Precast concrete foundation beam structure and method of construction thereof

Abstract

This invention provides a precast concrete foundation beam structure and a method for constructing it that offer high construction efficiency in super high-rise reinforced concrete buildings. [Solution] The method for constructing the foundation beam structure 1 is a method for constructing a foundation beam structure consisting of a foundation beam 5 and a pile head foundation 8 or an isolated foundation, wherein a pair of lower precast concrete beam members 10A, 10A are placed on a base plate between a pair of pile head foundations 8, 8, facing each other so as to form a portion of the joint space S1 in the beam width direction of the foundation beam 5, with a portion of the first stirrups protruding upward, a pair of upper precast concrete beam members 10B, 10B are placed on the pair of lower precast concrete beam members 10A, 10A, facing each other so as to form the remaining portion of the joint space S1 in the beam width direction, with stirrups 16 protruding in the beam width direction of the foundation beam 5, an overlap joint is formed at the joint forming portion with the stirrups 16 and the first stirrups, and concrete 20 is poured into the joint space S1 and the joint space S2.

Description

Technical Field

[0001] The present invention relates to a precast concrete foundation beam structure and a construction method thereof, and particularly to a foundation beam structure formed by using a plurality of half-precast concrete members for a precast concrete foundation beam and a construction method thereof.

Background Art

[0002] The foundation beam structure of a building is often constructed by conventional methods. However, in the construction by conventional methods, the construction labor and the construction period increase, so precast concrete may be used not only for the superstructure but also for the foundation beam structure which is the substructure.

[0003] When precast concrete is used for the foundation beam structure, in large buildings such as condominiums and buildings, since the beam formation and beam span of the foundation beam become large, the precast concrete foundation beam becomes considerably heavier than the precast concrete column. For this reason, a large crane corresponding to the size of the foundation beam is required at the site, which causes factors such as an increase in construction cost.

[0004] In order to address these problems, Patent Document 1 discloses a construction method of a foundation structure in which two precast concrete beam members are integrated with in-situ concrete to form a foundation beam, thereby reducing the weight per precast concrete beam member.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the invention described in Patent Document 1, in the case of a super high-rise reinforced concrete building where the beam depth of the foundation beam may be 4m, the weight of each precast concrete beam member becomes about 15t, making manufacturing, lifting, and transportation difficult. In particular, the dimensions exceed the loading limits of trucks, making transportation by truck impossible. For this reason, the foundation structure must be constructed using conventional methods. Consequently, it is difficult to improve construction efficiency.

[0007] Therefore, the object of the present invention is to provide a precast concrete foundation beam structure and a method for constructing the same, which offers good construction efficiency in super high-rise reinforced concrete buildings. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a method for constructing a precast concrete foundation beam structure, comprising a foundation beam and a pile head foundation or isolated foundation, characterized in that a pair of lower precast concrete beam members are placed on a base plate between a pair of pile head foundations or a pair of isolated foundations, facing each other so as to form a portion of a first joint space in the beam width direction of the foundation beam, thereby causing a portion of the first stirrups to protrude upward; a pair of upper precast concrete beam members are placed on the pair of lower precast concrete beam members, facing each other so as to form the remaining portion of the first joint space in the beam width direction, thereby causing a second stirrup to protrude in the beam width direction of the foundation beam; an overlap joint is formed between the second stirrups and the first stirrups in a joint forming portion formed below the pair of upper precast concrete beam members; and concrete is poured into the first joint space and the second joint space between the pair of upper precast concrete beam members and the pile head foundation or isolated foundation.

[0009] The joint forming portion may be formed at the lower part of the pair of upper precast concrete beam members by reducing the thickness of the upper precast concrete beam members.

[0010] It is preferable to have the lower beam main reinforcement protrude from the pair of lower precast concrete beam members in the direction of the long axis of the foundation beam, and the upper beam main reinforcement protrude from the pair of upper precast concrete beam members in the direction of the long axis of the foundation beam, and to arrange the third stirrups in the second joint space so as to surround the lower beam main reinforcement and the upper beam main reinforcement.

[0011] It is preferable to form 180° hooks at the ends of the first, second, and third stirrups.

[0012] The pair of lower precast concrete beam members and the pair of upper precast concrete beam members should be manufactured to have a weight less than or equal to the weight of the precast concrete column members that are placed on the upper surface of the pile head foundation or the isolated foundation.

