The invention relates to a hook iron arrangement, which is intended for use as a reinforcement element in a substantially elongated, cast concrete structure, and which includes one or more hook iron members that are discontinuous and placed in succession lengthwise of the concrete structure and/or extend continuously over at least part of its lengthwise dimension and are provided with a substantially crosswise hooking structure .

In traditional reinforcement systems for concrete products , a hook iron reinforcement which is crosswise to the longitudinal direction thereof is generally provided by means of so-called hoops or helical reinforcements . The term hoops is used in reference to steel wire loops , which are so-called frapped with a lashing wire to what are known as the main steel members of a reinforced concrete structure to be manufactured. On the other hand, the term helical reinforcement refers to a hook iron reinforcement element extending spirally around the main steel members . However, neither of these types of hook iron reinforcement is feasible in the event that the resulting structure is to have a hollow core, or if other product qualities or manufacturing ^' technique, such as e . g. slip casting, call for the passage of mechanical mandrel and/or compaction members through the reinforcement present in the structure during a casting operation. On the other hand, in the process of manufacturing for example prestressed reinforced- concrete structures , the main steel members consist of prestressed strands , ^■ in which case the fastening of

hook iron reinforcement elements solely by frapping does not provide sufficient reliability.

On the other hand, in the process of fabricating e . g . solid or hollow-core reinforced concrete beams , the manufacturing technique again has its own problems . Beams like this involve generally the use of special cap blocks , the function of which, especially when used in conjunction with a driven pile, is e . g. to strengthen the pile head for a strike, to serve as a ground-braking bit, to enable connecting piles to each other and/or to further enable attaching special bits to piles . Such cap blocks generally include a plate or a plate frame at the end thereof and hooking steel structures coupled therewith. The hooking steel structures , in turn, include end steel members , placed along the edges or in the corners of a beam being manufactured, and hook iron reinforcement elements in connection therewith. In addition and if necessary, , the cap blocks can also be provided e . g. with pile connection pieces and/or equipment . In traditional fabrication, the actual main steel members of such a pile structure and the end steel members of a cap block are engaged with each other manually by frapping with a lashing wire .

On the other hand, especially the main steel members of prestressed, subsequently slip-cast beams consist of prestressed strands . These strands are not cut off before casting, but adapted to travel within successive piles from pile to pile over the entire length of a casting bed. In addition, a plurality of such piles may be manufactured on the same bed side by side . The butt- to-butt cap blocks of successive piles are connected to each other for the duration of a casting operation

either by means of connection pieces , by separate fastening members or by manufacturing such blocks in a single piece, yet leaving a gap between the cap blocks for cutting the strands therethrough after the concrete has cured. At this point, the possible fastening members must also be cut, if necessary. The engagement of the cut-off ends of a strand with a pile head occurs as concrete is curing, which is why piles of this type have generally the heads thereof provided with extra reinforcement, whereby the strand slip, which occurs after the post-casting cutting procedure, settles an alignment therewith.

Another typical feature in slip casting technique is that a -structure in fabrication is cast on a long, flat and smooth casting bed, whereby a problem still existing in traditional technique relates to a proper placement of the cap blocks of successive piles for casting and to retaining their fixed position in a casting direction as the casting proceeds from pile to pile .

Another presently existing problem, especially in the fabrication of hollow-core concrete slabs , is that the traditional manufacturing technique does not provide a capability of applying machine-operated, i . e . especially slip-casting based fabrication technology for making sufficiently high strength hollow-core slabs , since, at present, the only possibility provided thereby is to make use of crosswise steel members , which are elongated and extended into the top shell of a cast structure and which are not, as such, capable of providing sufficient torsional rigidity without unacceptable mass increase .

The application publication DE 102 09 046 discloses a reinforcement element not consistent with traditional technology and consisting of two hook wires , said wires being set up to include opening points . The opening points of such reinforcement elements are intended to accommodate the main steel members of a reinforcement element, which is why this particular solution cannot be applied in a casting process performed without main steel members or in slip casting as such .

