JPS6233481B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for earthquake-proofing a hanging boiler during an earthquake, and an improvement in the earthquake-resistant structure of a hanging boiler that prevents damage to the strength members of the boiler body and boiler frame.

Generally, suspended boilers are designed to prevent thermal expansion of the boiler during operation from having an adverse effect on the boiler frame by suspending the boiler from the ceiling of the surrounding boiler frame to support its own weight. It is a form.

Such a suspended boiler may be subjected to vibrations of the boiler body and boiler frame due to various causes during boiler operation, horizontal shaking of the boiler body mainly due to strong winds, and horizontal seismic force due to earthquakes.

In particular, when a suspended boiler is subjected to horizontal force due to an earthquake, the seismic response of the boiler body and the boiler frame are different, resulting in a large relative displacement between the boiler body and the boiler frame, resulting in a so-called hanging structure.

For this reason, in a suspended boiler, the strength member (backstay) of the boiler body and the strength member (rigid frame structural member, rigid frame, brace structural member, truss structural member) of the boiler frame that surrounds the boiler body and supports the main body by suspending it. A stopper is installed between the boiler and the boiler frame to restrict relative lateral movement between the two, and seismic design is performed using the static horizontal seismic coefficient method based on the Building Standards Act, considering the boiler body and boiler frame as an integral structure. is normal.

Hereinafter, structural examples of conventionally known hanging boilers from an earthquake-resistant perspective and problems of these structures during strong earthquakes will be explained with reference to the drawings.

The boiler body 1 is suspended from the ceiling surface 3 of the boiler frame 2 via a number of hanging rods 4, as shown in FIG. As shown in Figure 2, in a drum-type boiler with a monowall structure, the boiler body 1
Since the furnace wall 7 is formed of water tubes 8, when the boiler starts operating, the boiler main body 1 is located at X ₀ -X ₀ , Y ₀ -Y ₀ and Z ₀ -Z ₀ in Thermal expansion occurs in each direction depending on the temperature of the water tube 8 using the starting point of elongation.
The furnace wall 7 is provided with backstays 9 at predetermined intervals in the horizontal direction as a strengthening member of the boiler body 1 in order to prevent vibrations of the furnace wall 7 due to earthquakes, swelling due to furnace pressure, and fluctuations in furnace pressure due to combustion. It is wrapped around the four sides like a tag. The cross section of the backstay 9 is generally made of I-shaped steel section, as shown in detail in Figures 3a, 3b, and 5, and has a structure that mainly handles bending and compression. (In a large suspended boiler, a large vertical backstay made of I-beam steel is installed perpendicular to the multiple horizontal backstays as shown above, and a horizontal truss structure is installed on the outside of the vertical backstay. Some have reinforced structures.) The horizontal tensile force applied to the furnace wall 7 is
Tension bar 10 provided separately on the outside of water pipe 8
Backstay 9 is in charge of
Points where the furnace wall 7 starts to elongate X ₀ −X ₀ and Y ₀
It is firmly attached by a bolt 13 via a stopper 11 welded to the water pipe 8 near -Y ₀ . The backstay 9 is further attached to the tension bar 10 via a plurality of staylaps 12 having elongated holes so that it can slide against the elongation of the furnace wall 7.

14 is a heat insulating material stretched on the outside of the furnace wall 7. In this way, the boiler main body 1 is normally free in the direction of elongation, but in the longitudinal and lateral directions of the can, there are points X ₀ −X ₀ , which are the starting points of elongation.
It is restrained by stoppers 15, 16, . . . provided at predetermined positions in a vertical plane passing through _Y0 - _Y0 .

