JP6202711B2 - Building structure - Google Patents

Description

  The present invention relates to a building structure that forms a uniform deformation mode in the height direction.

  The response characteristics of a building during an earthquake vary depending on the seismic waveform, the intensity of ground motion, the structural characteristics of the building, and the like. In general, interlayer deformation during an earthquake tends to increase the middle layer of a building, and it is important to suppress the interlayer deformation angle of this part. In order to suppress the deformation of the intermediate layer of a building, it is effective to make the deformation distribution in the height direction uniform during an earthquake. The most common method is to install a seismic isolation device on the building leg and the upper structure is rigidly deformed, but otherwise, it is a method to make the deformation distribution uniform in the height direction that has been studied and studied so far. Has the following three technologies.

(1) Response deformation control design
(2) Method of adjusting the yield shear force of each layer based on energy balance
(3) Method of improving response of maximum inter-layer deformation angle by installing a damper, etc.

  Patent Document 1 discloses a damping structure using a multi-layered wall that rocks a multi-layered wall and can disperse and absorb the energy of earthquakes acting on the building structure in each layer of the building structure. Disclose.

JP 2010-261297

(1) Response deformation control design In order to keep the response deformation within the target criteria for the seismic ground motion for design, distribution of the necessary restoring force characteristics that the building should have is determined in the height direction, and the response value of the design building is restored. You must make sure that you meet the criteria in the range of power.

(2) Method of adjusting the yield shear force of each layer based on the energy balance This method requires a number of steps as follows before a design that satisfies the target criteria.
(a) Static elasto-plastic analysis of a multi-story building frame model to calculate the shear force-interlayer deformation relationship of each layer
(b) Create a restoring force model to be used for dynamic analysis from the shear force-interlayer deformation relationship of each layer
(c) Perform eigenvalue analysis and calculate first-order natural period
(d) Conversion to an equivalent one-mass system model (creation of skeleton curve)
(e) Determine the required amount of damper using a formula derived based on energy balance

(3) Method of improving response of maximum interlaminar deformation angle by installing dampers, etc. Buildings are modeled with multi-mass points or solid frames, and dynamic elastic-plastic response analysis is performed to examine the maximum interlaminar deformation angle. When the maximum interlayer deformation angle does not satisfy the target criteria, it is necessary to repeatedly study until the maximum interlayer deformation angle satisfies the criteria by changing the cross section of the frame or installing a damper.

  In the methods (1) to (3) for making the deformation distribution uniform in the height direction, it is necessary to make assumptions in the structural analysis model as described above. Moreover, in the vibration damping structure using a multi-layered wall, a multi-layered wall, a damper, and a support part are needed separately.

  The present invention does not require various assumptions regarding the structural analysis model as in the prior art in view of the problems of the prior art as described above, and is uniformly deformed in the height direction by devising the structure of the frame. It aims at providing the building structure which can realize a mode.

In order to achieve the above object, the building structure according to the present embodiment has a pillar of a reinforced concrete structure, and a lowermost pillar of a plurality of floors that is designed so that the interlayer deformation of the building is uniform in the height direction. A semi-fixed structure is provided on the leg and the uppermost column head, and the semi-fixed structure reaches a bending yield moment earlier than other column ends during an earthquake, and a hinge is formed. The frame is designed to be a mechanism, and as the semi-fixed structure part, the tapered part gradually decreases toward the fixed end so that the secondary moment of the section becomes smaller compared to other column bases and column heads. And the main bar in the vicinity of the taper part is bent along the taper part, and a concrete adhesion removing section is provided around the main bar in the semi-fixed structure part, thereby providing the column base part and the stigma. Part is Wherein the serial hinge is a structure that does not even yield strength decreases formed.

  According to this building structure, a semi-fixed structure is provided in the lowermost column base and the uppermost column head so that the semi-fixed structure can be compared to other normal column ends during an earthquake. Since the bending yield moment is reached at an early stage and the hinge is formed in the semi-fixed structure, the deformation does not concentrate on the intermediate layer but occurs uniformly in the height direction. Thus, by devising the structure of the frame, a uniform deformation mode in the height direction can be realized. For this reason, various assumptions regarding the structural analysis model are not required as in the prior art.

  In the building structure, as the semi-fixed structure portion, a portion having a small cross-sectional dimension or a tapered portion gradually decreasing toward the fixed end so that the secondary moment of the cross-section is smaller than that of other column bases / column heads. By providing, a semi-fixed structure part can be constituted.

