JP2003150043A - Earthquake resistant design arithmetic unit for structure, and earthquake resistant design method for structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earthquake resistant design arithmetic unit for a structure and an earthquake resistant design method for the structure, which can facilitate design operation and reduce the design cost. SOLUTION: A structure model is structured by modeling an elevated bridge structure and its structure conditions are set as data; and ground conditions and various member section elements are set as data and stored in a data area. A dynamic nonlinear analysis of the structure model is taken to confirm predominance of vibration in primary mode during an L2 earthquake and a plastic hinge generation place of the structure model, and the bar arrangement of stakes of the elevated bridge structure is reviewed. A static nonlinear analysis is taken by using data which are stored in a data area so far to calculate the horizontal displacement quantity of the top position of the structure model and after the yield displacement quantity δy and yield seismic coefficient Khy of the elevated bridge structure are extracted, an equivalent natural cycle Teq is calculated. This is plotted to a necessary yield seismic intensity spectrum to read a response plasticity rate μ and calculate response displacement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic design of a structure capable of designing a viaduct without seismic resistance and having no underground girder with a high degree of accuracy and at a significantly reduced design cost and labor. Arithmetic device and method for seismic design of structures.

[0002]

2. Description of the Related Art In general ramen viaducts, underground girders are installed in the soil and the pile heads are rigidly connected to each other in order to provide sufficient seismic resistance against earthquake motion of the Hyogoken Nanbu Earthquake class. The structure is such that the load is distributed over the entire viaduct. However, in railway overpass construction in metropolitan areas, since it is difficult to secure a construction site, it is often necessary to plan a construction passage directly under the viaduct structure during construction. At this time, if the viaduct structure is a structure with underground beams, in order to ensure the safety of the passage for construction,
Not only does lining and earth retaining work be required at the location where the underground beam is to be constructed, but this also causes competition for work, which causes congestion, unsafety, and lengthening of work. Therefore, from the viewpoint of construction cost and construction period, there is a large loss due to the construction of underground beams.Therefore, it is often considered to use a viaduct structure without underground beams in the future elevated projects in urban areas. There is.

On the other hand, a new seismic design standard (design standard for railway structures, etc.) (hereinafter referred to as seismic standard) was established based on the lessons learned from the Hyogo-ken Nanbu Earthquake, and seismic motion with a high probability of occurrence (hereinafter referred to as L1 seismic motion). It is safe to say that the viaduct structure has sufficient seismic performance against extremely strong earthquake ground motion (hereinafter referred to as L2 ground motion) even if the occurrence probability is low. It stipulates that it must be done.

According to this new seismic standard, a viaduct structure whose vibration mode is relatively simple and where the yield position (plastic hinge) is clearly generated is comparatively used as a method for checking seismic performance at the design stage. The application of the non-linear spectrum method, which is a simple analysis method, is permitted. This analysis method was devised on the premise of designing a viaduct structure having underground beams.

[0005]

However, since the behavior of a viaduct structure without underground beams during a large-scale earthquake has not been clarified, it is not possible to specify the generation position of the plastic hinge, and the nonlinearity in the design stage is not identified. The applicability of the spectral method has not been confirmed. Therefore, in order to strictly check the seismic performance of the structure, it is necessary to perform dynamic nonlinear analysis by EWS or high-performance personal computer and accumulated calculation of finite element method analysis by dedicated software, which requires enormous labor, time and cost. There is a demand for establishment of a simpler design method.

In view of the above circumstances, the present invention provides a seismic design computer and a seismic design method for a structure, which can simplify the design work and reduce the design cost even in a viaduct without underground beams. It is an object.

[0007]

According to a first aspect of the present invention, there is provided a seismic design computing device for a structure, comprising: a structural condition of the structure; a ground condition on which the structure is constructed; ,
A data area for storing a load condition applied to the structure, a program area for storing a seismic design calculation program using the data stored in the data area, and a storage device having the program area and the data area And an arithmetic unit that performs arithmetic processing using the data in the data area stored in the storage device and the program in the program area,
An output device for outputting an arithmetic processing result by the arithmetic processing device, and a seismic design computing device for a structure, the structure being a viaduct structure without an underground beam, and the seismic design computing program. Is characterized in that the nonlinear spectrum method is applied.

