JPS5838286B2 - PC concrete plate with raised ribs in the center and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a PC concrete slab with raised central ribs and a method for manufacturing the same.

The outline is that it is a PC concrete plate consisting of a thin plate-like part with a wire mesh on the entire surface, a rib which is a protrusion extending the entire length of the upper surface of this thin part, and a PC steel wire passed under the rib. The rib is highest near the center of the entire length and gradually decreases in height toward the ends, and its manufacturing method is to make a PC concrete plate by a sliding molding method, and to create a sliding molding. As the rib portion forming member progresses, the first half is gradually pulled up and the second half is gradually lowered.

It has been 30 years since prestressed concrete was introduced to Japan.
During that period, it was widely used for roads, bridges, etc. as a concrete structure with no cracks, but most of them were PC concrete slabs with a rectangular cross section of the same length.

Unsatisfied with conventional PC concrete slabs, the present inventor created a unique PC concrete that combines so-called ferrocement, which is made by applying concrete (mortar) to a wire mesh to obtain thin wall toughness, and prestressed PC steel wire. We have developed a version and are applying for a patent (Japanese Patent Application Laid-open No. 53-28919 and No. 53-28919).
-73829, etc.) We have also developed a new sliding molding method as a mass production device and are currently applying for a patent (Japanese Unexamined Patent Publication No. 55428).
05, 55-41218, 55108552, etc.).

This new thin-walled, tough PC concrete slab dramatically increases its bending strength by adding ribs, which are concrete ridges, to one side.

For this reason, embedded formwork for RC (cast-in-place concrete) slabs that do not require shoring is thin, lightweight, and easy to use. It attracted attention for its unparalleled bending strength, and came to be used as a material for civil engineering and construction.

The present invention further improves the ribbed PC concrete plate by making the ribs have a raised central part along their entire length as mentioned above, thereby achieving the groundbreaking effects described below. He also developed the Surido Kaigata method to mass produce this.

Next, embodiments of the present invention will be described using the drawings.

Figure 1 is an elevational view of a PC concrete slab to which this invention is applied, and Figures 2 and 3 show two types of cross sections.
In both figures, the cross section on the left half is the end of the concrete slab, and the right half is the cross section at the center.

The plate-like thin part 1 usually has a thickness of 30 to 60 myn and a width of 1 to 2
The length depends on the design calculation, but it is possible to have a support interval of 10 m.

A wire mesh 2 is placed all over the inside to make it strong against cracking, and a PC steel wire 4 is passed under the rib 3.

The ribs 3 in the embodiment shown in FIG. 2 have the simplest rectangular cross section and are arranged in parallel, and the rib 3 in FIG.

What both of them have in common is that, as shown in the elevational view of FIG. 1, the central portion of the entire length of the ribs 3, 3' is raised highest, and the height gradually decreases toward both ends.

If this is used as an embedded formwork for a bridge, cast-in-place concrete will be placed on top of it up to the height of chain line C.

It is well known that in order to make a beam supported at both ends equally strong, its cross-sectional area, especially its height, should be made smaller toward the center of the beam.

This is simply a static reinforcement method that increases the section modulus toward the center to correspond to the magnitude of the bending moment.

In contrast, this invention should be called a dynamic reinforcement method that mainly uses prestress using a PC steel wire.

In the left half of Figures 2 and 3, in the cross section where the ribs 3 and 3' are low, P
The tensile stress of CMM4 causes compressive stress on the entire surface of the concrete.

However, as the height of the ribs 3 and 3l increases, the eccentricity of the PC steel wire 4 increases, and bow tension stress is generated at the upper edge of the rib near the center of the entire length of the concrete slab.

That is, the PC concrete slab of the present invention has compressive stress at the ends, like the conventional PC concrete slab, even if there is a difference in size from the top to the bottom of the cross section.

The center part, where the bending moment due to the load is large, becomes tensile stress near the upper edge of the cross section, and compressive stress below that, resulting in a pre-stress distribution suitable for a beam supported at both ends.

Of course, there is also a static effect due to the increased cross-sectional area of the center, but what is important is that as a PC concrete slab, the pre-stress before loading is ideally distributed.

The prestress distribution of the conventional PC concrete slab cross section did not change throughout the entire length of the slab, but this invention is the first to make this different between the edges and the center of the slab, resulting in uniform strength beams due to changes in prestress. , or PC with stronger bending resistance toward the center
It was made of concrete.

Note that tensile stress is generated on the top surface of the rib in the center of the concrete slab, and strong compressive stress is generated on the bottom surface, which causes the slab to warp, but if this slab is used as a beam, it will bend horizontally due to its own weight or the weight of the concrete cast on site. return.

This gives the inside of the concrete slab a prestress and a curvature that is advantageous as a beam, which is also one of the features of the concrete slab with central raised ribs of the present invention.

Next, as an example that is a modification of FIGS. 2 and 3, the PC shown in FIG.
Explain about concrete slab.

