JP6883509B2 - Structure damage judgment method and structure reinforcement method selection method - Google Patents

Description

The present invention relates to a method for determining damage to a structure and a method for selecting a method for reinforcing a structure. More specifically, it is decided which reinforcement method to select regarding the damage judgment of the bridge due to the tsunami or the flooding of the river, the judgment method for predicting the damage at the time of new design of the bridge, and the reinforcement design of the bridge. Regarding the selection method.

Conventionally, as a method for calculating the fluid force generated for a structure by a fluid, a determination method for evaluation using a Morrison equation or the like is known (Patent Document 1). Here, the Morrison equation is a method of calculating the horizontal fluid force that the structure receives from the fluid, and is calculated using the following equation.

ここで、ρ_wは、水の密度（ｋｇ／ｍ³）、Ｃ_dは、抗力係数，νは、流速（ｍ／ｓ）、Ａ_hは、有効鉛直投影面積（ｍ²）とする。

Here, ρ _w is the density of water (kg / m ³ ), C _d is the drag coefficient, ν is the flow velocity (m / s), and A _h is the effective vertical projected area (m ² ).

Further, there is known a method for calculating the breaking strength of these structures when the horizontal fluid force obtained by using the Morrison method or the like is received by the bridge girders, piers, bearings, etc. of the bridges which are the structures. Further, bridge collapse prevention methods and seismic / tsunami reinforcement methods for preventing damage caused by earthquakes and tsunamis are known (Patent Documents 2 and 3).

Japanese Unexamined Patent Publication No. 2012-149466 Japanese Unexamined Patent Publication No. 2016-75120 Japanese Unexamined Patent Publication No. 2016-75121

However, in the Morrison method, the horizontal force received by the bridge when the girder height is high and the water level difference occurs upstream and downstream of the bridge girder is underestimated, and the judgment accuracy is low and appropriate evaluation is difficult. .. In addition, it was possible to evaluate the damage judgment method for each part of the bridge girder, pier, bearing, etc. individually, but the judgment method that appropriately evaluates the outflow of the bridge girder and the destruction of the pier for the entire bridge is unknown.

Furthermore, there are known bridge girder outflow reinforcement methods that prevent the outflow of bridge girders and bridge pier destruction due to earthquakes and tsunamis, and pier reinforcement methods that reinforce piers. There was no known method that could evaluate which reinforcement method should be applied according to the amount of water increase and the flow velocity.

Therefore, the present invention has been made in view of the above problems, and in order to reduce damage to bridges due to flooding caused by tsunamis and heavy rains in rivers, and to realize early restoration, the presence or absence of damage and damaged parts are specified in advance. It is possible to appropriately select a damage judgment method that can perform damage judgment, a structure that should be prioritized for existing structures such as bridges, a bridge girder outflow reinforcement method, and a pier reinforcement method. The purpose is to provide a method for selecting a reinforcement method.

The method for determining damage to a structure according to the present invention for solving the above problems is a step of determining an assumed water level and an assumed flow velocity, and a horizontal flow acting on the structure using the assumed water level and the assumed flow velocity. The step of obtaining the physical strength and the lead DC physical strength, the step of obtaining the breaking resistance of the structure to support and prevent the bridge from falling, the step of obtaining the breaking resistance of the pier of the structure, and the horizontal flow. It is characterized by including a step of comparing physical strength and the breaking resistance of the support / bridge fall prevention, and a step of comparing the horizontal fluid force and the breaking strength of the pier.

Further, in the method for selecting a reinforcement method for a structure according to the present invention, a step of determining an assumed water level and an assumed flow velocity, and a horizontal fluid force acting on the structure and a lead DC using the assumed water level and the assumed flow velocity are used. The step of obtaining the physical strength, the step of obtaining the breaking resistance of the structure to support and prevent the bridge from falling using the lead DC physical strength, the step of obtaining the breaking strength of the pier of the structure, the horizontal fluid force and the support. of-girder prevent breakdown strength or by comparing the breaking strength of the previous SL pier, characterized in that it comprises the step of selecting the reinforcing method of the structure.

