JP2015232229A - Earthquake response analytical method for base isolation building and earthquake-proof safety evaluation method of base isolation device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earthquake response analytical method for a base isolation building in which the behavior of a base isolation device provided in the base isolation building is grasped in an earthquake with high accuracy and the safety can be evaluated reliably, and to provide an earthquake-proof safety evaluation method of the base isolation device using the earthquake response analytical method for the base isolation building.SOLUTION: An earthquake response analytical method for a base isolation building is configured by: integrating each member element of an upper structure 2 of the building, a base isolation layer 4 comprising a base isolation device, a joining slab 6 for connecting pile heads 10 of multiple foundation piles 8 with each other, and a lower structure 3 comprising a foundation pile 8 and a pile cap 7 with a seismic isolator installed therein and joining the pile head 10 with the joining slab 6 by including a model of the ground; constituting an earthquake response analysis model 1 for the base isolation building collecting the foundation pile 8 with high accuracy; triggering design ground motion to each part 11, 13 of the foundation pile 8 at the same time; and calculating a time history response result of each section of an integrated structural model from the upper structure 2 to the foundation pile 8 at the same time.

Description

  The present invention relates to a seismic response analysis method for a seismic isolation building and a seismic safety evaluation method for a seismic isolation device using a seismic response analysis method for a seismic isolation building, and more particularly, to a seismic isolation building provided with a seismic isolation device. The present invention relates to a seismic response analysis method for grasping behavior during an earthquake, and a seismic isolation safety evaluation method for a base isolation device that evaluates the safety of a base isolation device during an earthquake using the seismic response analysis method for base isolation buildings.

  Here, the seismic isolation building refers to a building in which a seismic isolation device or a seismic isolation system that exhibits a seismic isolation effect is incorporated in the structure of the building. In addition, the seismic isolation device includes, for example, natural rubber-based laminated rubber bearings, laminated rubber bearings with lead plugs, elastic sliding bearings, dampers, etc. Is included.

  In conventional seismic isolation buildings, the so-called “base seismic isolation method”, in which the base beam is rigid and a base isolation device is installed on the base beam, was the mainstream. In FIG. 9, the schematic structure of one Example of the basic seismic isolation method 40 is shown. The base seismic isolation method 40 includes an upper structure 41 of a building, a lower structure 42, and a seismic isolation layer 43 between the upper structure 41 and the lower structure 42 and in which a seismic isolation device 53 is installed. Here, the “base isolation layer” refers to a layer that exhibits a base isolation effect on a building by providing a plurality of base isolation devices over the entire predetermined layer. The upper structure 41 includes a column 44, a beam 45, and a floor slab 46. The lower structure 42 includes a foundation beam 47, a concrete slab 48, a pile cap 49, and a foundation pile 50 driven into the ground 52.

  In FIG. 9, the deformation mode which the seismic isolation apparatus 53 used for the basic seismic isolation method 40 assumes at the time of an earthquake is shown. Since the foundation beam 47 below the seismic isolation layer 43 where the seismic isolation device 53 is installed has high bending rigidity, the shear isolation layer 43 is superior to the bending deformation in the seismic isolation layer 43 in the same manner as the upper structure 41 during an earthquake. . Therefore, as shown in FIG. 9, the seismic isolation device 53 mainly generates a deformation mode called sway during an earthquake. Also, the joint between the pile head 51 of the foundation pile 50 and the foundation beam 47 or the pile cap 49 is a rigid joint, and the boundary condition of the pile head 51 is generally fixed even in the seismic design of the foundation pile 50. is there.

  FIG. 10 shows a sway rocking (SR) model 60 which is one seismic response analysis model corresponding to the basic seismic isolation method 40. This SR model is a model that takes into account the ground interaction in the building, and is composed of a superstructure member element 62, a seismic isolation layer model 64, and a substructure member element 69. In the conventional seismic response analysis method, the superstructure 41 and the pile foundation 50 are generally designed separately. That is, for the upper structure 41, for example, a foundation fixing model (not shown) mainly used when the deformation of the building lower structure 42 shown in FIG. 9 can be ignored, or the deformation of the building lower structure 42 is ignored. When it is not possible, it is designed using a response value obtained by time history analysis using a sway locking (SR) model 60 or the like mainly used. In the sway locking (SR) model 60 shown in FIG. 10, the member element 62 of the superstructure 41 is replaced with a mass point having mass (m) and rigidity (k). The base isolation layer is evaluated by a base isolation layer shear spring 68. Further, in the member element 69 of the lower structure 42, the bending deformation (θ) is evaluated by the rocking spring 65, and the shear deformation (δ) is evaluated by the sway spring 63. As for the seismic design of the foundation pile 50, the inertial force acting on the foundation pile 50 is obtained from the time history analysis, and the stress due to this inertial force and the stress due to the deformation of the ground 52 including additional bending are calculated by the square sum square root or the like. The method of adding is adopted. Here, “additional bending” means that when a horizontal force acts on a building during an earthquake or the like and a horizontal displacement (δ) occurs in the seismic isolation device that receives axial force (P) from the superstructure, the seismic isolation device The eccentric bending moment that occurs in Further, in the present specification, this “additional bending” is also referred to as “P-δ bending moment”, and a phenomenon in which such a bending moment is generated is referred to as “P-δ effect”. Although these seismic response analysis methods 60 are simple methods, it is difficult to say that they can accurately grasp the behavior of the base-isolated building 40 during an earthquake. In particular, the seismic design method 60 for the pile foundation 50 using inertial force is designed with excessive stress compared to the stress actually generated in the pile foundation 50 during an earthquake. However, in the conventional seismic response analysis method 60, from the viewpoint of ensuring safety against deformation of the seismic isolation device 53, the seismic design method 60 is adopted for convenience.

