JPH04144B2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention is applicable to hollow, direct ceilings such as concentrated housing, warehouses, and offices, where the span distance per unit is 7.
This relates to a long-span unsupported slab construction method that can reach up to 9 m.

``Conventional technology'' It is possible to reduce the weight of floors in housing complexes, warehouses, offices, etc., to achieve excellent performance in terms of floor sound insulation, and to make the floors of apartment buildings, warehouses, offices, etc. When configuring a hollow, direct ceiling where the floor plan is not restricted, this can be constructed using an unsupported semi-precast concrete version (registered trademark Omnia version) reinforced by an assembled steel truss with an inverted V-shaped cross section that can also be used as a general-purpose formwork. If you try to construct it by construction, the span is limited to 2.5 to 3 meters.

``Problems to be solved by the invention'' However, recently, the needs of users have become larger for apartment complexes, etc., and the spans have reached 7 to 9 meters.

For such long spans, the unsupported construction of the semi-precast concrete slab described above is extremely insufficient in both bending strength and bending rigidity, making it impossible and unable to cope with the current situation.

"Means for Solving the Problems" and "Operation" The present invention was made in view of the above circumstances, and its gist is that after manufacturing the product with a predetermined rounding, An assembled reinforcing bar truss consisting of double reinforcing bars and lattice reinforcing bars on the web is placed perpendicularly to the bed surface at the bottom of the slab at a predetermined position, and a concentrated load is applied until the truss bars become horizontal. In addition, while maintaining this state, concrete was placed on the flat part of the lower surface, hollow formwork was placed, and concrete was placed on the rib part in such a way that most of the assembled reinforcing bar truss was buried, and steam curing, etc. After developing strength, the load is released and prestress is introduced to create a semi-precast concrete slab with prestress introduced inverse rib assembly reinforcing bar truss reinforcement.This is transported to the slab construction site and the reinforcement at the top of the slab is A cover plate is laid between the reinforcing bars and the ribs, and then concrete is poured without support.We have developed a long-span unsupported slab construction method with a hollow, straight ceiling structure, which was completely impossible in the past. The point is that it has been realized.

"Example" This will be explained in detail below based on the drawings.

Figures 1a and b show the high bending strength used in the present invention;
These are front and side views of an assembled reinforcing bar truss 1 with high bending rigidity, as shown in the figure, upper and lower main members 1a and 1 are horizontally arranged.
a, 1b, 1b are made of double reinforcing bars, and the lattice reinforcing bars 1c of the web are made of the main materials 1a, 1a and 1.
b, 1b with a vertical staggered arrangement between the bridge inserts 1
It is formed by bridge welding between d and 1e, and exhibits much higher bending strength and bending rigidity than the above-mentioned inverted V-shaped cross section.

In the present invention, a semi-precast concrete slab is manufactured using such assembled reinforcing bar truss 1 as a reinforcing material, and at the same time, prestress is introduced.

That is, as shown in Fig. 2 A to D, the above-mentioned assembled reinforcing bar truss 1 is prepared with a predetermined recess 1' and placed in a vertical position at a predetermined position on the bed surface where the slab bottom reinforcement is laid. Then, in order to apply prestress when precasting is completed, a vertical load P is applied to this truss bar 1' to give a positive bending moment (preflexion).

The vertical load P is determined from the relationship between the stiffness of the reinforcing bars and the amount of prestress to be introduced by pressing down until the bulges become parallel.

Next, while holding down the truss bar 1', first place the lower flat part and then a hollow formwork material (not shown) for forming ribs, and then concrete the rib part (the truss bar 1' is located in the rib part). 2, and most of the truss bars 1' are buried as shown in Fig. 3.C. After the predetermined demolding strength is obtained (in the case of steam curing, demolding is possible the next day). The load applied to the truss is released and prestress is introduced into the concrete.

However, pre-stress is introduced here. Reverse rib assembly reinforcing bar truss reinforced semi-precast concrete version 1"
is produced.

