Disaster prevention shelter

Abstract

The challenge is to provide a disaster prevention shelter that can be installed inside wooden buildings at risk of collapse and that can ensure a safe space even if objects fall from a collapsed building. [Solution] The problem was solved by constructing a disaster prevention shelter that includes a truss structure on the left and right sides, support columns at the four corners, floor beams on the front and rear sides, and a roughly rectangular frame-shaped ceiling beam and ceiling board, wherein the lower chord of the truss structure has a configuration in which a tensile force is applied to a PC steel bar that has a ring body fixed to its outer surface and passes through a steel pipe filled with mortar or expanding mortar, and a compressive force is applied to the mortar or expanding mortar, so that the tensile load during an earthquake is applied simultaneously to both the PC steel bar and the steel pipe, and the diagonal members of the truss structure have a configuration in which a compressive load is applied to the mortar or expanding mortar filled inside the steel pipe.

Description

Technical Field

[0001] The present invention relates to a disaster prevention shelter that can ensure personal safety from disasters such as earthquakes and debris flows that crush houses.

Background Art

[0002] Patent Document 1 discloses an earthquake shelter that is composed of triangular structural units combined together.

[0003] Patent Document 2 discloses a shelter inner housing that includes a main body of a rectangular tube inserted into an outer housing, and a contact body that extends obliquely from a corner of the main body toward the outer housing and whose tip contacts the outer housing, and that sandwiches a concrete core material in cooperation with the outer housing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The earthquake shelter of Patent Document 1 has a structure consisting only of a triangular truss structure. However, since hollow pipes are used, the pipes are likely to buckle under axial compressive loads, so there is a problem that the compressive load resistance against collapsed buildings is low.

[0006] The shelter of Patent Document 2 uses a concrete core material, so the overall weight is extremely heavy, and there is a problem that it cannot be installed in a wooden building that has a risk of collapse.

[0007] This invention was conceived in view of these problems, and aims to provide a disaster prevention shelter that can be installed inside wooden buildings that are at risk of collapse, and that can secure a safe space even under the compressive load of a collapsed building. [Means for solving the problem]

[0008] The disaster prevention shelter according to claim 1 is a disaster prevention shelter having a form that combines a truss structure and a rectangular parallelepiped frame having a substantially square shape in plan view, comprising: two truss structures erected on the left and right sides of the rectangular parallelepiped frame, four support columns erected at the four corners of the rectangular parallelepiped frame, two floor beams connecting the lower ends and ends of the support columns between the front or rear sides of the rectangular parallelepiped frame, and four ceiling beams connecting the ends to the upper ends of the support columns so as to form a substantially square frame in plan view, wherein the truss structure has one lower chord The lower chord is composed of a main body and two diagonal members. The lower chord has ring bodies fixed to both ends of its outer surface, and mortar or expanding mortar filled inside a steel pipe coated with an adhesion inhibitor on its inner wall is sandwiched from both sides by two lower chord anchoring plates fitted inside the steel pipe. Prestress is applied to the PC steel rod by screwing anchoring plate nuts onto male threads at both ends of a PC steel rod that passes through the sheath inserted inside the steel pipe and the lower chord anchoring plates, thereby applying tensile force to the PC steel rod and compressive force to the mortar or expanding mortar, while the ends of the steel pipe are brought into contact with each other. The diagonal member has a configuration in which a fixing nut is screwed into the male threads of the PC steel rod that penetrate the two lower grid points, and a base portion fixed to the ring body is fixed to the lower grid points by fastening means, and the diagonal member is sandwiched on both sides between two diagonal member fixing plates, one of which is fitted into the steel pipe and the other of which protrudes from the end face of the steel pipe, with mortar or expanding mortar filled inside a steel pipe coated with an adhesion inhibitor on its inner wall, and a PC steel rod with a male thread screwed into it, one end of which is screwed into the diagonal member fixing plate and the other end of which protrudes from the diagonal member fixing plate The structure is characterized by having an upper and lower grid point where the diagonal member fixing plates abut each other, fixed by screwing fixing nuts into the male screws of the PC steel rods that pass through the upper or lower grid point, respectively, and a configuration in which the upper or lower grid point and the steel pipe are connected by screwing nuts into the male screws at both ends of the connecting rod material that passes through the upper or lower grid point and the flange portion at the end of the steel pipe, and a flat ceiling plate that is mounted on the upper end of the four corner support columns and the upper end of the diagonal member.

[0009] The disaster prevention shelter according to claim 2 is characterized in that, in claim 1, the support column, floor beam, or ceiling beam is sandwiched from both sides between two fixing plates having a portion fitted into the steel pipe and a portion protruding from the end face of the steel pipe, with mortar or expanding mortar filled inside a steel pipe coated with an adhesion inhibitor on its inner wall, and has a PC steel rod with a threaded male screw on one end screwed into the fixing plate and the other end protruding from the fixing plate, and is fixed to the connecting member to which the fixing plate abuts by screwing a fixing nut into the male screw of the PC steel rod that passes through the connecting member, and the connecting member and the steel pipe are connected by screwing nuts into the male screws at both ends of a connecting rod that passes through the connecting member and the flange portion at the end of the steel pipe.

[0010] The disaster prevention shelter according to claim 3 is characterized in that, in claim 1 or 2, the lower grid points, the base portion fixed to the ring body, the lower end of the support column, and the end of the floor beam are fixed to the lower blocks at the four corners by fastening means, the upper end of the support column, the end of the ceiling beam, and the ceiling board are fixed to the upper blocks at the four corners by fastening means, and the upper grid points and the ceiling board are fixed to the upper intermediate block by fastening means.

[0011] The disaster prevention shelter according to claim 4 is characterized in that, in claim 3, the upper grid point portion is separated for fixing each of the two diagonal members and can be integrated by fastening means.

[0012] The disaster prevention shelter according to claim 5 is characterized in that, in claim 3, diagonal braces made of rod-shaped steel are attached by fastening means to the corners between the ceiling beam and the support columns on the front and rear sides of the rectangular parallelepiped frame.

[0013] The disaster prevention shelter according to claim 6 is characterized in that, in claim 4, the bottom surfaces of the lower blocks at the four corners are made flat, and the shelter is provided with a flat base on which the lower blocks at the four corners can be placed or fixed. [Effects of the Invention]

[0014] The disaster prevention shelter described in claims 1 to 3 uses a member in which mortar or expansive mortar is filled inside a steel pipe. When a compressive load is applied in the axial direction of the steel pipe due to an earthquake or the like, the mortar or expansive mortar inside the steel pipe will be pushed outwards in the radial direction. However, the pipe-shaped steel pipe restrains the deformation caused by this pushing outwards, resulting in compressive stress in three dimensions, which exhibits a confined effect that increases strength and toughness. Therefore, the disaster prevention shelter forms a roughly rectangular parallelepiped frame, with a truss structure on the left and right sides. The lower chord is configured to be strong against tensile loads, and the diagonal members are configured to be strong against compressive loads. In addition, the columns, floor beams, and ceiling beams are made strong against seismic loads. As a result, even if a house collapses in an earthquake, the disaster prevention shelter will not collapse, thus protecting the lives of people staying inside the shelter.