The publication print DE 2 330 079 , on the other hand, discloses a reinforcement element , which is strengthened by means of a bracing wire extending by way of three lengthwise main steel members and welded alternately to each main steel member, thus establishing a so-called wraparound brace element . Because the discussed bracing wire is welded securely to the main steel members , the thus established reinforcement element provides a cage structure which is totally closed as far as casting is concerned, which solution cannot be utilized without main steel members , nor in slip casting as such.

On the other hand, particularly in reference to hollow- core reinforced concrete beams and with regard to pile heads used in connection therewith, it is prior knowledge to set reinforcement elements present therebetween under stress , as described e . g . in the publication GB 741 953 , which is effected by attaching the pile heads to prestressed strands by means of fastening members . However, the cited solution makes use of totally separate clamping elements , the large number of which and the excessive amount of manual clamping work required thereby lead to the outcome that such a solution is not applicable to large-scale

production or slip casting, in which the prestressed strands may travel in a continuous state through as many as dozens of piles .

From patent publication US 2003/0038398 it is previously further known to guide prestressed strands by means of head plates present at the butt-to-butt cap blocks of fabricated concrete structures . In this solution, the positions of prestressed strands are set by means of the head plate of each cap block, in which context there is no other purpose than to place said strands in correct positions in a casting operation .

Thus , the existing fabrication technology, regarding especially both solid and hollow-core reinforced concrete structures applicable as such to slip casting technique, is not at a very highly developed level and, therefore, resorting to old-fashioned, inefficient manufacturing technology is practically inevitable at present . On the other hand, the existing manufacturing technology calls for an unnecessary amount of manual labour as a sufficiently efficient machine-operated exploitation of traditional equipment is not possible in all relevant operations .

A hook iron arrangement according to the present invention has an objective of providing a decisive remedy to the above-described problems and of thereby raising substantially the existing state of the art . In order to accomplish this objective, a hook iron arrangement of the invention is principally characterized in that it comprises a wire-assembled hook iron reinforcement essentially open/openable at its top side at least during a casting operation for enabling the manufacture of a reinforced concrete slab

with improved torsional rigidity specifically by virtue of the hook iron reinforcement , a hollow-core slab, butt-to-butt manufactured reinforced concrete beams , slabs and/or the like in slip casting technique, the open/openable top side of the hook iron reinforcement enabling, during a casting operation, the lengthwise passage of a slip casting machine ' s top-supported actuators , such as a core mandrel , a compaction member and/or the like, through the crosswise hooking structures of the hook iron reinforcement element .

The most important benefits gained by a hook iron arrangement according to the invention should be said to include simplicity and efficiency regarding its construction and operation, by virtue of which it is possible to exploit slip casting technology in the fabrication of most diverse reinforced concrete structures . Firstly, by virtue of the invention it is possible to provide slip casting products with a structurally simple, machine-manufacturable/installable crosswise reinforcement, providing a possibility of increasing remarkably the torsional strength of e . g . hollow-core concrete slabs . Secondly, a hook iron arrangement according to the invention introduces also a technically highly advantageous coupling means regarding the cap blocks and the hook iron reinforcement element of reinforced concrete beams . By virtue of the invention it is further possible to expand the use of slip-cast piles , either hollow-core or solid, as their flexural strength and impact resistance improve remarkably from the present, in addition to which it is possible to outfit e . g . rock bit piles with necessary recesses and holes as early as in a casting process thereof for inspections performed during pile-driving.

Hence, a hook iron arrangement according to the invention enables a significant expansion of slip casting technique, such that the end result comprises concrete structures remarkably better than current ones in terms of their strength properties, including e . g. hollow-core slabs optimal in terms of their torsional rigidity/sizing/mass, by being able, despite the slip- casting technique exploited in their manufacture, to utilize reinforcement elements circling all the way around hollow recesses present therein.