In addition to the semi-fixed structure, it is preferable that the frame is designed to have a mechanism in which a hinge is formed at the beam end.

  According to the building structure of the present invention, it is not necessary to make various assumptions regarding the structural analysis model as in the prior art, and it is possible to realize a uniform deformation mode in the height direction by devising the structure of the frame. it can.

The figure (a) which shows the column head which has a semi-fixed structure part by this embodiment, the figure (b) which also shows a column base part, sectional drawing (c) cut | disconnected in cc line direction, and cut | disconnected in dd line direction It is sectional drawing (d) tried. The figure (a) which shows the column head which has another semi-fixed type structure part by this embodiment, the figure (b) which shows a column base part, the sectional view (c) cut along the cc line direction, and the dd line direction It is sectional drawing (d) cut | disconnected. It is a top view of the building structure of the analysis object in the earthquake response analysis of this embodiment. FIG. 4 is a diagram (a) in which the building structure to be analyzed in FIG. 3 is viewed from a direction IVA in FIG. 3 and a diagram (b) illustrating a model in which the column beam of the building structure to be analyzed is a fishbone shape. It is the graph (a) which shows roughly the stress-strain relationship of the concrete used in the analysis of this embodiment, and the graph (b) which shows schematically the stress-strain relationship of a reinforcing bar. It is a deformation | transformation conceptual diagram of the stigma column base semi-fixed model with which the deformation angle of each layer assumed substantially in the earthquake response analysis of this embodiment. It is the figure (a) which shows the yield mechanism of the conventional stigma pillar base fixed model assumed in the analysis of this embodiment, and the figure (b) which similarly shows the yield mechanism of the stigma pillar base semi-fixed model of this embodiment. It is the graph which compared the maximum interlayer deformation angle (maximum value in a time history) of the conventional fixed model obtained by the analysis of this embodiment, and the stigma column base semi-fixed model of this embodiment. For the stigma semi-fixed model of this embodiment and the conventional fixed model obtained by the analysis of this embodiment, the maximum inter-layer deformation angle for each layer using ELCENTRO waves reflecting the ground amplification characteristics of Machida (in the time history) It is a graph which shows a maximum value. It is a graph which similarly shows each layer maximum interlayer deformation angle (maximum value in a time history) using a TAFT wave. It is a graph which similarly shows each layer maximum interlayer deformation angle (maximum value in a time history) using a HACHINOHE wave. For the stigma-type semi-fixed model and the conventional fixed model of this embodiment obtained by the analysis of this embodiment, the maximum interlayer deformation angle of each layer using ELCENTRO waves reflecting the ground amplification characteristics of Futtsu (in the time history) It is a graph which shows a maximum value. It is a graph which similarly shows each layer maximum interlayer deformation angle (maximum value in a time history) using a TAFT wave. It is a graph which similarly shows each layer maximum interlayer deformation angle (maximum value in a time history) using a HACHINOHE wave. It is a figure which shows the example which provided the yield mechanism isolation | separation type structure in the semi-fixed structure part of the column base of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1A is a view showing a column head having a semi-fixed structure portion according to the present embodiment, FIG. 1B is a view showing a column base portion, FIG. 1C is a cross-sectional view taken along the cc line direction, and FIG. It is sectional drawing (d) cut | disconnected in the direction.

  As shown in FIG. 1A, the column head CU of the column C includes a semi-fixed structure portion 11 having a reduced cross section between the upper end of the column C and the upper slab 1. Similarly, as shown in FIG. 1B, the column base portion CL of the column has a semi-fixed structure portion 12 whose cross section is reduced between the lower end of the column and the lower slab 2. The column C is made of reinforced concrete, and a plurality of main bars R1, R3 are arranged inside the concrete, and shear reinforcing bars R2, R4 are arranged inside the concrete at a predetermined pitch. The main reinforcement R3 extends to the semi-fixed structure parts 11 and 12 and the slabs 1 and 2, and the column ends of the column head CU and the column base CL are fixed to the upper slab 1 and the lower slab 2 to become fixed ends. ing. In FIGS. 1A and 1B, illustration of the shear reinforcement bars R2 and R4 is omitted.

  The semi-fixed structure parts 11 and 12 have the cross section of FIG. 1 (d), are configured to be smaller than the cross section of the column C of FIG. 1 (c), have fewer main bars, and other semi-fixed structure parts. The secondary moment of the cross section is smaller than that of the column base and the column head without.