A method for designing earthquake resistance of a structure according to claim 2 is
It is characterized by designing a viaduct structure without seismic resistance and without underground beams by using a seismic design calculation program using the nonlinear spectrum method.

A seismic design method for a structure according to claim 3 is:
The bending strength ratio of the pile in the structure is set to 1.25 to 2.00 times.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A seismic designing computing device for structures and a seismic designing method for structures according to the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 is a block diagram of a seismic design computing device for a structure. The earthquake-resistant design computing device 1 for a viaduct structure 8 according to the present invention comprises an input device 2 for inputting data as appropriate, a structural condition 13 for the viaduct structure 8, a ground condition 14 for constructing the viaduct structure 8, the viaduct. A data area 3 in which various data such as member cross-section specifications 15 of the structure 8 and load conditions 16 applied to the viaduct structure 8 are stored, and the data area 3
A recording device 6 having a program area 4 in which a seismic design calculation program using a non-linear spectrum method is stored using various data stored in the recording device 6; and a calculation process using data in the program stored in the recording device 6. And an output device 7 for outputting the calculation processing result. The output device 7 may be a display, a printer, a hard disk, or the like.

According to the seismic design computing program stored in the program area 4 of the seismic design computing apparatus 1 of the present invention, when designing a viaduct structure without underground beams, an L2 which is a very strong earthquake even if the occurrence probability is low. The non-linear spectrum method is used as a means to verify that it has sufficient seismic performance against earthquake motion.

In the non-linear spectrum method, the static non-linear analysis is performed on the viaduct structure 8, the yield seismic intensity khy and the equivalent natural period Teq are obtained, and these two numerical values are plotted on the required yield seismic intensity spectrum to obtain the response. The non-linear response value of the viaduct structure 8 is obtained by reading the plasticity rate. This method is applied when the structural system is relatively simple and the first-order vibration mode is predominant, and where the plastic hinge generation point is clear, and is used for general viaduct structures with underground beams. Has been.

On the other hand, regarding various data used in the present invention,
As the structural condition 13 of the viaduct structure 8 without underground beams,
The structural type, basic type, and the shape and size of the study cross section to be modeled of the viaduct structure 8 are converted into data, and the ground condition 14 for constructing the viaduct structure 8 is a supporting ground 12a and a surface ground. 12b types, their respective depths, and N values are converted into data. Further, as the member cross-section specifications 15 of the viaduct structure 8, the cross-sectional shapes of the upper beam 9, the pillar 10 and the pile 11, the amount of reinforcing bars and the safety factor are made into data.

As shown in the flowchart of FIG. 2, the flow of seismic design of the structure having the above-described structure is calculated by the seismic design computing device, which comprises 10 steps from step S1 to step S10. The flow is shown below.

The structural type and basic type of the viaduct structure 8 without underground beams are determined (step S1).

Next, using the structure model 8a and the ground condition 14, three types of load cases (combining four patterns) are assumed, and design calculation by the limit state design method is performed to obtain the structure model 8a. The distribution of the acting stress is calculated to determine the cross-sectional shape, dimensions, bar arrangement, etc. (step S
2).

In the recording device 6, the viaduct structure 8 is modeled to construct a structure model 8a, the structural condition 13 thereof is converted to data, and the ground 12 is modeled to convert the ground condition 14 into data. The data is stored in the data area 3 (steps S3 and S4).

Similarly, the member cross-section specifications 15 of the structure model 8a are converted into data and stored in the data area 3 in the recording device 6 (step S5).

For the structure model 8a modeled in step S3, a dynamic nonlinear analysis (time history response analysis) is performed in the computing device 5 using the seismic design computing program stored in the program area 4, and the L2 earthquake 1 of time
The predominance of vibration in the next mode and the plastic hinge generation point of the structure model 8a are confirmed, and the yield order is output to the output device 7. Based on this output result, the reinforcement of the piles 11 in the viaduct structure 8 is reviewed according to the situation (step S6).

From the data stored in the data area 3 so far, a static non-linear analysis is performed in the arithmetic unit 5 by using the seismic design calculation program stored in the program area 4, and the ceiling of the structure model 8a is calculated. The horizontal displacement amount at the end position is calculated, and the relationship between them is graphed as a load displacement curve and output by the output device 7 (step S7).