The dependent claims directed to a hook iron arrangement according to the invention disclose preferred embodiments relating thereto .

A detailed description of the invention will be presented in the following specification with reference to the accompanying drawings, in which

figs . 1-3 show a few preferred optional, longitudinally continuously extending wire-assembled hook iron members, used in a hook iron arrangement of the invention, in side views (a) , end views (b) , top plan views (c) and perspective views

(d) ,

fig. 4 shows one hook iron arrangement of the invention when used in connection with the cap block of a hollow-core reinforced concrete beam to be manufactured particularly by slip casting,

fig . 5

shows a further enlarged detail from a butt- to-butt connection of the cap blocks shown in fig. 4,

fig. 6 shows one preferred hook iron arrangement of the invention when used in connection with a hollow-core beam,

fig. 7 shows still another preferred hook iron arrangement of the invention when used in connection with a hollow-core beam structure,

figs . 8a-8d shows a still further optional hook iron arrangement in an end view, side and top plan views , in a top perspective view, as well as in an enlargement of a detail indicated in fig. 8c , and

fig . 9 shows a hook iron arrangement consistent with the latter alternative, when used in connection with a hollow-core beam structure .

The invention relates to a hook iron arrangement, which is intended for use as a reinforcement element in a substantially elongated, cast concrete structure, and which includes one or more hook iron members that are discontinuous and placed in succession lengthwise s of the concrete structure and/or extend continuously over at least part of its lengthwise dimension s and are provided with a substantially crosswise hooking structure TR. The hook iron arrangement comprises a wire-assembled hook iron reinforcement 1 , C, C essentially open/openable a at its top side at least

during a casting operation for enabling the manufacture of a reinforced concrete slab with improved torsional rigidity specifically by virtue of the hook iron reinforcement , a hollow-core slab, butt-to-butt manufactured reinforced concrete beams , slabs and/or the like in slip casting technique, the open/openable top side of the hook iron reinforcement enabling, during a casting operation, the lengthwise s passage of a slip casting machine ' s top-supported actuators , such as a core mandrel , a compaction member and/or the like, through the crosswise hooking structures TR of the hook iron reinforcement element .

The hook iron member 1 , extendable during a casting operation around one or more cores of a hollow-core concrete structure manufactured especially by slip casting technique, and extending continuously in its lengthwise direction s , comprises , particularly in reference to the alternative examples shown in figs . 1- 3 , in the sense of cross-section, a hoop-like wire assembly circling back and forth around the longitudinal axis s , having its circling direction reversed at the opening point a of a hook iron reinforcement formed thereby. In this context, it is also possible to utilize assemblies , which in relaxed positions remain partially nested within each other as far as their opening point a is concerned or which remain open to begin with.

In a further preferred embodiment, although not shown in the drawings , it is possible that a relative spacing e between the crosswise hooking structures TR of a hook iron reinforcement formed by the continuous hook iron member 1 be made variable in the lengthwise direction s , especially for enabling regulation regarding local

strength properties of a concrete structure to be manufactured.

Consequently, in its relaxed condition, the hook iron reinforcement as shown in figs . 1-3 can be open or closed, in which case it opens during a casting operation e . g . as a result of being tensioned by a mechanical element present in the casting machine . A hook iron reinforcement element of the above type can be manufactured in advance, worked on with a separate auxiliary device during a casting operation or else worked on in the actual casting machine . By the above means , it is possible to adjust the thickness of a hook iron reinforcement element, i . e . the relative spacing of its crosswise hooking loops in the longitudinal direction of a concrete structure to be manufactured.