[0015] Furthermore, by making it difficult for the filled mortar or expanding mortar to adhere to the inner wall of the steel pipe, the axial compressive load received by the mortar or expanding mortar is less likely to be transmitted to the steel pipe. As a result, while a steel pipe with only a cavity and no mortar filling is prone to buckling under axial compressive loads, the steel pipe is less prone to buckling and can withstand compressive loads approximately twice that of the steel pipe with only a cavity, thus achieving a confined effect.

[0016] The disaster prevention shelter described in claim 4 separates the upper nodal points and then integrates the separated parts, so that even if the tips of the PC steel rods protrude from both ends of the lower chord member's steel pipe, the lower chord member can be interposed between the two lower nodal points, and even if the tips of the PC steel rods protrude from both ends of the diagonal member's steel pipe, the diagonal member can be interposed between the lower nodal point and the upper nodal point, thus achieving the effect of being able to assemble a truss structure with the lower chord member and two diagonal members.

[0017] The disaster prevention shelter described in claim 5 can increase the strength of the corner between the ceiling beam and the support column, thereby providing the effect of making the disaster prevention shelter even less likely to collapse.

[0018] When the disaster prevention shelter according to claim 6 is installed indoors, the weight of the disaster prevention shelter is dispersed over the entire installation space of the disaster prevention shelter, so that the floor of the house is not damaged by each lower block where the weight of the disaster prevention shelter is concentrated, and the effect is achieved.

Brief Description of the Drawings

[0019] [Figure 1] It is a perspective view of the disaster prevention shelter of the present invention without a base. [Figure 2] It is a perspective view of the disaster prevention shelter of the present invention provided with a base. [Figure 3] It is a perspective view of the disaster prevention shelter of the present invention without a ceiling board and a base. [Figure 4] It is an explanatory view of a state where a user enters the disaster prevention shelter of the present invention and is sleeping. [Figure 5] It is a longitudinal sectional explanatory view of a truss structure. [Figure 6] It is a longitudinal sectional explanatory view of a lower chord member. [Figure 7] It is a sectional explanatory view of a lower chord member. (a) is an enlarged sectional explanatory view of part A in FIG. 6, and (b) is a sectional explanatory view of C-C in FIG. 6. [Figure 8] It is a longitudinal sectional explanatory view of a diagonal member. [Figure 9] It is an enlarged sectional explanatory view of part B in FIG. 8. [Figure 10] It is an explanatory view of a method for assembling a truss structure. [Figure 11] In FIG. 5, it is an explanatory view of a configuration in which a divided upper lattice portion of a diagonal member is reinforced with a gusset plate. [Figure 12] It is an explanatory view of a floor beam or a ceiling beam. (a) is an explanatory view of a longitudinal section, (b) is an enlarged explanatory view of part D in (a), and (c) is an explanatory view of a side view. [Figure 13] It is an explanatory view of a column. (a) is an explanatory view of a longitudinal section, (b) is an enlarged explanatory view of part E in (a), and (c) is an explanatory view of a side view. [Figure 14]In the diagrams illustrating the blocks, (a) is an enlarged view of section L in Figure 3, which is a perspective view illustrating the lower block; (b) is an enlarged view of section H in Figure 3, which is a perspective view illustrating the upper block; and (c) is an enlarged view of section M in Figure 3, which is a perspective view illustrating the upper middle block. [Figure 15] This figure shows the relationship between the maximum load applied to each steel pipe specimen, whether or not it has mortar filling or a ring. [Modes for carrying out the invention]

[0020] The disaster prevention shelter 1 of the present invention is designed to be installed inside buildings that are not earthquake-resistant, such as evacuation sites, evacuation buildings, or wooden houses, which are at risk of collapsing in an earthquake. It ensures a safe space even if an earthquake suddenly occurs and the building collapses while the person is sleeping or relaxing, thus preventing them from being crushed. As shown in Figure 4, for example, the user 80 can enter the disaster prevention shelter 1 and sleep inside. The size can be tailored to the purpose, for example, to provide a space for one person to sleep, two people to sleep, three people to sleep, four people to sleep, or a living room or gathering space.

[0021] The disaster prevention shelter 1 of the present invention, as shown in Figures 1 to 3, is a disaster prevention shelter 1 having a form that combines a truss structure and a rectangular parallelepiped frame which is substantially square in plan view, comprising two truss structures erected on the left and right sides of the rectangular parallelepiped frame, four support columns 4 erected at the four corners of the rectangular parallelepiped frame, two floor beams 5 connecting the lower ends and ends of the support columns 4 between the front or rear sides of the rectangular parallelepiped frame, and four ceiling beams 6a, 6b whose ends are connected to the upper ends of the support columns 4 so as to form a substantially square frame in plan view, and the truss The structure consists of one lower chord member 2 and two diagonal members 3a and 3b. As shown in Figure 6 or Figure 7, the lower chord member 2 has ring bodies 17 fixed to both ends of its outer surface, and mortar or expanding mortar 12 filled inside a steel pipe 11 coated with an adhesion inhibitor (not shown) on its inner wall is sandwiched from both sides by two lower chord member fixing plates 13 fitted inside the steel pipe 11. Fixing plate nuts 16 are screwed onto male threads at both ends of a PC steel bar 15 that passes through the sheath 14 inserted inside the steel pipe 11 and the lower chord member fixing plates 13, thereby applying tensile force to the PC steel bar 15 and the mortar. With the barrel or expanding mortar 12 subjected to compressive prestress, the ends of the steel pipe 11 are brought into contact with two lower grid points 7a and 7b, respectively, and fixed by screwing fixing nuts 19 onto the male threads of the PC steel rod 15 that penetrate the lower grid points 7a and 7b, and the base portion 35 fixed to the ring body 17 is fixed to the lower grid points 7a and 7b by fastening means, and the diagonal members 3a and 3b are configured such that, as shown in Figure 8 or Figure 9, mortar or expanding mortar 22 filled inside the steel pipe 21, which has an adhesion inhibitor (not shown) applied to its inner wall, is inserted from both sides, front The PC steel rod 25 is sandwiched between two diagonal brace fixing plates 23, each having a portion fitted inside the steel pipe 21 and a portion protruding from the end face of the steel pipe 21. One end of the PC steel rod 25 is screwed into the diagonal brace fixing plate 23 and the other end protrudes from the diagonal brace fixing plate 23, and the PC steel rod 25 is fixed to the upper grid points 8a, 8b and the lower grid points 7a, 7b, respectively, by screwing fixing nuts 28 into the male threads of the PC steel rod 25, which pass through the upper grid points 8a, 8b or the lower grid points 7a, 7b, respectively.The structure has a configuration in which nuts 61 are screwed onto male threads at both ends of a connecting rod 29 that passes through 7b and the flange portion 27 at the end of the steel pipe 21, thereby connecting the upper grid points 8a, 8b or the lower grid points 7a, 7b to the steel pipe 21, and includes flat ceiling plates 30 mounted on the upper ends of the four corner support columns 4 and the upper ends of the diagonal members 3a, 3b.

