FI109715B - Method for load transfer mainly for use in bridge structures - Google Patents

Abstract

This invention is a new method to achieve composite action between girders (3) and a concrete slab (1), as well as within the slab itself. The load transmission within the slab (1) is improved by the invention in the following way. The inferior capacity of the concrete to carry transverse forces is repaired by the composite load carrying capacity of the profile's edge flanges (9), upwards inclined top flanges (10) and upwards extended top parts (11). Due to this fact the slab may be made thinner than usual. Shear forces between steel (2) and concrete (17) are effectively transmitted by mechanical contact between the vertical edges (16) of the cuts (12) and the reinforcing bars (13). Due to the fact that the bottom flange of the case profile (8) is capable of resisting the entire tensile force in the cross section, maximum moment carrying capacity is obtained, whereupon main reinforcement may be omitted.

Description

109715 f S 1

LOAD TRANSFER METHOD FOR USE IN PRIMARY SILTARA CONSTRUCTIONS

FÖRFARANDE FÖR BELASTNINGSÖVERFÖRING FRÄMST FÖR ANVÄNDNING I BROKONSTRUKTIONER

The present invention is directed to a novel method for cooperating between load-bearing beams and a concrete slab, as well as within the concrete slab itself. The invention may be used in automobile, railway, bicycle and pedestrian bridges 5 or similar structures.

Technical area

A bridge, small, medium, or large, is usually constructed of two parallel main beams extending directly from one pillar to the other, or over several intermediate supports. The beams support the bridge lane for the traffic in question, the resulting load being transferred to the ground via beams and bridge supports. The bridge carriageway attached to the bridge-15 beams consists of structures made of wood, steel or concrete, or a combination of these materials, and is usually: coated with a layer of bitumen or concrete. Concrete, ·. the bridge roadway is usually made in a mold, which may be prefabricated or built on site, directly attached to the main beams. Small and medium-sized bridges typically use traditional planking I 1 · ··· * · and large bridges pre-fabricated planking shapes. The boarding mold may either extend over the entire length of the bridge 25 or be constructed for each new:::: part of the finished slab. Suitable anchoring connectors can then be cast into the slab. Betonite-rails must be carefully fixed before casting and casting - ;;; around the connectors 30 welded into the mold and into the beams. Thus, the concrete slab can receive shear forces 2,109,715 and act in conjunction with the bridge beams. This method of cooperating between the bridge lane and bridge beams makes the manufacturing step expensive, slow and dangerous.

5

Prior art

The most common way of transmitting shear forces and of cooperating between a bridge slab and bridge beams 10 is to weld, bolt or shoot the shear receiving connectors on a flat top surface of the bridge beams, which may be steel or concrete. These shear receiving connectors, which may be welded bolts, threaded bolts, steel lugs or other suitable anchoring connectors (see Figure 1), are fitted with reinforcing steels which serve to prevent cracking of the concrete due to the highly concentrated forces caused by the shear receiving connectors. In addition, reinforcement is used to distribute the compressive force exerted by the connectors on the entire concrete slab. Of course, all this reinforcement entails costs that you would like to limit. Also welding and bolt inspection is: time consuming and costly and for quality reasons. indoors. Numerous connectors are generally! "25 distracting when moving and working molds and casting concrete, which also results in * · '· time wastage and increased costs. Significant fatigue load" V "bolted • V: bolts use is generally unacceptable due to the highly concentrated forces acting on the concrete 30.

The traditional way of transferring the load to the main beams is to allow the * reinforcing steel in the slab to accept torsion - ;;; tensile stresses due to momentum. The plate is usually ·; · '35 too thin to allow the use of cutting steel. The plate must therefore be made very thick in order to receive the transverse forces exerted by the wheel 3 109715 and other loads. One alternative way of absorbing torque-induced tensile forces is to utilize a used 5 steel corrugated molding material with dents or bumps that are assumed to adhere to the underside of the concrete slab. This method is not generally accepted and is not used on road bridges.