In the embodiment of FIG. 3, this is the hollow part 6 of the hollow rib 3.
You can think of it as eliminating the lower thin-walled part, but it is better to think of it as creating a groove-like shape in the thin-walled part 1, just as when creating ribs on a steel plate, you bend it into a groove-like shape. .

This channel-shaped PC concrete slab also has P in its lower horizontal part 1.
The C steel wire 4 is inserted, and the wire mesh 2 is also entirely inserted into the part that will become the grooved rib 5.

The ribs 5 in this case are also low at the edges of the plate and high at the center, forming a curve like the ribs 3 in FIG.

In the embodiments shown in FIGS. 2 and 3, the lower surface is flat, but in the embodiment shown in FIG. 4, the slope of the upper surface of the rib 3 is the same as that of the lower surface.

This is used as an embedded formwork, and cast-in-place concrete C is placed on top of it.
When you hit , the top surface becomes flat.

In the embodiment shown in FIG. 5, the height of the grooved rib 5 is constant throughout the entire length of the plate, and the central raised rib 3 is raised thereon.

When these PC concrete slabs with central raised ribs are used as embedded formwork for concrete bridge construction, they not only reduce the need for shoring as they can withstand long support intervals due to their strong bending resistance despite their light weight, but also provide compression on the top surface. It takes advantage of the strengths of a composite material that includes cast-in-place concrete that is resistant to heat, wire mesh that is resistant to tension on the underside, and ready-made concrete slabs containing PC steel wire.

Now, the manufacturing method for the above-mentioned PC concrete concrete 1/plate with raised central ribs is as follows: make a wooden or steel formwork using conventional techniques, lay wire mesh 2, pass the PC steel wire 4 under tension, and pour concrete. There are no technical difficulties.

Alternatively, the flat thin plate part 1 shown in Fig. 2 is made using hardened concrete using the sliding method developed by the present inventor, and a side plate matching the width of the rib 3 is erected on top of the flat thin plate part 1. Depending on the required slope of the height, hard concrete may be poured and leveled.

However, with these known techniques, a formwork must be manufactured every time the dimensions of the PC concrete slab change.

And the required dimensions often change. Therefore, there has been a need for a manufacturing method that can quickly respond to certain dimensional changes and that is easy to work with.

The manufacturing method of the second invention of the present application satisfies this demand.

This will be explained together with the manufacturing apparatus shown in FIG. 6 and below.

The manufacturing method of this invention applies the hardened concrete sliding molding method described above.

Therefore, using a long lower frame 10, a sliding upper frame 11, and a PC steel wire tensioning device 12, the hardened concrete on the lower frame 10 is transferred to the upper frame 1.
As step 1 progresses, it is successively shaped into the desired cross-sectional shape.

Of course, before concrete is laid on the lower frame 10, wire mesh is laid on the lower frame 10 and the PC steel wire is kept under tension.

Examples of the sliding upper frame 11 are shown in FIGS. 9-11.

The underframe 12 rests on rails 10a on both sides of the lower frame 10 and moves forward by being pulled by a winch (not shown) at the front, and the vibration isolators placed on this underframe 12 at right angles to the direction of travel via anti-vibration rubber 13. The main materials are beams 15, 16, and 17 with motors 14, concrete guide vibration members 18 attached to the front beams 15 and 16, and molding material 19 attached to the beam 17.

The guide vibration material 18 is a plate material attached under the beams 15 and 16 to guide and vibrate the concrete, and distributes the concrete appropriately before entering the molding material 19 and adds vibration to improve fluidity.

The forming material 19 is placed under the beam material 17, and is used to slide and shape the concrete into the desired cross-sectional shape.

A thin-walled part forming member 19 fixed to the beam member 17 on the shape member 19
a, and an adjustment mechanism 20 attached to the beam member 17 adjacent to this member 19a, and a rib portion forming member 19b that can be moved up and down and stopped by a screw operating mechanism 20 in FIG.

The screw 20a is used for pulling up, and the screw 20b is used for pressing down.This is a manual adjustment mechanism before the adjustment mechanism 20 is mechanized, and if anything, it corresponds to height fluctuations of a rib of a constant height. be.

This adjustment mechanism 20 will be explained with reference to FIG. 12, which is a mechanized embodiment thereof.

This figure shows both the thin-wall portion 19a and the rib portion 19b of the shaped member 19 attached below the beam 17, as seen from the front.

Each rib portion molding member 19b is adjacent to the thin wall portion molding member 19a fixed to the beam member 17, and is raised and lowered by each adjustment mechanism 20.

Although not shown inside the adjustment mechanism 20, a horizontal worm wheel for pulling up the member 19b is rotatably driven by a worm attached to an interlocking shaft 20c.

The interlocking shaft 20c is rotated by a motor 21.

Note that since the automatic adjustment mechanism is basically just moving each member up and down automatically at the same time, it goes without saying that it can be designed in various ways using well-known technology.

Using the above-mentioned sliding forming device, after laying the wire mesh, fixing the PC steel wire, and tensioning, hard concrete is sequentially dropped onto the long lower frame 10, spread evenly, and the sliding upper frame 11 is placed there. We will proceed.