[0022] As shown in Figure 12 or 13, the support column 4, the floor beam 5, or the ceiling beams 6a and 6b are constructed by sandwiching mortar or expanding mortar 52, which is filled inside a steel pipe 51 coated with an adhesion inhibitor (not shown) on its inner wall, between two fixing plates 53, each having a portion inserted into the steel pipe 51 and a portion protruding from the end face of the steel pipe 51. A PC steel bar 55 with a male screw thread is attached to one end of the fixing plate 53 and the other end protruding from the fixing plate 53. The fixing plate 53 is fixed to the connecting member 45 or connecting member 46 by screwing a fixing nut 58 onto the male screw of the PC steel rod 55 which passes through the connecting member 45 or connecting member 46, and nuts 62 are screwed onto the male screws at both ends of the connecting rod material 59 which passes through the connecting member 45 or connecting member 46 and the flange portion 57 at the end of the steel pipe 51, thereby connecting the connecting member 45 or connecting member 46 and the steel pipe 51.

[0023] As shown in Figures 1 to 3, the disaster prevention shelter 1 has a form that combines a truss structure and a rectangular parallelepiped frame which is roughly square in plan view, and comprises two truss structures erected on the left and right sides of the rectangular parallelepiped frame, four support columns 4 erected at the four corners of the rectangular parallelepiped frame, two floor beams 5 which connect the lower ends and ends of the support columns 4 between the front or rear sides of the rectangular parallelepiped frame, four ceiling beams 6a and 6b whose ends are connected to the upper ends of the support columns 4 to form a roughly square frame in plan view, and a ceiling panel 30 which is sized to cover the area enclosed by the four ceiling beams 6a and 6b in plan view.

[0024] The ends of each of the lower chord member 2, the diagonal members 3a and 3b, the four support columns 4, the two floor beams 5, and the four ceiling beams 6a and 6b are fixed to either the lower grid points 7a and 7b, the upper grid points 8a and 8b, the connecting members 45a and 45b, and the connecting members 46a and 46b. The lower grid points 7a and 7b, the upper grid points 8a and 8b, the connecting members 45a and 45b, and the connecting members 46a and 46b are fixed to either the lower blocks 41a to 41d, the upper blocks 42a to 42d, or the upper intermediate blocks 43a and 43b using fastening means such as bolts and nuts. The bolts may be ordinary bolts, but high-tensile steel bolts are preferred.

[0025] The lower chord member 2, the diagonal members 3a and 3b, the support column 4, the floor beam 5, and the ceiling beams 6a and 6b are each formed by PC steel rods 15, 25, and 55 protruding from both ends of the respective steel pipes 11, 21, and 51. The lower chord member 2 is fixed to the lower grid points 7a and 7b by screwing in fixing nuts 19 through the holes in the lower grid points 7a and 7b, and the diagonal members 3a and 3b are fixed to the lower grid points 7a and 7b or the upper grid points 8a and 8b by screwing in fixing nuts 28 through the holes in the lower grid points 7a and 7b or the upper grid points 8a and 8b. The support column 4 is fixed to the connecting members 45a and 45b by screwing fixing nuts 58 through the holes in the connecting members 45a and 45b, the floor beam 5 is fixed to the connecting members 46a and 46b by screwing fixing nuts 58 through the holes in the connecting members 46a and 46b, and the ceiling beams 6a and 6b are fixed to the connecting members 46a and 46b by screwing fixing nuts 58 through the holes in the connecting members 46a and 46b.

[0026] As shown in Figures 3, 12, or 14(a), at any of the four corners, the lower grid points 7a, 7b, the connecting member 45a at the lower end of the support column 4, and the connecting members 46a, 46b at the end of the floor beam 5 are fixed to the lower blocks 41a to 41d with fastening means such as bolts and nuts. As shown in Figure 3 or 14(b), at any of the four corners, the connecting member 45b at the upper end of the support column 4, the connecting members 46a, 46b at the ends of the ceiling beams 6a, 6b, and the ceiling board 30 are fixed to the upper blocks 42a to 42d with fastening means such as bolts and nuts. As shown in Figure 3 or 14(c), the upper grid points 8a, 8b and the ceiling board 30 are fixed to the upper intermediate blocks 43a, 43b with fastening means such as bolts and nuts, and the ceiling beam 6a is restricted in the vertical direction by the U-shaped cross-section portion of the upper intermediate blocks 43a, 43b.

[0027] The lower blocks 41a to 41d, the upper blocks 42a to 42d, and the upper intermediate blocks 43a and 43b are made of metal such as iron, and one or more of the lower grid points 7a and 7b, the upper grid points 8a and 8b, the connecting members 45a and 45b, and the connecting members 46a and 46b are fixed with fastening means such as bolts. This fixes the frames of the lower chord member 2, the diagonal members 3a and 3b, the support columns 4, the floor beams 5, and the ceiling beams 6a and 6b. Furthermore, the configurations of the lower blocks 41a to 41d, the upper blocks 42a to 42d, and the upper intermediate blocks 43a and 43b are not limited to those shown in Figures 14(a) to (c), but can be any configuration in which the support columns 4, the floor beams 5, the ceiling beams 6a and 6b, the lower grid points 7a and 7b, or the upper grid points 8a and 8b can be fixed by fastening means or the like.

[0028] Next, the lower grid points 7a and 7b will be described. The lower grid points 7a and 7b are made of steel and, as shown in Figure 5, can be configured to fix the end of the lower chord member 2 and the lower ends of the diagonal members 3a and 3b to one of the lower blocks 41a to 41d, respectively. Therefore, the configuration of the lower grid points 7a and 7b can be either a configuration M (as shown in Figure 5) in which the part that fixes the end of the lower chord member 2 and the part that fixes the lower ends of the diagonal members 3a and 3b are integrated, or a configuration N (not shown) in which they are provided separately. In both configuration M and configuration N, they can be fixed to one of the lower blocks 41a to 41d.

[0029] Next, the upper grid points 8a and 8b will be described. As shown in Figure 5, the upper grid points 8a and 8b are provided separately and divided into the upper grid point 8a for the diagonal member 3a and the upper grid point 8b for the diagonal member 3b. After joining the upper grid point 8a and the upper grid point 8b, nuts are screwed onto PC steel bars 26 with threaded male screws that pass through the through holes of the upper grid point 8a and the upper grid point 8b to join the upper grid point 8a and the upper grid point 8b. As shown in Figure 14(c), gusset plates 33a covering the surface of the upper grid point 8a and the surface of the upper grid point 8b, or gusset plates 33b covering the back surface of the upper grid point 8a and the back surface of the upper grid point 8b, are fixed to the front and back sides of the upper grid point 8a and the upper grid point 8b, respectively, with fastening means such as bolts.