[0013] It is preferable to place a first core reinforcement to connect the first stirrups and the second stirrups in the beam depth direction of the foundation beam, and to place a second core reinforcement to connect the upper and lower parts of the third stirrups in the beam depth direction of the foundation beam.

[0014] It is preferable to form cotters between the pair of lower precast concrete beam members and the pair of upper precast concrete beam members.

[0015] The precast concrete foundation beam structure according to the present invention is a foundation beam structure for a foundation beam and a pile head foundation or isolated foundation, characterized in that a pair of lower precast concrete beam members, each having a portion of a first stirrup protruding upward, are placed on a base plate facing each other so as to form a portion of a first joint space in the beam width direction of the foundation beam; a pair of upper precast concrete beam members, each having a second stirrup forming an overlap joint with the first stirrup at a joint forming section provided at the bottom, are placed on the pair of lower precast concrete beam members facing each other so as to form the remaining portion of the first joint space in the beam width direction; and cast-in-place concrete is poured into the first joint space and the second joint space between the pair of lower precast concrete beam members and the pair of upper precast concrete beam members and the pile head foundation or isolated foundation. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a precast concrete foundation beam structure with good construction efficiency and a method for constructing the same in super high-rise reinforced concrete buildings. [Brief explanation of the drawing]

[0017] [Figure 1] (a) is a front view showing a precast concrete foundation beam structure according to an embodiment of the present invention, and (b) is a plan view of (a). [Figure 2] (a) is a cross-sectional view of the beam shown along the section IIa-IIa in Figure 1(a), and (b) is a cross-sectional view of the beam shown along the section IIb-IIb in Figure 1(a). [Figure 3] (a) is a side cross-sectional view of the lower half-precast concrete beam member according to an embodiment of the present invention, and (b) is a rear view of (a). [Figure 4] (a) is a side cross-sectional view of the upper half-precast concrete beam member according to an embodiment of the present invention, and (b) is a rear view of (a). [Figure 5](a)-(d) are diagrams for explaining a method of constructing a precast concrete foundation beam structure according to an embodiment of the present invention. [Figure 6] (a) is a front view showing a precast concrete foundation beam structure according to a modification, and (b) is a plan view of (a).

Mode for Carrying Out the Invention

[0018] The foundation beam structure and its construction method according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or equivalent components. Also, in each figure, for the sake of simplification of the figure, the illustration of stirrups, width stop bars, etc., which are not features of the invention, is omitted.

[0019] Figs. 1(a), (b), Figs. 2(a), (b) show a foundation beam structure 1 of a foundation beam and a pile head foundation according to an embodiment of the present invention. The foundation beam structure 1 includes a joint space S1 between the foundation beam 5 and the pile head foundation 8, and lower (half) precast concrete foundation beam members 10A, 10A (hereinafter referred to as lower precast beam members 10A) installed so that their main surfaces face each other with a predetermined interval, and upper (half) precast concrete foundation beam members 10B, 10B (hereinafter referred to as upper precast beam members 10B) placed on the lower precast beam members 10A. The foundation beam 5 and the pile head foundation 8 are integrated by placing in-situ concrete 20 in the joint space S2 therebetween. The foundation beam structure 1 constitutes, for example, a foundation beam structure of a super high-rise building with a height of 60 m or more, the column span S = 7 m, the weight per precast concrete column member 7 (hereinafter referred to as precast column member 7) constituting the column 6 is about 10 t, the cross-section is 1000 mm × 1000 mm, and the length is 4000 mm. Also, as the ready-made pile P, a cast-in-place reinforced concrete pile with Φ = 2000 mm is driven.

[0020] The foundation beam 5 is a beam with a beam width W = 1000 mm, which comprises precast beam members 10A, 10A at the lower part with a beam height H = 4000 mm, a beam height H1 = 2000 mm, a length L = 7000 mm, a beam width W1 = 250 mm, a beam width W2 = 500 mm, and a weight of about 7.5 t per piece, and precast beam members 10B, 10B at the upper part with a weight of about 6.5 t per piece as components.