It is preferable to add a scraper before the upper sliding frame 11 and add a finishing part afterward.

The above-mentioned guide vibrating material pre-treats the concrete 1, 1-, and the molding material forms the concrete into the desired cross-sectional shape and advances.

At the position where the end of the lower frame 10, that is, the end of the PC concrete slab, is to be molded, the rib forming member 19b is adjusted to the height of the rib at the end.

If the adjustment mechanism 20 displays the height of the member 19b (or rib), the height can be easily adjusted.

The member 19b is adjacent to the thin-walled portion forming member 19a and can be moved up and down by
Since it can be stopped, the adjustment mechanism 20 can be manually or automatically operated to gradually raise the first half of the length of the plate and gradually lower it for the second half as the plate progresses.

It is easy to make several plates in one process as shown in Figure 7.

The shape of the slope of the upper surface of the rib 3 is determined by the lifting speed.

Therefore, in order to make smooth adjustment, it is desirable to use a small computer or a cam to link the traveling distance and the amount of elevation of the member 19b, so as to obtain the slope of the curve as designed and calculated.

In the case of a PC concrete plate with hollow ribs 3l as shown in Fig. 3, first, only the flat thin-walled part 1 is made by sliding or shaping, and then a foamed resin material, plywood, etc. having the same shape as the hollow part 6 is made on top of it. The embedded core is fixed, concrete is spread on it, the sliding upper frame is advanced, and the desired external shape of the rib 3' is formed by controlling the height of the above-mentioned cliff part or shaped member.

In order to make a structure in which the height of the grooved rib 5 changes as shown in Fig. 4 by the sliding or forming method, the upper and lower formwork must be moved at the same time, which is troublesome, but it is possible to make it as shown in Fig. 5. The lower mold can be fixed easily.

In the case of small-scale production, it is easier to use sliding molding for the parts whose cross sections do not change, and for the ribs whose cross sections change, place side frames on the left and right, fill them with concrete by hand, and construct them one after another moving forward.

The ribs are not necessarily the entire length of the plate, but may be as short as about two-thirds of the center.

The PC concrete slab of the present invention and its manufacturing method have been explained above with reference to a small number of embodiments. However, depending on the application and the conditions of the manufacturing factory, without changing the gist, designers and field engineers may use known techniques. Can be varied and applied in a variety of ways.

This invention is the first ribbed PC concrete plate.
We realized a dynamic reinforcement method in which the prestress is different between the ends and the center, and the more the center is, the more prestress distribution is applied to the cross section to increase its bending strength.

Unlike the conventional static strengthening method by increasing the cross-sectional area, this method achieves the effect of increasing bending strength by distributing pre-stress, that is, generating tensile stress on the upper side and compressive stress on the lower side, even if the cross-sectional area is the same.

Added to this is the static reinforcement effect due to the increase in rib cross-sectional area.

In addition, as a manufacturing method for the PC concrete plate with raised ribs in the center, the molding material of the upper frame for the sliding molding is divided into thin parts and rib parts, and only the rib part is gradually pulled up during sliding molding. , by pulling it down, it became possible to slide form concrete slabs with different rib dimensions using the same forming device.

[Brief explanation of the drawing]

Figure 1 is an elevational view of one embodiment of this invention, Figures 2 to 5 are cross-sectional views of four embodiments, Figures 6 and 7 are elevational views of two manufacturing apparatuses, and Figure 8 is the same. Plan view, Figures 9 and 10 are 8th
FIG. 11 is an enlarged view of the main part of FIG. 9, and FIG. 12 is an explanatory diagram of the same automated rib member adjustment mechanism seen from the front. 1...Plate-like thin wall portion, 3...Rib, 4...
...PC steel wire, 10...Long bottom frame, 11
......Sliding upper frame, 12...PC steel wire tension device, 19...Mold material, 19a...
Thin wall part molding member, 19b... Rib part molding member,
20...Adjustment mechanism.

Claims (1)

[Scope of Claims] 1. A plate-shaped thin wall portion with a wire mesh on the entire surface, a rib that is a protrusion extending the entire length of this thin wall portion, and a P that passes under the rib.
A PC concrete plate with raised ribs in the center, which is made of C steel wire, and is characterized in that the ribs are highest near the center of the entire length and gradually decrease in height toward the ends. 2. When shaping the hardened concrete on the lower frame into the required cross-sectional shape one by one as the upper frame advances using a long lower frame, sliding upper frame, and PC steel wire tensioning device, the sliding upper frame is A molded material attached under a beam perpendicular to the direction of travel can be raised, lowered, and stopped by a thin-walled shaping member fixed to the beam and an adjustment mechanism attached to the beam adjacent to this member. This method of manufacturing a PC concrete plate with raised ribs in the center is characterized in that the rib part-forming member is divided into rib part-forming members, and as the rib part-forming member progresses, the first half of the plate length is gradually raised and the second half is gradually lowered.