[0030] Next, the steel pipes 11, 21, and 51 will be described. The steel pipes 11, 21, and 51 generally have high tensile strength. The steel pipe 11 is a component of the lower chord member 2, the steel pipe 21 is a component of the diagonal members 3a and 3b, and the steel pipe 51 is a component of the support column 4, the floor beam 5, or the ceiling beams 6a and 6b. The outer diameter of the steel pipe 11 or the steel pipe 21 is set to 50 to 100 mm, and the outer diameter of the steel pipe 51 is set to 30 to 50 mm.

[0031] Next, the relationship between the maximum load applied to each steel pipe specimen, with and without mortar filling and with and without a ring, was tested. Steel pipes with a diameter of 101.6 mm and a thickness of 3.2 mm were used, and the aforementioned adhesion inhibitor was not applied. The maximum load applied to specimen V, which was filled with mortar but without a ring, specimen W, which was filled with mortar and had a ring attached, and specimen U, which was just steel pipe without mortar filling or a ring, was tested. As shown in Figure 15, the results showed that specimen V or specimen W, which was filled with mortar, could withstand approximately twice the maximum load applied to specimen U, which was just steel pipe without mortar filling.

[0032] Next, the mortar or expansive mortar 12, 22, 52 will be described. First, the mortar 12, 22, 52 will be described. The mortar 12, 22, 52 is poured after mixing water with cement in a weight ratio of 30 to 60% by weight. The steel pipes 11, 21, 51 filled with the mortar 12, 22, 52 have approximately twice the axial compressive strength due to the confining effect, as shown in Figure 15, compared to hollow steel pipes not filled with the mortar 12, 22, 52.

[0033] Therefore, the lower chord member 2, the diagonal members 3a, 3b, the support column 4, the floor beam 5, and the ceiling beams 6a, 6b, which use steel pipes 11, 21, 51 filled with the mortar 12, 22, 52, have a confining effect in which, when an axial compressive load is applied due to an earthquake or the like, the radial spreading of the mortar 12, 22, 52 is restrained by the steel pipes 11, 21, 51, thereby significantly increasing the compressive strength and deformation strength.

[0034] Next, the expansive mortars 12, 22, and 52 will be described. The expansive mortars 12, 22, and 52 are poured by further mixing an expansive agent with a cement-to-water mixing ratio of 20 to 40% by weight, based on the mixing ratio of cement to water of the mortar. The expansive agent can be any expansive agent that expands the mortar, such as a statically crushed agent that causes strong expansion, or an expansive agent that causes expansion by chemical reaction.

[0035] Furthermore, when comparing the rigidity when 100% by weight of mortar is filled into the steel pipe and when 30% by weight of the mortar is replaced with the expansive material, the initial rigidity was significantly increased when 30% by weight of the mortar was replaced with the expansive material compared to when only mortar was used. This is because increasing the proportion of expansive mortar causes expansion pressure to act at the interface between the expansive mortar and the steel pipes 11, 21, and 51, resulting in a confining effect at a stage before compressive loads are applied. Therefore, a confining effect can be obtained in two stages: before compressive loads such as earthquakes are applied, and when compressive loads such as those that cause buildings to collapse due to earthquakes are applied, resulting in a greater confining effect.

[0036] Next, the PC steel bars 15, 25, and 55 will be described. The PC steel bars 15, 25, and 55 are round bars with a portion that forms a male screw, and have very high strength, such as carbon steel or alloy steel, and have very high tensile strength compared to general reinforcing bars.

[0037] Next, the adhesion inhibitor will be described. The adhesion inhibitor is applied to the inner walls of the steel pipes 11, 21, and 51 before the mortar or expansive mortar 12, 22, and 52 are poured, and has the effect of preventing the inner walls of the steel pipes 11, 21, and 51 from adhering to the mortar or expansive mortar 12, 22, and 52. Examples include grease or asphalt. By applying the adhesion inhibitor, compressive loads due to earthquakes, etc., are applied as little as possible to the steel pipes 11, 21, and 51, which are weak in compression but strong in tension, and are weak in tension but strong in compression, so that the compressive loads are applied only to the mortar or expansive mortar 12, 22, and 52, which are weak in tension but strong in compression. As a result, buckling of the steel pipes 11, 21, and 51 is less likely to occur, a confined effect is obtained in which compressive stress is generated three-dimensionally in the mortar or expansive mortar 12, 22, and 52, and the compressive strength is improved compared to when the adhesion inhibitor is not applied.

[0038] Next, the lower chord anchoring plate 13, the diagonal anchoring plate 23, and the anchoring plate 53 will be described. The lower chord anchoring plate 13, the diagonal anchoring plate 23, and the anchoring plate 53 are made of steel and, as shown in Figures 7, 9, 12, and 13, have outer diameters that have radial gaps G1, G2, and G3 with the inner walls of the steel pipes 11, 21, and 51. They have the function of distributing impact loads generated by earthquakes, etc., throughout the mortar or expansive mortar 12, 22, and 52 filled inside the steel pipes 11, 21, and 51, thereby uniformly transmitting compressive force. After filling the steel pipes 11, 21, and 51 with the mortar or expansive mortar 12, 22, and 52 and casting them, the lower chord anchoring plate 13, the diagonal anchoring plate 23, and the anchoring plate 53 are inserted from both ends of the steel pipes 11, 21, and 51 toward the inside.

[0039] Next, the truss structure will be described. As shown in Figure 5, the truss structure forms a triangular shape with one lower chord member 2 and two diagonal members 3a and 3b. Both ends of the lower chord member 2 and the lower ends of the two diagonal members 3a and 3b are fixed at the lower grid points 7a and 7b, and the upper ends of the two diagonal members 3a and 3b are fixed at the upper grid points 8a and 8b. The advantage of using this truss structure is that, compared to a square, a triangle is less likely to change shape even when external forces are applied. Therefore, even if large objects such as buildings that collapse from above during an earthquake try to crush it, it is less likely to collapse than a square structure.

[0040] Furthermore, by fixing one lower chord member 2 and two diagonal members 3a and 3b at the lower grid points 7a and 7b and the upper grid points 8a and 8b, the expansion of the triangle angle is constrained. As a result, bending moments other than compression are also applied to the lower chord member 2 or the diagonal members 3a and 3b. Therefore, the compressive force applied in the axial direction to the lower chord member 2 or the diagonal members 3a and 3b is reduced as a tensile load is applied to the surface of the steel pipes 11 and 21 of the lower chord member 2 or the diagonal members 3a and 3b.