Further, in the method for selecting the reinforcement method for the structure according to the present invention, it is preferable to select the bridge girder outflow reinforcement method when the horizontal fluid force is larger than the fracture strength for preventing the bearing / collapse.

Further, in the reinforcing method selecting method of a structure according to the present invention, when the horizontal fluid force is greater than the breakdown strength of the previous SL pier, it is preferable to select a pier reinforcement method.

According to the method for determining damage to a structure according to the present invention, there is a step of obtaining the breaking strength of the bridge pier of the structure by using the vertical DC physical strength to obtain the breaking strength of supporting the structure and preventing the bridge from falling. It is possible to calculate the yield strength by adding the lift, buoyancy and down force, which are the fluid forces in the vertical direction, and it is difficult to make an appropriate evaluation by the judgment method using the conventional Morrison method. It is possible to make an appropriate damage judgment.

Further, according to the method for selecting a reinforcement method for a structure according to the present invention, it is possible to accurately determine what kind of reinforcement method the structure requires for the assumed water level and flow velocity. It is possible to select an appropriate construction method based on this determination result.

The figure for demonstrating the fluid force applied to a bridge. The flow chart of the damage determination method and the reinforcement method selection method of the structure which concerns on this embodiment. The figure for demonstrating the outflow of a bridge girder of a bridge. The figure for demonstrating the destruction of the pier of a bridge.

Hereinafter, the method for determining damage to the structure and the method for selecting the reinforcing method according to the embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a fluid force applied to a bridge, FIG. 2 is a flow diagram of a method for determining damage to a structure and a method for selecting a reinforcement method according to the present embodiment, and FIG. 3 is a flow diagram of a bridge. It is a figure for demonstrating the outflow of a bridge girder, and FIG. 4 is a figure for demonstrating the destruction of a pier of a bridge.

As shown in FIG. 1, the method for determining damage to a structure and the method for selecting a reinforcement method for a structure according to the present embodiment are based on, for example, assuming that a tsunami hits a bridge 10 as a structure. The damage is assumed, and the reinforcement method is selected according to the assumed damage.

The bridge 10 has a pier 11 as a substructure and a bridge girder 12 as a superstructure, and the bridge girder 12 is mounted on the pier 11 via a support portion 14 mounted on the upper part of the pier 11. It has a structure like this. Further, the pier 11 and the bridge girder 12 are connected and fixed by the bridge collapse prevention device 13. The bridge collapse prevention device 13 adopts various conventionally known configurations.

Here, the damage determination method of a structure according to the present embodiment, as shown in FIG. 2, the step of determining an assumed water level H ₀ and assuming a flow rate V ₀ (S101), assuming the water level H ₀ and assuming flow velocity V ₀ (S102) to obtain _{the horizontal fluid force F x} acting on the bridge 10 using the above, and the _{step to obtain the lead DC physical force F z} acting on the bridge 10 using the _{assumed water level H 0} and the assumed flow velocity V _0. (S103), _{a step of calculating the breaking strength R girder} for bearing / collapse prevention of the bridge 10 using the lead DC _{physical strength F z} (S104), and a step of calculating the breaking strength R _column of the pier 11 of the bridge 10 (S105). A step of comparing the horizontal fluid force F _x with the breaking strength R _girder for bearing / bridge collapse prevention (S106) and a step of comparing the horizontal fluid force F _x with the breaking strength R _column of the pier 11 (S107) are provided. There is.

In the step (S101) of determining the assumed water level H ₀ and the assumed flow velocity V ₀ , how much water increase occurs due to factors such as the surrounding environment of the bridge 10 to be damaged and an earthquake or heavy rain, and the flow velocity at that time. Determine how much is.