Further, to explain the structure of the stopper 15 in detail, in the example shown in FIGS. 4 and 5, the stopper 1
5 are two strength members 16 of the boiler frame 2,
The boiler body 1 consists of a female stopper 17 installed vertically between the female stoppers 16 and female stoppers 18, 18, which are attached to the backstay 9 with a clearance of several millimeters and sandwich the male stopper 7.
The vertical and horizontal relative displacement between the backstay 9 and the strength member 16 of the boiler frame 2 due to the thermal expansion of the boiler frame 2 is absorbed, and the horizontal direction across the male stopper 17 and the female stopper 18, 18 is A strength member 16 of the boiler frame 2 and a backstay 9, which is a strength member of the boiler body 1, are connected as a stopper 15 for restricting relative lateral movement during an earthquake or other events.

In addition, the stopper 1 shown in FIGS. 6 and 7
In another example of 5, the starting point of elongation of boiler body ₁
-X ₀ , Y ₀ -Y ₀ A long bumper column 25 that penetrates multiple floors of the boiler frame 2 via a horizontal cantilever 20 and a brace 21 or a horizontal cantilever 22 is attached to the strength member 16 of the boiler frame 2 near Y 0 -Y 0 . , is firmly attached as a part of the boiler frame 2 with a large number of bolts 26. Female stoppers 18, 18 welded to a plurality of backstays 9 (two per floor) attached to the boiler body 1 sandwich the bumper pillar 25 with a slight gap as shown in FIG. There is. d is a gap provided between the protrusion 14 provided on the backstay 9 and the bumper column 25, which is larger than the maximum elongation of the boiler body 1.

In such a stopper 15, the horizontal force applied to the boiler frame 2 during an earthquake is directly transmitted from the male stopper 17 or bumper column 25 to the backstay 9 via the female stopper 18, and the boiler frame 2 vibrates together with the boiler body 1. do.

At this time, the reaction force based on the inertial force of the boiler body 1, which the bumper column 25 receives, is transmitted to the bumper column 25 via a plurality of female stoppers 18, 18, . . . provided on each floor. The horizontal force transmitted to the bumper column 25 bends the bumper column 25 and is distributed to the joining members such as the horizontal cantilever beam 20, the brace 21, and the horizontal cantilever beam 22, and strengthens the strength member 16 of the boiler frame 2 installed there. , 16 to the boiler frame 2 and transmitted to the base of the boiler frame 2.

Furthermore, as illustrated in FIGS. 8 and 9, backstays 9, 9... are attached to the four sides of the furnace wall 7.
and the strength members 16 of the boiler frame 2,
A strong rod-shaped stopper 15,
15 is also known.

This type of stopper 15 also has a pin-shaped coupling member 31 which is a component of the stopper 15 firmly attached to the backstay 9, and a coupling member consisting of a bracket 32 and a pin 33 which are firmly attached to the strength member 16 of the boiler frame 2. It consists of a rod 35 equipped with.

This type of stopper 15 is also designed to avoid the influence of thermal expansion of the boiler body 1, but the horizontal force applied to the boiler frame 2 during an earthquake is transmitted through the stopper 15 to the strength member of the boiler body 1. As in the previous example, the vibration is transmitted to a certain backstay 9, and the boiler frame 2 and boiler main body 1 vibrate together.

There is also a type of stopper 15 that is installed near the starting point of elongation of the boiler body 1, _X0 - _X0 , _Y0 - _Y0 ; It is similar to the one shown in FIGS. 8 and 9 in that 1 vibrates as a unit.

As explained above for each example, in the conventionally known stopper 15, the boiler frame 2 and the boiler main body 1 are integrated and have a structure that vibrates horizontally, so that not only the mass of the boiler frame 2 but also the large weight The inertial force of the mass including the mass of the boiler body 1 acts on the boiler frame 2 via the stopper 15, and becomes larger than the seismic response of the frame 2 alone.

Therefore, when the scale of the earthquake is large and the base acceleration of the frame 2 increases, the inertia force increases approximately proportionally, and the strength member 16 of the boiler frame 2 and the backstay 9, which is the strength member of the boiler body 1, increase.
Excessive stress is generated.

For this reason, the strength member 1 of the boiler frame 2
6. It is necessary to ensure that the backstay 9 and the stopper 15 are sufficiently strong. If this is not done, either or both of the backstay 9 of the boiler body 1 to which the stopper 15 is firmly attached and the strength member 16 of the boiler frame 2 will be damaged in the event of a major earthquake, causing serious damage to the suspended boiler. It is thought that it will become.

