JP5482518B2 - Stress measurement method for existing members joined by cylindrical members - Google Patents

Description

  The present invention relates to a method of quickly and easily measuring stress applied to an existing member, which is a member of an existing steel tower and other members, and is particularly joined by a cylindrical member such as a bolt.

  Steel towers standing on soft ground, etc., are subjected to secondary stress on the members due to ground subsidence, non-uniform displacement of the foundation due to earthquake fluctuations and the like. Knowing how much force is actually applied due to the deformation and fluctuation of these members is an important factor in examining the strength of the steel tower.

  Conventionally, however, these stresses are only predicted or estimated when a new steel tower is designed. Japanese Patent Laid-Open No. 2004-228561 inputs the frame shape and members of a steel tower divided into a plurality of nodes, creates analysis model data, performs stress analysis and other analyses, outputs the analysis results, and designs and diagnoses the steel tower It is a steel tower design and diagnosis system.

  Further, Patent Document 2 is a steel tower abdominal material replacement method and a steel tower abdomen replacement examination system, in which an abdominal material replacement device is attached to the existing steel tower, and the abdominal material is removed from the existing steel tower. It is an abdominal material replacement examination system for a steel tower that examines stress acting on peripheral members around the replacement device and the abdominal material replacement device, and the strength of the abdominal material replacement device and the peripheral members corresponding to the stress. In this case, when the abdominal material to be replaced is removed, the steel tower structure is changed, so that the stress of the abdominal material replacement device and its peripheral members is different from the original design value. Therefore, it is necessary to examine the strength of the abdominal material replacement device and its surrounding members. Therefore, the stress of the abdominal material replacement device and its peripheral members is obtained by three-dimensional analysis.

Japanese Patent No. 3787799 JP 2005-350954 A

Patent Documents 1 and 2 both determine the stress of a member by analysis. In addition, it is common to measure the change in force as a change in another physical quantity in a state where force is not applied and a state where force is applied, and in a state where no force is applied (initial state) Measurement is required. It is difficult to measure the magnitude of the force in a state where the force is already acting like a member of a structure.
As described above, there is no method for easily measuring the stress applied to members such as abdominal members of existing steel towers, particularly members joined by cylindrical members such as bolts.

  Therefore, the present invention is intended to provide a method for easily measuring the stress applied to an existing member joined by a cylindrical member, not limited to a steel tower member.

  According to the first aspect of the present invention, in measuring the stress of the member to be measured joined by the cylindrical member, the member that holds the cylindrical member is unlocked, and the movable torque of the cylindrical member is measured. The stress measurement method for the existing member is obtained by obtaining the stress of the member to be measured based on the relationship between the movable torque obtained in advance and the stress of the member to be measured.

  According to a second aspect of the present invention, in the first aspect of the present invention, the relationship between the previously obtained movable torque and the stress of the member to be measured is such that the stress value of the member to be measured is the movable torque value of the cylindrical member. The stress measurement method for existing members, which is a proportional relationship, was used.

  The invention according to claim 3 is the stress measurement method for an existing member according to claim 1 or 2, wherein the movable torque of the cylindrical member is measured with a digital torque wrench.

  According to the first and second aspects of the invention, in order to measure the stress of the existing member to be measured, the maximum torque (movable) that the cylindrical member such as a bolt that joins the member to be measured and the other member moves. (Torque) is measured and applied to a relational expression between the previously determined movable torque and stress of the member to be measured, whereby the stress of the member to be measured can be measured quickly and easily.

  According to the invention of claim 3, the movable torque of the cylindrical member can be easily measured by using the digital torque wrench.

  In the present invention, in measuring the stress of a member to be measured joined by a cylindrical member such as a bolt, a member such as a nut locking the cylindrical member is loosened, and the movable torque of the cylindrical member is measured. The stress measurement method for the existing member is obtained by obtaining the stress of the member to be measured by the relational expression between the movable torque obtained in advance and the stress of the member to be measured.