10 One traditional way to make beam bridges is to make the slab with reinforcement that rigidly secures the slab to massive concrete beams. Another common way is to use steel beams, e.g. I-beams, in which the upper flange is attached to a flexible web plate below. 15 The above structure is complicated and expensive to implement. The latter structure leads to large heat movements in variable weather conditions and requires support and careful work.

Purpose and main features of the invention

The object of the invention is to provide an overall solution to the problem. The invention is a new way to completely combine structural elements known from other applications! 25 newly constructed elements to handle load transfer both between the beams and the slab and within the slab itself. The invention provides a fast, economical: · | · Safe and secure execution of work.

I ► * 30 The interaction between the beams and the slab is not built here::: by means of bolts, splitting or shear reinforcement, but by a special type of »bolt joint which in the first step transmits the shear forces from the beams to the steel 35 cassettes placed over them and which» · 4,109,715 additionally projecting over beams. In the second step, the cassettes are capable of distributing the shear forces over a larger slab width due to the high rigidity in the slab plane. A special threaded bolt with a hardened tip is used for the shear connection 5 between the beam and the cartridge. Together with the spacer, which at the same time acts as a stationary model for the screws, or alternatively with the other spacers, an extremely high fatigue resistance in the joint is achieved, which is thus well suited for transferring fatigue loads. The cartridge has - a substantially flat lower flange, - edge flanges extending from the lower flange of both sides almost perpendicularly upwardly, and 15 - inwardly or vertically upward and thereafter inwardly and obliquely upwardly extending symmetrically upper flanges terminating in vertically upwardly facing upper edges for.

20 Inward and oblique flanges provide support for the guide used to drill through both the cassette and the plate flange. A flat bottom flange allows for the required number of special bolts. * ·. install. The shape of the cassette and the fact that the cassette 25 is pressed with a special tool against the adjacent profile,. \ enables both the transfer of compressive force between the cartridges and the transfer of force from the bottom corner of the cartridge to the concrete; / multiaxial compression. The gap between the bottom of the cassette and the beam • * can be sealed with adhesive or elastic sealant 30, in the form of a tape or as a brush.

* «· ·::: The invention improves load transfer within the lane, as follows. The cartridge flanges, 'i! the joint bearing capacity of the obliquely uppermost upper flanges and the upwardly facing uppermost 35 compensates the lack of ability of the concrete 5 109715 to receive transverse forces. For this reason, the track can be made thinner than normal. Between steel and concrete, the shear forces are effectively transmitted through the mechanical contact between the notch edges and the reinforcing steel 5. The vertically extended profile of the profile causes the forces to be transferred close to the resultant of the compressive force of the concrete. The material thickness of the cassette is so large that all tensile steels in the lower part of the slab in the cross direction 10 of the bridge are replaced by the lower flange of the cassette itself. Maximum torque bearing capacity is achieved by allowing the bottom flange of the cartridge to receive the full traction force of the cross-section. Maximum load bearing capacity is achieved, also for the opposite sign bending moment, since the lower flange of the cartridge itself is capable of receiving the torque-induced compression force. The flanges of the cassette inwards and obliquely upwards, together with reduced concrete steels, allow for more reliable casting of concrete and provide a higher quality slab. Extreme-20 its good ability, at a given slab thickness, to receive both torque and transverse forces, thus giving the slab an overwhelming ability to withstand high centralized forces.

♦ <», ··. The shape of the side beam and the fact that the tight underside and the 25 insulating layer at the top of the slab protect the concrete and slab bolts, make the concrete, bolts and / or reinforcement on each side well protected against road salts, wetting and carbonation.

I »« • t · 30 When using concrete beams with two ;; adjacent web plate, the advantage is obtained that the concrete beam bridge compensates for temperature changes, which often results in simpler and cheaper ground supports, bearings and joints. At the same time, a structure with good torsional stiffness and 109715 6 stability is obtained, with or without concrete filler. The benefits of a beam beam bridge; lightness and a high degree of prefabrication are also achieved. The special bolted joint, together with the dimensions and shape of the cassette, according to the invention results in perfect cooperation between the beams and the slab 5 in the longitudinal direction of the bridge, allowing the joint to be flexible enough to receive horizontal forces and beam moments.

