Retrofitting structure for existing building

Abstract

Provided is a retrofitting structure for existing building that does not require the addition of a foundation specific to the retrofitting structure, can implement seismic retrofitting at any floors only of the existing building, and hardly causes a large drawing force resulting from eccentric bending moment that may act on the seismic retrofitting structure. A retrofitting structure 100 for existing building includes: a reinforcing frame 10 including a frame member 11 and a vibration control member 12 interposed in the frame member, the reinforcing frame being provided on an outer wall surface of an existing building B having an overhang T on the outer wall surface so as to surround the overhang T; and a vertical truss member 30 and a horizontal truss member 20 configured to couple the reinforcing frame 10 and the outer wall surface.

Claims

1. A retrofitting structure for existing building comprising: a reinforcing frame including a frame member and a vibration control member interposed in the frame member, the reinforcing frame being provided on an outer wall surface of an existing building having an overhang on the outer wall surface so as to surround the overhang; and a vertical truss member and a horizontal truss member configured to couple the reinforcing frame and the outer wall surface, wherein a horizontal shear force acting on the reinforcing frame is transmitted to the existing building via the horizontal truss member, and a vertical force resulting from eccentric bending moment acting on the reinforcing frame is transmitted to the existing building via the vertical truss member.

2. A retrofitting structure for existing building comprising: a connection frame including a frame member, the connection frame being provided on an outer wall surface of an existing building having an overhang on the outer wall surface so as to surround the overhang; a reinforcing frame to be connected to the connection frame, the reinforcing frame including a frame member and a vibration control member interposed in the frame member; and a vertical truss member and a horizontal truss member configured to couple the connection frame and the reinforcing frame, wherein a horizontal shear force acting on the reinforcing frame is transmitted to the existing building via the horizontal truss member and the connection frame, and a vertical force resulting from eccentric bending moment acting on the reinforcing frame is transmitted to the existing building via the vertical truss member and the connection frame.

3. The retrofitting structure for existing building according to claim 1, wherein the vibration control member includes any one of a stud-type damper, a brace, and a brace with a damper.

4. The retrofitting structure for existing building according to claim 1, wherein the overhang includes any one type or a plurality of types of a balcony, a externally-attached louver, and eaves.

5. The retrofitting structure for existing building according to claim 1, wherein a plurality of the overhangs are provided at the existing building with intervals in the vertical direction and in the horizontal direction, and the retrofitting structure is attached to a part of the overhangs only.

6. The retrofitting structure for existing building according to claim 2, wherein the vibration control member includes any one of a stud-type damper, a brace, and a brace with a damper.

7. The retrofitting structure for existing building according to claim 2, wherein the overhang includes any one type or a plurality of types of a balcony, a externally-attached louver, and eaves.

8. The retrofitting structure for existing building according to claim 2, wherein a plurality of the overhangs are provided at the existing building with intervals in the vertical direction and in the horizontal direction, and the retrofitting structure is attached to a part of the overhangs only.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 schematically shows the state where a retrofitting structure of Embodiment 1 of the present invention is provided on the outer wall surface of an existing building.

(2) FIG. 2 schematically shows the retrofitting structure of Embodiment 1 that is provided on the outer wall surface of the existing building.

(3) FIG. 3 is an enlarged view of a part of the retrofitting structure of Embodiment 1.

(4) FIG. 4 is a view taken along the arrow IV of FIG. 3.

(5) FIG. 5 is a view taken along the arrow V of FIG. 3.

(6) FIG. 6 is a view taken along the arrow VI of FIG. 3.

(7) FIG. 7 describes a cross-sectional force generated at the retrofitting structure, where FIG. 7(a) shows a shear force at the reinforcing frame, FIG. 7(b) shows bending moment at the reinforcing frame, FIG. 7(c) shows axial forces at members making up the retrofitting structure, and FIG. 7(d) shows a shear force at the joint between the retrofitting structure and the outer wall surface of the existing building.

