JP2006283463A - Half-precast floor slab and its construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of an economical floor slab with good constructibility and excellent durability enabling resistance to a positive and negative bending moment area, and also to provide a construction method for the floor slab. <P>SOLUTION: In an H-shaped steel 41, protrusions are provided on the outer surfaces of flanges 41a and 41b by rolling. A plurality of holes 42 are provided in the web of the H-shaped steel 41 in the longitudinal direction of the H-shaped steel; the pieces of H-shaped steel are juxtaposed; and lower distributing bars 43a pass through the plurality of holes 42, respectively. After that, a plurality of panels 47, where lower-layer concrete 44 is placed in a slab shape in such a manner as to cover the lower flange 41a of the H-shaped steel and the lower distributing bar 43a, are laid on site, and upper-layer concrete 49 is collectively placed on the upper section of the lower-layer concrete 44 on site by using the lower-layer concrete 44, placed in the slab shape, of the panel 47 as a form. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a half precast slab and a construction method thereof, in particular, a floor slab for a bridge such as a road bridge and a railway bridge, and a structure of a floor slab used for an artificial ground or a pier, and the construction thereof. It is about the method.

  As prior art relating to the present invention, Patent Document 1, Non-Patent Document 1, Non-Patent Document 2, and the like are known.

  In Patent Document 1, as shown in FIG. 1 (corresponding to FIG. 1 of Patent Document 1), a steel bar 17 having a hole 18 in a web 17a as a main member and having a large cross-sectional performance is used. In the state where the reinforcing bar portion 16 composed of 14 and the reinforcing bar 15 is arranged, a semi-precast (half prefab) floor slab panel 2 in which the lower (tensile side) concrete 11 is previously placed is laid on site. After placing the reinforcing steel bars 3 on top of it, the upper concrete layer C including the joints between the panels is cast and integrated at the site, providing excellent workability at the site and reducing the floor slab thickness. Obtaining version 1 is described. Moreover, since the hole 18 provided in the web 17a of the shape steel 17 exhibits the effect of preventing the deviation from the concrete, it is not necessary to dispose a stud gibber or the like, and effects such as reduction in processing man-hours and floor slab thickness can be mentioned. ing.

  In Non-Patent Document 1, as shown in FIG. 2, a steel strip 21 provided with a plurality of circular holes as a main reinforcing bar equivalent material is welded to a bottom steel plate 22, and the bottom steel plate 22 has a strength equivalent to a tensile reinforcing steel. The steel panel 20 manufactured at the factory as a member is transported to the site, arranged on the main girder, and the concrete plate 23 is casted and integrated on the site using the bottom steel plate 22 of the steel panel 20 also as a formwork to form a floor slab. Thus, it is described that a lightweight and highly durable floor slab is obtained. In the figure, 24 is a power distribution reinforcing bar.

  Further, in Non-Patent Document 2, as shown in FIG. 3 (corresponding to FIG. 1 of Non-Patent Document 2), a CT section steel 31 obtained by half-cutting an H-section steel having protrusions on the outer surface of the flange as the main member is formed. After laying a panel welded to the bottom steel plate 32, which also serves as a frame-side pulling side structural member, and then consolidating the concrete 33, it is for lightweight long spans with reduced cross-sectional performance and reduced floor slab thickness. It is described that a steel / concrete composite deck is obtained. The protrusion 31a provided by rolling on the upper surface of the flange of the CT steel 31 exhibits the effect of preventing the deviation from the concrete 33, so that it is not necessary to dispose the stud gibber 34 and the like, and the effects such as reduction in processing man-hours and floor slab thickness are achieved. Is mentioned. In the figure, reference numeral 35 denotes a distribution reinforcing bar.

JP 2000-38798 A “Development of composite floor slabs for labor saving in production and construction” Yokogawa Bridge Technical Report, No. 24 (January 1995), pp. 72-81 "Design of composite floor slabs using T-shaped steel gibbles with protrusions" Proceedings of the 2nd Road Bridge Slab Symposium (November 2000), pp. 243-250

  However, in the prior art according to Patent Document 1, since the bottom flange 17b of the shape steel 17 and the slip prevention material for the concrete 11 are not arranged, the crack dispersibility is inferior, the crack width is large, and there is a problem in durability against steel corrosion. May occur. In order to avoid this, it is necessary to arrange the tensile reinforcing bars 14 between the structural steel members 17 to a certain degree, and there is a problem that the amount of reinforcing bars increases.