[0021] As shown in FIGS. 3(a) and (b), in the lower precast beam member 10A, the lower beam main reinforcement 13 is arranged so as to protrude from the end faces 41, 42 in the long axis direction of the beam concrete 11, and the stirrups 15 are arranged so as to protrude above the beam concrete 11.

[0022] The lower beam main reinforcement 13 is surrounded in a U shape by the stirrups 15 that are arranged so as to protrude in the beam width direction from the inner surface 43 of the beam concrete 11 and partially protrude from the upper end of the beam concrete 11 inside and outside the beam concrete 11 of the lower precast beam member 10A. 180° hooks are formed at both ends of the stirrups 15. Also, in the part of the stirrups 15 protruding in the beam width direction, the spacer bars 18A are arranged from the bottom to the top. 180° hooks are also formed at both ends of the spacer bars 18A, and one hook is hung on the lower beam main reinforcement 13. The inner surface 43 of the beam concrete 11 facing the other lower precast beam member 10A is a surface corresponding to the concrete placement surface during the manufacture of the precast slab, and the unevenness of the surface during manufacture remains as it is, enhancing the adhesion to the cast-in-place concrete 20.

[0023] As shown in Figures 2(a), 4(a), and 4(b), the upper precast beam member 10B is reinforced such that the upper main beam reinforcement 14 protrudes from the end faces 41 and 42 in the long axis direction of the beam concrete 11. In addition, a joint forming section 17 is formed in the upper precast beam member 10B (below the beam concrete 11) by reducing the thickness of the member, and one end of the stirrup reinforcement 16 on the outer surface 45 side protrudes from the joint forming section 17. The other end of the stirrup reinforcement 16 is also reinforced so as to protrude towards the inner surface 43 side. The joint forming section 17 is a trapezoidal recessed portion in side view, located on the inner surface 43 side of the lower part of the beam concrete 11, and a lap joint J1 between the stirrup reinforcement 16 and the stirrup reinforcement 15 is formed in this portion.

[0024] The upper beam main reinforcement 14 is surrounded in an inverted U-shape by stirrups 16 arranged inside and outside the beam concrete 11 of the upper precast beam member 10B, extending from the inner surface 43 of the beam concrete 11 in the beam width direction and protruding into the joint forming section 17 below the beam concrete 11. 180° hooks are formed at both ends of the stirrups 16. In addition, core reinforcement 18B is arranged from top to bottom on the portion of the stirrups 16 that protrudes in the beam width direction. 180° hooks are also formed at the lower end of the core reinforcement 18B.

[0025] Furthermore, as shown in Figure 1(a), cotters 19 are formed at the upper end of the lower precast beam member 10A and the lower end of the upper precast beam member 10B. The cotters 19 are formed so that when the upper precast beam member 10B is placed in a predetermined position on the lower precast beam member 10A, the cotters 19A and B face each other. When cast-in-place concrete 20 is poured into the joint space S1, which will be described later, the cast-in-place concrete 20 is also filled into the cotters 19, and the lower precast beam member 10A and the upper precast beam member 10B are integrated.

[0026] (Joint structure in the beam width direction and beam depth direction) The foundation beam 5 is placed on the leveling concrete at the bottom of a trench (not shown) formed by excavating the ground, with the lower precast beam members 10A, 10A facing each other with their stirrups 15, 15 protruding toward the inner surface 43 side (beam width direction) facing each other, as shown in Figure 2(a), with a gap of 500 mm (W2 in Figure 2(a)) (part of the joint space S1). Furthermore, the upper precast beam members 10B, 10B are placed on the upper ends of the lower precast beam members 10A, 10A with their joint forming portions 17, 17 facing downwards, their stirrups 16, 16 protruding toward the inner surface 43 side (beam width direction) facing each other, with a gap of 500 mm (W2) (another part of the joint space S1) facing each other, so that the outer surface 45 is flush with the lower precast beam members 10A, 10A. In the joint forming section 17, stirrups 15 and 16 overlap each other near their rebar ends by a predetermined length to form an overlap joint J1. Also, on the beam width center side, stirrups 15 and 16 overlap each other near their rebar ends by a predetermined length to form an overlap joint J2. Furthermore, core reinforcing bars 18A and 18B overlap each other near their rebar ends by a predetermined length to form an overlap joint J3. Cast-in-place concrete 20 is poured into the joint space S1, thereby integrating the lower precast beam members 10A, 10A, the upper precast beam members 10B, 10B, and the cast-in-place concrete 20.