_{In the step (S102) of obtaining the horizontal fluid force F x} acting on the bridge 10 using the assumed water level H ₀ and the assumed flow velocity V ₀ , the horizontal direction is based on the shape of the bridge 10, including the case where the girder height is high. Calculate the horizontal fluid force F _{x acting on.} As for this calculation method, any calculation method may be adopted as long as the horizontal fluid force can be calculated, but considering the girder height, it is preferable to calculate using the following formula. is there.

ここで、ρは、水の密度（ｋｇ／ｍ³）、gは、重力加速度（ｍ／ｓｅｃ²）、Ｈ₁は、上流側水位（ｍ）、νは、流速（ｍ／ｓ）、Ｃ_cは、縮脈係数とする。また、ｑは、流量（ｍ²／Ｓ）であって、流速νと上流側水位Ｈ₁の積である。

Here, ρ is the density of water (kg / m ³ ), g is the gravitational acceleration (m / sec ² ), H ₁ is the upstream water level (m), ν is the flow velocity (m / s), and C. _{Let c} be the contraction coefficient. Further, q is the flow rate (m ² / S), which is the product of the flow velocity ν and the upstream water level H _1.

_{The step (S103) of obtaining the vertical DC physical force F z} acting on the bridge 10 using the assumed water level H ₀ and the assumed flow velocity V ₀ is in the vertical direction based on the shape of the bridge 10, including the case where the girder height is high. Calculate the plumb bob physical strength F _{z that acts on.} As for this calculation method, any calculation method may be adopted as long as the fluid force in the vertical direction can be calculated, but considering the girder height, it is preferable to calculate using the following formula. is there.

ここで、ｐ_上(x,z)は、任意点の上面圧力（Ｎ／ｍ²）であり、ｐ_下(x,z)は、任意点の下面圧力（Ｎ／ｍ²）であり、Ａは、任意点の面積（ｍ²）であり、ρは、水の密度（ｋｇ／ｍ³）であり、gは、重力加速度（ｍ／ｓｅｃ²）であり、ｈ▲₁▼、桁上流側水位（ｍ）であり、Ｈ_柱は、柱高さ（ｍ）であり、Ｈ_桁は、桁高（ｍ）であり、Ｈ_防音壁は、防音壁高さ（ｍ）であり、ｈ_(x)は、ｘ位置の水位（ｍ）であり、ν_x(x,z)は、座標（ｘ，ｚ）における水平方向の流速（ｍ／ｓ）であり、ν_x▲₁▼は、桁上流側水面の水平方向の流速（ｍ／ｓ）であり、ν_x▲₂▼は、桁下流側桁下の水平方向の最大流速（ｍ／ｓ）であり、ν_x▲₃▼は、桁下流側桁下面の水平方向の流速（ｍ／ｓ）であり、ｘ₀は、最大流速線の起点のｘ座標（ｍ）である。

Here, _{above p (x, z)} is the upper surface pressure (N / m ² ) at _{an arbitrary point, and below p (x, z)} is the lower surface pressure (N / m ² ) at an arbitrary point. Is the area of an arbitrary point (m ² ), ρ is the density of water (kg / m ³ ), g is the gravity acceleration (m / sec ² ), h ▲ ₁ ▼, upstream side of the girder. Water level (m), H _pillar is pillar height (m), H _girder is girder height (m), H _{soundproof wall} is soundproof wall height (m), h _{(x )} Is the water level (m) at the x position, ν _{x (x, z)} is the horizontal flow velocity (m / s) at the coordinates (x, z), and ν _x ▲ ₁ ▼ is the girder upstream. The horizontal flow velocity (m / s) on the water surface on the side, ν _x ▲ ₂ ▼ is the maximum horizontal flow velocity (m / s) under the girder downstream of the girder, and ν _x ▲ ₃ ▼ is the downstream flow path of the girder. It is the horizontal flow velocity (m / s) of the lower surface of the side girder, and x ₀ is the x coordinate (m) of the starting point of the maximum flow velocity line.

