KR100685222B1 - Double concrete structures - Google Patents

Abstract

       The present invention is to produce a double concrete structure using a high-performance steel fiber reinforced concrete and general concrete concrete structures used in bridges, underground structures or building structures, the high-performance steel fiber reinforced concrete is a steel fiber, blast furnace slag It is produced by mixing the cement with a certain compounding ratio, and cast it to a predetermined thickness on the part receiving the tensile force of the double concrete structure, and cast or cure precast concrete by placing a certain thickness on the part above it. One integrated double concrete structure.

       The high-performance steel fiber reinforced concrete is water: 170 kg / ㎥, cement: 490 kg / ㎥, fine aggregate: 678 kg / ㎥, coarse aggregate: 805 kg / ㎥, coarse aggregate maximum size: 13 mm, slump: 210 mm, air volume: 3.7 %, Water / binder ratio: 26%, silica fume: 33 kg / m 3, blast furnace slag: 131 kg / m 3, high performance water reducing agent: 9.81 kg / m 3, steel fiber ratio: 1.5%.

       The present invention is to suppress the occurrence of the rapid crack in the double concrete structure produced by using a high-performance steel fiber reinforced concrete to add a fiber to the concrete to control the fiber cracks to increase the ductility and toughness, Fine mineral admixtures such as silica fume and blast furnace slag are appropriately substituted with matrices (sand + cement-based materials) to induce density.

       In addition, through the addition of these additives to increase the adhesion performance of the aggregate and reinforcing steel fibers to maintain the load carrying capacity of the matrix, the strength is increased, and the initial crack, the working load and the bending stiffness was improved.

       As described above, the present invention forms a high-performance steel fiber reinforced concrete layer on a portion of a tension portion of a general concrete structure or a general prestressed concrete structure, and by constructing an integral double concrete structure having a general concrete layer of normal strength thereon, general prestressed concrete Compared with the structure, the initial crack and ultimate load can be increased, and the reinforcing steel fiber can control the crack to reduce the width of the main crack and suppress the progress of the main crack, so that it can be effectively used to increase the safety, usability and durability of the structure. At the same time, the girder of the bridge can be made longer to extend the geometric space of the bridge, and when the structure is applied to the underground structure, a wider underground space can be secured.

       High performance steel fiber reinforced concrete, double concrete structure, double prestressed concrete structure, steel fiber,

Description

       Double concrete structures             

       1 is a view showing a double prestressed concrete structure of a double concrete structure using a high strength steel fiber reinforced concrete of the present invention.

       Figure 2 (a) (b) is a view showing a cross section of the point portion and the central portion of the double prestressed concrete structure of Figure 1, respectively.

       Figure 3 (a) (b) is a cross-sectional view for showing a layer formed by pouring a general concrete and high-performance steel fiber reinforced concrete to manufacture a double prestressed concrete structure of a double concrete structure of the present invention.

       Figure 4 (a) (b) is a view showing that a double prestressed concrete (PSC) girder as a double prestressed concrete structure of a double concrete structure of the present invention.

       Figure 5 (a) (b) is a view showing the application of the double prestressed concrete girder, the double prestressed concrete structure of the present invention to bridges and underground structures.

       Figure 6 (a) (b) is a load-deflection curve graph showing the comparison between the flexural stiffness and load bearing capacity of the double prestressed concrete structure and the general prestressed concrete structure of the present invention.

       Figure 7 (a) (b) is a view showing a comparison of the propagation pattern of the main crack between the double prestressed concrete structure and the general prestressed concrete structure of the present invention.

       8 is a view showing that the high-performance steel fiber reinforced concrete is poured on the preflex beam which is another embodiment of the double concrete structure of the present invention.

       Figure 9 (a) (b) is a view showing that the high-performance steel fiber reinforced concrete or pre-stress is added to the I-beam, another embodiment of the double concrete structure of the present invention.