  In the prior arts according to Non-Patent Documents 1 and 2, since the steel cross section is extremely asymmetrical in the vertical direction, additional measures such as increasing the amount of reinforcing bars are required in the negative bending region such as on the main girder. Further, since the bottom steel plates 22 and 32 are exposed, there is a problem that a corrosion prevention work is required and a maintenance cost is separately generated.

  The present invention was made in order to solve the above-described problems, is economical, has good workability, and has a durable slab structure that can resist positive and negative bending moment regions, and its construction. It is an object to provide a method.

  The present invention provides a web of an H-section steel (strength member corresponding to the main reinforcing bar) with a protrusion on the outer surface of the flange by rolling, and a plurality of holes are provided in the longitudinal direction of the H-section steel. After the shape steels were juxtaposed and the lower distribution steel bars penetrated through the plurality of holes, the lower concrete layer was placed in advance in a plate shape so as to cover the lower flange and the lower distribution steel bars of the H-shaped steel. Half precast, characterized in that a plurality of panels are laid at the site (construction site), and the lower concrete layer placed in the form of the panel is used as a formwork, and the upper concrete layer is placed at the top of the panel. The floor slab solves the problem of crack dispersibility of the underlayer concrete according to Patent Document 1 as a conventional technology, the problem in the negative bending region in Non-Patent Documents 1 and 2, and the problem related to corrosion prevention of the bottom steel plate, and the workability is improved. Excellent durable floor It is intended to provide.

  The effect of this invention is shown below.

  (1) Since the H-section steel with flange outer surface protrusion is used as it is, a vertically symmetric cross section can be obtained, so that even a negative bending region can be handled without distinction from a positive bending region.

  (2) A uniform floor slab is obtained because the lower layer concrete, which also serves as a formwork, and the upper layer concrete that is installed on site are integrated through a plurality of holes provided in the H-shaped steel web with flange outer surface protrusions. It is done.

  (3) Since the protrusion on the outer surface of the flange exerts the effect of preventing the deviation from the concrete, the integrity of the lower concrete that is previously placed as a mold and the covered concrete that covers the lower flange surface of the H-shaped steel is ensured. In addition, sufficient crack dispersibility can be obtained without additional reinforcing reinforcing bars as in Patent Document 1, and durability against steel corrosion is improved. Furthermore, the bottom steel plate as in Non-Patent Documents 1 and 2 is not used, and the lower surface is covered with concrete, so that a corrosion prevention work is not required.

  (4) Compared to the case where H-shaped steel without protrusions is used, the adhesion between the steel member and the concrete is maintained close to the final strength, and thus has a large load resistance and deformability.

  In particular, when fiber reinforced concrete with high tensile strength is used for the lower concrete that is previously placed for use as a formwork, it is possible to omit the central reinforcing bar in the direction of the distribution reinforcing bar, which is necessary to prevent cracking when placing the upper concrete. Thus, the weight can be reduced. Furthermore, since the crack dispersibility is better than that of ordinary concrete and the crack width is small, it is possible to improve the durability even in severe corrosive environments such as marine environments.

  In addition, if at least a part of the lower-stage reinforcing bars and upper-stage reinforcing bars are made of steel pipes that penetrate the H-shaped steel web holes, the load distribution performance of the floor slab will be improved, and the strength and durability of the floor slab will be improved. Further improvement is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings illustrating the examples.

  FIGS. 4 to 6 show the construction process from the state in which the H-shaped steel with flange outer surface projection and the reinforcing bar, which are steel members, are arranged at predetermined positions in the first embodiment until the upper layer concrete is placed on the spot. .

  First, in the yard near the factory or on-site construction site, as shown in FIG. 4, a hole (referred to as a web hole) is formed in the longitudinal direction in the web in the lower concrete concrete form 46 arranged to have a predetermined panel shape and size. ) 42, for example, by rolling, a plurality of H-shaped steels 41 having protrusions on the outer surfaces of the upper and lower flanges 41b and 41a are juxtaposed, and the lower distribution reinforcing bars 43a are inserted through the web holes 42.

  Thereafter, the lower concrete layer 44 (see FIG. 5) is placed so as to cover the lower flange 41a of the H-shaped steel 41 and the lower stage reinforcing steel bars 43a. At this time, in order to connect the half precast panels 47 locally, the panel connecting loop reinforcing bars 48 are embedded through the mold 46.