(8) FIG. 8 schematically shows the state where a retrofitting structure of Embodiment 2 of the present invention is provided on the outer wall surface of an existing building.

(9) FIG. 9 schematically shows the retrofitting structure of Embodiment 2 that is provided on the outer wall surface of the existing building.

(10) FIG. 10 is an enlarged view of a part of the retrofitting structure of Embodiment 2.

(11) FIG. 11 schematically describes a conventional method of adding a framed steel brace structure.

(12) FIG. 12 schematically shows cross-sectional forces generated at the framed steel brace structure.

(13) FIG. 13 schematically describes a retrofitting structure by a conventional stud-type damper.

DESCRIPTION OF EMBODIMENTS

(14) The following describes embodiments of a retrofitting structure for existing buildings of the present invention, with reference to the drawings. Although the drawings illustrate a condominium as one example of the existing buildings, the existing buildings as a target include various architectural structures other than a condominium, such as a building and various buildings for public facilities (and public transportation facilities). Although the drawings show an example of providing a retrofitting structure on the outer wall surface of all dwelling units from a middle-level floor to an upper-level floor of the existing building, a retrofitting structure may be provided on the entire outer wall surface of the existing building, may be provided at any floor only, or may be provided at any dwelling unit on any floor. Even when the retrofitting structure is provided on the entire outer wall surface of the existing building, the retrofitting structure of the present invention does not require the addition of a foundation specific thereto.

(15) (Embodiment 1 of Retrofitting Structure for Existing Building)

(16) FIG. 1 schematically shows the state where a retrofitting structure of Embodiment 1 of the present invention is provided on the outer wall surface of an existing building, FIG. 2 schematically shows the retrofitting structure of Embodiment 1 that is provided on the outer wall surface of the existing building, and FIG. 3 is an enlarged view of a part of the retrofitting structure of Embodiment 1. FIGS. 4 to 6 are a view taken along the arrow IV of FIG. 3, a view taken along the arrow V thereof and a view taken along the arrow VI, respectively.

(17) As shown in FIG. 1, the existing building B is a multi-level floor condominium having a plurality of dwelling units on each floor, where each dwelling unit is provided with a balcony T and a window Wi at the back of the balcony T (see FIG. 6).

(18) In the illustrated form, seismic retrofitting is not required on the lower floors of the existing building B, and is installed from a middle-level floor to an upper-level floor.

(19) A reinforcing frame 10 is prepared beforehand, which is made up of a frame member 11 including vertical members 11a and horizontal members 11b that are steel members assembled into a frame form so as to surround a balcony T of each dwelling unit from a middle-level floor to an upper-level floor (so as to surround the balcony T in the front view), and vibration control members 12 interposed at the vertical members 11a, and the thus prepared reinforcing frame 10 is conveyed to the site. In the illustrated example, each floor has three dwelling units, and the number of openings that are defined by the frame members 11 making up the reinforcing frame 10 is six in each row. This means that a vertical member 11a of the frame member 11 is provided at some position along the balcony T of each dwelling unit. As is understood also from FIGS. 4 and 6, each dwelling unit in this form has a wall Wa at the center position, and the vertical member 11a is provided at a position in front of this wall Wa, so that the view from the windows Wi of the dwelling units is not blocked. In another form, a groove may be provided on the outer surface of the balcony T, and a vertical member 11a may be disposed in this groove.

(20) In this way, the reinforcing frame 10 is disposed so as to surround the balcony T of each dwelling unit, and is disposed at a position that does not block the view from the windows Wi.

(21) Herein, the reinforcing frame 10 as a whole is configured by assembling steel members, such as H-steels or I-steels, into a lattice shape to make up a frame member 11, and interposing a vibration control member 12 at some position along each of the vertical members 11a making up the frame member 11.

(22) As the vibration control member 12 to be interposed at some position of each vertical member 11a, a stud-type vibration control damper (hysteresis type damper made of steel materials, viscoelastic damper made of high-damping rubbers, and viscosity damper made of fluid) may be used.