       <Explanation of symbols for the main parts of the drawings>

       10 bridge 11: PC steel wire

       12: rebar 13: general concrete

       14: anchorage 15: bridge deck

       16: column, piers 17: upper flange

       18 abdomen 19 lower flange

       20: double prestressed concrete structure

       21: high performance steel fiber reinforced concrete 22: type I steel

       30: double prestressed concrete (PSC) girder

       40: preflex beam 50: double concrete structure

       60: type I beam 70: prestressed type I beam

       The present invention relates to a double-concrete structure in which high-performance steel fiber reinforced concrete produced by mixing steel fibers in concrete at a predetermined ratio is cast in a predetermined thickness on a part of a tension portion, and then cast or pre-stressed with general concrete.

       The high-performance steel fiber reinforced concrete is water: 170 kg / ㎥, cement: 490 kg / ㎥, fine aggregate: 678 kg / ㎥, coarse aggregate: 805 kg / ㎥, coarse aggregate maximum size: 13 mm, slump: 210 mm, air volume: 3.7 %, Water / binder ratio: 26%, silica fume: 33 kg / m 3, blast furnace slag: 131 kg / m 3, high performance water reducing agent: 9.81 kg / m 3, steel fiber ratio: 1.5%.

       The double concrete structure of the present invention is to cast a high-performance steel fiber reinforced concrete to a certain thickness of the tension portion and the ordinary concrete is placed thereon, the type is a double prestressed concrete (PSC) girder and a preflex beam that is a double prestressed concrete structure High-performance steel fiber reinforced concrete is placed in the lower casing of the I-type steel where the preflex is introduced, and a PC is placed in the lower flange of the I-type steel or the I-beam with the high-performance steel fiber-reinforced concrete in the lower flange of the I-type steel. Various types of structures such as prestressed I-beams made by installing steel materials and placing high-performance steel fiber reinforced concrete on the lower flanges and prestressing into the PC steels, as well as structures in which high-performance steel fiber-reinforced concrete is placed on the part under the slab. Widely used at night To the structures.

        An object of the present invention is a double prestressed concrete (PSC) as a double concrete structure manufactured using high-performance steel fiber reinforced concrete to increase the ductility and toughness by mixing fine mineral admixtures such as steel fiber and silica fume, blast furnace slag to concrete It is to suppress the development of flexural cracks generated in the structure while increasing the ultimate load applied to the structure while suppressing the occurrence of the initial crack occurring in the double prestressed concrete structure such as girder.

       Another purpose is to build the bridges, high-rise buildings and offshore structures, and other large concrete structures in order to build up the strength, stiffness, toughness and ductility and durability of the construction materials required for these large structures. It is to develop construction materials with superior characteristics.

       In general, in general concrete structures, cracks occur in concrete structures due to lower tensile strength than compressive strength, and thus sag increases due to decrease in rigidity of concrete structures, and also due to excessive sagging due to continuous increase of external load. As a result, cracks continue to progress in the concrete structure, thereby reducing the integrity of the concrete structure, thereby reducing the structural performance due to the reduction in safety and durability of the structure.

       In addition, high-strength concrete exhibits higher compressive strength than normal-strength concrete as mechanical properties such as early strength increase, durability increase through watertightness, dry shrinkage and bleeding decrease, but tensile strength to compressive strength decreases with increasing strength. There is also a problem of brittle fracture characteristics.

       In the present invention, the steel fiber reinforced concrete with steel fibers added to compensate for these disadvantages can increase the ductility and toughness by inhibiting the rapid crack growth by the crack control action of the fiber. However, applying only fibers to concrete did not effectively increase the compressive and tensile strengths. Therefore, fine mineral admixtures such as silica fume and blast furnace slag are appropriately substituted in the matrix to induce density. Through this, high performance steel fiber reinforced concrete was applied to the concrete structure to increase the strength by suppressing the degradation of concrete stiffness after initial cracking by increasing the adhesion performance with aggregates and reinforcing fibers so that the matrix (sand + cement-based material) maintains the load bearing capacity. .

       Therefore, the present invention has been proposed to improve the above problems, the production of steel fiber reinforced concrete with the addition of steel fibers to the general concrete when applied to the concrete structure by using it sharply due to the crack control action of the fibers contained in the concrete In addition to suppressing the development of cracks and increasing the ductility and toughness, fine mineral admixtures such as silica fume and blast furnace slag are appropriately substituted in the matrix to induce density, The high performance steel fiber reinforced concrete that increases the strength and suppresses the decrease of the concrete stiffness after initial cracking by making the matrix (sand + cement-based material) maintain the load-bearing capacity by increasing the adhesion performance of , Such a double As a kind of crete structure, it is applied to the double prestressed concrete structure to increase the usability and stability of the structure compared to the general prestressed concrete structure, and to improve the durability by reducing the corrosion of reinforcing steel by inhibiting cracks. You can save money.