  After the lower concrete 44 is cured, the lower concrete formwork 46 is disassembled and demolded to produce a half precast floor slab panel 47 as shown in FIG.

  After transporting the manufactured half precast floor slab panel 47 to the site erection position and laying it in a state where the panel connecting loop rebar 48 is fitted, as shown in FIG. The lower concrete 44, which is penetrated and arranged, is cast into a plate shape of the panel 47, and the upper concrete 49 is placed on the spot so as to cover the upper flange 41b of the H-shaped steel 41 with projections. Thus, the floor slab is completed.

  In addition, as a shape of the web hole 42, although it is a circular hole in FIGS. 4-6, it shows to FIG. 7 (A) so that the fall of the fatigue strength of the H-section steel 41 by the stress concentration in a hole part can be avoided. Such a triangle 53 with arcs 52 at the corners, or a polygon 54 with arcs 52 at the corners as shown in FIG. Is also possible.

  The lower concrete 44 is integrated through the protrusions of the lower flange 41a of the H-shaped steel with protrusions, the web holes 42, and the lower stage reinforcing steel bars 43a, but the lower surface covering portion 50a (see FIG. 5) should be peeled off. For prevention, at least the reinforcing bar mesh 51 (see FIG. 4) can be embedded in the covering portion 50a.

  Moreover, since the concrete thickness required as a formwork can be reduced by using dense concrete having high tensile strength such as fiber reinforced concrete as the lower concrete 44, the thickness of the lower concrete can be reduced, and the panel weight at the time of erection (When the maximum dimension is determined by the transport length or width) or the size of the half precast floor slab panel 47 can be increased (when the maximum panel dimension is determined by the transport weight limit). In addition, durability can be ensured without increasing the covering thickness even in places where the amount of attached salt is large, such as in the marine environment.

  Further, a part of the lower-stage distribution reinforcing bar 43a and the upper-stage distribution reinforcing bar 43b is a steel pipe 55 penetrating the circular web hole 42 of the H-section steel 41 as in the second embodiment shown in FIG. It is also possible to improve the load distribution performance of the slab and improve the strength and durability of the floor slab.

The perspective view which notched the part which shows the prior art described in patent document 1 The perspective view which cut off one part which shows the prior art described in the nonpatent literature 1 The perspective view which notched the part which shows the prior art described in the nonpatent literature 2 The perspective view which shows the first construction process of 1st Embodiment of this invention. Similarly, the perspective view which notched the part which shows the construction process next to FIG. Similarly, the perspective view which shows the construction process next to FIG. The perspective view which shows the modification of a web hole shape The perspective view which shows the principal part of 2nd Embodiment of this invention.

Explanation of symbols

41 ... H-shaped steel 41a ... Lower flange 41b ... Upper flange 42 ... Web hole 43a ... Lower distribution bar 43b ... Upper distribution bar 44 ... Lower concrete 46 ... Formwork 47 ... Half precast slab panel 48 ... Panel connecting loop Reinforcing bar 49 ... Upper concrete 51 ... Reinforcing bar mesh 55 ... Steel pipe

Claims (4)

A plurality of holes are provided in the longitudinal direction of the H-shaped steel in the H-shaped steel web with protrusions on the outer surface of the flange by rolling, and the H-shaped steel is juxtaposed, and the lower distribution reinforcing bars are passed through the plurality of holes. After that, a plurality of panels were laid on site to cover the lower flange of the H-shaped steel and the lower distribution steel bars, and the lower layer concrete was laid in the form of a plate.
A half precast floor slab comprising lower concrete placed in a plate shape of the panel as a frame and upper concrete placed on the upper portion of the concrete.   2. The half precast floor slab according to claim 1, wherein fiber reinforced concrete is used for the plate-like lower concrete placed in advance.   The half precast slab according to claim 1, wherein a steel pipe is used for at least a part of the reinforcing bar penetrating the hole of the H-shaped steel. A plurality of holes were provided in the longitudinal direction of the H-shaped steel in the H-shaped steel web having protrusions on the outer surface of the flange by rolling, and the H-shaped steel was juxtaposed, and the reinforcing bars penetrated the plurality of holes. After that, laying a plurality of panels on the site where the lower concrete and the lower stage reinforcing steel bars are covered with plate-like lower concrete,
A method for constructing a half precast slab, characterized in that a lower concrete layer placed in a plate shape of the panel is used as a form frame, and an upper concrete layer is collectively placed on the upper part thereof on site.

Images