JPS584006A - Continuous type bridge using prestressed steel beam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] This relates to a continuous type bridge using a steel girder.As a bridge girder, a pre-deflection load is applied to the steel girder in advance, and the lower seven lunges on the tension side are Commonly known as a pre-beam, concrete is placed to surround the 7th lunge, and after the concrete hardens, the casting deflection load is released and prestress stress is introduced into the lower 7th lunge concrete using the restoring force of the steel girder. Prestressed steel girders are already known (41 Publication n-to Sanco Reference No.) 0 After erecting such prestressed steel girders on-site, web concrete and slab concrete F are placed, and the steel A girder whose girder is completely covered with Km concrete is called a pre-beam composite girder.Since the lower flange concrete and slab concrete of this pre-beam composite girder are composited with the steel girder, the bending stiffness is increased, Since the girder height can be lower than that of composite girders, it is extremely advantageous for constructing bridges that are subject to girder height restrictions. In addition, since the steel girder itself is not exposed, it has the advantage of not requiring maintenance such as painting, making no noise, and being fire resistant.

When constructing a bridge using pre-beam composite girders that have these advantages, it is possible to consider whether to use a simple support type or a continuous support type, but in the case of a continuous support type composite girder, intermediate support The negative force acting near the concrete slab is due to the moment! We have to deal with the problem of cracking. To deal with this problem, for example, for positive curves, temporarily load the front load in the moment area, or jack up the intermediate support to temporarily reduce the steel at the ψ support. Tensile stress is applied to the 7 lunges on the girder, and after the concrete for the intermediate fulcrum member is placed and hardened, the above-mentioned preload is removed or jacked down to support the prestress stress of the concrete for the intermediate fulcrum member. There is a way. However, all countermeasures for negative moments near the intermediate support must be carried out at the construction site, and the methods are complicated, so they cannot necessarily be said to be appropriate for construction. For these reasons, although the prestressed steel girder used in the present invention has the above-mentioned advantages, it has not been constructed as a continuous support type, and has traditionally been used in simple support type bridges.

The present invention aims to take advantage of the advantages of pre-beam composite girders made of prestressed steel girders, which have the above-mentioned advantages, and to further apply them to a continuous composite girder type that is advantageous in terms of malleability, vehicle running properties, etc. The purpose of this project is to provide a continuous type bridge that simplifies the procedure for introducing prestress stress into the concrete deck slab at the intermediate support.
Span members made of ordinary prestressed steel girders with prestressed concrete on the lower 7 lunges are installed in the spans that receive positive bending moments, and prestressed steel girders are constructed near the intermediate supporting points that receive moments for negative bends. Placing slab concrete on the tensile side due to bending K and releasing the pre-bending load after the concrete has hardened. The feature is that both steel girders are connected and constructed in a continuous manner.

Next, the construction process of a continuous type bridge according to the present invention will be described in detail with reference to the illustrated embodiment. FIG. 2 is a side view showing the manufacturing process of member (1); FIG. .

As shown in No. 11ii4, the span member (1) is made of K11, similar to the production of known prestressed steel girders. That is, figure a
A camber is applied to the steel girder (1) and K in advance as shown in the figure, and then a forward deflection load (pre-loading) is applied to the steel girder (1) to cancel the camber with the steel girder (1) supporting both sides as shown in the figure. 7) Give a nail. In this state, the steel girder (1
), concrete (j) is poured leaving the lower 7-lunge (J) K girder unconnected end (41) on the tensile side, and when the concrete (j) reaches the specified strength, it is The deflection load Pt is released, and the lower 7 lunge concrete (j) K prestress stress is introduced by the restoring force of the steel girder.

The intermediate fulcrum member (λ) shown in Figure 1 is basically manufactured in the same way as the span member (1) described above, but in this case, the steel girder (K) that applies the forward deflection load Pf is used above and below the 7 lunges (4
) (7) is located on the prestressed steel girder for span members (
1), are arranged in the opposite way. In other words, the steel girder opening (as shown in Fig. aK) initially moves the lower 7 langes (7) upward IKIIIi, and in this state the upper 7 langes (7) as shown in Fig. 2.
≦) gives a forward deflection load Pf such that it becomes the tension side 0
Next, at this stage, slab concrete (t) is poured leaving the girder connection end (9) on the upper flange (t) on the tension side, and 9
When the concrete (1) reaches a predetermined strength, the pre-deflection load Pf is released and the zero-order prestress stress is introduced into the floor slab concrete (r) by the restoring force of the steel girder (r). As shown in Fig. 2 d, the girder connecting ridges (d) were left in place like the slab concrete (t), and the ginnib concrete (10
) and the lower 7 langes (7), concrete (l/) will be poured to form a composite member with the main steel girder covered from (//) K of (l). Web Concrete (/'s and lower 7 range concrete) (//
), no prestress is introduced. The intermediate support member (λ) made of the deformed prestressed steel girder manufactured in this way is #! As shown in Figure λ, the girder is rotated up and down and returned to the correct position, and then stocked until it is erected.

The span member (1) and the intermediate fulcrum member (-) obtained by the above manufacturing process are constructed in the order shown in Fig. 3a to (iK. That is, first, as shown in Fig. Ja, the temporary pen) (
/J), etc. to create a span member (/l) and an intermediate fulcrum member (λ).
The girder connecting end (≠) of the span member and the intermediate fulcrum member (J) 1 exposed in advance support the vicinity of the girder connecting end of the span member.
7) Attach the girder connecting end (9) to the splice plate (
13) and securely connect using high-strength bolts.