       In addition, the double prestressed concrete structure as a double concrete structure, such as the present invention has a structural structure that is almost similar to the case where the entire cross-section of the member is composed of steel fiber reinforced concrete and when the steel fiber is partially used and reinforced in the entire cross-section It is confirmed to have performance and can be called economic.

       Therefore, the fabrication of double prestressed concrete structures is well suited to the development of cost-saving technologies for social overhead capital in the short and long term, and the new concept that satisfies the stability and usability as well as economic feasibility due to the development of double prestressed concrete structures. You can create a structure of.

In consideration of the above, the high performance steel fiber reinforced concrete developed to suppress the flexural cracking of general prestressed concrete structures caused by the weak tensile strength of concrete and increase the initial crack and the ultimate load, To produce prestressed concrete structures.

       The present invention is water: 170 kg / ㎥, cement: 490 kg / ㎥, fine aggregate: 678 kg / ㎥, coarse aggregate: 805 kg / ㎥, coarse aggregate maximum size: 13 mm, slump: 210 mm, air volume: 3.7%, water Binder ratio: 26%, silica fume: 33 kg / m3, blast furnace slag: 131 kg / m3, high performance water reducing agent: 9.81 kg / m3, steel fiber ratio: 1.5% )to be.

       In addition, the high-performance steel fiber reinforced concrete 21 of the present invention, when compared to the concrete of general ordinary strength, first by mixing the silica fibers and blast furnace slag of steel fibers and mineral admixtures for increasing the ductility, toughness and tensile strength in the concrete mixture Its reinforcement differs from ordinary ordinary strength concrete.

       Construction method for manufacturing a structure such as double prestressed concrete (PSC) girder 30, which is a double prestressed concrete structure 20 as a double concrete structure 50 produced using the high-performance steel fiber reinforced concrete 21 Is as follows.

       The reinforcing bars 12 are assembled according to the shape of the structure to be fabricated and placed, and the PC steel wire 11 is disposed for the introduction of tensile force, and then the high-performance steel fiber reinforced concrete 21 is poured to a certain height of the tensile part to have a constant thickness. The high-performance steel fiber reinforced concrete (21) layer is formed, and then the ordinary concrete (13) of ordinary strength is cast and cured to a certain height so that the general concrete layer is formed to a certain thickness, and after curing, the PC The prestress is introduced into the steel wire 11 to manufacture the double prestressed concrete structure 20. In particular, the general concrete 13 layer and the high-performance steel fiber reinforced concrete 21 is characterized in that the double prestressed concrete structure 20 is an integral double concrete structure 50 to be integrated with each other.

       Hereinafter, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

           1 is a view showing a double prestressed concrete structure, which is a double concrete structure manufactured by using the high strength steel fiber reinforced concrete of the present invention, as a double prestressed concrete structure 20 as a double prestressed concrete girder 30 as an example As described above, the first step is to reinforce the reinforcing bar 12 to have the shape of the girder, and then install the PC steel wire 11, while installing the fixing holes 14 on both sides of the reinforcing bar for the shape of the girder by installing the PC The steel wire 11 is fixedly installed and the PC steel wire is installed at the lower part of the girder at the center part, and then the high-strength steel fiber reinforced concrete 21 is poured to a certain thickness of the tension part, and then the double prestressed concrete structure 20 is placed thereon. Placing ordinary concrete 13 with general strength up to the overall thickness of the girder As the double concrete structure 50 produced by introducing the prestress by tensioning the PC steel wire 11, a double prestressed concrete girder 30, which is a double prestressed concrete structure 20, is shifted to install a bridge. It was installed on the piers.

       Figure 2 (a) (b) is a view showing a cross section of the point portion and the central portion of the double prestressed concrete structure of Figure 1, respectively, the point portion and the central portion at both ends of the double prestressed concrete girder 30 of FIG. To show the cross section.