The present invention has been made for the purpose of improving the earthquake-resistant structural defects of the known hanging boilers described above.

In order to achieve the above object, the present invention provides a stopper for restricting relative lateral movement between a strength member of a boiler body and a strength member of a boiler frame that surrounds the boiler body and supports the body in suspension. In the earthquake-resistant structure of a suspended boiler, the stopper is composed of a pair of male and female stoppers attached to a strength member of the boiler frame and a strength member of the boiler body, respectively, and is configured to receive seismic force. To provide an earthquake-resistant structure for a suspended boiler, in which at least one of the stoppers is configured to have a weak rigidity so that the stopper undergoes plastic deformation faster than both of the strength members.

According to the present invention, when a small external force is applied to the boiler body, the external force is transmitted to the boiler frame via the stopper and supported by the boiler frame,
When a large external force is applied, at least one of the male stopper or female stopper plastically deforms faster than both strength members so that the reaction force from the boiler frame is not transmitted to the boiler body, thereby preventing serious damage to the boiler body. do.

Next, the present invention will be specifically explained with reference to embodiments shown in FIGS. 10 to 16.

As shown in FIGS. 10 and 11, the male stopper 17 attached to the backstay 9 is designed to be weaker than the female stoppers 18, 18 attached to the strength member 16 of the boiler frame 2. In addition,
A male stopper may be provided in which a part of the male stopper 17 is provided with a weak part such as a notch. Further, the male stopper 17 may be directly welded to the backstay 1, or the male stopper 17 may be welded directly to the backstay 1, or the male stopper 17 may be welded directly to the backstay 1, or the male stopper 17 may be welded directly to the backstay 1.
It may also be fixed to the backstay 9 with bolts 26 via.

In the case of this example, the boiler body 1 that occurs during an earthquake
When the seismic force is small, the stopper reaction force R caused by the relative displacement between the boiler frame 2 and the boiler frame 2 causes the male and female stoppers 18, 17 to deform to a small extent (first
Figure 2 B-O-A). However, in the event of a major earthquake, the reaction force R
becomes proportionally large, plastic deformation occurs at the base of the male stopper 17, which has relatively weak strength, and the stopper reaction force R reaches a ceiling (FIG. 12 AC). When the direction of the seismic force changes, it passes along the path DEF... as shown in Figure 12, resulting in a so-called hysteresis phenomenon.

During small and medium-sized earthquakes, such as those caused by wind, which occur frequently, the stopper has the same effect as before, but in the event of a large earthquake, the stopper reaction force R becomes large and exceeds the set value, so the male stopper 17 is plastically deformed and the reaction force R reaches its peak. Therefore, the seismic force acting on the heavy boiler body 1 from the boiler frame 2 via the stopper 15 is reduced, and the seismic response is also reduced.

Furthermore, the damping effect due to the history of the stopper reaction force R also reduces the response.

By locally weakening a part of the male stopper 17, plastic deformation can be reliably concentrated in that part, and by smoothing the finish of that part, large plastic deformation can be achieved without damage. acceptable. Note that the same effect can be obtained even if a weak portion is provided in a part of the female stopper 18 in FIGS. 13 and 1.
Figures 4 and 15 are multi-point stoppers 15 with the same idea.
In this embodiment, a female stopper 5 having holes 50, 50, 50 facing the male stopper 17 is shown.
1 is fixed to the strength member 16 of the boiler frame 2 by a horizontal beam 22, and the rest is the same as in the example shown in FIG. Therefore, the seismic effect is also the same as in the case shown in FIG.

FIG. 16 shows an L-shaped structure in which the male stopper 17 is easily bent and torsionally deformed compared to the embodiment shown in FIG. 10.
The structure, action, and effect are the same, except for the shape of the letters.

Further, the second embodiment shown in FIGS. 17 and 18 will be specifically explained.