[0041] Next, the lower chord member 2 will be described. As shown in Figures 6 and 7, the lower chord member 2 has ring bodies 17 fixed to both ends of its outer surface by welding or the like, and the mortar or expanding mortar 12 filled inside the steel pipe 11, which has an adhesion inhibitor applied to its inner wall, is sandwiched from both sides by two lower chord member fixing plates 13 fitted inside the steel pipe 11. Fixing plate nuts 16 are threaded onto male threads at both ends of a PC steel bar 15 that passes through the sheath 14 inserted inside the steel pipe 11 and the lower chord member fixing plates 13. As a result of the insertion, the PC steel rod 15 is subjected to tensile prestress, and the mortar or expanding mortar 12 is subjected to compressive prestress. The ends of the steel pipe 11 are then fixed to the two lower grid points 7a and 7b, which are in contact with each other, by screwing fixing nuts 19 onto the male threads of the PC steel rod 15 that pass through the lower grid points 7a and 7b, and the base portion 35 fixed to the ring body 17 is fixed to the lower grid points 7a and 7b by fastening means.

[0042] Furthermore, after the mortar or expanding mortar 12 filled inside the steel pipe 11 has hardened, the mortar or expanding mortar 12 is sandwiched between the lower chord anchoring plates 13, and tensile stress is applied to the PC steel bar 15 from both ends using center hole jacks, and the anchoring plate nuts 16 are screwed in to apply prestress. Then, grout is injected into the sheath 14 through which the PC steel bar 15 passes, through a small hole (not shown) that penetrates the lower chord anchoring plate 13.

[0043] The ring body 17 can be, for example, about 100 mm wide and about 3 to 5 mm thick, and is fixed to the steel pipe 11 by welding. The base portion 35, which is fixed to the ring body 17 by welding, is fixed to the lower grid points 7a and 7b by fastening means, so that tensile force is transmitted from the lower grid points 7a and 7b to the steel pipe 11 through the ring body 17. In addition, both ends of the PC steel bar 15 are fastened and fixed to the lower grid points 7a and 7b by the fixing nuts 19, so that tensile force is transmitted from the lower grid points 7a and 7b to the PC steel bar 15. Therefore, when roofing materials collapse due to an earthquake or the like and a load is applied from above in a crushing direction, the tensile load generated at the lower grid points 7a and 7b is transmitted simultaneously to both the PC steel bar 15 and the steel pipe 11.

[0044] The PC steel bars 15 of the lower chord member 2 are subjected to prestressing by tensile force during factory manufacturing, prior to their delivery to the site, and the steel pipes 11 are strong against tensile force. Therefore, the lower chord member 2 can withstand a strong tensile load suddenly applied due to an earthquake.

[0045] Furthermore, a radial gap G1 is formed between the inner wall of the steel pipe 11 and the lower chord anchoring plate 13. This gap G1 has the effect of preventing compressive stress from being applied to the steel pipe 11 when the anchoring plate nut 16 is screwed into the PC steel bar 15 to push the lower chord anchoring plate 13 inward and applying prestress, while compressive stress is applied only to the mortar or expanding mortar 12. As a result, when the mortar or expanding mortar 12 expands radially, circumferential tensile stress is generated in the steel pipe 11, restraining the expansion, thus making the confined effect more effective before an earthquake occurs. In the case of the steel pipe 11 with a large diameter of 70 to 100 mm, when applying prestress, the PC steel bar 15 is tensioned by pulling from both ends with a center hole jack and then the anchoring plate nut 16 is screwed in.

[0046] Therefore, in the lower chord member 2, the PC steel rod 15 is subjected to prestressing due to tensile force, and the steel pipe 11 is strong against tensile force. When pressure is applied that crushes the ceiling plate 30 due to an earthquake or the like, tensile loads are applied to the lower grid points 7a and 7b of the truss structure. This allows both the PC steel rod 15 and the steel pipe 11 to withstand the tensile load simultaneously from the lower grid points 7a and 7b, thus preventing the truss structure from collapsing.

[0047] Next, the diagonal members 3a and 3b will be described. As shown in Figures 8 and 9, the diagonal members 3a and 3b are made by sandwiching mortar or expanding mortar 22, which is filled inside a steel pipe 21 on which an adhesion inhibitor has been applied to the inner wall, between two diagonal member fixing plates 23, which have a portion fitted inside the steel pipe 21 and a portion protruding from the end face of the steel pipe 21. They have a PC steel bar 25 with a male screw threaded into one end, which is screwed into the diagonal member fixing plate 23 and the other end which protrudes from the diagonal member fixing plate 23, and the upper grid points 8a, which are in contact with the diagonal member fixing plates 23 respectively. The diagonal members 3a and 3b are fixed to the upper and lower grid points 8a and 8b, respectively, by screwing fixing nuts 28 onto the male threads of the PC steel bar 25, which passes through the upper and lower grid points 8a and 8b, respectively, and nuts 61 are screwed onto the male threads at both ends of the connecting rod 29, which passes through the upper and lower grid points 8a and 8b, respectively, and the flange portion 27 at the end of the steel pipe 21, thereby connecting the upper and lower grid points 8a and 8b, or the lower grid points 7a and 7b, to the steel pipe 21. The diagonal members 3a and 3b are configured in an unprestressed state.

[0048] Furthermore, as shown in Figure 8, the connection between the flange portion 27 of the steel pipe 21 and the upper node portions 8a and 8b, or as shown in Figures 8 and 9, the connection between the flange portion 27 and the lower node portions 7a and 7b, is made by screwing nuts 61 onto male threads at both ends of a connecting rod 29, which has holes that pass through the flange portion 27 and the upper node portions 8a and 8b, or holes that pass through the flange portion 27 and the lower node portions 7a and 7b, from both sides. The connecting rod 29 has male threads formed at both ends, and the rest of the rod is in the form of a round bar. Furthermore, the nut 61 may be a combination of a spring washer and a nut, or a locking nut, and the diameter of the holes in the upper grid points 8a and 8b, or the holes in the lower grid points 7a and 7b, should be such that the upper grid points 8a and 8b, or the lower grid points 7a and 7b, can move using the connecting rod 29 as a guide rod.

[0049] As a result, when a compressive load due to an earthquake or the like is applied to the lower grid points 7a, 7b and the upper grid points 8a, 8b, the diagonal brace fixing plate 23 and the lower grid points 7a, 7b, or the diagonal brace fixing plate 23 and the upper grid points 8a, 8b, move relative to the steel pipe 21 using the connecting rod 29 as a guide rod, thereby compressing the mortar or expanding mortar 22, and further enhancing the confining effect when a compressive load due to an earthquake or the like is applied. On the other hand, when a tensile load due to an earthquake or the like is applied to the lower grid points 7a, 7b and the upper grid points 8a, 8b, the lower grid points 7a, 7b, or the upper grid points 8a, 8b, pull the steel pipe 21, which has high tensile strength, via the connecting rod 29.

[0050] The PC steel bar 25 has the function of connecting the upper node points 8a, 8b or the lower node points 7a, 7b to the diagonal brace fixing plate 23, and the function of transmitting the load applied to the upper node points 8a, 8b or the lower node points 7a, 7b to the diagonal brace fixing plate 23.