       Figure (a) shows a cross-section of both ends of the point portion, the PC steel wire 11 is arranged at both ends to introduce the prestress to the girder 30, the PC steel wire to the fixing unit 14 provided at both ends (11) shows the settling.

       In addition, the high-precision steel fiber reinforced concrete (21) is cast in a predetermined thickness on the lower portion of the girder (30), and the general concrete (13) is poured thereon, thereby pre-integrating the double prestressed concrete girder (30). Will be produced.

       Figure (b) shows a cross section of the central portion of the girder, the high-performance up to a constant thickness of the reinforcing bar 12 and PC steel wire 11 installed in the tension section and the girder 30 arranged in the shape of the girder 30 The steel fiber reinforced concrete 21 is poured, and the general concrete 13 is poured on it to produce a totally integrated double prestressed concrete girder 30.

       In order to install the double prestressed concrete structure 20, the high-performance steel fiber reinforced concrete 21 having a certain thickness is poured on the tension part and the general concrete 13 is poured thereon. The high-performance steel fiber reinforced concrete placed on the tension part 21 ) 4 to 8 hours have passed after placing the concrete (13) on it.

       The casting after 4 to 8 hours is to prevent the interfacial adhesion failure while forming a uniform layer between the high-performance steel fiber reinforced concrete (21) layer and the general concrete (13) layer.

       Figure 3 (a) (b) is a cross-sectional view for showing the layer formed by pouring general concrete and high-performance steel fiber reinforced concrete in order to manufacture a double prestressed concrete structure of the present invention, the casting of high-performance steel fiber reinforced concrete (21) layer After 4 hours as shown in (a) and after 8 hours as shown in (b), in the case of the general concrete layer in which ordinary concrete 13 was poured, the 4 hours and after 8 hours, respectively The homogeneous layer with the boundary line between the two concrete layers is almost straight.

       In addition, if the experiment was conducted with 0, 1, 2, 4, 6, and 8 hours of spacing time between the two layers to investigate the separation of the layers between the two layers during loading, the bending test may be terminated. It was observed that the layers between the two layers did not separate until the time of 12 hours was placed between the two concrete layers, resulting in layer separation.

       Therefore, a distinct uniform layer is formed between the two layers, and the interval of the concrete placing time between the two layers, which does not occur when the external load is applied, is set to 4 to 8 hours.

       In this way, the casting time is set by placing the spacing time between the two concrete layers and then a tension force is introduced to the pc steel wire 11 so that the pre-stress which is a tension force is introduced into the double prestressed concrete structure 20 which is the double concrete structure. .

       Figure 4 (a) (b) is a view showing the production of double prestressed concrete girder (PSC) girder as a double prestressed concrete structure of a double concrete structure of the present invention,

       As the above-mentioned high-performance steel fiber reinforced concrete (21) was cast to a certain height of the tension portion, and then after 4 to 8 hours, the concrete concrete (13) manufactured by pouring the general concrete (13) of general strength as Various embodiments of the double prestressed concrete girder 30, which is a double prestressed concrete structure 20, are shown.

       (A) is formed in the upper portion of the "T" shaped girders 30 to form the upper flange 17 and the lower portion of the upper flange 17 to form the abdomen 18 as a whole "T" shaped It is.

       As shown in the figure, the high-performance steel fiber reinforced concrete 21 is poured from the lower part of the abdomen 18, which is a tension part, to a certain height, and then, after 4 to 8 hours, the general concrete is spread over the entire abdomen 18 and the upper flange 17. After pouring (13), the already installed PC steel wire (11) to introduce a tension force to the pre-stressed double concrete structure 50 is a double prestressed concrete structure (20) double prestressed concrete girder (30) To show what you are making,

       (b) the upper and lower flanges (17, 19) formed on the upper and lower portions of the "I" -shaped girders 30, and the middle of the upper and lower flanges to form the abdomen (18) as a whole "I" shape It is.

       As shown in the drawing, the lower flange 19, which is a tensioning part, is poured with high-performance steel fiber reinforced concrete 21, and then, after 4 to 8 hours, the general concrete 13 is poured over the entire abdomen 18 and the upper flange 17. After curing, the already installed PC steel wire 11 is to introduce a tension force to show the production of the double prestressed concrete girder 30 is a pre-stressed double prestressed concrete structure 20.