[0027] (Joining structure in the longitudinal direction of the beam) Furthermore, as shown in Figures 1(a) and 1(b), in the joint space S2, the lower beam main reinforcement bars 13 and upper beam main reinforcement bars 14, which protrude from both axial end faces 41 and 42 of the lower precast beam member 10A and the upper precast beam member 10B, are joined to the beam main reinforcement connection bars 9, which are arranged to protrude from the side surface of the pile head foundation 8, via mechanical joints 30. Furthermore, at the joint site, as shown in Figure 2(b), stirrups 21 from below and stirrups 22 from above are arranged at a predetermined reinforcement pitch in the longitudinal direction of the beam, with overlapping joints J4 formed by overlapping the ends of each reinforcement bar by a predetermined length, surrounding the lower beam main reinforcement bars 13, the upper beam main reinforcement bars 14, and the beam main reinforcement connection bars 9. Also, on the center side of the foundation beam width, core reinforcement bars 23A from below and core reinforcement bars 23B from above are arranged at a predetermined reinforcement pitch in the longitudinal direction of the beam, with overlapping joints J5 formed by overlapping the ends of each reinforcement bar by a predetermined length. Cast-in-place concrete 20 is poured into the joint space S2, integrating the foundation beam 5 and the pile head foundation 8. Furthermore, the main column reinforcement (not shown), positioned to protrude from the upper surface of the pile head foundation 8, is connected to the mechanical joint (not shown) at the lower end of the precast column member 7. The precast column member 7 and the pile head foundation 8 are reinforced with specified structural and assembly reinforcement (not shown), ensuring the necessary strength and load-bearing capacity.

[0028] (Construction method for foundation beam structure 1) First, the pile head foundation 8 is formed by placing concrete and arranging the required reinforcement at the top of the cast-in-place reinforced concrete pile P, or by placing a precast pile cap member manufactured in a factory.

[0029] Between the pile head foundations 8, as shown in Figure 5(a), one lower precast beam member 10A is placed on the leveling concrete C at a predetermined position on the leveling concrete C of the bottom of a trench (not shown) formed by excavating the ground, and the other lower precast beam member 10A is moved and placed side by side with a predetermined distance D between them so that their inner surfaces 43 face each other. Then, formwork is assembled on the side of the joint space S2 and formwork support is carried out. In addition, in the joint space S2, the lower beam main reinforcement 13 and the beam main reinforcement connecting reinforcement 9 are joined with mechanical joints 30, and stirrups 21 are placed below them in a U-shape, with a predetermined reinforcement pitch in the longitudinal direction of the beam. Similarly, core reinforcement 23A is placed below the lower beam main reinforcement 13, with a predetermined reinforcement pitch in the longitudinal direction of the beam.

[0030] As shown in Figure 5(b), cast-in-place concrete 20 is poured into the lower half of the joint space S1 between the lower precast beam members 10A, 10A, which is placed on the leveling concrete C, up to a position slightly below the top surface of the lower precast beam members 10A, and is allowed to cure for a predetermined period. At the same time, cast-in-place concrete 20 is also poured into the joint space S2 up to the same height as the joint space S1, and is allowed to cure for a predetermined period.

[0031] As shown in Figure 5(c), one upper precast beam member 10B is placed on the upper end of one lower precast beam member 10A such that their outer surfaces 45 are flush. Similarly, the other upper precast beam member 10B is placed on the upper end of the other lower precast beam member 10A such that their outer surfaces 45 are flush.

[0032] Furthermore, in the joint space S2, the upper beam main reinforcement 14 and the beam main reinforcement joining reinforcement 9 are joined with a mechanical joint 30, and stirrups 22 are placed from above in an inverted U shape, overlapping the ends of the stirrups 21 by a predetermined length to form overlap joints J4, and reinforcement is placed in the longitudinal direction of the beam at a predetermined reinforcement pitch. Similarly, core reinforcement 23B is placed from above, overlapping the ends of the core reinforcement 23A by a predetermined length to form overlap joints J5, and reinforcement is placed in the longitudinal direction of the beam at a predetermined reinforcement pitch.