  2A is a view showing a column head having another semi-fixed structure portion according to the present embodiment, FIG. 2B is a view showing a column base portion, FIG. 2C is a cross-sectional view taken along the cc line direction, and FIG. It is sectional drawing (d) cut | disconnected in the line direction.

  2A and 2B, the column head CU of the column C has a tapered semi-fixed structure portion 21 between the upper end of the column C and the upper slab 1, and the column of the column C The leg portion CL has a tapered semi-fixed structure portion 22 between the lower end of the column C and the lower slab 2.

  The semi-fixed structure portions 21 and 22 in FIG. 2 are different from FIG. 1 in that their cross-sectional areas are gradually reduced toward the fixed end. That is, as shown in FIGS. 2A, 2B, and 2D, the semi-fixed structure portions 21 and 22 are gradually reduced in cross-sectional area toward the fixed end at the four corners of the column C in FIG. There are such tapered portions 21a, 22a.

  In this example, as shown in FIG. 2C, a plurality of main bars R1 (including main bars R1 ′ at four corners), R3, and shear reinforcement bars R2, R4, and R5 are arranged as in FIG. Yes. In the semi-fixed structure portions 21 and 22 having the taper portions 21a and 22a, as shown in FIGS. 2A, 2B, and 2D, the main reinforcing bars R1 ′ at the four corners are bent to a position just before the slabs 1 and 2. It extends. In FIGS. 2A and 2B, the illustration of the shear reinforcement bars R2 and R5 is omitted.

  The semi-fixed structure parts 21 and 22 are less in number of main bars because the main bars R1 'at the four corners do not extend to the slabs 1 and 2, compared to the column bases and heads without other semi-fixed type structure parts. Due to the tapered portions 21a and 22a, the moment of inertia of the cross section gradually decreases toward the fixed end.

  In addition, since the semi-fixed structure portions 21 and 22 in FIG. 2 are provided with tapered portions 21a and 22a at the four corners of the column C, the corner portion at the fixed end of the column due to the input of an oblique horizontal force at the time of an earthquake is provided. Crushing can be prevented. In addition, although the taper part was provided in the four corners of the column C, damage other than the corner part can be reduced by providing it in addition to the corner part. For example, the semi-fixed structure portions 21 and 22 may be configured in a truncated cone shape and the tapered portion may be provided on the entire circumference.

  1 and 2, the semi-fixed type support part by the semi-fixed type structure parts 11, 12, 21, 22 provided in the column head part CU and the column base part CL is a fixed support part (semi-fixed type). Since the secondary moment of section is small compared to (without a structural part), rotation deformation is easy with a smaller acting moment.

  In the building structure composed of the column head CU and the column C having the column base CL in FIGS. 1 and 2, the semi-fixed structure portion 11, 12 or 21, 22 is compared with other normal column ends during an earthquake. As a result, the bending yield moment is reached at an early stage, and the hinges are formed by the semi-fixed structure portions 11, 12 or 21, 22, so that deformation does not concentrate on the intermediate layer but occurs uniformly in the height direction.

  The hinge is a portion where an acting moment exceeding the possessed cross-sectional performance is applied, and is also called a yield hinge. In this portion, the operating moment is maintained instead of becoming zero, but a large increase in the operating moment cannot be expected. Hereinafter, this portion is also referred to as a hinge portion.

Further, the frame structure of the building structure according to the present embodiment includes a semi-fixed structure part 11, 12 or 21, 22 that reaches a bending yield moment when a earthquake occurs and a hinge is formed, and the semi-fixed structure part 11, Other than 12 or 21, 22, it is preferable that the mechanism is designed so that a hinge is formed at the beam end. In order to form a hinge at the end of the beam, in the general structural design method, the ratio of the total bending strength (ΣcMu) of the upper and lower columns at the node to the total bending strength (ΣbMu) of the left and right beams is A beam hinge is assumed to have the following relationship.
ΣcMu ≧ 1.4 × ΣbMu
here,
ΣcMu: Sum of the bending strength of the column base above the node and the bending strength of the column head below the node ΣbMu: The bending strength of the left beam end of the node and the bending strength of the right beam end of the node total

  Next, the seismic response analysis performed on the building structure in which the column base and the column head have a semi-fixed structure will be described. The analysis was carried out by RESP-F3T, an architectural structure analysis program of Structural Planning Laboratory.