As shown in FIG. 17, a male stopper 17 is attached to the backstay 9, and a plate 18a and its support plate 18b are arranged as female stoppers facing the male stopper 17. Note that 18a and 18b may be directly welded to the strength member 16 of the boiler frame 2, or
The base plate 40 may be attached by bolts 26.

At the time of an earthquake, a stopper reaction force R is generated due to the relative displacement between the boiler body 1 and the boiler frame 2, and the plate 18a and the support plate 18b are
are deformed to a small extent under tension and compression, respectively, but as the ground motion increases, the tensile force of the plate 18a and the compressive force of the support plate 18b also increase in proportion (Fig. 18OA), and the elastic buckling strength of the support plate (Fig. 18OA) increases. 18
(corresponding to point A in the figure) and buckles, 18b in Figure 17
It deforms as shown in Figure 18 and becomes unable to bear the compressive force, and the stopper reaction force R decreases along AC in Figure 18. However, when the ground motion becomes small, the deformation of the support plate 18b is within the elastic range, so as shown in FIG.
Return along CO. For ground motion in the opposite direction, a reaction force R acts on the other side of the female stopper, producing the same effect as above (Fig. 18 O→B→D→
O).

In the event of small to medium earthquakes such as those that occur frequently due to wind, the conventional stopper effect is maintained, and in the event of a large earthquake, the support plate buckles beyond the set buckling strength and the stopper reaction force R decreases, resulting in a smaller earthquake response. .

The above was a case where the support plate 18b buckles elastically, but the effect is the same when the support plate 18b buckles elastically.In this case, the 17th Stopper 1 with base plate 40 as shown on the left side of the figure
It may be set to 5.

[Brief explanation of the drawing]

Figure 1 is a side view showing the schematic structure of a suspended boiler, Figure 2 is a cross-sectional view of the same structure taken along the - line in Figure 1, and Figure 3a is an enlarged cross-section with a part of the boiler main body omitted. Figure 3b is a view taken along arrow bb in Figure 3a, Figure 4 is a side view showing an example of a known stopper, Figure 5 is a cross-sectional view taken along line - in Figure 4;
FIG. 6 is a sketch showing different known examples of stoppers;
Figure 7 is a cross-sectional view taken along the - line in Figure 6;
The figure shows a part of a hanging boiler in cross section to explain still another known example of the stopper, and FIG. 9 is an enlarged vertical cross-sectional view taken along the line - in FIG. 8, and FIG. 11 is a cross-sectional view showing an embodiment of the present invention, FIG. 11 is a longitudinal sectional view taken along the line XI-XI in FIG. 10, and FIG. 12 is a relationship between reaction force R and displacement δ in the embodiment shown in FIG. 10. 13 is a side view showing a stopper 15 of a different structure implementing the same means as shown in FIG. 10, FIG. 14 is an enlarged vertical sectional view taken along line XI-XI in FIG. The figure is a cross-sectional view taken along the - line in Figure 14, and Figure 16.
The figure is a sketch diagram illustrating a stopper 15 having a different structure implementing the same means as shown in FIG. 10, FIG. 17 is a plan view showing a second embodiment, and FIG. It is a graph showing the relationship between force R and displacement δ. 1...Boiler body, 2...Boiler frame, 3
...Ceiling surface, 4...Hanging rod, 9...Back stay,
15...stopper, 16...strength member, 17...
...Male stopper, 18...Female stopper, R...Reaction force, δ...Relative displacement.

Claims (1)

[Claims] 1 Earthquake resistance of a suspended boiler comprising a stopper for restricting relative lateral movement between a strength member of the boiler body and a strength member of a boiler frame that surrounds the boiler body and supports the body in suspension. In the structure, the stopper consists of a pair of male and female stoppers attached to the strength member of the boiler frame and the strength member of the boiler body, respectively, and deforms plastically faster than both of the strength members when subjected to earthquake force. An earthquake-resistant structure for a suspended boiler, characterized in that at least one of the stoppers has a weak rigidity.