  On the other hand, seismic isolation devices have been developed and spread as devices that can withstand high axial forces and large shear deformations that occur during an earthquake. Therefore, although it has high followability with respect to sway, the problem that the performance of a seismic isolation device falls with respect to two-way bending deformation is pointed out. For example, Non-Patent Document 1 entitled “New knowledge about the limit performance of a high-damping rubber-based laminated rubber bearing when it is applied in two horizontal directions” and the high-damping rubber-based laminated rubber bearing is subjected to two-way bending deformation. The critical performance is reported. Here, it has been reported that when the inclination angle of the laminated rubber bearing by two-way bending increases, the function of the laminated rubber bearing may be lowered.

  Thus, for example, a base-isolated device such as a laminated rubber bearing has been widely used as a device that exhibits a high seismic isolation effect because it exhibits high followability to interlayer deformation occurring in the superstructure of a building during an earthquake. And, in order to make the function of this seismic isolation device fully function, a construction method in which the base beam is rigid and the seismic isolation device is installed on the base beam has become common. The features of the seismic isolation device and the construction method of the seismic isolation building using the seismic isolation device are not limited to laminated rubber bearings, and are the same in, for example, laminated rubber bearings with lead plugs or elastic sliding bearings.

  In recent years, new construction methods or construction methods have been proposed to rationalize by reducing or omitting foundation beams. For example, Patent Document 1 discloses a specific example of the “pile head seismic isolation method” in a narrow sense. Here, the seismic isolation device was fixed on the pile head of the steel pipe pile, and the upper structure was fixed on this seismic isolation device, so it became possible to rationalize the foundation structure by omitting the conventional foundation beam . And the pile heads of the steel pipe pile were connected with the foundation slab which is a connection member. Thereby, even when receiving a horizontal force due to an earthquake, the plurality of steel pipe piles are displaced in the same direction without being horizontally displaced, and the plurality of steel pipe piles as a whole resist the horizontal force. In this specification, the seismic isolation device is fixed on the pile head of a steel pipe pile, and the conventional method of omitting the foundation beam by fixing the superstructure on the seismic isolation device is the `` pile head isolation method '' in a narrow sense. Called.

  On the other hand, in the 1995 Hyogoken-Nanbu Earthquake, a large number of damage occurred in piles with pile heads rigidly connected, and stress was concentrated on the pile heads. As shown in Non-Patent Document 2, various types of “pile head semi-rigid joint construction methods” have been proposed. This semi-rigid pile head construction method not only reduces the pile head bending moment during an earthquake, but also rationalizes foundation piles and foundation beams. In this specification, among the pile head semi-rigid joint construction methods, a construction method using pile head semi-rigid joints for a building provided with a seismic isolation device is referred to as a “pile head seismic isolation method” in a broad sense.

  The above-mentioned “pile head seismic isolation method” in the broad sense described above is that pile head connection parts such as {pile caps} are provided on the pile head, the foundation beam is a foundation structure such as “tethering slab” and the pile head is bent. This is a construction method that reduces the constraint effect and rationalizes the conventional foundation beam. Especially in warehouses and distribution centers that have a large floor area compared to the number of floors, the ratio of the construction cost of the foundation beam in the total construction cost is higher than that of high-rise buildings, and the effect of reducing the construction cost is large. It is expected as an effective construction method. However, since the foundation beam was reduced and rationalized, generation of harmful rotation amount (θ) of the seismic isolation device at the time of earthquake, which was not a problem when the foundation beam was rigid, has become a problem. . The following countermeasures have been proposed for this problem.

  Patent Document 2 discloses a seismic isolation device with a rotation control spring mechanism that controls the rotation of the seismic isolation device by suppressing the bending moment generated in the pile head of the steel pipe pile during an earthquake and does not cause harmful rotation to the seismic isolation device. Is disclosed. Here, a laminated rubber seismic isolation device, a flat foundation beam that connects steel pipe piles, a seismic isolation device support block that supports the laminated rubber seismic isolation device, and a seismic isolation device support block. A pile cap composed of a support block anchoring portion fixed to the pile head of the steel pipe pile by a set of reinforcing bars, and the pile cap is generated by the earthquake motion due to the adjusted fixing degree with the steel pipe pile to be joined It is described that the pile head bending moment to be reduced, resisting as a rotating spring against the reduced pile head bending moment, and controlling the rotation amount of the laminated rubber seismic isolation device within the allowable rotation amount at the time of earthquake .

  Patent Document 3 also discloses a simple and reliable seismic isolation device that controls the rotational stiffness of the pile head joint against the pile head bending moment that occurs during an earthquake and does not cause harmful rotation to the seismic isolation device. A control mechanism is disclosed. Here, the pile cap and the pile cap fixing part are joined by a joining reinforcing bar, and the joining reinforcing bar is fixed to the concrete in the pile cap, and the second joining reinforcing part to be fixed to the concrete in the foundation pile. A rotation amount control unit provided in the pile head joint, and when the tensile force generated in the joint rebar by the pile head bending moment exceeds a predetermined value, a rotation amount control unit is formed to form a hinge due to tensile yield inside. It is described that the rotational rigidity of the pile head joint is reduced to a predetermined value by the hinge inside the part, and the rotation amount of the seismic isolation device at the time of an earthquake is controlled within an allowable rotation amount. That is, due to the occurrence of hinges due to tensile yielding, the joint reinforcing bars and the like are elongated, and the performance of the rotary spring of the pile cap is lowered. The rotational force of the pile cap is reduced due to the reduced performance of the rotary spring, and harmful deformation of the laminated rubber seismic isolation device during an earthquake is avoided.

  The above-described rotation control spring mechanism of Patent Literature 2 and the seismic isolation device rotation control mechanism of Patent Literature 3 are mechanisms for controlling the rotation of the seismic isolation device in the event of an earthquake and not causing harmful rotation in the seismic isolation device. is there. In this way, the problem with the broad-sense pile head seismic isolation method that reduces the foundation beam and rationalizes it, or makes the foundation pile pile head joint semi-rigid, is to install such a mechanism in the seismic isolation device. It was solved with.