  Thereby, the stress of the existing member can be measured by a simple method.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing the principle of the present invention, and FIG. 2 is an explanatory side view showing a mounting location of an existing member measured in Example 1 of the present invention.

  Secondary stress is applied to the web 3 connected to the main pillar 2 near the foundation of the tower 1 shown in FIG. As shown in FIG. 1, the abdomen 3 and the main pillar 2 are joined by a cylindrical member, that is, a bolt 4. In such a case, the stress of the abdominal material 3 or the main columnar material 2 which is a plate-like member acts on the bolt 4 as a shearing force. Therefore, the nut (not shown) that locks the bolt 4 is loosened, and the maximum torque (movable torque) at which the bolt 4 moves is measured. When the shearing force (= member stress) is high, the rotational resistance (friction resistance) of the bolt increases and the movable torque increases. On the other hand, when the shearing force is low, the movable torque of the bolt is also low.

  Next, the relationship between the movable torque and the stress (shearing force) of the member is examined. For this purpose, the stress values of various abdominal materials were actually obtained, and the movable torque of the bolts at the joints between the abdominal materials and the main column material was obtained. These results are shown in Table 1.

  In Table 1, “measured torque value N · m” represents the movable torque value of the bolt, and “stress measured value kN” represents the center of gravity axis of the upper and side surfaces of the abdomen as shown in FIG. Each strain gauge is attached, a turnbuckle is provided along the abdomen, and one end is fixed via a mounting jig fixed to the abdomen, and the other end is fixed to the main column with a mounting wire. The existence stress was calculated from the change in strain of the target abdominal material when the stress of the target abdominal material was released by contracting the turnbuckle, and this shows the value measured for each abdominal material of various steel towers. In addition, the bolt and the nut of a nut which join a belly material and a main pillar material are loosened beforehand, and the distortion when the bolt becomes rotatable is measured.

  The intersection of each “measured torque value / N · m” in Table 1 and each corresponding “stress measured value / kN” is shown in FIG. 4. The horizontal axis represents the bolt movable torque value (N · m), and the vertical axis Is plotted in a graph with the member axial force (kN, stress value).

As a result, as shown in the graph, it was found that the plotted intersections can be displayed in a substantially straight line, where the shearing force is F and the movable torque is τ, both are in a proportional relationship F∝τ. In this way, by measuring the movable torque of the bolt 4, the stress of the abdomen 3 can be quantified. In the case of Table 1, the relationship between the two is that when the stress of the member is y and the movable torque value of the bolt is x,
y = 0.1594x + 0.9802.

  As described above, when measured by the measuring method of the present invention, it is extremely easy to measure the movable torque of the bolt 4 at the joint portion of the existing member to be measured with a digital torque wrench or the like. The stress value of the member to be measured can be easily obtained.

It is explanatory drawing which shows the principle of this invention. It is explanatory side view which shows the attachment location of the to-be-measured member of Example 1 of this invention. It is a description side view of the apparatus which measures the true stress value of the member in Example 1 of this invention. It is a graph which shows the relationship between the volt | bolt movable torque value of Example 1 of this invention, and the axial force (stress value) of a member.

1 Steel tower 2 Main pillar material 3 Abdomen 4 Bolt

Claims (3)

In the stress measurement of the member to be measured joined by the cylindrical member,
Unlocking the member locking the cylindrical member, measuring the movable torque of the cylindrical member,
A stress measurement method for an existing member, wherein the stress of the member to be measured is obtained based on the relationship between the movable torque obtained in advance and the stress of the member to be measured.   2. The relationship between the previously determined movable torque and the stress of the member to be measured is a relationship in which the stress value of the member to be measured is proportional to the movable torque value of the cylindrical member. Of stress measurement of existing members.   The method for measuring stress of an existing member according to claim 1 or 2, wherein the movable torque of the cylindrical member is measured with a digital torque wrench.

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