[0051] A radial gap G2 is formed between the inner wall of the steel pipe 21 and the diagonal brace fixing plate 23. The gap G2 prevents compressive load from being applied to both ends of the steel pipe 21 when a compressive load is applied, thereby preventing lantern buckling that occurs in shallow areas from both end faces of the steel pipe 21.

[0052] Therefore, when pressure is applied to crush the ceiling panel 30 due to an earthquake or the like, compressive loads are applied to the upper and lower grid points 8a and 7a, and the upper and lower grid points 8b and 7b, which fix both ends of the diagonal members 3a and 3b of the truss structure, respectively, and the PC steel rods 25 transmit the compressive load to the diagonal member fixing plate 23. At this time, the gap G2 and the adhesion suppressing material prevent the compressive load applied to the diagonal member fixing plate 23 from being transmitted to the steel pipe 21, but instead transmit it to the mortar or expanding mortar 22, thereby effectively creating a confining effect and preventing the truss structure from collapsing.

[0053] Next, the structure of the node points of the triangular truss structure, which comprises the lower chord member 2 and the diagonal members 3a and 3b, and the method of assembling the truss structure will be described. The structure of the node points of the truss structure and the method of assembling the truss structure are merely examples shown in this invention, and the structure of the node points and the method of assembling the truss structure are not limited to this example and may be any other as long as the triangular truss structure can be assembled using the lower chord member 2 and the diagonal members 3a and 3b.

[0054] As shown in Figure 10, the joint between the diagonal members 3a and 3b at one of the three node points of the triangular truss structure is divided into an upper node point 8a and an upper node point 8b. The tip of one side of the PC steel rod 15 of the lower chord member 2 is passed through the hole in the lower node point 7a and one side of the lower chord member 2 is fixed with the fixing nut 19. The lower end of the PC steel rod 25 on the lower end side of the diagonal member 3a is passed through the hole in the lower node point 7a and the lower end side of the diagonal member 3a is fixed with the fixing nut 28. The protruding PC steel rod 25 on the upper end side of the diagonal member 3a is passed through the hole in the upper node point 8a and the fixing nut 28 is screwed in to fix the upper node point 8a to the upper end side of the diagonal member 3a. This creates a combination H of the lower grid point 7a, the upper grid point 8a, the lower chord member 2, and the diagonal member 3a.

[0055] On the other hand, the lower end of the protruding PC steel rod 25 is passed through the hole in the lower grid point 7b on the lower end side of the diagonal member 3b and the lower grid point 7b is fixed by screwing in the fixing nut 28. On the upper end side, the upper end of the protruding PC steel rod 25 is passed through the hole in the upper grid point 8b and the upper grid point 8b is fixed by screwing in the fixing nut 28. This creates a combination K of the diagonal member 3b, the upper grid point 8b, and the lower grid point 7b.

[0056] Then, the combination K is moved in the direction of the arrow S as shown in Figure 10 and set on the combination H. Then, as shown in Figure 5, the tip of the PC steel rod 15 protruding from the other side of the lower chord member 2 is pushed through the hole in the lower grid point 7b and the lower chord member 2 and the lower grid point 7b are fixed with the fixing nut 19, the upper grid point 8a and the upper grid point 8b are brought into contact and the PC steel rod 26 is passed through it and nuts are screwed in from both sides to connect the upper grid point 8a and the upper grid point 8b.

[0057] Then, as shown in Figure 11, the front surfaces of the upper node portion 8a and the upper node portion 8b are attached to a steel gusset plate 33a and fixed with fastening means, and the back surfaces are attached to a steel gusset plate 33b and fixed with fastening means. The PC steel bar 26 and the gusset plates 33a and 33b strengthen the connection between the upper node portion 8a and the upper node portion 8b.

[0058] Next, the support column 4 will be described. As shown in Figures 13(a) to (c), the support column 4 is constructed by sandwiching mortar or expanding mortar 52, which is filled inside a steel pipe 51 coated with an adhesion inhibitor on its inner wall, between two fixing plates 53, each having a portion fitted inside the steel pipe 51 and a portion protruding from the end face of the steel pipe 51. The support column 4 has a PC steel rod 55 with a male screw threaded into one end of the fixing plate 53 and the other end protruding from the fixing plate 53. The PC steel rod 55 is fixed to the connecting members 45a and 45b, which are in contact with the fixing plates 53, by screwing fixing nuts 58 into the male screw threads of the PC steel rod 55, which passes through the connecting members 45a and 45b. In addition, nuts 62 are screwed into the male screw threads at both ends of a connecting rod 59 that passes through the connecting members 45a and 45b and the flange portion 57 at the end of the steel pipe 51, thereby connecting the connecting members 45a and 45b to the steel pipe 51. As shown in Figure 14(a), the connecting member 45a is fixed to the lower blocks 41a to 41d by fastening means, and as shown in Figure 14(b), the connecting member 45b is fixed to the upper blocks 42a to 42d by fastening means. Also, as shown in Figures 13(a) and (b), a radial gap G3 is formed between the inner wall of the steel pipe 51 and the fixing plate 53. The support column 4 is constructed without prestressing.

[0059] Next, the floor beam 5 will be described. As shown in Figures 12(a) to (c), the floor beam 5 is made of a steel pipe 51 on which an adhesion inhibitor is applied to the inner wall, and filled with mortar or expanding mortar 52, sandwiched from both sides by two fixing plates 53, each having a portion fitted inside the steel pipe 51 and a portion protruding from the end face of the steel pipe 51. It has a PC steel bar 55 with a male screw threaded into it, one end of which is screwed into the fixing plate 53 and the other end protruding from the fixing plate 53. In this configuration, the connecting members 46a and 46b are in contact with the anchoring plate 53 without any prestress applied, and are fixed to the connecting members 46a and 46b by screwing fixing nuts 58 onto the male threads of the PC steel rod 55 that passes through the connecting members 46a and 46b. Furthermore, nuts 62 are screwed onto the male threads at both ends of a connecting rod 59 that passes through the connecting members 45a and 45b and the flange portion 57 at the end of the steel pipe 51, thereby connecting the connecting members 46a and 46b to the steel pipe 51. As shown in Figure 14(a), the connecting members 46a and 46b are fixed to the lower blocks 41a to 41d by fastening means. Also, as shown in Figures 12(a) and (b), a radial gap G3 is formed between the inner wall of the steel pipe 51 and the anchoring plate 53. The floor beam 5 is constructed without prestress.