Japanese Patent No. 3899354 Japanese Patent No. 5082085 Japanese Patent No. 5082085

New knowledge about critical performance of high damping rubber-based laminated rubber bearings when applied in two horizontal directions. Technical Committee Seismic Isolation Member Group, etc. 87 2012.2 Research Report on New Technology Survey “Pile Head Semi-Rigid Bonding Method” Construction Cost Management System Study Group New Technology Study Study Group Construction Cost Study 2008 WINTER

  As described above, a mechanism for controlling the amount of rotation generated in a base isolation device provided in a base isolation building during an earthquake and preventing harmful rotation in the base isolation device has been proposed. However, if the seismic isolation building as a whole behaves during an earthquake and the amount of rotation and shear deformation received by the seismic isolation device installed in the base isolation building can be grasped with high accuracy, such a mechanism is more effective. It is possible to make use of it. This is because the behavior of seismic isolation devices installed in seismic isolation buildings during earthquakes is closer to that of precision instruments than the behavior of structures such as columns and beams, and its precise control is possible. It is.

  The conventional seismic response analysis method for base-isolated buildings cannot accurately grasp the amount of rotation generated in the base-isolated device, so the base beam is made rigid so that the design is on the safe side for the base-isolated device. A seismic isolation device was installed. However, if a seismic response analysis method for seismic isolation buildings is proposed that can accurately calculate the bending deformation and shear deformation that the seismic isolation device installed in the building will receive in the event of an earthquake and reliably evaluate its safety. Thus, the above-described safety design is not required, and the seismic design of a higher dimension seismic isolation building is possible.

  For example, the conventional method of rationalizing by reducing or omitting the foundation beams is more rational because the behavior of the base-isolated building at the time of the earthquake can be accurately grasped by the more accurate seismic response analysis method for base-isolated buildings. Design becomes possible. In addition, when the pile head semi-rigid joint construction method is adopted in contrast to the so-called “pile head rigid joint construction method” where a lot of damage occurs in the pile with the pile head rigidly joined and stress concentrates on the pile head. However, more accurate design is possible because the more accurate seismic response analysis method for base-isolated buildings can grasp the behavior of a semi-rigid pile head during an earthquake with high accuracy.

  Moreover, the above-mentioned broad-headed pile head seismic isolation method was originally intended for pile foundations with relatively good ground, but is being adopted for base-isolated buildings built on sites with special ground conditions. In particular, in soft ground, the behavior of base-isolated buildings during an earthquake must be grasped more accurately. Therefore, the seismic response analysis method for base-isolated buildings that can reflect the special characteristics of the ground properties more accurately in the design of the building and sufficiently evaluate the seismic safety of the base-isolated device is essential.

  The purpose of this application is to solve such problems, grasp the behavior of the seismic isolation device installed in the base isolation building at the time of the earthquake with high accuracy, and reliably evaluate its safety. And providing a seismic safety evaluation method for seismic isolation devices using seismic response analysis methods for seismic isolation buildings.

  In order to achieve the above object, the seismic response analysis method for a seismic isolation building according to the present invention is a seismic response analysis method used for a seismic isolation building having a seismic isolation device between an upper structure and a lower structure of a building. Superstructure, seismic isolation layer where seismic isolation devices are installed, foundation pile, foundation structure connecting pile heads of multiple foundation piles, and pile head of foundation structure and foundation pile supporting seismic isolation device The seismic response analysis model for base-isolated buildings is constructed by integrating the lower structure consisting of the pile head connection part that joins the part with the ground, including the ground, and consolidating the foundation piles into a single longitudinally continuous member element The design earthquake motion is applied to each part of the foundation pile at the same time, and the time history response result of each part of the integrated structural model from the superstructure to the foundation pile is calculated at the same time.

  With this configuration, the seismic response analysis method for base-isolated buildings is a structural model in which the superstructure of the building, base isolation layer, foundation structure, pile head connection, foundation pile, and ground are integrated. A seismic isolation layer with a modeled device was installed. This makes it possible to accurately calculate the stress and deformation experienced by the seismic isolation device in the behavior of the entire structure during an earthquake, and accurately affect the influence of the seismic isolation device installed in the building for the entire structure. It became possible to reflect well. In other words, the upper structure, which was separated for the sake of convenience in the conventional seismic response analysis method, and the lower structure consisting of the foundation structure, the pile head connection part, and the foundation pile were integrated and analyzed, and further the seismic isolation The seismic response analysis method can be used to reliably evaluate safety by setting a seismic isolation layer for a device that requires a high level of analysis accuracy.

  The seismic response analysis method for base-isolated buildings applied design seismic motion to each part of the foundation pile at the same time. Thereby, it became possible to calculate each time history response result of the integrated structure from the superstructure to the foundation pile at the same time. In the conventional analysis method, for the pile design, the inertial force acting on the pile is obtained from the time history analysis, and the stress due to this inertial force and the stress due to ground deformation including additional bending are added by the square sum of squares. Was adopted. In this seismic response analysis method for base-isolated buildings, each time history response result of the integrated structure from the superstructure to the foundation pile can be calculated at the same time, and more accurate seismic response analysis results can be obtained .

  In addition, in the seismic response analysis method for seismic isolation buildings, it is preferable that the seismic isolation layer of the seismic response analysis model is provided with a bending spring that calculates the amount of rotational deformation of the seismic isolation device based on the time history. As a result, the amount of rotation of the bending spring can be ascertained from the time history, and the seismic response analysis method for seismic isolation buildings can provide information that can be used to evaluate seismic safety evaluations related to rotational deformation of seismic isolation devices. Can do.

  Further, in the seismic response analysis method for seismic isolation buildings, it is preferable that a shear spring for calculating the horizontal displacement of the seismic isolation device according to the time history is provided in the seismic isolation layer of the seismic response analysis model. As a result, the amount of displacement of the shear spring can be ascertained from the time history, and the seismic response analysis method for seismic isolation buildings can provide information that enables seismic safety evaluation regarding the horizontal displacement of the seismic isolation device. it can.