10 Image list

Figure 1 shows a bridge deck with its structures.

Fig. 2 shows a bolt joint 15 between the cassette and the main beam having a spacer plate and a reinforcing steel bar inserted into the notch in the cassette.

Figure 3 shows a threaded bolt, a hardened tip and one example of a spacer.

20

Figure 4 shows a special tool used to press the cartridges against each other during installation.

»· • · I ·. Figure 5 shows a steel beam having an I-profile. The upper-> · • 25 flanges have a bottom hole.

* »· / T: Figure 6 shows a steel beam with two web plates.

,; : The upper flange has through holes.

Figure 7 shows how shear forces from bolts to shear; :: as a local concrete tension tile.

I> ·

Figure 8 shows how the edge beam is secured to the cassette tapes by self-tapping screws.

, »35 7 109715

Figure 9 shows how the shear forces in the cassette web without adhesion can provide the necessary bending compression stress in the concrete slab.

Figure 10 shows how horizontal forces act on a concrete slab in cooperation with the main beam.

Figure li shows how the inner torque arm is larger in the slab than in a conventional concrete slab 10, where the tension is applied to the lower part.

Fig. 12 shows how the inner torque arm is larger in the slab than in a conventional concrete slab in which the lower part is subjected to compression stress.

15

Figure 13 shows that the cover at a given bolt arrangement is controlled elastically to the beams because the cassette cross-section may be elastically deformed.

20

Figure 14 shows an example of sealing between a cassette profile and a bar.

* i y * • «·, Description of Application Examples» · '25, The cross-section of the bridge may be as shown in Figure 1. A concrete slab (1) is cast over the supporting beams (3) of the bridge i i ». The concrete (17) is molded in the form of cassette profiles (2) transversely over the beams (3) and bolted thereto. The cassette profiles (2) extending beyond the beams have an edge bar at the end ;, · 1 (Figure 8). There is a dense insulating layer (19) on the tile.

I I f / »», ·, The steel cassettes (2) are bolted to the beams (3) to cooperate between the beams (3) and the plate 35 (1). The profiles (2) are shaped such that S I »

* (I

Ttl I * I * »8 109715 is a substantially flat lower flange (8), edge flanges (9) extending from the lower flange on both sides almost perpendicularly upward, and inwardly or vertically upwards and thereafter inwardly and obliquely upwardly 5 preferably symmetrically directed upper flanges (10) ), which terminate vertically upwardly directed upper portions (11) having openings (12) open at the top for concrete steels (13).

10 When a certain number of cassettes (2) are mounted on the beams (3), they are bolted into place by joining in the joint shown in Fig. 2. A special tool is used to provide the contact pressure required for mounting between the flanges (9) of the profiles (2), Fig. 4 (14). The holes for bolts 15 are simultaneously drilled in accordance with Figures 5, 6 and 7 of the lower flange (8) of the profiles (2) and the upper flange of the beam (3). The threaded bolts (4) having a hardened point (5) are then fixed with a pneumatic or electric screwdriver through the cassette profile and the upper flange.

20 A spacer is mounted between the bolt head and the lower flange of the profile (8), in the form of a plate (6) shown in the figure, with a *. the task is to tighten the bolts (4) precisely so that the correct flexibility is achieved. The profile (2) divides the forces across the bridge width and transmits the forces to the slab (Fig. 10). **. 25 (Figure 7). Alternative spacers ♦ · · / / (7) can be used. The gap between the bottom of the profile and the beam can be • sealed with glue or sealant (Fig. 14).