The analysis target building structure is a five-story reinforced concrete infinite uniform ramen, the analysis target plane is 6m x 6m as shown by hatching in Fig. 3, and the control area per pillar is 36m ² , unit area The hit weight was 12 kN / m ² . The analysis target column beam is shown by hatching in FIG. 4A, and FIG. 4B shows a model with a fishbone shape. As the semi-fixed structure of the column to be analyzed, the semi-fixed structure portion with a reduced cross section in FIG. 1 is used, and the height h of the semi-fixed structure portion is ½ of B due to the column C as shown in FIG. It was.

  Table 1 shows the details of the column cross section to be analyzed. New RC model was used for nonlinear characteristics of concrete. FIG. 5A shows the stress-strain relationship of concrete. The nonlinear performance of the reinforcing bars was a Masing type bilinear model, and the post-yield stiffness was 1/1000 of the initial stiffness. FIG. 5B shows the stress-strain relationship of the reinforcing bars.

  Table 2 shows details of the cross section of the beam to be analyzed. The restoring force characteristics of the beam were taken as the Takeda model, the yield stiffness reduction rate was 0.3, and the crack moment was 1/3 of the yield moment.

  Table 3 shows the details of the semi-fixed structure of the column base and stigma to be analyzed.

  Seismic motion is based on the notification wave that conforms to the acceleration response spectrum of “very rarely occurring seismic motion” specified in the Ministry of Construction Notification No. 1461 in the open engineering foundation, and the literature (Hisashi Hiraishi, Masako Kaneko, Takahiro Hiratsuka "Study on seismic response prediction of buildings considering the effect of seismic amplification characteristics", Architectural Institute of Japan, 641, 1303-1309, 2009.07) Seismic ground motion reflecting the ground amplification characteristics of Machida City was adopted.

  FIG. 6 is a conceptual diagram of deformation of the stigma-base semi-fixed model in which the deformation angle of each layer is almost uniform, assumed in the seismic response analysis of the present embodiment. The stigma column base semi-fixed model is a model in which the semi-fixed structure portion of the present embodiment is provided on the lowermost layer column base and the uppermost layer stigma.

  As shown in FIG. 6, the same rotation angle is generated in the hinge portion formed in the semi-fixed structure portion of the lowermost column base and the uppermost column head, and the rotation angle of the layer accompanying the elastic deformation is increased except for the hinge portion. It is not. In FIG. 6, the interlayer displacement angle Ri of each layer is obtained by the following equation (1) using the rotation angle θp of the hinge portion and the elastic deformation angle θe at the inflection point position of the column. In this deformation model, if the elastic deformation angle at the inflection point position of the column is greatly different in each layer, the deformation angle of each layer does not become uniform or if plasticization progresses, this elastic deformation angle is The rotation angle is considerably smaller than the rotation angle of the hinge portion, and the difference is considered not to have a significant effect.

Ri = θp + θe
However,
θp: rotation angle of the hinge portion (here, the region of the semi-fixed structure portion) of the lowermost column base and the uppermost column head θe: deformation angle of the column due to deformation other than the hinge portion (elastic flexible length of the column) 1/2 height is the inflection point)

  FIG. 7A shows the yield mechanism of the conventional stigma-pillar fixed model assumed in the analysis of this embodiment, and FIG. 7B shows the yield mechanism of the stigma-column base semi-fixed model of this embodiment.

  FIG. 8 shows the maximum inter-layer deformation angle (in the time history) of the conventional fixed model obtained by the analysis of the present embodiment and the stigmatic column base semi-fixed model in which the semi-fixed structure is provided on the stigmatic column base of the present embodiment. It is the graph which compared (the maximum value of). As shown in FIG. 8, the maximum inter-layer deformation angle of one layer of the stigma column base semi-fixed model (semi-column base semi-fixed and pedestal semi-fixed) of this embodiment is larger than that of the conventional fixed model (post-fixed and pedestal fixed). The maximum interlayer deformation angle of 5 layers increased by about 15.00%, but the maximum interlayer deformation angle from 2 layers to 4 layers decreased by about 22.30%, 25.59% and 8.13%.

  As described above, the maximum response value of the interlayer deformation angle as a whole can be reduced by using the stigma-base semi-fixed model of the present embodiment, compared with the result of the conventional fixed model, and the maximum interlayer The analysis results showed that the deformation angle could be made almost uniform.

  Next, the same analysis was performed for different seismic motions. The seismic motion uses a notification wave that conforms to the acceleration response spectrum of the “very rare seismic motion” prescribed in the Ministry of Construction Notification No. 1461, and the phase characteristics are observed waves (representative 3 waves ELCENTRO, TAFT, HACHINOHE) phase 3 types. Based on the above literature, using SHAKE, the ground motions reflecting the two types of ground amplification characteristics of Machida City, Tokyo, which corresponds to the second type of ground and Futtsu City, Chiba Prefecture, which corresponds to the first type of ground, respectively 6 types) were used as the ground motion to verify the performance of the semi-fixed stigma model.