  In addition, in the seismic response analysis method for base-isolated buildings, in the seismic response analysis model, an acceleration waveform is input as a design seismic motion to the node provided at the lower end of the foundation pile, and the design is applied to the longitudinal node of the foundation pile. It is preferable that an earthquake displacement waveform is input as a seismic motion through a horizontal ground spring. Thereby, the seismic motion for design is made to act on each part of a foundation pile at the same time, and a more accurate analysis result can be obtained.

  In addition, in the seismic response analysis method for base-isolated buildings, it is preferable that an eccentric bending moment generated by horizontal displacement of the base isolation device during the earthquake is applied to the base isolation layer of the seismic response analysis model according to the time history as an additional bend. . Thereby, it can be set as the response analysis model which reflects the behavior of the building at the time of an earthquake more accurately.

  In addition, in the seismic response analysis method for base-isolated buildings, the seismic response analysis model must be either a model in which group piles are aggregated into one pile or a model in which group piles are multiple piles. Is preferred. As a result, the effect of the group pile can be reflected in the analysis model, and either a simpler response analysis model or a more precise response analysis model can be selected from the design conditions or the like in the seismic design of the group pile.

  Furthermore, the seismic response analysis method for base-isolated buildings is based on the fact that the ground mass directly under and near the building acts as an additional mass on the foundation pile of the seismic response analysis model, and the shear stiffness of the ground directly under and near the building acts as an additional ground spring. It is preferable to act. Thereby, it can be set as the response analysis model which reflects the influence of the ground with respect to a foundation pile more accurately at the time of an earthquake.

  In addition, the seismic isolation safety evaluation method of the seismic isolation device using the seismic response analysis method for seismic isolation building was set with the amount of rotation of the seismic isolation device calculated from the time history response result regarding the deformation amount of the bending spring. It is preferable to evaluate the safety against the rotational deformation performance of the seismic isolation device during an earthquake from the relationship with the allowable rotation amount of the seismic isolation device. Thereby, each time history response result of the structure integrated by the earthquake response analysis method can be calculated at the same time, and a more accurate analysis result can be obtained, and at the same time, the rotational deformation of the seismic isolation device at the time of the earthquake Seismic safety can be reliably evaluated.

  Further, the seismic isolation safety evaluation method of the seismic isolation device using the seismic response analysis method for seismic isolation buildings includes the horizontal displacement of the seismic isolation device calculated from the behavior of the shear spring and the set seismic isolation device tolerance. It is preferable to evaluate the safety against the horizontal displacement performance of the seismic isolation device during an earthquake from the relationship with the horizontal displacement. As a result, each time history response result of the structure integrated by the earthquake response analysis method can be calculated at the same time, and a more accurate analysis result can be obtained, and at the same time, the horizontal movement of the seismic isolation device during an earthquake can be obtained. Seismic safety can be reliably evaluated.

  As described above, according to the seismic safety evaluation method for basic seismic isolation buildings according to the present invention, the behavior of the seismic isolation device provided in the seismic isolation building at the time of the earthquake can be grasped with high accuracy, and the safety can be ensured. It is possible to provide seismic response analysis methods for seismic isolation buildings that can be evaluated and seismic safety evaluation methods for seismic isolation devices using seismic response analysis methods for base isolation buildings.

It is sectional drawing which shows one Example of the base isolation building in which the seismic response analysis method for base isolation buildings based on this invention is used. It is sectional drawing which shows schematic structure of one Example about the structure of the base isolation layer provided in the base isolation building. It is sectional drawing which shows the deformation | transformation mode at the time of the earthquake around the seismic isolation apparatus shown in FIG. It is explanatory drawing which shows the outline | summary of one basic analysis model used for the seismic response analysis method for seismic isolation buildings. It is explanatory drawing which shows the outline | summary of the coupled analysis model which added the additional bending moment to the seismic isolation layer of the basic analysis model of FIG. 4, and added the member element of the additional ground to the lower structure. It is sectional drawing which shows the integrated and the whole pile model which united the upper structure, the lower structure, and the seismic isolation layer, and modeled the whole foundation pile. It is explanatory drawing which shows one Example of the rotation control mechanism which controls the amount of rotation deformation at the time of the earthquake of the seismic isolation apparatus provided in the base isolation building. It is a flowchart which shows the step of the seismic safety evaluation method of a seismic isolation apparatus. It is sectional drawing which shows the deformation | transformation mode with which the schematic structure of one Example of a basic seismic isolation method and the seismic isolation apparatus used for a basic seismic isolation method are assumed at the time of an earthquake. It is explanatory drawing which shows the sway rocking (SR) model of the superstructure which is one seismic response analysis model corresponding to a basic seismic isolation method.

(Seismic isolation building)
Hereinafter, embodiments of the seismic safety evaluation method for seismic isolation buildings according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing one embodiment of a base-isolated building 20 in which the seismic safety evaluation method for base-isolated buildings is used. The seismic safety evaluation method for a base-isolated building includes an upper structure 21 of a building composed of columns 24, beams 25, and a floor slab 26, and a lower structure 22 composed of a foundation pile 30 that is placed on the ground 32 and supports the building. The seismic isolation layer 23 between the upper structure 21 and the lower structure 22 and provided with the seismic isolation device 33 is used for the seismic isolation building 20. Here, in this specification, the structure above the seismic isolation layer 23 in the seismic isolation building 20 is referred to as the upper structure 21, and the structure above the seismic isolation layer 23 is referred to as the lower structure 22. Although it is set as the structure that 22 is connected by the seismic isolation layer 23, it is not restricted to this structure.