Thereafter, from the load displacement curve shown in step S7, the yield displacement amount δy and the yield seismic intensity Khy of the viaduct structure are calculated.
Is extracted and stored in the data area 3 in the recording device 6, and then the seismic-resistant design calculation program stored in the program area 4 is used in these to calculate the equivalent natural period Teq of the structure model 8a in the calculation device 5. Is calculated and stored in the data area 3 in the recording device 6 (step S
8).

The required yield seismic intensity spectrum 17 prepared in advance is stored in the data area 3 in the recording device 6 by using the input device 2, and the calculation result of step S8 is dropped and graphed and output by the output device 7. From this output result, the response plasticity coefficient μ is read and stored in the data area 3 using the input device 2, and the seismic design calculation program stored in the program area 4 is used together with the yield displacement amount δy calculated in step S8. Then, the computing device 5 calculates the response displacement and stores the calculation result in the data area 3 in the recording device 6 (step S9).

Using the seismic design calculation program stored in the program area 4, the arithmetic unit 5 checks the damage level of the upper beam 9, the pillar 10 and the pile 11 to determine whether or not the seismic performance is satisfied. The result is output to the output device 7 (step S10).

The seismic design method for viaduct-free viaduct structures using the above-mentioned structural seismic design computing device will be described in detail below.

(Step S1) First, the structural condition 13 of the viaduct structure 8 by the target pile foundation ramen without underground beams is set.

(Step S2) As the load condition applied to the structure model 8a, a fixed dead load and an additional dead load are loaded as an initial load zone, and a dead load (at the time of earthquake) and a train load (at the time of earthquake) are set. These are combined into three patterns in the same way as general design, and using this, the structure model 8
The distribution of the stress acting on a is calculated, and the shape, dimensions, bar arrangement, etc. of the cross section are designed by the conventional limit state design method.

(Step S3) With respect to the viaduct structure 8, the entire structure is modeled as one body, and members such as the upper beam 9, pillars 10 and piles 11 constituting the viaduct structure 8 are wire rods, and the ground 12 is a spring. The structure model 8a is created as. At this time, all joints between the members are rigidly connected. In the embodiment of the present invention, FIG.
A viaduct structure 8 without an underground beam as shown in is considered as a structure model 8a.

(Step S4) The ground 12 is modeled as
Each of the left and right 30 m of the viaduct structure 8 is modeled and connected to the free ground outside through a viscous boundary by a damper in the horizontal direction and a fixed boundary in the vertical direction. Also, the thickness of the modeled area in the depth direction is
The maximum diameter of the pile 11 is assumed to be the same, and the free ground is calculated as 10 ⁶ times this.

In this embodiment, the ground 12 is covered by the surface layer 1
2a and base layer 12b are assumed to be included, and the N value of each layer is calculated. Further, in setting the non-linear model of the ground 12, the stress-strain relationship during repeated loading is defined using a modified Ramberg-Osgood model that is generally used.

(Step S5) The upper beam 9, pillar 10,
In modeling members such as the pile 11 and the like, RC cross-sectional shapes of these members are designed by static linear analysis using a wire rod-spring model. The design horizontal seismic intensity Kh is set to 0.4. Also, the effect on seismic response displacement is ignored. Furthermore, for the restoring force characteristics of each member, a stiffness deterioration type trilinear model that is generally used as a restoring force model is used, and the effects of axial force fluctuation due to horizontal inertial force during earthquake are considered for the pillars 10 and the piles 11. ing.

(Step S6) Whether or not the non-linear spectrum method can be applied to the structure model 8a set with such conditions is verified by accumulating analysis data by the time history response analysis method. Step two
The structure model 8a set in 1 is set so that the members whose cross-sections have been designed by the static linear analysis simultaneously undergo bending yield. However, in consideration of restoration in the event of an earthquake, etc., the pillars 10 that have surrendered in advance and the pillars 1 that exist underground are
It is necessary to suppress the damage of 1.

