cables embedded therein. In an embodiment, the higher grade steel cable are tensioned prior to being embedded and then released from this tension to transfer the tension to the construction beam thereby increasing the load strength thereof with less material.

[0049] With reference to the drawings, non-limiting illustrative embodiments will now be described so as to exemplify the disclosure and not limit the scope thereof.

[0050] FIGS. 1 and 2 show a construction beam 10, whereas FIGS. 3 and 4 show a construction beam 10 that is similar to construction beam 10. The beams 10, 10 can be made of steel, aluminum, concrete and other suitable materials as can be contemplated by the skilled artisan.

[0051] Each beam 10 and 10 comprises a main longitudinal body 12 defining the length of the beam as well as opposite beam ends 14a and 14b. The main longitudinal body 12 includes a tubular part 16 thereof that runs along the length of the beam 10, 10. In this example, beam 10, 10 is an I beam and the tubular part 16 is formed at the I beam base. Of course, other beam configurations can be contemplated by the skilled artisan within the scope of the present disclosure with tubular parts positioned at other beam sections as is exemplified in FIGS. 7, 8 and 9 described further below.

[0052] The tubular part 16 defines a cavity 18 therein circumscribed by an inner wall 20 of the tubular part 16 as well as open tube ends 22a and 22b at each longitudinal beam end 14a and 14b leading to the cavity 16.

[0053] Each beam 10,10 at least one steel cable 24 embedded within the cavity 18 with the rest of the cavity space being filled with grout 26.

[0054] In the example of FIGS. 1 and 2, beam 10 includes four steel cables 24 therein, whereas in the example of FIGS. 3 and 4, beam 10 includes three cables 24 therein.

[0055] The cables 24 are tensioned prior to grouting and include cable end portions 30 that outwardly protrude from the cavity 18 via the open tube ends 22a and 22b during tensioning. Once sufficiently tensioned the outwardly protruding ends 30 are cut and the tension thereof is applied to the construction beam thereby strengthening the construction beam.

[0056] Turning to FIG. 6, the method of making a construction beam in accordance with the present disclosure will be further described. FIG. 6 shows at step (A) a tubular part 16 receiving a cable 24 within its cavity 18 via open tube end 22a. At step (B), the cable 24 is positioned with the cavity 16 and its end portions 30a and 30b respectively protrude outwardly of the cavity 16 via tube ends 22a and 22b respectively. Cable end portion 30b is anchored (via an anchor element 32) and at step (C) cable end portion 30a is further pulled outwardly of the cavity 16 by a pulling force (arrow P) applied thereon resulting in an opposite tension force (arrow T) on the cable 24. At step (D), the cavity 18 is grouted 26 and thus the cable 24 is embedded therein. Once the cable 24 is solidly embedded, the cable end portions 30a and 30b are cut at step (C) thereby releasing the cable 24 from the external stress between anchor 32 and the pulling force P as shown in step (E). Once released from the stress force P, the tensioning force T is transferred to the beam via the grout 26 providing a tensioned construction beam.

[0057] Turning to FIG. 4 the transfer load (tension force T) to the construction beam 10 causes a camber in the beam. Usually, the camber will be caused at a center area of the beam length but the position of the camber can be modulated.

[0058] With reference to FIG. 5, this modulation is provided by positioned deviator elements 34 at different points along the length of the area, the deviator elements 34 are positioned above and below the cables 24 (three cables 24 shown here as in FIG. 4). The deviator elements 34 are cross members running perpendicular to the length of the cables 24 and being connected at each end thereof to the inner wall 20. The cavity 18 is filled with grout 26 after the deviator elements 34 have been positioned as described above.

[0059] FIG. 7 shows a beam 100 including top and bottom parts 102 and 104 respectively and a central tubular part 106 for containing the cables 24 therein.

[0060] FIG. 8 shows a beam 200 having a flat base 202 with a central part 204 upwardly extending therefrom carrying a top tubular part 206 containing the cables 24 therein.