[0033] As shown in Figure 5(d), cast-in-place concrete 20 is poured up to the top of the upper precast beam member 10B into approximately the upper half of the joint space S1 between the upper precast beam members 10B, 10B, which are placed on the lower precast beam members 10A, 10A, and into the cotters 19 (not shown), and then cured for a predetermined period. At the same time, cast-in-place concrete 20 is also poured into the joint space S2 to the same height as the joint space S1, and then cured for a predetermined period. After the predetermined curing period, the formwork is dismantled and the formwork is removed to complete the foundation beam structure 1.

[0034] As described above, the foundation beam 5 and the pile head foundation 8 are integrated to form the foundation beam structure 1.

[0035] According to the foundation beam structure 1 of this embodiment, the foundation beam 5 is formed by four precast members: lower precast beam members 10A, 10A and upper precast beam members 10B, 10B, each weighing less than or equal to approximately 10 tons of precast column member 7, and cast-in-place concrete 20 that joins and integrates them. Therefore, at the construction site and the precast factory, the lower precast beam members 10A, 10A and upper precast beam members 10B, 10B that constitute the foundation beam 5 with a beam depth of 4m for a super high-rise building can be lifted using the same lifting equipment used to lift the precast column member 7. Consequently, there is no need to use lifting equipment with high lifting capacity, costs can be reduced, transportation by truck becomes possible, and handling at the construction site and in the precast factory becomes easier, improving work safety. Furthermore, since lower precast beam members 10A, 10A and upper precast beam members 10B, 10B are used, labor can be reduced compared to foundation beams using conventional construction methods, thus shortening the construction period and improving construction accuracy, thereby improving construction efficiency. In addition, since core reinforcement 18A, 18B and 23A, 23B are provided, the strength of the foundation beam 5 can be efficiently increased, improving construction efficiency. Moreover, since stirrups 15, 16 and 21, 22, core reinforcement 18A, 18B and 23A, 23B are connected with lap joints with 180° hooks, and cotters are formed between the lower precast beam members 10A, 10A and the upper precast beam members 10B, 10B, the foundation beam 5 is optimally integrated, improving construction efficiency.

[0036] (modified version) In the above embodiment, each precast member constituting the foundation beam 5 was less than or equal to the weight of one precast column member 7. However, if the lifting capacity of the lifting machine used at the construction site of the foundation beam structure 1 has the capacity to lift something heavier than the weight of one precast column member 7, then each precast member constituting the foundation beam 5 may be heavier than the weight of one precast column member 7 by that margin.

[0037] In the above embodiment, the foundation beam 5 and the pile head foundation 8 were integrated, but the foundation beam and the isolated foundation may also be integrated. The type of pile may also be other than a cast-in-place reinforced concrete pile.

[0038] In the above embodiment, a joint forming portion was formed in the upper precast beam member. However, for example, if the thickness of the beam concrete in the joint forming portion is insufficient, a lap joint may be formed by allowing the stirrups of the upper and lower precast beam members to protrude inward without forming a recess for the joint forming portion in the upper precast beam member. Alternatively, as long as a lap joint can be formed, the joint forming portion may be recessed into a shape other than a trapezoid in side view.

[0039] Furthermore, in the above embodiment, there were four precast beam members constituting one foundation beam 5. However, if the precast beam members become heavy, for example, as shown in Figure 6, a joint space S3 may be provided in the central part of the foundation beam 5 in the longitudinal direction to divide the precast beam members and make them eight precast beam members 50 (50A, 50B). Alternatively, one or more joint spaces S3 may be provided in the foundation beam 5 to increase the number of precast beam members and make the weight of each precast beam member less than or equal to the weight of the precast concrete column member 7. Or, instead of increasing in the longitudinal direction of the beam, precast beam members may be placed in the depth direction of the beam, or they may be increased in both the longitudinal and depth directions.

[0040] In the above embodiment, core reinforcement bars 18 and 23 were provided in the foundation beam 5. However, if core reinforcement bars are not necessary based on structural calculations, they may be omitted, or their number may be increased or decreased as needed.

[0041] In the above embodiment, cotters were formed on the lower precast beam member 10A and the upper precast beam member 10B. However, the shape of the cotters is not limited to those shown in the figures; for example, one side may be convex and the other concave, or other shapes may be used. If cotters are not required based on structural calculations, they may be omitted.