In still another preferred embodiment, a hook iron arrangement according to the invention is intended especially for the fabrication of concrete-casting manufacturable, reinforced concrete structures provided with cap blocks and tension transmitting brace members, such as steel braces placed along the edges or in the corners , prestressed strands EP and/or the like, each cap block including at least a head element A and end steel members B, the hook iron reinforcement element being arranged to circle around the end steel members B over at least part of the lengthwise dimension s . In reference to figs . 4 and 5 , depicting one embodiment of this type, the hook iron reinforcement element C , which is open/openable a at what in crosswise sense is its top side, is fixedly welded to one or more end steel members B of such a cap block. In addition, the cap block has its head element A provided with a lead- through E for a slip casting machine ' s top-supported

actuators , such as a core mandrel , compaction members and/or the like . In the embodiment of figs . 4 and 5 , the hook iron reinforcement is implemented by several individual , wire-assembled hook iron members C fixedly welded to one or more end steel members B at points successive in the lengthwise direction s . At this time, it should be generally noted that pile cap products are particularly suitable for insert moulding, while the use of an opening hook iron reinforcement effected without actual cap blocks is equally suitable for extruder-performed casting .

In the solution of figs . 4 and 5 , the cap blocks have a hook iron reinforcement element of opened design, such that the leading end of an individual hook wire lies in an opening zone a, the hook wire extending around externally of the end steel members B and the wire having its tail end also located in the discussed opening zone . Hence , the leading and tail ends of a hook wire constitute flexible protrusions , which deflect e . g . as a core mandrel or a compaction element ' s carrier means is driven through the reinforcement element . The foregoing type of hook iron reinforcement element can also be implemented e . g. in such a way that one of the protruding ends is sufficiently short for not having to deflect during a casting process . Thus , the short end is fixedly welded to an upper end steel member of the corresponding side, as well as by its bottom portion to lower end steel members . The other protruding end, in this type of embodiment, is sufficiently long, respectively, so as to extend e . g . diagonally across the opening point . By not fixing it by welding to the upper end steel member, the flexibility of this end can be increased . Thus , with respect to what is displayed in figs . 4 and 5 ,

this type of hook iron reinforcement is asymmetrical , wherein the shorter protruding end is inflexible having been fixed by welding to the upper end steel member and, respectively, its other end, directed e . g . diagonally as described above, is flexible in design by being disengaged from an end steel member of the corresponding side . It is further preferred that this type of hook iron reinforcement element be implemented in such a way that the reinforcement element has the short end and the longer end of each successive hook iron member arranged alternately on either side of its opening point .

Particularly in the situation 1 shown in figs . 4 and 5 , the slip casting operation of two or more lengthwise s successive hollow-core reinforced concrete structures is effected by having, in a further preferred embodiment, the butt-to-butt cap blocks thereof adapted to be braced in a fixed position by exploiting the prestressing force of the bracing members by reversing their direction by means of a reversing system provided on the cap blocks . In the illustrated embodiment , the reversing system comprises angle modification guides k, such as hooks kl , k2 , k3 , k4 or the like, present at the end opposite to the cap blocks ' head element A, provided for bracing members , such as prestressed strands EP or the like . In yet another preferred embodiment , the ends of the end steel members B opposite to the head element A is fitted with a continuous appendix D having its top and bottom edge provided with the angle modification guides k. The reversing system further has each head element A provided with guide/lead-through systems L; Ll , L2 , L3 intended for the angular modification/lead-through of

bracing members , such as the prestressed strands EP or the like .