[0061] FIG. 9 shows a beam 300 having a top tubular part 302, a central tubular part 304, and a bottom tubular part 306 all of which contain one or more cables 24 therein.

[0062] Tensioning of the beam as provided herein is dependent on the tensioning force of the cable, the number of cables, the length and thickness of the beam and the structural configuration of the cable. Suitable beam strengths can thus be provided by modulating the foregoing parameters to meet desired load strength.

[0063] In an embodiment, the construction beam of the disclosure provides for reducing costs, weight and size of an I beam by adding strength via tensioned 270 grade cables embedded therein. In an embodiment, a lower grade steel I beam is grouted with higher grade pre-tensioned steel cables making this beam more effective (greater load strength) and relatively less costly since less beam steel is required for greater load strength. Thereby lighter construction beams are provided due to less steel providing greater strength and longer spans. Lighter beams also provide for easier and faster construction time in addition to less supporting steel being required for such beams. Less steel also provides for height reduction of the of the beam which is convenient for constructing buildings with more floors.

[0064] Turning now to FIGS. 10 to 16, there is shown a system 350 for tensioning steel cables 24 of construction beams 10. The cables 24 are inserted within the tubular part 16 of the beam 10. Each longitudinal end section 25a and 25b of the cable 24 is connected to an anchoring unit 352a and 352b.

[0065] The anchoring units 352a, 352b include respective perforated walls 354a, 354b, which are connected to respective support structure 356a, 356b. Longitudinal sections end 25a and 25b are positioned through apertures 358 (see FIG. 13) of walls 354a and 354b and kept in place via stoppers 360 (e.g. donut). In this way, end 25a is blocked against being pulled inwardly relative to wall 354a as shown by arrow 361a and end 25b is blocked against being pulled inwardly relative to wall 354b as shown by arrow 361b. The foregoing results in anchoring the cable 24 at anchoring points 362a and 362b thereof at each anchoring unit 352a and 352b.

[0066] An actuator 364 such as a ram as shown in the examples of FIGS. 11 and 12, provides for pulling the free end 27a of the cable 24 inwardly therein in order to tension the anchored cable 24 as discussed herein.

[0067] Once the tensioning process is completed, the tubular part 16 is filled with grout 26 and the ends 25a and 25b are cut off so that no cable portion protrudes from either end 22a or 22b of the tubular part 16. As previously described, the pre-stressed cable transfers its tension to the construction beam 10 thereby strengthening the construction beam 10.

[0068] As previously discussed, tensioning of the cable 24 causes a camber which can be modulated by deviators 366 further examples of which are illustrated in FIG. 16 which shows deviators 366i, 366ii, 366iii 366iv, and 366v. These deviators include plates 368 welded to the inner floor 17 of the tubular part 16 defining holes 370 along its width 372 for receiving cables 24 therein. The position of the holes 370 along the height 374 of the plates 368 provides the deviation height of the cable 24 at deviation points 376 along the length of the cable 24 within the tubular part 16. The deviation points 376 are the contact points between the cable 24 and the deviators 366. The deviators 366i, 366ii, 366iii 366iv, and 366v show holes 370 at different heights for providing different deviation heights.

[0069] Turning now to FIGS. 17 to 19, there is shown a system 400 for tensioning steel cables 24 of construction beams 10. The cables 24 are inserted within the tubular part 16 of the beam 10. The respective longitudinal end sections 25a of the cables are connected to an anchoring and actuation assembly 410. The respective end sections 25b of the cables 24 are connected to an anchoring unit 412.

[0070] The anchoring and actuation assembly 410 comprises an anchoring unit 414 and a guide unit 416 positioned rearwardly of the anchoring unit 414. Lateral actuators 418 in the form of hydraulic pumps interconnect the guide unit 416 to the anchoring unit 414. The lateral actuators 418 forwardly push the anchoring unit 414 away from the guide unit 416 as shown by arrow 420. The anchoring unit 414 comprises a perforated front wall 422 mounted a support structure 424 and providing for the sections 25a to be passed therethrough and anchored thereon via a donut 360. The anchoring unit 414 is movable via rollers or along rail guides.