[0042] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of each claim. That is, embodiments obtained by combining technical means that have been appropriately modified within the scope of the claims are also included in the technical scope of the present invention. [Explanation of symbols]

[0043] 1,2 Foundation beam structure 5,5A foundation beam 6 pillars 7. Precast concrete column members (precast column members) 8 Pile head foundation 9 Beam main reinforcement connection reinforcement 10.50 Precast concrete foundation beam members (precast beam members) 10A, 50A Lower precast concrete foundation beam member (lower precast beam member) 10B, 50B Upper precast concrete foundation beam member (Upper precast beam member) 11. Beam concrete 13 Lower beam main reinforcement 14 Upper beam main reinforcement 15,16,21,22 Ribs 17 Joint forming section 18,18A,18B,23,23A,23B Core muscle 19 Cotters 20 Cast-in-place concrete 30 Mechanical couplings J1, J2, J3, J4, J5 Overlap joint P Precast piles (cast-in-place reinforced concrete piles) S1,S2,S3 joint space

Claims

1. A method for constructing a foundation beam structure consisting of a foundation beam and a pile head foundation or isolated foundation, A pair of lower precast concrete beam members are placed on the base plate between a pair of pile head foundations or a pair of independent foundations, facing each other so as to form a portion of the first joint space in the beam width direction of the foundation beam, thereby causing a portion of the first stirrups to protrude upward. By placing a pair of upper precast concrete beam members opposite each other in the beam width direction to form the remaining portion of the first joint space, and by placing them on the pair of lower precast concrete beam members, the second stirrups are made to protrude in the beam width direction of the foundation beam, and an overlap joint is formed between the second stirrups and the first stirrups in the joint forming portion formed below the pair of upper precast concrete beam members. Concrete is poured into the first joint space and the second joint space between the pair of upper precast concrete beam members and the pile head foundation or the independent foundation. A method for constructing a precast concrete foundation beam structure, characterized by the following features.

2. The joint forming portion is formed at the lower part of the pair of upper precast concrete beam members by reducing the thickness of the upper precast concrete beam members. A method for constructing a precast concrete foundation beam structure according to feature 1.

3. The main reinforcement bars of the lower beam are made to protrude from the pair of lower precast concrete beam members in the direction of the long axis of the foundation beam. The main reinforcement bars of the upper beam are made to protrude from the pair of upper precast concrete beam members in the direction of the long axis of the foundation beam. In the second joint space, a third stirrup is arranged to surround the main reinforcement of the lower beam and the main reinforcement of the upper beam. A method for constructing a precast concrete foundation beam structure according to feature 1.

4. 180° hooks are formed at the ends of the first, second, and third ribs. A method for constructing a precast concrete foundation beam structure according to feature 3.

5. The pair of lower precast concrete beam members and the pair of upper precast concrete beam members are manufactured to have a weight less than or equal to the weight of the precast concrete column members that are placed on the upper surface of the pile head foundation or the isolated foundation. A method for constructing a precast concrete foundation beam structure according to feature 1.

6. A first core reinforcement is placed to connect the first stirrups and the second stirrups in the beam depth direction of the foundation beam. A second core reinforcement is placed to connect the upper and lower parts of the third stirrups in the beam depth direction of the foundation beam. A method for constructing a precast concrete foundation beam structure according to feature 3.

7. Cotters are formed between the pair of lower precast concrete beam members and the pair of upper precast concrete beam members. A method for constructing a precast concrete foundation beam structure according to feature 1.

8. A foundation beam structure consisting of a foundation beam and a pile head foundation or isolated foundation, A pair of lower precast concrete beam members, each with a portion of the first stirrups protruding upward, are placed on the base plate facing each other in the beam width direction of the foundation beam, forming a portion of the first joint space. A pair of upper precast concrete beam members, each having a second stirrup forming an overlap joint with the first stirrup at a joint forming section located at the bottom, are placed on the pair of lower precast concrete beam members, facing each other in the beam width direction to form the remaining portion of the first joint space. Cast-in-place concrete was poured into the first joint space and the second joint space between the pair of lower precast concrete beam members and the pair of upper precast concrete beam members and the pile head foundation or isolated foundation. A precast concrete foundation beam structure characterized by the following features.

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