  In the present embodiment, the lower structure 22 is provided with a pile cap 29 that is a pile head connecting portion on which the seismic isolation device 33 is installed, and a connecting slab 27 that is a foundation structure. The configuration is not limited to this. For example, the connecting slab 29 may be a beam material such as a flat beam. Further, for example, a “pile head seismic isolation method” in which the pile cap 29 is omitted and the seismic isolation device 33 is installed directly on the foundation pile 30 may be used. Further, the upper structure 21 may be of any structural form such as a steel structure, a reinforced concrete structure, a steel reinforced concrete structure, or the like. Furthermore, the foundation pile 30 provided in the ground 32 may be of any pile type such as, for example, a steel pipe pile, a concrete cast-in-place pile, or a PC pile.

(Structure of seismic isolation layer)
In FIG. 2, the schematic structure of one Example about the structure of the base isolation layer 23 provided in the base isolation building 20 in which this seismic response analysis method for base isolation buildings is used is shown. FIG. 3 shows a deformation mode of the seismic isolation layer 23 shown in FIG. 2 during an earthquake. The upper structure 21 includes a column 24, a beam 25 having high bending rigidity, and a floor slab 26. On the other hand, the pile cap 29 which connects the seismic isolation apparatus 33 and the pile head 39 of a foundation pile is mutually connected by the connecting slab 27 with comparatively low bending rigidity. When receiving a horizontal force due to an earthquake, the connecting slab 27 displaces the plurality of foundation piles 30 in substantially the same direction without being horizontally displaced so that the plurality of foundation piles 30 as a whole resist the horizontal force.

In the conventional seismic isolation building 40 shown in FIG. 9, a so-called “base seismic isolation method” in which the base beam 47 is rigid and the base isolation device 53 is installed on the base beam 47 has been adopted. In this basic seismic isolation method, shear deformation is superior to bending deformation in the seismic isolation layer 43 during an earthquake. Therefore, although the seismic isolation device 53 swayed greatly (δ) in the lateral direction, the amount of rotation (Θ) of the seismic isolation device 53 was negligible. In the seismic isolated building 20, a construction method is used in which the beam elements are rationalized by using a conventional foundation beam 47 having a high bending rigidity as a connecting slab 27 having a relatively low bending rigidity. As a result, as shown in FIG. 3, a greater amount of rotation (Θ) is generated in the seismic isolation device 33 during an earthquake. That is, the amount of rotation (Θ) is between the upper flange 34a of the seismic isolation device connected to the large beam 45 having high bending rigidity and the lower flange 34b of the seismic isolation device connected to the connecting slab 27 having relatively low bending rigidity. Occur. This rotation amount (Θ) has two-direction rotation amounts Θx and Θy corresponding to the two-way bending Mx and My, respectively, and the maximum rotation amount (Θ _max ) is (Θx + Θy) ^1/2 , and this rotation amount There is a possibility that the function of the seismic isolation device 33 is lowered due to (Θ _max ).

(Seismic response analysis method for base-isolated buildings)
4 and 5 show a seismic response analysis model 1 for a seismic isolation building used in the seismic response analysis method for a seismic isolation building according to the present invention. First, FIG. 4 shows an outline of a basic analysis model 1a which is one of the seismic response analysis models 1 for base-isolated buildings. The basic analysis model 1a includes a superstructure 2 of a building, a seismic isolation layer 4 provided with a seismic isolation device 33, a tether slab 6 which is one embodiment of the foundation structure, and a pile cap which is one embodiment of a pile head connecting portion. 7. The foundation pile 8 and the ground were integrated. Furthermore, it is an “integrated / pile consolidation model” in which the foundation piles 8 are consolidated into a model that is continuous in the vertical direction. In this basic analysis model 1a, a large black circle indicates “mass (m)”, a small black circle indicates “node”, and a bar indicates a “member element”.

(Configuration of basic analysis model)
The basic analysis model 1a of the superstructure 2 is a multi-mass point analysis model in which the mass (m) of each layer of the building is replaced with a mass point 17a, and the shear stiffness (k) of each layer of the building is replaced with a shear spring 16a. is there. In addition, the large beam member element 5 on the upper part of the seismic isolation layer 4 provided with the seismic isolation device 33 is replaced with roller support at both ends, and the mass around the large beam is concentrated at the mass point 17b. Further, both end portions of the member element 6 of the connecting slab 27 at the lower part of the seismic isolation layer 4 are replaced with roller supports, and the mass of the connecting slab and the like is concentrated at the mass point 17c. Further, the foundation pile is divided into longitudinal member elements 8, and the mass of each member element 8 is replaced with a mass point 17d. Further, the shear rigidity of the ground is replaced by the shear spring 16c. And the fixed degree of the junction part of the pile head part 10 of the member element 8 of a foundation pile and the member element 7 of a pile cap becomes semi-rigid joining, and is evaluated by the pile head bending spring 15b.

(Modeling of seismic isolation floor)
The seismic isolation layer 4 is provided with a seismic isolation layer bending spring 15 a that calculates the amount of rotational deformation of the seismic isolation device 33 based on the time history. The seismic isolation layer 4 is provided with a seismic isolation layer shear spring 16b that calculates the horizontal displacement of the seismic isolation device 33 based on the time history. With the seismic isolation layer bending spring 15a and the seismic isolation layer shear spring 16b, the bending deformation and the shear deformation that the seismic isolation device 33 receives in the seismic isolation layer 4 during an earthquake can be evaluated. In this way, the seismic isolation layer 4 provided with the seismic isolation device 33 is provided between the upper structure 2 and the lower structure 3, and modeling is performed by the seismic isolation layer bending spring 15a and the seismic isolation layer shear spring 16b. The amount of deformation that the seismic isolation device 33 receives can be clearly understood.