[0071] The anchoring unit 414 comprises a perforated rear wall 426 mounted a support structure 428 and providing for the sections 25b to be passed therethrough and anchored thereon via a donut 360.

[0072] When a forward movement is imparted to anchoring unit 414 (as shown by arrow 420), the cables 24 are placed under stress as they are being longitudinal stretched. The tubular part 16 is then grouted with the stressed cables 24 therein and the cable sections protruding from the beam 10 are cut at points 24 and 24.

[0073] FIGS. 20 and 21 show the strands of cables 24 within tubular part 16 of the beam 10 with deviators 430, 430, 430 positioned therein spanning the width of the inner channel 18 of the tubular part 16 and being welded to inner side walls 19 defining the channel 432. The channel 432 is shown to be filled with grout 26. The deviators 430, 430, 430 are positioned above or below the strand modulated the camber thereof at positions C1, C2, C3 of the cable 24.

[0074] In one example, a W625 steel beam, 20-ft span, tensioned as described herein with four 0.6 low-relaxation strands showed a substantial increase in performance: allowable uniform load increased from approximately 290 lb/ft to 950 lb/ft (3.3 improvement), and mid-span point load capacity from 3.6 to 12 kips-all within service deflection criteria.

[0075] In one embodiment, the load of a beam is improved between about 2.7 to 3.6 times.

[0076] Indeed, the present method and resulting beams provide for using beams with less material thus less height which have a similar load capacity to beams with greater material and greater height. Thus, lighter beams and less tall beams can be used to provide the load capacity of heavier and taller beams. This has several advantages including material cost savings, easier transport and assembly and the beams take less spacing allowing for building more floors or greater floor to ceiling spaces if desired within a building having a predetermined height.

[0077] The present disclosure provides for locating high strength low relaxation strand along the underside of a steel beam to provide additional strength and deflection control. The engineering principles of superimposed loading and load balancing of the self-weight (i.e., dead load) of the beam and floor are the primary concepts being addressed.

[0078] The diagrams of FIG. 22 demonstrate the contribution of prestressing described herein, where the superposition of stresses from gravity loading and prestressing are opposite to one another, yielding a net reduction in total stress and allowing for larger spans and/or increased loading.

[0079] The design condition for any beam is dependent upon multiple factors (design loads, floor performance criteria, usage, etc.), but the effect of prestressing will allow the beam to improve upon the span (I) depth (d), weight (w) and capacity of a conventional steel beam shown in FIG. 23.

[0080] In an embodiment, the prestressed steel beam of the present disclosure, spans on the order of about 20% to about 40% more than a comparable conventional steel beam.

[0081] In an embodiment, the depth of the steel beam portion of the prestressed steel beam of the present disclosure is on the order of about 15% to about 40% less than a comparable conventional steel beam.

[0082] In an embodiment, the weight of the steel beam portion of the prestressed steel beam of the present disclosure is in the order of about 20% to about 45% less than a comparable conventional steel beam.

[0083] In an embodiment, the capacity of the prestressed steel beam of the present disclosure is in the order of about 25% to about 45% more than that of a comparable conventional steel beam.

[0084] The various features described herein can be combined in a variety of ways within the context of the present disclosure so as to provide still other embodiments. As such, the embodiments are not mutually exclusive. Moreover, the embodiments discussed herein need not include all of the features and elements illustrated and/or described and thus partial combinations of features can also be contemplated. Furthermore, embodiments with less features than those described can also be contemplated. It is to be understood that the present disclosure is not limited in its application to the details of construction and parts illustrated in the accompanying drawings and described hereinabove. The disclosure is capable of other embodiments and of being practiced in various ways. It is also to be understood that the phraseology or terminology used herein is for the purpose of description and not limitation. Hence, although the present disclosure has been provided hereinabove by way of non-restrictive illustrative embodiments thereof, it can be modified, without departing from the scope, spirit and nature thereof and of the appended claims.