(23) Referring back to FIG. 1, when the reinforcing frame 10 is installed at the existing building B, connection plates 40 are firstly provided at appropriate positions of the outer wall surface of the existing building B. These connection plates 40 can be provided at the outer wall surface using an adhesion-type post-installed anchors, for example.

(24) After the connection plates 40 are installed on the outer wall surfaces of the existing building B, then openings defined by the reinforcing frame 10 (openings defined by vertical members 11a and horizontal members 11b) are positioned so as to surround the balcony T and in the vicinity of the connection plates 40. Then the connection plates 40 and the reinforcing frame 10 are mutually connected via horizontal truss members 20 and vertical truss members 30, whereby the retrofitting structure 100 is installed on the outer wall surface of the existing building B. That is, the retrofitting structure 100 is made up of the reinforcing frame 10, the horizontal truss members 20 and the vertical truss members 30.

(25) Each of the horizontal truss members 20 and the vertical truss members 30 can be formed with a steel member, such as a L-steel, a C-steel or a square pipe, and both of the horizontal truss members 20 and the vertical truss members 30 in the illustrated example is prepared by assembling two L-steels so as to have a T-letter shape cross section.

(26) As shown in FIGS. 3 and 4, each of the connection plates 40 installed on the outer wall surface of the existing building B is provided with a connection piece 60 made of steel that protrudes from the connection plate 40, and the frame member 11 of the reinforcing frame 10 also is provided with connection pieces 50 made of steel.

(27) The connection pieces 50, 60 are inserted into gaps between two L-letter shaped abutting ends making up the horizontal truss members 20 and the vertical truss members 30, and they are connected mutually by welding or with bolts, whereby the outer wall surface of the existing building B and the reinforcing frame 10 are connected via the horizontal truss members 20 and the vertical truss members 30.

(28) The illustrated retrofitting structure 100 is installed so as to surround the overhangs T, such as a balcony, provided on the outer wall surface of the existing building B, which includes the reinforcing frame 10 having the vibration control members 12 that is coupled to the outer wall surface via the vertical truss members 30 and the horizontal truss members 20. In this way, the reinforcing frame 10 is installed so as to surround the balcony T, and therefore the view from the windows of the existing building B is not blocked. Further, the reinforcing frame 10 and the outer wall surface are connected via the horizontal truss members 20 and the vertical truss members 30, whereby a horizontal shear force acting on the reinforcing frame 10 can be transmitted to the existing building B via the horizontal truss members 20, and a vertical force resulting from the eccentric bending moment acting on the reinforcing frame 10 can be transmitted to the existing building B via the vertical truss members 30. Therefore this does not require the addition of a foundation specific to the retrofitting structure 100, and can implement seismic retrofitting on any floors, whereby the retrofitting structure 100 obtained can have excellent effectiveness for construction and such economic efficiency.

(29) Next, referring to FIG. 7, a cross-sectional force generated at the members making up the retrofitting structure and a reaction force generated at the connection portion between the retrofitting structure and the existing building are described below. Specifically FIG. 7(a) shows a shear force at the reinforcing frame, FIG. 7(b) shows bending moment at the reinforcing frame, FIG. 7(c) shows axial forces at members making up the retrofitting structure, and FIG. 7(d) shows a shear force at the joint between the retrofitting structure and the outer wall surface of the existing building.

(30) In FIG. 7(a) showing a shear force, a shear force Q acts on a stud-type damper interposed between vertical members at the center during earthquake. Then, due to this shear force Q, a shear force V(=Qwh/2) acts on the horizontal members 11b (horizontal beams) of the reinforcing frame 10, and bending moment acting on the reinforcing frame is transmitted to the horizontal truss members and the vertical truss members, and therefore a local shear force in the direction orthogonal to the axis of the members, which poses a problem to a stud-type damper and results from transmission of bending moment to the joints between the retrofitting structure and the outer wall surface of the existing building, does not occur. A shear force only will be transmitted to the horizontal truss members and the vertical truss members.