In this context, the fixed position of cap blocks refers to a secure engagement thereof with the prestressed strands , such that , firstly, the movement thereof during a casting operation is prevented in the lengthwise direction of a concrete structure being manufactured and, secondly, the crosswise orientation thereof is maintained. In this case, the passage of individual prestressed strands is feasible to effect through a pair of cap blocks as shown in figs . 4 and 5 , e . g . as follows : the lower left-side prestressed strand has been guided to the lower guide hook kl of a first cap block, after which it passes to the recess Ll in the plate-structured head elements of the cap blocks and further to the guide hook k3 of a second cap block. Thence forward, the prestressed strand continues to extend in the same direction as it had when arriving at the first cap block . The passage of the upper left-side prestressed strand proceeds respectively as follows : k2 - L2 - k4. An alternative design in this case is the one that the lower prestressed strand approaches the lower guide hook kl of the first cap block, from where it continues forthwith to the upper guide hook k4 of the second pile cap, after which it continues to extend thenceforth as an upper prestressed strand of the pile . The passage of the upper strand proceeds respectively as follows : k2 - k3. Thus , the strand that came to contact with a pair of caps as an upper prestressed strand continues to extend as a lower prestressed strand. Consequently, in the latter case, the strands cross over each other by extending through guide recesses L3 present in the cap blocks ' head plates .

According to what is described above and shown in figs . 4 and 5 , the strands are threaded into the hooks , followed by effecting a simultaneous prestressing thereof . Since each strand makes a bend when passing by the cap blocks , the prestressing results in crosswise forces at the bracing points k, L, which together with friction serve to keep the cap blocks immobilized.

Pigs . 6 and 7 illustrate hook iron reinforcement elements of the type shown in figs . 1-3 used in connection with a five-cavity slab and a hollow-core reinforced concrete beam. As depicted in fig . 6 , a hook iron arrangement of the invention can be used for bracing e . g. a wall between each cavity by means of reinforcement elements extending vertically thereon.

Particularly in reference to the embodiment illustrated in figs . 8a-8d and 9 , which is alternative to what is displayed in figs . 4-6 , a hook iron arrangement of the invention is intended especially for the fabrication of concrete-casting manufacturable, reinforced concrete structures provided with one or more tension transmitting brace structures , such as steel braces placed along the edges and/or in the corners , prestressing strands EP and/or the like . In this solution, the hook iron reinforcement element C comprises a tension transmitting horizontal structure VR, having coupled therewith a vertical structure TR which is open/openable a at what in crosswise sense is its top side . Especially, according to what is shown in figs . 8b and 8c , the vertical structure TR comprises diagonal steel members set in an inclined position, preferably in directions opposed to each other at an angle of 45 ' , at the ends of reinforced concrete beams or the like to be manufactured in a butt-to-butt

fashion in the longitudinal direction s . Thus , the vertical structure TR, which is secured to the horizontal structure VR extending continuously across the coupling point of reinforced concrete structures to be manufactured in a butt-to-butt fashion, leaves the caps II of the reinforced concrete structures to be manufactured with a cut-off point , whereby they are readily severable by cutting just the horizontal reinforcements VR without having to use so-called cutting formes .

In this solution, the passage of the prestressed strands EP is implemented by means of extensions D ¹ , present at the ends of the hook iron arrangements C and having pairwise adjacent hooks k5 , kβ and k7 , whereby the prestressed strands EP associated with the horizontal structures VR, as shown in fig . 9 , are prestressable for casting, as described above . In the type of solution shown in figs . 8a-8d and 9 , the cap blocks of butt-to-butt manufacturable reinforced concrete beams , slabs or the like are constituted solely by the hook iron arrangement C ' .

It is self-evident that the invention is not limited to the embodiments illustrated or described above, but can be varied within the basic concept of the invention according to any given functions and applications .

Hence, it is clear in the first place that the type of hook iron member extending continuously in the lengthwise direction, as shown in figs . 1-3 , is feasible also in the type of cap blocks shown in figs .

4 and 5. On the other hand, in certain type of solutions , it may be possible to design the cap blocks also completely without actual end steel members , but an opening/openable hook iron reinforcement element of

the invention is engaged directly with the head plates . In addition, the plate-structured head frames of cap blocks , as shown for example in figs . 4 and 5 , are feasible to couple with each other either by means of separate connection elements or by welded steel spacers , which are severed, after the concrete has cured, through a gap between the head plates or frames , at the same time enabling also the cutting of possible spacers connecting the cap blocks .