       5 (a) (b) is a view showing the application of the double prestressed concrete girder, the double prestressed concrete girder to the bridge and the underground structure as a double concrete structure of the present invention, the double prestressed concrete structure manufactured in FIG. A double prestressed concrete girder 30, which is (20), is fabricated to build a pier 16 as shown in FIG. (A), and a double prestressed concrete girder 30, which is a double prestressed concrete structure 20, is installed thereon. Next, it is shown that the slab is placed on the bridge (10) with the bridge top plate (15) is installed, and when applied to the bridge in this way increases the span length than when the general prestressed concrete girder is applied to the bridge As it can be expected, there is an advantage that the lower geometry space of the bridge becomes wider.

       In addition, when applying the double prestressed concrete girder 30, which is a double prestressed concrete structure 20 to the underground structure, as shown in Figure (b) has an advantage that the geometric space of the bridge is widened by applying to the Figure (a) It can be applied to the underground space has the advantage of securing a wider underground space.

       Figure 6 (a) (b) is a load-deflection curve graph showing the comparison of the flexural stiffness and load bearing capacity between the double prestressed concrete structure and the general prestressed concrete structure of the double concrete structure of the present invention, Figure (a) is It is a load-deflection curve obtained through the bending test for the double prestressed concrete structure 20 and the general prestressed concrete structure, and (b) shows a total of 4 for the double prestressed concrete structure 20 and the general prestressed concrete structure. It is a load-deflection curve obtained from a bending test with a cyclic load of steps.

       In the load-deflection curve graph, two general prestressed concrete structures (NPC I, NPC II) and high-performance steel fiber reinforced concrete 21 according to the present invention are respectively 200 mm (DPC I) and 300 mm (DPC II) at the lower end of the tension section. , Flexural tests were performed on three double prestressed concrete structures 20 fabricated with a height of 400 mm (DPC III).

       Comparing and analyzing the figures (a) and (b), the initial crack load was increased by 24% in DPC I, 52% in DPC II, and 67% in DPC III compared to NPC, and the use load was increased by DPC compared to NPC. 29% in I, 43% in DPC II, and 52% in DPC III.

       The initial flexural stiffness represents the load-deflection curve slope prior to the initial crack and the increase in flexural stiffness represents a reduction in the deformation of the structure for loads of equal magnitude. Initial flexural stiffness increased by 20% in DPC I, 20% in DPC II, and 22% in DPC III, depending on the height of the high-performance steel fiber reinforced concrete (21).

       In terms of usability, the load bearing capacity for the same deflection is significantly increased by 18% in DPC I, 30% in DPC II and 52% in DPC III compared to NPC.

       Therefore, by applying the high-performance steel fiber reinforced concrete 21 to the tension portion in part through the experiment, it is possible to improve the initial crack and the use load while controlling the bending crack.

       Figure 7 (a) (b) is a view showing the comparison of the propagation pattern of the main crack between the double prestressed concrete structure and the general prestressed concrete structure of the present invention, Figure (a) is a general frist mentioned in FIG. Experimental results for the rest concrete structure, Figure (b) is the experimental results for the double prestressed concrete structure 20 produced by pouring the high-performance steel fiber reinforced concrete 21 of the present invention to a certain height.

       As shown in Figs. (A) and (b), as shown in the results of the experiment in Fig. (A), the cracks of the NPC are significantly advanced to the compression part when the fracture is reached, but in Fig. (B) As shown in the experimental results, the DPC can confirm the effect of suppressing the growth of the main crack than the main crack progress of the experimental results of FIG.

       This is to suppress the progression of the main crack by increasing the ductility, toughness and tensile strength of the high-performance steel fiber reinforced concrete (21) by mixing the silica fibers and blast furnace slag, which is a steel fiber and fine mineral admixture applied to the high performance steel fiber reinforced concrete (21) While the crack width is slowed down.

        8 is a view showing the high-performance steel fiber reinforced concrete is poured into the preflex beam, which is another embodiment of the double concrete structure of the present invention, in which the lower flange 19 of the I-type steel 22 bent upwards is introduced. The present invention relates to a preflex beam (40) manufactured by placing high-performance steel fiber reinforced concrete (21) on a reinforced lower casing reinforcing bar and placing general concrete (13) thereon, and fixed to a lower flange (19) on which tensile force is applied. The high-performance steel fiber reinforced concrete 21 of thickness is poured, and the general concrete 13 is poured on it.