(Configuration of coupled analysis model)
FIG. 5 shows an outline of the coupled analysis model 1b in which the additional bending moment 12 is input to the seismic isolation layer 4 of the basic analysis model 1a of FIG. 4 and the additional ground member element 9 is added to the lower structure 3. As with the basic analysis model 1a, this coupled analysis model 1b is also the superstructure 2 of the building, the seismic isolation layer 4 provided with the seismic isolation device 33, the connecting slab 6 as an example of the foundation structure, the pile head connection part The pile cap 7, the foundation pile 8, and the ground which are one Example of were integrated. Furthermore, it is an “integrated / pile consolidation model” in which the foundation piles 8 are consolidated into a model that is continuous in the vertical direction. Also in this coupled analysis model 1b, a large black circle indicates “mass (m)”, a small black circle indicates “node”, and a bar indicates “member element”.

  Then, the eccentric bending moment 12 generated by the displacement (δ) of the base isolation layer 4 in the basic analysis model 1a of FIG. 4 is added to the base isolation layer 4 with time history, so that the P-δ effect of the base isolation layer 4 is obtained. More accurate earthquake behavior can be reflected. Further, the mass of the ground immediately below or near the building acts on the mass 17e as the mass of the additional ground on the member element 8 of the foundation pile. Further, the rigidity of the ground immediately below or near the building acts as the additional ground spring 16d. As a result, it is possible to add the influence of the ground directly under the building or in the vicinity to the seismic response analysis. In particular, the influence of the soft ground on the pile behavior can be reflected in the seismic response analysis.

(Modeling of foundation pile)
FIG. 6 shows an integrated / pile overall model in which the upper structure 2, the lower structure 3, and the seismic isolation layer 4 are integrated to model the entire foundation pile 8. FIG. 6A shows a plan view of the seismic isolation building 20. In this plan view, pillars 24 shown in cross section are connected by beams 25, and small beams 19 are provided on the floor surface. A structure obtained by cutting the plan view in the vertical direction along the composition plane 18 indicated by a one-dot chain line is modeled in FIG. The basic analysis model 1a and the coupled analysis model 1b described above are models in which the entire foundation pile 30 is integrated into the member element 8 of one foundation pile. In this modeling, the seismic response of the entire structure including the foundation pile 30 can be grasped, but it is difficult to grasp the behavior of each seismic isolation device 33 and the foundation pile 30. On the other hand, the pile overall model of FIG. 6 takes out one structural surface of the base-isolated building 20, aggregates the upper structure 21 in the surface, and the base-isolated layer 23 provided with the base-isolating device 33 shown in FIG. As a whole model in which the tether slab 27, the pile cap 29, the foundation pile 30, and the ground 32 are individually modeled, the group pile is a model in which a large number of foundation piles 30 are evaluated. And the seismic isolation layer 4 is provided with the seismic isolation layer bending spring 15a and the seismic isolation layer shear spring 16b for every seismic isolation device 33 similarly to the basic analysis model 1a of FIG. 4 and FIG. With this modeling, the additional bending moment 12 can be input for each seismic isolation device 33. Thereby, the behavior of each seismic isolation device and foundation pile can be more accurately reflected in the seismic response analysis.

(How to input earthquake motion)
As shown in FIGS. 4 and 5, the seismic response analysis model 1 for a base-isolated building is provided with a ground motion input node 14 at a pile lower end portion 11 of a member element 8 of a foundation pile, and an acceleration waveform is input as a design ground motion. Is done. Moreover, the seismic motion input node 13 is provided at a predetermined vertical pitch of the member element 8 of the foundation pile, and an earthquake displacement waveform is input via the ground axial spring 16c as a design seismic motion. In other words, this seismic response analysis method for base-isolated buildings was designed to apply design seismic motion to each part of the base pile member element 8 at the same time, and integrated from the upper structure 2 to the base isolation layer 4 and the lower structure 3. The time history response result of each part of the structural model is calculated at the same time.

(Rotation control mechanism of seismic isolation device)
FIG. 7 shows an embodiment of a rotation control mechanism that controls the amount of rotational deformation of the seismic isolation device 33 provided in the base isolation building 20 during an earthquake. Based on the seismic response analysis result for the base-isolated building, measures for structural design are examined as described later so as not to cause harmful rotation in the base-isolated device 33. Patent Document 2 and Patent Document 3 propose a rotation control mechanism of the seismic isolation device 33 as one embodiment of the countermeasure. The pile cap 29 and the foundation pile 30 at the lower part of the seismic isolation device 33 are provided with joint reinforcing bars 36 and fixed by the upper anchor 35a and the lower anchor 35b, and the connecting slab 27, the pile cap 29 and the foundation pile 30 are integrated. ing. The joining rebar 36 has a plurality of joining rebars 36 arranged in a circle in accordance with the cross section of the circular foundation pile 30. The joint reinforcing bars are separated by a distance (d). Further, a coupler 37 is provided on the joining rebar 36 with a boundary between the pile cap 29 and the foundation pile 30 interposed therebetween. A rotational stiffness adjusting sheet 38 is provided at the boundary between the pile cap 29 and the foundation pile 30.

  As described in Patent Document 2 and Patent Document 3, each component described above functions as a rotation control mechanism of the seismic isolation device 33. That is, the pile cap 29 and the pile head 39 of the foundation pile are not completely fixed but are semi-rigid. When the fixing degree (φ) of the semi-rigid junction is completely fixed, φ = 1, and when the pin junction is φ = 0, an intermediate value between 0 and 1 is obtained. The amount of rotation that the seismic isolation device 33 receives during an earthquake can be adjusted by changing the degree of fixation (φ). For example, when the interval (d) between the joining reinforcing bars is increased, the bending rigidity (EI) of the joining portion is increased and the fixing degree is close to 1. On the other hand, when the interval (d) of the joining reinforcing bars is reduced, the bending rigidity (EI) of the joining portion is lowered and the fixing degree is close to zero. Moreover, the material which has the yield strength or cross-sectional area adjusted to the coupler 37 is used, it is made to yield at the time of an earthquake, a hinge is generated, and the rotational performance of the pile cap 29 can be reduced. Furthermore, the tensile force generated in the joint rebar 36 can be controlled by limiting the range of the concrete cross section that bears the compressive force of the rotational stiffness adjusting sheet 38 provided on the pile head 39 of the foundation pile. The method for adjusting the amount of rotational deformation at the time of earthquake of the seismic isolation device 33 is not limited to the above method, and for example, it is also possible by changing the specifications such as adjusting the strength of reinforcing bars and concrete or adjusting the cross-sectional area. Other methods are possible.