[0060] Next, the ceiling beams 6a and 6b will be described. As shown in Figures 12(a) and (b), the ceiling beams 6a and 6b have a PC steel bar 55 with a screw thread threaded into one end, which is screwed into the fixing plate 53 and the other end protruding from the fixing plate 53, and the mortar or expanding mortar 52 filled inside the steel pipe 51, which has an adhesion inhibitor applied to its inner wall, sandwiched from both sides by two fixing plates 53. With no prestress applied to the rod 55, the connecting members 46a and 46b, to which the anchoring plate 53 abuts, are fixed by screwing fixing nuts 58 onto the male threads of the PC steel rod 55 that pass through the connecting members 46a and 46b, and nuts 62 are screwed onto the male threads at both ends of the connecting rod material 59 that passes through the connecting members 46a and 46b and the flange portion 57 at the end of the steel pipe 51, thereby connecting the connecting members 46a and 46b and the steel pipe 51. As shown in Figure 14(b), the connecting members 46a and 46b are fixed to the upper blocks 42a to 42d by fastening means, and as shown in Figure 14(c), the ceiling beams 8a and 8b are restricted in the vertical direction by the upper intermediate blocks 43a and 43b in the middle of the longitudinal direction. As shown in Figures 12(a) and (b), a radial gap G3 is formed between the inner wall of the steel pipe 51 and the fixing plate 53. The ceiling beams 6a and 6b are constructed without prestressing.

[0061] In the support columns 4, floor beams 5, and ceiling beams 6a and 6b, a radial gap G3 is formed between the inner wall of the steel pipe 51 and the fixing plate 53. The gap G3 prevents compressive loads from being applied to the ends of the steel pipe 51 when pressure is applied to crush the ceiling plate 30 due to an earthquake or the like, and when a compressive load is applied to the connecting members 45a and 45b or 46a and 46b, thus preventing lantern buckling from occurring at both ends of the steel pipe 51.

[0062] In the support columns 4, floor beams 5, and ceiling beams 6a and 6b, nuts 62 are screwed onto male threads at both ends of a connecting rod 59 that passes through the through holes of the connecting members 45a and 45b, or the through holes of the connecting members 46a and 46b, and through holes in the flange portion 57 at the end of the steel pipe 51, thereby connecting the connecting members 45a and 45b, or the connecting members 46a and 46b, to the steel pipe 51. The connecting rod 59 has male threads formed at both ends, and the rest of it is in the form of a round bar. Furthermore, the nut 62 may be a combination of a spring washer and a nut, or a locking nut, and the diameter of the through holes in the connecting members 45a, 45b, or the connecting members 46a, 46b, should be such that the connecting members 45a, 45b, or the connecting members 46a, 46b, can move using the connecting rod 59 as a guide rod.

[0063] As a result, when alternating compressive and tensile loads due to earthquakes, etc., are applied to the connecting members 45a, 45b or 46a, 46b, the anchoring plate 53 and the connecting members 45a, 45b or 46a, 46b move relative to the steel pipe 51 using the connecting rod 59 as a guide rod, thereby compressing the mortar or expanding mortar 52, and the confining effect when compressive loads due to earthquakes, etc. are applied can be further enhanced. On the other hand, when tensile loads due to earthquakes, etc., are applied to the connecting members 45a, 45b or 46a, 46b, the connecting members 45a, 45b or 46a, 46b pull the steel pipe 51, which has high tensile strength, via the connecting rod 59.

[0064] Therefore, the support column 4, the floor beam 5, and the ceiling beams 6a and 6b all possess high compressive strength, high tensile strength, and high deformation strength.

[0065] Next, the ceiling plate 30 will be described. As shown in Figures 1, 3, or 14(b), the ceiling plate 30 is a flat steel plate, for example, 2-3 mm thick, fixed by fastening means to the upper surface of the ceiling plate mounting base 38 formed on the upper blocks 42a-42d, which connect the upper ends of the four corner support columns 4, and to the upper surface of the upper intermediate blocks 43a, 43b, which connect the upper ends of the diagonal members 3a, 3b. Due to its weight, it is divided as needed and placed on the upper blocks 42a-42d and the upper intermediate blocks 43a, 43b with fastening means, and if necessary, it is fastened and fixed to the ceiling beams 8a, 8b using fastening means with connecting devices (not shown).

[0066] Next, the bracing 39 will be described. As shown in Figures 1 to 3, the bracing 39 is made of a rod-shaped steel material such as an L-shaped steel or steel pipe, and is attached by fastening means to the corners between the ceiling beams 8a and 8b and the support columns 4 on the front and rear sides of the rectangular parallelepiped frame. This increases the restraining force against the collapse of the support columns 4.

[0067] Next, the base 40 will be described. As shown in Figure 2 or Figure 4, the base 40 is a flat plate, such as wooden plywood or steel plate, on which the lower blocks 41a to 41d, which have flat bottom surfaces at the four corners, can be placed or fixed. The thickness of the plywood is appropriately selected from a range of 5 to 7.5 mm depending on the size and weight of the disaster prevention shelter 1, and in the case of steel plates, the thickness is appropriately selected from a range of 2 to 3 mm. The material and size of the base 40 are not limited to the above example, and any material or size is acceptable as long as the lower blocks 41a to 41d can be placed or fixed. The fixing method should be an easily fastened means such as bolts and nuts that can be used on-site.

[0068] The base 40 prevents concentrated loads from being placed on the floor of a wooden house, which could damage the flooring, such as tatami mats. It also maintains the vertical positional relationship of the lower blocks 41a to 41d when a crushing force is applied to the ceiling board 30 during an earthquake, thus making it difficult for the truss structure and the rectangular parallelepiped frame including the support columns 4 to deform. Furthermore, when the lower blocks 41a to 41d are fixed to the base 40, it prevents the base 40 and the lower blocks 41a to 41d from shifting even during severe lateral shaking caused by an earthquake.

[0069] Furthermore, since the mortar or expansive mortar 12, 22, 52 is transported to the site in a hardened state within the steel pipes 11, 21, 51, the lower chord member 2, the diagonal members 3a, 3b, the support columns 4, the floor beams 5, the ceiling beams 6a, 6b, the lower grid points 7a, 7b, the upper grid points 8a, 8b, the connecting members 45a, 45b, the connecting members 46a, 46b, the ceiling boards 30, and the base 40 can be transported and assembled on-site to the disaster prevention shelter 1 using fastening means such as bolts and nuts.

[0070] The following explains how the aforementioned disaster prevention shelter 1 can secure a safe space even inside a building that collapses due to an earthquake or the like. When a house collapses due to an earthquake or the like, the roof and other parts of the collapsed house fall and apply a crushing force to the upper surface of the ceiling plate 30 of the steel plate of the disaster prevention shelter 1. As a result, a crushing force is applied from above to the truss structure and the support columns 4 that support the ceiling plate 30 from below, so that a compressive load is applied to the diagonal members 3a and 3b of the truss structure, a tensile load is applied to the lower chord member 2, and a compressive load is applied to the support columns 4.

[0071] As shown in Figures 1 to 3, the upper blocks 42a to 42d and the upper intermediate blocks 43a and 43b are fixed to the ceiling panel 30. As shown in Figure 3, the upper block 42a and the upper block 42b are connected by the ceiling beam 6a, the upper block 42a and the upper block 42c are connected by the ceiling beam 6b, the upper block 42c and the upper block 42d are connected by the ceiling beam 6a, and the upper block 42b and the upper block 42d are connected by the ceiling beam 6b. This structure makes it difficult for the upper blocks 42a to 42d and the upper intermediate blocks 43a and 43b to shift in position or height.