Calculating a fracture strength R _digits of the bearing-girder prevention of bridge 10 with vertical fluid force F _z (S104) has already destroyed strength of bearing-girder prevention of bridge 10 with vertical fluid force F _z calculated Calculate the R _digit. Here, the destructive resistance R _girder for bearing and collapse prevention of the bridge 10 means the maximum value of the fluid force at which the bridge girder 12 does not flow out from the bridge 10 when the bridge 10 receives the fluid force, and is referred to as the outflow of the bridge girder 12. As shown in FIG. 3, when the bridge 10 receives a fluid force, the pier 11 is not damaged, but the bridge collapse prevention device 13 connecting the bridge girder 12 and the pier 11 is damaged and the bridge collapse prevention device 13 is damaged from the bearing portion 14. It means that the bridge girder 12 falls off. Regarding the calculation method of the breaking strength R _girder for bearing / collapse prevention, any calculation method may be adopted as long as the breaking strength for bearing / collapse prevention of the bridge 10 can be calculated. It is preferable to calculate the bearing friction resistance using the above, and to calculate the bearing friction resistance by regarding it as the breaking strength of the bearing / bridge collapse prevention.

ここで、μは、摩擦抵抗であり、Ｗは、上部工である橋桁１２の重量（Ｎ）である。

Here, μ is the frictional resistance, and W is the weight (N) of the bridge girder 12 which is the superstructure.

_{The step (S105) of calculating the breaking strength R column} of the pier 11 of the bridge 10 refers to the maximum value of the fluid force at which the pier 11 is not damaged when the bridge 10 receives the fluid force. As shown in 4, it means that the bridge girder 12 does not flow out, but the pier 11 is damaged. As for the calculation method of the fracture strength, any calculation method may be adopted as long as the fracture strength of the bridge pier 11 can be calculated, but the bending / shear strength received by the bridge pier 11 is calculated by using the following formula. It is preferable to calculate and calculate the bending / shear strength as the fracture strength.

ここで、Ｍ_udは、橋脚の設計曲げ耐力（ｋＮ・ｍ）であり、Ｌ_aは、橋脚のせん断スパン（ｍ）であり、Ｖ_ydは、橋脚の設計せん断耐力（ｋＮ）である。

Here, M _ud is a bridge pier design Bending Strength of (kN · m), L _a is a bridge pier shear span (m), V _yd is the pier design shear capacity (kN).

In the step (S106) of comparing the horizontal fluid force F _x with the breaking strength R _{girder for bearing / collapse prevention, the horizontal fluid force F x} acting on the bridge 10 is obtained using the _{assumed water level H 0} and the assumed flow velocity V _{0. The horizontal fluid force F x} calculated in the step (S102) and the step (S104) of calculating _{the breaking strength R girder} of the bridge 10 for bearing / collapse prevention using the vertical DC physical strength F _z and the breaking of the bearing / bridge collapse prevention, respectively. Compare with the bearing R _girder. Here, when the horizontal fluid force F _x is smaller than the breaking strength R _{girder for} bearing / collapse prevention, the bridge girder 12 does not flow out, so that the horizontal fluid force F _x and the breaking strength of the pier 11 are the next steps. The step (S107) of comparing the _{R columns is executed.} When the horizontal _{fluid force F x is larger than the fracture strength R girder for} bearing / collapse prevention, the bridge girder 12 receives the fluid force due to _{the assumed water level H 0} and the assumed flow velocity V ₀ due to the tsunami or heavy rain flooding. It is possible to determine the damage that the tsunami flows out from the bridge pier 11.

Further, in this case, since it can be selected that the bridge girder outflow reinforcement method is necessary, an appropriate structure reinforcement method can be selected. In this case, various bridge girder outflow reinforcement methods can be adopted as to what kind of bridge girder outflow reinforcement method is applied.