  9 shows the maximum inter-layer deformation angle (maximum value in the time history) for each layer using ELCENTRO waves reflecting Machida's ground amplification characteristics in the stigma-type semi-fixed model and the conventional fixed model of this embodiment. FIG. 10 shows the maximum interlayer deformation angle (maximum value in time history) using waves, and FIG. 11 shows the maximum interlayer deformation angle (maximum value in time history) using HACHINOHE waves.

  In addition, in the stigma-type semi-fixed model of this embodiment and the conventional fixed model, the maximum inter-layer deformation angle (maximum value in the time history) of each layer using ELCENTRO waves reflecting the ground amplification characteristics of Futtsu is shown in FIG. FIG. 13 shows the maximum interlayer deformation angle (maximum value in the time history) using the TAFT wave, and FIG. 14 shows the maximum interlayer deformation angle (maximum value in the time history) of the HACHINOHE wave.

  As shown in FIGS. 9 to 14, in the case of the conventional fixed model, the maximum deformation angle of the second layer and the third layer becomes large even in the case of different spectra of seismic motion, whereas in the stigma-base semi-fixed model of this embodiment, It can be said that the maximum deformation angle of the second layer and the third layer is suppressed, and the function of uniform deformation is substantially maintained.

  Next, an example in which the proof strength is not reduced even when a hinge is formed on the column base portion / column head having the semi-fixed structure portion of the present embodiment will be described with reference to FIG. 15 is a view showing an example in which a yield mechanism separation type structure is provided in the semi-fixed structure part of the column base of FIG.

As shown in FIG. 15, the yield mechanism separation type structure is configured by providing a concrete adhesion removal section GP around the main reinforcement R 1 in the semi-fixed structure portion 22 of the column base CL. Adhesion between main reinforcement R 1 and the concrete in the section GP is removed, since the main reinforcement R1 semi stationary structure portion 22 is separated from the concrete, can reduce damage of the concrete. That is, in the event of an earthquake, the main reinforcement R 1 yields to absorb the energy of the earthquake, while the void GP prevents the concrete from being damaged. As a result, even if a large deformation occurs in the semi-fixed structure portion 22 due to the earthquake, Almost never drops. The semi-fixed structure 21 of the column head CU in FIG. 2 also has a yield mechanism separation structure similar to that described above.

  As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the semi-fixed structure portion 11 of the column base and the semi-fixed structure portion 12 of the column head in FIG. 1 do not necessarily have the same cross-sectional shape. For example, as in the analysis example (Table 3) The cross section of the semi-fixed structure portion 11 of the column base may be larger than the cross section of the semi-fixed structure portion 12 of the column head.

  Further, the semi-fixed structure portion 21 of the column base and the semi-fixed structure portion 22 of the column head in FIG. 2 need to have the same vertical length and the inclined angles of the tapered portions 21a and 22a. And can be changed as appropriate.

  Further, it is a matter of course that the yield mechanism separation type structure similar to that of FIG. 15 may be configured in the semi-fixed structure part 11 of the column base and the semi-fixed structure part 12 of the column head in FIG.

DESCRIPTION OF SYMBOLS 1 Upper slab 2 Lower slab 11, 12, 21, 22 Semi-fixed structure part 21a, 22a Taper part C Column CL Column base part CU Column head GP Adhesion removal section R1, R1 ', R3 Main reinforcement R2, R4, R5 Shear reinforcement muscle

Claims (2)

The columns are reinforced concrete and the interlayer deformation of the building is designed to be uniform in the height direction.The structure is semi-fixed to the lowermost column base and the uppermost column head of the multiple floors. Provided,
The semi-fixed structure is designed to be a mechanism designed to reach a bending yield moment and form a hinge earlier than other column ends during an earthquake,
As the semi-fixed structure, there is provided a tapered portion that gradually decreases toward the fixed end so that the secondary moment of section is smaller than that of the other column bases and column heads, It is bent along the taper part,
By providing a concrete adhesion removal section around the main bar in the semi-fixed structure, the column base and the column head have a structure in which the yield strength does not decrease even if the hinge is formed. Building structure. The building structure according to claim 1 , wherein the building structure is designed to have a mechanism in which a hinge is formed at a beam end portion other than the semi-fixed structure portion.

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