       The beam made in this way can reinforce the tensile force of the concrete to introduce a larger amount of pre-placement, thereby reducing the height of the beam, and also increasing the span of the beam, thereby making it possible to bridge bridges or structures between longer spans. There is an advantage to install.

       Figure 9 (a) (b) is a view showing that the high-performance steel fiber reinforced concrete or pre-stress is added to the I-beam, another embodiment of the double concrete structure of the present invention, the lower part of the general I-shaped steel 22 A beam manufactured by pouring a high-performance steel fiber reinforced concrete 21 of a certain thickness on the flange 19 and casting a concrete concrete 13 on it after a certain time is landscaped, as shown in (a) as described above. After casting a high-performance steel fiber reinforced concrete 21 on the lower flange 19 of the I-type steel 22, after a certain time has elapsed is the I-beam (60) manufactured by pouring the concrete (13) on it,

       (B) shows the fixing fixture 14 on both sides of the lower flange 19 of the I-type steel 22 and interconnects the PC steel wire 11 to the fixing fixture 14, and then the lower flange 19 Prestressed I-beam (70) in which high-strength steel fiber reinforced concrete (21) is cast in a constant thickness of a predetermined time, and after pre-stressing is applied to the PC steel wire (11) after pouring concrete concrete (13) on it. )to be.

       In order to manufacture the various beams mentioned above, reinforcing the reinforcing bars to make a strong effect on the adhesion force of the concrete and the load applied to the beam to be cast in the future to all the skilled in the art As a matter of course, in the present invention, the present invention is described in detail by placing high-performance steel fiber reinforced concrete or by pouring general concrete.

       The double prestressed concrete structure according to the present invention can suppress the generation and growth of flexural cracks occurring in the tensile part of the structure by partially applying high-performance steel fiber reinforced concrete, and can improve the initial cracking, working load, and flexural rigidity. have.

       In addition, the double prestressed concrete structure can be applied to a part of the tensile part of the structure without applying high-performance steel fiber reinforced concrete to the shear surface, thereby ensuring effective construction and economic efficiency, and double prestressed concrete structure instead of the general prestressed concrete structure in the girder of the bridge. By applying, it is possible to achieve the long span of bridges compared to general prestressed concrete structures by controlling cracks, preventing corrosion, reducing deflection, increasing load capacity, improving load bearing capacity and structural stiffness, and securing more space when applied to underground structures. It is an efficient yet economic invention.

Claims (10)

      After reinforcing the reinforcing bars forming the skeleton of the structure, arranging the PC steel wire, and after pouring a high-performance steel fiber reinforced concrete to a certain height of the tensile part after a certain period of time to pour the general concrete of the general strength, the PC steel wire In the fabrication of a pre-stressed concrete structure in which tension is applied to The high performance steel fiber reinforced concrete is water; 170kg / m³, cement: 490kg / m³, fine aggregate: 678kg / m³, coarse aggregate: 805kg / m³, coarse aggregate maximum size: 13mm, slump: 210mm, air volume: 3.7%, water / binder ratio: 26%, silica fume: 33kg / m³, blast furnace slag: 131kg / m³, high performance water reducing agent: 9.81kg / m³, steel fiber ratio: double concrete structure characterized by mixing according to the mixing ratio of 1.5% delete delete delete delete delete        The method of claim 1,        The silica fume and blast furnace slag is a mixture composed of fine minerals, and when mixed with concrete, it becomes a dense structure to increase the adhesion performance with aggregates and steel fibers mixed in concrete, thereby increasing the strength of cured concrete and inhibiting the progress of cracking. Double concrete structure characterized by doing.        The method of claim 1,        After the predetermined time has elapsed, after the high-performance steel fiber reinforced concrete is poured to a certain height of the tension portion, a double concrete structure characterized in that the general concrete is poured after 4 to 8 hours.        The method of claim 1,        Double concrete structure characterized in that the load-bearing capacity for flexural stiffness and deflection increases according to the pouring height of the high-performance steel fiber reinforced concrete. delete

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