This was carried to the slab construction site as shown in FIG.
(steel plates, keystones, veneers, etc.) are laid, reinforcements 5 at the top of the slab are placed, and cast-in-place concrete 6 is placed to complete the construction.

In other words, pre-stress is introduced by using truss bars that originally have high bending strength and high bending rigidity, and the truss bars are used in place of shear connectors, and the pre-cast is ribbed (the length of the truss bars is 1').
(so high that it is almost buried), the rigidity of the entire slab is extremely high, and it is firmly integrated without cracking during concrete pouring, allowing unsupported construction with a span of 7 to 9 m. Become.

Further, the formation of the hollow 13 is advantageous because a high hollow can be secured by simply laying the plate 4 using the reverse ribs prior to placing the upper concrete 6.

Figures 4a and 4b show an example of how the precast concrete slab 1'' and the girder are attached, and Figure a shows how the precast concrete slab 1'' is attached to both sides of the SRC girder 7, and 8 in the figure is a plate anchor. 9 indicates the lower end anchor reinforcement according to the method, 9 indicates the upper end anchor reinforcement, and 9a indicates the lap length of the upper end reinforcement reinforcement 9.

Figure b shows a semi-precast concrete plate 10 reinforced with the conventional assembled steel truss with an inverted V-shaped cross section as described above, as a jump corridor and balcony on one side of the girder 7, and a precast concrete plate of the present invention on the other side. 1" in the figure.
Reference numeral 1 indicates the lower end reinforcement, and 12 and 14 indicate the upper end reinforcement, respectively.

``Effects of the Invention'' As described above, according to the present invention, it is possible to achieve 7 to 7, which is suitable for a flat housing complex with a good ceiling finish.
A 9m long span slab can now be constructed without support or formwork (no demolding process), resulting in greater labor savings and shorter construction times than conventional construction methods.

[Brief explanation of drawings]

Figures 1a and b are front and side views of the assembled reinforcing bar truss adopted in the present invention, Figures 2 a to d are manufacturing process diagrams of the reinforced precast concrete version of the inverted rib assembled reinforcing bar truss introducing prestressing of the present invention, and Figure 3. The figure is a longitudinal sectional view of a slab according to the present invention, and FIGS. 4a and 4b are explanatory diagrams of an example of the girder arrangement according to the present invention. 1... Assembly reinforcing bar truss, 1a, 1b... Main material,
1c...Lattice reinforcing bar, 1d, 1e...Insert bar,
1'...Truss bar, 1''...Prestress introduction reverse rib assembly reinforcing bar truss reinforcement semi-precast concrete version, 2...Concrete, 3...Rib, 4...
Plate, 5... Slab top reinforcement, 6... Cast-in-place concrete, 7... SRC girder, 8... Bottom anchor reinforcement,
9... Upper end reinforcement, 9a... Lap length of upper end reinforcement, 10... Precast concrete version, 1
1...Lower end reinforcement, 12...Upper end reinforcement, 13...
...Hollow, 14...Top end reinforcement.

Claims (1)

[Claims] 1. After having been fabricated with a predetermined relief in advance, the assembled reinforcing bar truss, which consists of double reinforcing bars as the lower main member and lattice reinforcing bars on the web, is placed at a predetermined position on the bed surface of the slab bottom end reinforcement. Concentrated load is applied until the truss bars become horizontal, concrete is placed on the flat bottom part while maintaining this state, and hollow formwork is placed, and most of the assembled reinforcing bar truss is Concrete is placed in the rib section in such a manner that the ribs are buried, and the strength is developed through steam curing, etc., and the load is released and prestress is introduced. Inverse rib assembly and reinforcement truss reinforced semi-precast concrete plate. This method is characterized in that the slab is transported to a slab construction site, reinforcement is arranged at the top of the slab, a cover plate is laid between the ribs, and concrete is poured without support. Shoring slab method.