Therefore, regarding the bar arrangement of the pile 11 in the cross-sectional specifications of the pile 11, the pile 1 in the structure model 8a is
Based on the case where the bending strength ratio of 1 is 1.00, the time history response analysis is performed for the model in which the amount of reinforcing bar of the pile 11 is adjusted within the range where the bending strength ratio of the pile 11 is 0.50 to 2.00. Verify the plastic hinge generation position. In the structure model 8a, in the case where the pile 11 or the beam preceding breakage occurs, the procedure is returned to the step S5 again and adjustment is performed by increasing the reinforcing bar amount of the pile 11.

The generally used direct integration method (Newmark's β method) is used for the dynamic nonlinear analysis, and the damping force is a stiffness proportional type. At this time, the damping constant α given from the primary and secondary modes of the eigenvalue analysis result is assigned to the structure (the upper beam 9, the column 10, and the pile 11) and the ground 12, respectively. As the input seismic motion during the dynamic nonlinear analysis, the L2 seismic motion spectrum II seismic wave defined in the seismic resistance standard is directly input from the basic surface in seismic design.

Here, setting the bending strength ratio of the pile to 1.25 to 2.00 will be described in detail. As a result of analyzing the structure model 8a without an underground beam by using dynamic non-linear analysis, as shown in FIG. 4, when the structure model 8a when the crown deformation reaches the maximum, Although the amount of deformation of the upper end of the pillar 10 is significantly larger than that of the pile 11, it shows a deformation mode in which the pillar 10 and the pile 11 are integral members, which is generally a primary mode vibration. I understood it.

At this time, the bending strength ratio of the pile 11 in the structure model 8a was set to 0.5 to 0.25 pitch and analyzed. When the bending strength ratio of the pile 11 was 1.25 to 2.00 times, the generation position of the plastic hinge was determined. Was confirmed to be the upper end of the column 10 in almost all analysis cases.
Therefore, it can be judged that the pile 11 can be escaped from a catastrophic failure by setting the bending strength ratio of the pile 11 in the structure model 8a to 1.25 to 2.00 times.

Further, by adjusting the amount of rebar of the pile 11,
By setting the pile bending strength ratio within the desired range of 1.25 to 2.00, the structure model 8a that models the viaduct structure 8 without underground beams has a relatively simple structural system and the primary vibration mode is superior. And that the location where the plastic hinge occurs is clear, which satisfies the conditions for applying the nonlinear spectrum method. Accordingly, if the bending strength ratio of the pile 11 in the structure model 8a is set to 1.25 to 2.00 times, the structure model 8a that models the viaduct structure 8 without an underground beam is a structure that avoids the advance yielding of the pile 11. However, it was confirmed that it is possible to verify the seismic performance by applying the seismic design program using the nonlinear spectrum method.

(Step S7) Based on the results of Steps S1 to S6, static non-linear analysis is performed by the displacement increment method in which the ground inertial force is applied to the position of the upper beam 9 as a concentrated load and the displacement amount corresponding thereto is sequentially incremented. I do. FIG. 5 shows a load displacement curve showing the relationship between the seismic intensity obtained by the static nonlinear analysis and the horizontal displacement of the structure model 8a. From Fig. 5, yield displacement δy and yield seismic intensity Khy are calculated. The yield displacement amount δy and the yield seismic intensity Khy are the points at which the member of the structure model 8a yields first, and are the first inflection points of the load displacement curve shown in FIG.

(Step S8) Using the yield displacement amount δy and the yield seismic intensity Khy obtained in step S7, the equivalent natural period Teq of the structure model 8a is calculated by the equation (1).

[0040]             Teq = 2.0 * √ (δy / Khy) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (1) Teq: Equivalent natural period δy: Yield displacement Khy: Yield seismic intensity

(Step S9) The required yield seismic intensity spectrum 17 at the planned construction site of the viaduct structure 8 without underground beams is prepared in advance, and the equivalent natural period Teq obtained from the equation (1) is plotted on it. To do. The required yield seismic intensity spectrum 17 is shown in FIG. The response plasticity coefficient μ is read from the plotted position in FIG. 6, and the response displacement amount is calculated by the equation (2) using these calculation results.

[0042]             Response displacement = δy * μ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (2) δy: Yield displacement μ: Response plasticity

(Step S10) Upon receiving these results,
Inspecting the damage level of the upper beam 9, the pillar 10 and the pile 11,
It is determined whether or not the structure model 8a satisfies the seismic performance. In response to these determination results, if the target viaduct structure 8 is not within the desired damage level, the structural condition 13 and the member cross-section specifications 15 are reconsidered, and the process returns to step S2 and again. This is to check the soundness of seismic performance.