Next, as shown in Fig. 3 b', the central lower surface of the intermediate support member <2) is supported from the front intermediate support (/J), and at the same time, the temporary pen (/J) is removed to form a continuous girder. . After that, the span member (1) and the intermediate fulcrum member (
e) Exposed girder connection and end of steel girder in K (4=)
(9) Lower 7 lunge (J) (7) K, pour the lower 7 lunge filler concrete (lj). After curing of the above filler concrete (13), as shown in Figure 3d, the floor slab concrete (/7) of the upper 7 lunges (Za) of the span member (/) is installed. Not only the top of the connecting end (ge) but also the top 7 langes of the girder connecting end (9) of the intermediate fulcrum member (2).
≦), and cast the intermediate support member (2) to the position where it contacts the floor slab concrete (t), and also cover the span member (1).
Place the web concrete (n) on the web at K in the same way as the slab concrete until it touches the web concrete (l) at the intermediate support member (C). Therefore, at this stage, all of the steel members (1) and (λ) The continuous girder covered with concrete has been completed, and the subsequent dead loads such as ground covering, handrails, pavement, etc., or live loads such as vehicle width, etc., will be handled by the lower 7 lunge prestressed concrete F and the slab concrete. It acts on the continuous composite girder combined with the girder.

The continuous type bridge according to the present invention has the structure described above and has the following advantages.

As mentioned above, when constructing a conventional continuous composite girder type bridge, the negative bending that occurs near the intermediate supporting member is due to the bending of the floor and concrete slab due to the moment. There are problems such as cracking, and methods to solve this problem include applying a temporary preload in the positive bending moment region as described above, or jacking up the intermediate support, and then increasing the strength of the steel girder at the intermediate support. Because the procedure is to apply tensile stress to the upper 7 lunges, pour concrete for the intermediate fulcrum member slab, remove the preload after it hardens, and apply prestress stress to the middle r [fl fulcrum slab concrete by jacking down the fulcrum. However, in the continuous type bridge according to the present invention, the basic principle of prestressed steel girder is applied to the intermediate supporting member (K), and the construction is extremely complicated in terms of on-site construction. By pouring slab concrete (r) on the tension side of the girder and releasing the preload, prestress stress is introduced into the slab (7) (r), and this slab concrete < r
) prestress introduction work is carried out in advance for each member at the stage prior to girder erection, i.e. in a factory or on-site yard where workability is good, so workability is extremely good. Since it is sufficient to simply connect the intermediate member (C) and the intermediate fulcrum member (2), there is an advantage that countermeasures against negative bending moments at the intermediate fulcrum portion are significantly simplified overall.

In addition, in the bridge of the present invention, both the span member (1) and the intermediate support member -) are steel girders (/l, (J
) 1, and the member (1) (λ) that has only one member has prestress stress introduced into a predetermined part in advance, and there is a continuity between the members to which these prestress stresses have been introduced. This has the advantage that this can be done reliably and easily by connecting steel girders as structural members.

In addition, the intermediate fulcrum member (2) is a steel girder (co) with a predetermined length.
, and both ends of this intermediate fulcrum member (12) are connected to the span member (1), so this connected part can be set in a section where the bend is not large and the sign of the moment changes. Therefore, there is no problem with load-bearing strength, and it is possible to create an extremely rational structural type that corresponds to the bending moment distribution of the continuous girder.

In addition, the handling of girders during erection is not as complicated as in the case of a simple type bridge with conventional prestressed steel girders, and the erection work can be carried out safely. It is superior in terms of economy, earthquake resistance, vehicle drivability, aesthetics, etc. compared to that of a simple type bridge, and its moment balance is better, so the girder height/span ratio is lower than that of a simple type bridge.
? fP et al.

This has the effect that it can be made into a very slender and beautiful bridge.

[Brief explanation of the drawing]

Figures 1a to 1C are side views showing the manufacturing process of the bridge span member according to the present invention, Figure 1a to e are side views showing the manufacturing process of the intermediate support member, and Figures 3a to d are side views showing the manufacturing process of the intermediate support member. A side view showing the process of constructing the girder, Figure 1 is a sectional view taken along the line IV-P/ in FIG. 1C, and FIG. 5 is a sectional view taken along the line v-v in FIG. 2e. In the figure, (1)...Span member, (2)...Intermediate fulcrum member, (
31 (7)...Lower flange, (+') (9)...Girder connection end, (j)' Crt)...Lower 7 lunge concrete, (≦1 (/1>...Top) 7 lunges, (zl
(/7)...Slab concrete, (/of (1g)--
・Web concrete, (/, 2)...Temporary vent, (
/J)... Splice spray 11 (/4I)... Intermediate bearing, (tS)... Filling concrete. Patent applicant: Kawada Kogyo Co., Ltd. 3 Figure 3:

Claims (1)

[Claims] L In the span part that receives the positive bending moment F, a span member made of a normal prestressed steel girder is constructed by applying prestress stress to the concrete placed in the lower 7 flanges of the steel girder, and the span part receives the negative bending moment F. Concrete deck F is placed near the intermediate supporting member of the steel girder on the tensile side 7 of the pre-bending K, and after the concrete has hardened, the pre-bending is done by releasing the load and applying prestress stress to the concrete deck. In addition, an intermediate support member made of a deformed prestressed steel girder with non-prestressed concrete provided on the lower 7 lunges was erected, and both band members were connected to create a span member instead of being constructed as a continuous girder. A continuous type bridge using prestressed steel girders characterized by pouring slab concrete and web concrete and finally covering all of the steel girders with concrete.