(Seismic safety evaluation method for seismic isolation devices)
The bending rotation amount (θ) of the seismic isolation device 33 calculated from the time history response result regarding the deformation amount of the bending spring 15a in the seismic response analysis for the seismic isolation building, and the set allowable rotation amount (Θ ₀ ) of the seismic isolation device 33 ) To evaluate the safety against the rotational deformation performance of the seismic isolation device 33 during an earthquake. That is, for example, the connecting slab 27, the foundation pile 30, and the pile cap 29 so that the bending rotation amount (θ) of the seismic isolation device 33 calculated from the behavior of the bending spring 15a falls within the allowable bending rotation amount (Θ ₀ ). Adjust the bending stiffness (EI). The bending rigidity (EI) around the seismic isolation device 33 can be adjusted by the fixing degree (φ) between the pile cap 29 and the pile head 39 of the foundation pile. Further, it can be adjusted by lowering the rotational performance of the pile cap 29 by pulling and yielding the coupler 37 of the joining rebar 36 in the event of an earthquake to generate a hinge. Furthermore, it can be adjusted by the rigidity adjustment sheet 38.

In a general seismic design of buildings, upper as horizontal displacement of the floor, which is calculated from the behavior of the upper structure 2 of the superstructure shear spring 16a ([delta]) falls within the allowable horizontal displacement (delta ₀₎ within the structure The shear rigidity (GA) of each floor of 2 is adjusted. In the present invention, in addition to these seismic design, the horizontal displacement (δ) of the seismic isolation device 33 calculated from the behavior of the seismic isolation layer shear spring 16b as part of the seismic safety evaluation of the seismic isolation device 33 is the allowable horizontal displacement. The shear stiffness (GA) of the seismic isolation layer 23 is adjusted so as to be within (Δ ₀ ). For example, since the seismic isolation layer 23 has superior shear deformation with respect to the seismic force, the measures such as adjusting the shear rigidity (GA) in the seismic isolation layer 23 to suppress the shear deformation amount, etc. It can be performed.

In FIG. 8, the step of the seismic safety evaluation method of the seismic isolation apparatus 33 is shown with a flowchart. Each step is indicated by reference numerals S1 to S6. First, an allowable bending rotation amount (Θ ₀ ) and an allowable horizontal displacement amount (Δ ₀ ) during an earthquake of the seismic isolation device 33 that is a laminated rubber bearing are set (S 1). Next, specifications such as reinforcing bars and concrete are determined, and bending stiffness (EI) and shear stiffness (GA) in the seismic isolation layer 4 are calculated (S2). Moreover, the fixed degree (phi) of the pile head of the foundation pile 30 joined to the pile cap 29 is calculated (S3). Then, the bending stiffness (EI), shear stiffness (GA), and fixing degree (φ) are input to the seismic response analysis program for seismic isolation buildings (S4). Then, from the seismic response analysis result, it is examined whether or not the maximum bending rotation amount (θ _max ) is smaller than the allowable bending rotation amount (Θ ₀ ) (S5). Return to S3. Further, from the seismic response analysis result, it is examined whether or not the maximum horizontal displacement amount (δ _max ) is smaller than the allowable horizontal displacement amount (Δ ₀ ) (S6). If it is smaller, the process ends. If larger, the process returns to S2 or S3. .

1 Seismic response analysis model for base-isolated buildings, 1a Basic analysis model, 1b Coupling analysis model, 2,62 Superstructure model, 3,69 Substructure model, 4,64 Base-isolation layer model, 5 Large beam member Element, 6 Connecting slab or foundation structural member element, 7 Pile cap or pile head connection element, 8 Foundation pile member element, 9 Additional ground member element, 10 Pile head, 11 Pile lower end, 12 Addition Bending moment (P-δ bending moment), 13 Ground motion (time history displacement) input node, 14 Ground motion (time history acceleration) input node, 15 bending spring, 15a Seismic isolation layer bending spring, 15b Pile head bending spring, 16, 66 Shear spring, 16a Superstructure shear spring, 16b, 68 Seismic isolation layer shear spring, 16c Ground axial spring, 16d Additional ground shear spring, 16e Pile tip ground axial spring, 17, 6 Mass, 17a mass (superstructure), 17b mass (girders joints), 17c mass (pile cap, connecting slabs, etc.), 17d mass (foundation piles), 17e mass (additional ground), 18 Plane,
19 Small beam, 20 Base-isolated building (uses seismic response analysis method for base-isolated buildings), 40 Base-isolated building based on base-isolation method, 21,41 Superstructure, 22,42 Substructure, 23,43 Base-isolated layer 24,44 Pillar, 25,45 Beam, 26,46 Floor slab, 27 Connecting slab, 28,48 Concrete slab, 29,49 Pile cap (Pile head connection part), 30,50 Foundation pile, 32,52 Ground, 33,53 Seismic isolation device, 34a Upper flange of seismic isolation device, 34b Lower flange of seismic isolation device, 35 anchor, 35a Upper anchor, 35b Lower anchor, 36 Joint rebar, 37 coupler, 38 Rotation stiffness adjustment sheet, 39, 51 Pile head of foundation pile, 47 foundation beam, 60 sway rocking (SR) model, 61 fixed point, 63 sway spring, 65 rocking spring, m mass, Rigidity.