The damage level is an evaluation standard that is classified into 3 ranks according to the damage condition of the member when evaluating the member performance defined in the earthquake resistance standard, and is generally applied.

According to the above-mentioned structure, in the seismic design of the viaduct structure 8 without underground beams, a simple nonlinear spectrum method can be applied as a method for checking the seismic performance, so that the labor cost and the design cost are greatly increased. It is possible to reduce.

In the seismic design of the viaduct structure 8 without underground beams, the bending strength ratio of the pile in the structure model 8a is set to 1.25.
Since it can be set up to be ~ 2.00 times, it can be easily dealt with only by adjusting the amount of reinforcing bar to be arranged in the pile 11, and the position where the plastic hinge is generated is the upper end of the column 10 and the pile 11 is devastating. It is possible to escape from destruction.

[0047]

According to the structure seismic design computing apparatus of claim 1, the structural condition of the structure, the condition of the ground on which the structure is constructed, and the member cross-sectional specifications of the structure, A data area for storing a load condition applied to the structure, a program area for storing a seismic design calculation program using the data stored in the data area, and a storage device having the program area and the data area , A seismic design of a structure having an arithmetic device for performing arithmetic processing using data in a data area stored in the storage device and a program in a program area, and an output device for outputting an arithmetic processing result by the arithmetic processing device In the arithmetic device, the structure is a viaduct structure without underground beams, the seismic design calculation program, since the nonlinear spectrum method is applied, Even at high cross-linked structure without the center sill, it is possible to perform highly accurate seismic design with a simple device.

According to the seismic design method for a structure according to claim 2, since a viaduct structure having no underground girder with secured seismic resistance is designed by using a seismic design calculation program using a nonlinear spectrum method, Labor costs and design costs can be significantly reduced.

Since the bending strength ratio of the pile in the structure according to claim 3 is set to 1.25 to 2.00 times, the position where the plastic hinge is generated is set to the upper end portion of the column to escape the pile from a catastrophic failure. Is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a seismic design computing device for a structure according to the present invention.

FIG. 2 is a flow chart showing a seismic design method for a structure according to the present invention.

FIG. 3 is a diagram showing a structure model according to the present invention.

FIG. 4 is a diagram showing a modified view of the structure model according to the present invention.

FIG. 5 is a diagram showing a relationship between seismic intensity and horizontal displacement of the structure model according to the present invention.

FIG. 6 is a diagram showing a required yield seismic intensity spectrum according to the present invention.

[Explanation of symbols]

1 Seismic design computing device 2 input devices 3 data areas 4 Program area 5 arithmetic unit 6 recording device 7 Output device 8 Viaduct structure 9 Upper beam 10 pillars 11 piles 12 ground 12a Support ground 12b Surface ground 13 Structural conditions 14 Ground conditions 15 Member cross-section specifications 16 load conditions 17 Required yield seismic intensity spectrum

Claims (3)

[Claims] 1. A data area for storing structural conditions of a structure, ground conditions for constructing the structure, member cross-sectional specifications of the structure, and load conditions applied to the structure, A program area for storing a seismic design calculation program using the data stored in the data area, a storage device having the program area and the data area, and data of the data area and the program area stored in the storage device A seismic-resistant design arithmetic device for a structure, comprising: an arithmetic device that performs arithmetic processing using a program; and an output device that outputs the arithmetic processing result by the arithmetic processing device, wherein the structure is a viaduct without underground beams. A seismic design computing device for a structure, which is a structure and in which a nonlinear spectrum method is applied to the seismic design computing program. 2. A seismic design method for a structure using the seismic design computing device for a structure according to claim 1, wherein a viaduct structure having no underground girder with secured seismic resistance is utilized by a non-linear spectrum method. A seismic design method for structures, characterized by designing using a seismic design calculation program. 3. The method for designing earthquake resistance of a structure according to claim 2, wherein the bending strength ratio of the pile in the viaduct structure without the underground beam is set to 1.25 to 2.00 times. Seismic design method.