The step of comparing the horizontal fluid force F _x and the breaking strength R _column of the pier 11 (S107) is a step of obtaining _{the horizontal fluid force F x} acting on the bridge 10 using the _{assumed water level H 0} and the assumed flow velocity V _{0 (S107). S102) and the horizontal fluid force F x} calculated in the step (S105) of calculating _{the breaking strength R column} of the pier 11 of the bridge 10 are compared with the breaking strength R _{column of the pier 11.} Here, when the horizontal fluid force F _x is smaller than the fracture strength of the pier 11, the pier 11 is not damaged, so that even if a tsunami or heavy rain flood occurs due to the _{assumed water level H 0} and the assumed flow velocity V _0, It can be determined that the bridge is not destroyed and the bridge 10 does not need to be reinforced.

Further, when the horizontal _{fluid force F x} is larger than the fracture strength R _column of the pier 11, the pier 11 is damaged when the bridge 10 receives the fluid force due to _{the assumed water level H 0} and the assumed flow velocity V ₀ due to the tsunami or heavy rain flooding. It is possible to make a damage judgment to do so.

Further, in this case, since it can be selected that the pier reinforcement method is necessary, an appropriate structure reinforcement method can be selected. In this case, various pier reinforcement methods can be adopted as to what kind of pier reinforcement method is applied.

As described above, according to the method for determining damage to a structure and the method for selecting a reinforcement method for a structure according to the present embodiment, the vertical DC physical strength is used to obtain the breaking resistance for bearing the structure and preventing the bridge from falling, and the structure is used. Since it is equipped with a process to determine the breaking resistance of the bridge pier, it is possible to calculate the resistance force in consideration of the lifting force, buoyancy force and down force, which are the fluid forces in the vertical direction, and the judgment method using the conventional Morrison method is appropriate. It is possible to make an appropriate damage judgment even for bridges with bridge girders with high girder height, which was difficult to evaluate, and it is possible to accurately damage what kind of reinforcement method the structure requires for the assumed water level and flow velocity. Since the determination can be made, it is possible to select an appropriate construction method based on the determination result.

The method for determining damage to the structure and the method for selecting the reinforcement method for the structure according to the present embodiment are the horizontal fluid force, the vertical DC physical strength, the proof stress for supporting / collapse prevention, and the pier destruction using the above formulas 2-5. Although the case where the proof stress is calculated has been described, the specific calculation method is not limited to these mathematical formulas, and various calculation methods can be applied. It is clear from the description of the claims that the form with such changes or improvements may be included in the technical scope of the present invention.

10 bridges, 11 piers, 12 bridge girders, 13 collapse prevention devices, 14 bearings.

Claims (4)

The process of determining the assumed water level and the assumed flow velocity,
A step of obtaining the horizontal fluid force and the vertical DC physical strength acting on the structure using the assumed water level and the assumed flow velocity.
The process of obtaining the destructive strength of the structure to prevent bearings and bridge collapse using the vertical DC physical strength, and
The process of determining the breaking strength of the pier of the structure and
The process of comparing the horizontal fluid force with the breaking strength of the bearing / bridge collapse prevention,
The process of comparing the horizontal fluid force and the breaking strength of the pier,
A method for determining damage to a structure, which comprises. The process of determining the assumed water level and the assumed flow velocity,
A step of obtaining the horizontal fluid force and the vertical DC physical strength acting on the structure using the assumed water level and the assumed flow velocity.
The process of obtaining the destructive strength of the structure to prevent bearings and bridge collapse using the vertical DC physical strength, and
The process of determining the breaking strength of the pier of the structure and
A method for selecting a structure reinforcement method, which comprises a step of comparing the horizontal fluid force with the fracture strength of the bearing / bridge collapse prevention or the fracture strength of the pier to select a structure reinforcement method. In the method for selecting a reinforcement method for a structure according to claim 2.
A method for selecting a reinforcement method for a structure, which comprises selecting a bridge girder outflow reinforcement method when the horizontal fluid force is larger than the fracture strength of the bearing / bridge collapse prevention. In the method for selecting a reinforcement method for a structure according to claim 2.
A method for selecting a reinforcement method for a structure, which comprises selecting a pier reinforcement method when the horizontal fluid force is larger than the fracture strength of the pier.

Images