(31) As shown in FIG. 7(b), bending moment M.sub.G(=Qh/4) is generated at the central vertical member of the connection frame, and bending moment Mc(=Qh/2) is generated at the horizontal beams at the connection portion with the central vertical member.

(32) Next. FIG. 7(c) shows the distribution of axial forces of trusses making up the reinforcing frame, where an axial force N.sub.q acting against eccentric bending moment due to the shear force Q acting on the stud-type damper 12 can be represented as N.sub.q=Qd/w.

(33) Meanwhile an axial force Nv acting against eccentric bending moment of the shear force V at the horizontal members 11b can be represented as Nv=2Vd/h=Qd/h.

(34) In this way, since an axial force is a force where the tensile force and the compression force have the same value and are in the same direction, the axial force at the bundle member 11c can be represented as N=Nq+Nv=2Qd/h.

(35) FIG. 7(d) shows the support reaction forces due to an axial force of a truss making up the reinforcing frame 10, which is used for design load at the connection portion between the existing building B and the retrofitting structure 100. Herein no bending moment is transmitted to this connection portion, and a tensile force and a shear force will be transmitted there. Then, this shear force acts in the axial direction of the members making up the reinforcing frame 10 only, thus facilitating the design at the connection portion between the members making up the reinforcing frame.

(36) (Embodiment 2 of Retrofitting Structure for Existing Building)

(37) Referring to FIGS. 8 to 10, a retrofitting structure for existing building that is Embodiment 2 is described below. FIG. 8 schematically shows the state where a retrofitting structure of Embodiment 2 of the present invention is provided on the outer wall surface of an existing building, FIG. 9 schematically shows the retrofitting structure of Embodiment 2 that is provided on the outer wall surface of the existing building, and FIG. 10 is an enlarged view of a part of the retrofitting structure of Embodiment 2.

(38) The retrofitting structure 100A in the drawings is configured by attaching a connection frame 40A made of steel on the outer wall surface of the existing building B using an adhesion-type post-installed anchors, and then connecting the reinforcing frame 10 and the connection frame 40A via horizontal truss members 20 and vertical truss members 30.

(39) As shown in the drawings, the connection frame 40A includes vertical members only at a part corresponding to the lower-level floors where seismic retrofitting is not required.

(40) Instead of attaching a large number of connection plates 40 on the outer wall surface of the existing building B as in the retrofitting structure 100, the connection frame 40A that is assembled beforehand is attached on the outer wall surface, whereby the retrofitting structure 100A can be installed in a shorter construction period than that of the retrofitting structure 100.

(41) In this retrofitting structure 100A as well, a cross-sectional force generated at the reinforcing frame 10, axial forces generated at the members making up the structure, and reaction forces at the connection portions between the reinforcing frame 10 and the connection frame 40A are the same as those shown in FIG. 7.

(42) Therefore, in this retrofitting structure 100A as well, the support reaction forces due to an axial force of a truss making up the reinforcing frame 10 is used for design load at the connection portion between the existing building B and the retrofitting structure 100A, and no bending moment is transmitted to this connection portion, and a tensile force and a shear force will be transmitted there.

(43) While certain embodiments of the present invention have been described in details with reference to the drawings, the specific configuration is not limited to the above-stated embodiments, and it should be understood that we intend to cover by the present invention design modifications without departing from the spirits of the present invention.

REFERENCE SIGNS LIST

(44) 10 Reinforcing frame 11 Frame member 11a Vertical member 11b Horizontal member 11c Bundle member 12 Vibration control member (stud-type damper) 20 Horizontal truss members 30 Vertical truss members 40 Connection plate 40A Connection frame 50, 60 Connection piece 100, 100A Retrofitting structure B Existing building T Balcony (overhang)