• · ·, · · 30 When the profiles (2) are mounted on the load-bearing beams (3) and::: the edge beams are mounted on the profiles by means of the self-tapping * .t screws (Fig. 8). The reinforcement (13) is intended,; * according to Fig. 9, both to ensure cooperation between the concrete (17):> 35 and the steel profiles (2) and to provide a reinforcement 9 109715 in the longitudinal direction of the bridge. Once the profiles (2) are installed and the reinforcement is completed, the concrete (17) is cast onto the bridge. Finally, an insulating layer (19) is applied on the wear concrete or bitumen.

5

Some non-restrictive suggestions regarding material and dimensions should be mentioned. The cassette profile (2) is made of sheet steel with a thickness of 4-7 mm. The total depth of the profile (2) can be 110 to 130 10 mm, the depth from the symmetrical bevelled flange (10) to the lower flange 80 to 100 mm and the total width of the profile 400 to 450 mm. The punched notches (12) in the finished upper part of the profile are 50 mm apart, the edges are vertical and horizontal. The bolt of strength class 10.9 has 15-meter M12 to M16 threads.

The method of cooperating between the described bolt joint and the steel profile mounted on the beams can also be used in other similar structures, such as parking planes and midsoles for heavy goods vehicles.

* * · · K «·

Claims (8)

10 109715 A bridge structure or a similar structure consisting of steel beams (3) mounted on two or more supports, a cover formed thereon of a steel cassette profile (2) and concrete (17) molded into and over a profile to form a concrete slab (1). ); the structure is shaped such that - cooperation between the steel beams (3) and the concrete slab (1) is achieved; cooperative means that the concrete slab, in one section across its entire width, is capable of receiving a total crushing force equal to that of the tensile beams capable of receiving, and that the structure has high strength bolts to transfer this force from the steel beam to the concrete slab; co-operation is also achieved between the cassette profiles (2) and the concrete slab itself in the transverse direction, and so that: - the slab (1) is capable of receiving large centralized loads without reducing the load bearing capacity of the cassette profile during casting; : - horizontal lower flange (8),:, * - edge flanges (9) extending on both sides of the lower flange almost: 'j': perpendicular upwards, then upper flanges (10) ending vertically upwards:, '* · 11) with notches for concrete steels ... '(12) open upwards, *, characterized in that the above upper flanges (10) extend obliquely in i * and upwards 4-7 mm thick steel plate, so large:: ': to achieve rigidity that they can transfer forces (Fig. 7) • t: · · further to concrete (17) and through the contact (Fig. 9) can transfer shear forces for cooperation 109715 11 to reinforcing steel bars (13) with a total depth of 110-130 mm, while the distance between the lower flanges (8) and the upper inward and upward flanges (10) is 80-100 mm. mm to allow them to transfer shear forces for interaction from almost the plane at which the resultant clamping force is formed and for the cassette profiles (2) to be 400 to 450 mm wide to distribute shear forces from beams to structure over a wide width (Fig. 10). Structure according to claim 1, characterized in that the upper surface of the steel beams (3) is substantially in contact with the substantially flat lower flange (8) of the cassette profiles (2) connected to the steel beams (3) by at least 10.9 strength bolts (4). to cooperate between the steel beams and the concrete slab. Structure according to Claim 2, characterized in that the bolts (4) are provided with spacers (6,7) and threadable into precisely formed holes in order to provide good fatigue resistance properties for the joint. The structure according to claim 3, characterized in that: the spacers consist of templates (6) which precisely define: T: the location of the bolts (4). ·. The structure according to any one of claims 2 to 4, characterized in that the bolt holes ·; · 'open in a closed space (Fig. 6) protected from the climate ,,! * * Impressions. The structure according to claim 5, characterized in that it is a closed space. ': (Fig. 6) is filled with concrete. 109715 12 Structure according to one of Claims 1 to 4, characterized in that the bolt holes are bottom holes (Figure 5). A structure according to any one of the preceding claims, characterized in that the cassette profiles (2) are pressed against each other by a special tool (14) in order to achieve load transfer in the concrete slab at the lower flange height of the cassette profile (8). t * * t »* •» * • i · s 1 I 1 *> t I »! t t 109715 10