Japanese Patent No. 3899354 Japanese Patent No. 4934769 Japanese Patent No. 5082085

In order to achieve the above object, the seismic response analysis method for a base-isolated building according to the present invention includes an upper structure of the base-isolated building, a lower structure including a foundation pile and a pile cap, and a space between the upper beam and the lower connecting slab. In the seismic response analysis method for base-isolated buildings using the seismic response analysis model for base-isolated layers, each layer of the building is replaced with a mass point and a shear spring, and the upper beam of the base-isolated layer is one mass point The base isolation layer is replaced with a roller-supported member element, and the seismic isolation layer calculates the amount of rotational deformation of the base isolation device based on the time history and the horizontal displacement of the base isolation device based on the time history. The seismic isolation device is replaced by a shearing spring, and the substructure is replaced by a member element with one mass point and roller support at both ends, and the foundation pile is divided in the vertical direction. Multiple parts required And a plurality of mass points, the shear stiffness of the ground is replaced by a plurality of shear springs connected to the plurality of mass points, and the degree of fixation of the semi-rigid connection between the column head of the foundation pile and the pile cap is provided at the column head The design ground motion is applied to each mass point of the foundation pile at the same time, and the eccentric bending moment generated by the horizontal displacement of the seismic isolation device during the earthquake is applied to the bending spring according to the time history as an additional bending. As a result, the time history response results of each part of the integrated seismic response analysis model from the superstructure to the foundation pile are calculated at the same time, and the influence of the earthquake behavior in the integrated superstructure and substructure is analyzed. Based on the relationship between the amount of rotation of the seismic isolation device calculated from the time history response result regarding the deformation amount of the received bending spring and the set allowable rotational amount of the seismic isolation device, Security against rotation deformation performance is characterized in that it is evaluated.

In addition, in the seismic response analysis method for seismic isolation buildings, in the seismic response analysis model, an acceleration waveform is input as a design seismic motion at one node provided at the lower end of the foundation pile, and multiple vertical vibrations of the foundation pile are obtained. the quality point preferably seismic displacement waveform is input through the soil axial spring as a design ground motion. Thereby, the seismic motion for design is made to act on each part of a foundation pile at the same time, and a more accurate analysis result can be obtained.

As described above, according to the seismic response analysis method for base-isolated buildings of the base-isolated building according to the present invention and the seismic safety evaluation method for base-isolated devices using the seismic response analysis method for base-isolated buildings , Seismic response analysis method for seismic isolation building and seismic response analysis method for seismic isolation building that can grasp the behavior of the seismic isolation device installed in the base isolation building with high accuracy and reliably evaluate its safety. A method for evaluating seismic safety of seismic devices can be provided.

Claims (9)

In the seismic response analysis method used for seismically isolated buildings with seismic isolation devices between the superstructure and substructure of the building,
The superstructure of the building,
A seismic isolation layer with seismic isolation devices;
A lower structure comprising a foundation pile, a foundation structure that connects the pile heads of a plurality of foundation piles, and a pile head connection part that supports the seismic isolation device and joins the foundation structure and the pile head of the foundation pile; And seismic response analysis model for base-isolated buildings, in which foundation piles are integrated into a continuous element in the vertical direction.
The design seismic motion is applied to each part of the foundation pile at the same time,
A seismic response analysis method for base-isolated buildings that calculates the time history response results of each part of the integrated structural model from the superstructure to the foundation pile at the same time.   2. The seismic response analysis method for a seismic isolation building according to claim 1, wherein a seismic isolation layer of the seismic response analysis model is provided with a bending spring for calculating the amount of rotational deformation of the seismic isolation device with time history. Seismic response analysis method for base-isolated buildings.   3. The seismic response analysis method for a seismic isolation building according to claim 1 or 2, wherein a shear spring is provided in the seismic isolation layer of the seismic response analysis model to calculate the horizontal displacement of the seismic isolation device according to time history. A seismic response analysis method for base-isolated buildings.   The seismic response analysis method for a seismic isolation building according to any one of claims 1 to 3, wherein the seismic response analysis model includes an acceleration waveform as a design seismic motion at a node provided at a lower end portion of a foundation pile. A seismic response analysis method for base-isolated buildings, in which the displacement waveform at the time of earthquake is input to the vertical nodes of the foundation pile as a seismic motion for design via a horizontal ground spring.   The seismic response analysis method for base-isolated buildings according to any one of claims 1 to 4, wherein the seismic base layer of the seismic response analysis model includes an eccentric bending caused by a horizontal displacement of the base isolation device during an earthquake. Seismic response analysis method for base-isolated buildings, characterized in that moments are acted upon by time history as additional bending.   The seismic response analysis method for base-isolated buildings according to any one of claims 1 to 5, wherein the seismic response analysis model includes a model in which group piles are aggregated into one pile, or a large number of group piles. A seismic response analysis method for base-isolated buildings, characterized in that one of the pile models is used.   The seismic response analysis method for a seismic isolation building according to any one of claims 1 to 6, wherein a ground mass immediately below or near the building acts as an additional mass on the foundation pile of the seismic response analysis model, A seismic response analysis method for base-isolated buildings, in which the shear stiffness of the ground directly under or near the building acts as an additional ground spring.   A seismic safety evaluation method for a seismic isolation device using the seismic response analysis method for a seismic isolation building according to any one of claims 1 to 7, wherein the seismic safety evaluation method is calculated from a time history response result regarding a deformation amount of a bending spring. The seismic isolation device is characterized by evaluating the safety against the rotational deformation performance of the seismic isolation device during an earthquake from the relationship between the rotation amount of the seismic isolation device and the set allowable rotation amount of the seismic isolation device. Safety assessment method. The seismic isolation safety evaluation method for a seismic isolation device according to claim 8, wherein the horizontal displacement of the seismic isolation device calculated from the behavior of a shear spring and the set allowable horizontal displacement of the seismic isolation device Seismic safety evaluation method for seismic isolation devices, characterized by evaluating the safety against seismic isolation device horizontal displacement performance during earthquakes.

Images