[0072] At the front and rear of the rectangular parallelepiped frame, the braces 39 are provided at the corners between the support columns 4 and the ceiling beams 6a and 6b, and the truss structure is formed on the left and right sides of the rectangular parallelepiped frame, so that the support columns 4 at the four corners can be firmly fixed at their upper ends.

[0073] Furthermore, as shown in Figure 3, the lower block 41a and the lower block 41b are connected by the lower chord member 2, the lower block 41a and the lower block 41c are connected by the floor beam 5, the lower block 41c and the lower block 41d are connected by the lower chord member 2, and the lower block 41b and the lower block 41d are connected by the floor beam 5, thus creating a structure in which the position and height of the lower blocks 41a to 42d are less likely to shift. Moreover, by placing the lower blocks 41a to 41d on the base 40, the structure can be made even less likely to shift the position and height of the lower blocks 41a to 41d.

[0074] Therefore, when a compressive load is applied to the diagonal members 3a and 3b of the truss structure, a tensile load is applied to the lower chord member 2, and a compressive load is applied to the support column 4, the disaster prevention shelter 1 is less likely to collapse due to the compressive load resistance and tensile load resistance of the truss structure, as well as the compressive load resistance of the support column 4, and a safe space can be secured.

[0075] Next, an example of how the disaster prevention shelter 1 can be used will be explained. For example, as shown in Figure 4, the user 80 sleeps in the disaster prevention shelter 1, which is assembled inside a wooden house. In the event that an earthquake occurs while the user is sleeping and the wooden house collapses, the disaster prevention shelter 1 will not collapse, so a space for survival is secured, allowing the user to calmly deal with the situation. [Explanation of Symbols]

[0076] 1. Disaster prevention shelter 2 Lower chord 3 Diagonals 4 pillars 5 Floor beam 6 Ceiling beams 7 Lower case part 8 Upper grid point section 11 Steel pipe 12 Mortar or expansive mortar 13 Lower chord anchoring plate 14 Sheath 15 PC steel bar 16 Nuts for fixing plates 17 Ring Body 19 Fixing nuts 21 Steel pipe 22 Mortar or expansive mortar 23. Diagonal brace fixing plate 25 PC Steel Bar 26 PC Steel Bar 27 Flange section 28 Fixing nuts 29 Connecting bar 30 Ceiling panels 33 Gusset Plate 35 Base 38 Ceiling plate mounting section 39. Bracing 40 bases 41 Lower block 42 Upper block 43 Upper Middle Block 45 Connecting member 46 Connecting member 51 Steel pipe 52 Mortar or expansive mortar 53 Fixing plate 55 PC Steel Bar 57 Flange section 58 Fixing nuts 59 Connecting bar 61 Nut 62 nuts 80 User G1 gap G2 gap G3 gap H combination K combination

Claims

1. A disaster prevention shelter having a form that combines a truss structure with a rectangular frame that is roughly square in shape when viewed from above, The rectangular frame comprises two truss structures erected on the left and right sides, four support columns erected at the four corners of the rectangular frame, two floor beams connecting the lower ends and ends of the support columns between the front or rear sides of the rectangular frame, and four ceiling beams connecting the ends to the upper ends of the support columns to form a roughly rectangular frame in plan view. The aforementioned truss structure is composed of one lower chord and two diagonal members. The lower chord member has a configuration in which ring bodies are fixed to both ends of the outer surface, and mortar or expanding mortar filled inside a steel pipe coated with an adhesion inhibitor on its inner wall is sandwiched from both sides by two lower chord member fixing plates fitted inside the steel pipe, and prestress is applied to the PC steel rod by screwing fixing plate nuts onto male threads at both ends of a PC steel rod that passes through the sheath inserted inside the steel pipe and the lower chord member fixing plates, thereby applying tensile force to the PC steel rod and compressive force to the mortar or expanding mortar, and the ends of the steel pipe are fixed to two lower grid points that abut each other by screwing fixing nuts onto male threads of the PC steel rod that pass through the lower grid points, and the base portion fixed to the ring body is fixed to the lower grid points by fastening means. The diagonal member is formed by sandwiching mortar or expanding mortar, which is filled inside a steel pipe coated with an adhesion inhibitor on its inner wall, between two diagonal member fixing plates, each having a portion fitted inside the steel pipe and a portion protruding from the end face of the steel pipe. It has a PC steel rod with a male thread screwed into one end of the diagonal member fixing plate and the other end protruding from the diagonal member fixing plate. The diagonal member fixing plates are fixed to the upper and lower grid points, respectively, by screwing fixing nuts into the male threads of the PC steel rod, which pass through the upper or lower grid point, respectively. Furthermore, nuts are screwed into the male threads at both ends of a connecting rod that passes through the upper or lower grid point and the flange portion at the end of the steel pipe, thereby connecting the upper or lower grid point and the steel pipe. A disaster prevention shelter characterized by comprising a flat ceiling plate mounted on the upper ends of the four corner support columns and the upper ends of the diagonal members.

2. The disaster prevention shelter according to claim 1, characterized in that the support column, floor beam, or ceiling beam is sandwiched on both sides between two fixing plates having a portion fitted into the steel pipe and a portion protruding from the end face of the steel pipe, with mortar or expanding mortar filled inside a steel pipe coated with an adhesion inhibitor on its inner wall, and has a PC steel rod with a male screw threaded into one end, which is screwed into the fixing plate and the other end which protrudes from the fixing plate, and is fixed to a connecting member to which the fixing plate abuts by screwing a fixing nut into the male screw of the PC steel rod which passes through the connecting member, and the connecting member and the steel pipe are connected by screwing nuts into the male screws at both ends of a connecting rod that passes through the connecting member and the flange portion at the end of the steel pipe.

3. The disaster prevention shelter according to claim 1 or 2, characterized in that the lower grid points, the base portion fixed to the ring body, the lower end of the support column, and the end of the floor beam are fixed to the lower blocks at the four corners by fastening means, the upper end of the support column, the end of the ceiling beam, and the ceiling board are fixed to the upper blocks at the four corners by fastening means, and the upper grid points and the ceiling board are fixed to the upper intermediate block by fastening means.

4. The disaster prevention shelter according to claim 3, characterized in that the upper grid points are separated for fixing each of the two diagonal members and can be integrated by fastening means.

5. The disaster prevention shelter according to claim 3, characterized in that diagonal braces made of rod-shaped steel are attached by fastening means to the corners between the ceiling beam and the support column at the front and rear sides of the rectangular parallelepiped frame.

6. The disaster prevention shelter according to claim 1, characterized in that the bottom surfaces of the lower blocks at the four corners are made flat, and the shelter is provided with a flat base on which the lower blocks at the four corners can be placed or fixed.

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