;.o

vn un 4J

C

^4

W

- e.s

o

(J

C.l

Fig. 2.14-2 Relation between Ice Thickness and Ice Pressure

A : Temp, rising ratio 2.8’C/h (5°F/h)

13 : Temp, rising ratio 5.6°c/h (10°f/h) c : Temp, rising ratio 8.4°c/h (15°f/h)

Both sides of reservoir free.

Both sides of reservoir completely restrained

Note: “Completely restrained conditions on both sides” means that both side banks are sharply inclined and stable, and “both sides free” means that both side banks are so gently inclined that the ice edge may slip up reducing the ice pressure. ,

10. Change in hydraulic pressure by [lowing water

As for change in hydraulic pressure by flowing water, the hydrau­lic stress distribution around the hydraulic gate changes depending on the shapes of the gate leaf and the gate guide when the leaf is opera­ted while the water is flowing. Horizontal load and vertical load also change from those in static water, and thus this effect should be con­sidered for gate leaf strength and operating loads.

According to actual past results, the increase in load due to vibra­tion is approximately 10% of the static load for design at maximum.

11. Effect by temperature change

“Effect by temperature change” means shrinkage and expansion' of the-gate leaf due to the temperature change in conjunction with the condition when the gate was installed. When the gate leaf is re­strained, the leaf, roller bearing, guide and concrete are adversely af­fected, and thus consideration should be given to the temperature change by providing a clearance for the gate guides and guide rollers.

Article 15. Combination of Loads

The loads in the previous Article shall be considered in combination with the following:

1. Normally: own weight, hydrostatic pressure, sediment pressure, wave pressure, buoyancy, wind load, snow load, effect by temperature change, hydraulic pressure change by flowing water and load increase due to vibrations caused by the hydraulic pressure change, and gate operating force or ice pressure.

2. During earthquake: own weight, hydrostatic pressure, sediment pres­sure, wave pressure, buoyancy, ice pressure, snow load, dynamic pres­sure during earthquake, and inertia force during earthquake. I

t

Description:

The combination of loads should be decided depending on purpose, type and installation place. Generally, each load should consider the following:

1. Own weight: Hydraulic gate with a height less than 1/10 leaf width.

2. Sediment pressure: Hydraulic gate installed at a sedimentary silt foun-

dation.

3. Operating force: Tensile force of wirerope and friction force of sup­port for a radial gate. For other gates the operating force transmission part should be checked.

4. Ice pressure: When no freezing prevention device is attached in an ex­tremely cold region.

5. Wave pressure: Where special consideration is required for pressure by wave crash.

6. Hydraulic pressure change by running water and load increase by vibra­tion caused by the hydraulic pressure change: Hydraulic gate operated in a high head, bottom of a large hydraulic gate at a relatively high head, hydraulic gate of a long span, hydraulic gate which discharges with water on its back, with the exception of a high pressure gate provid­ed with a vibration restraint device.

7. Effect by temperature change: Especially a long span gate, etc.

8. Wind load: A gate leaf lifted up above the water surface.

9. Snow load: A horizontal main girder and gate arm, etc., of a hydrau­lic gate in a heavy snow region and which require consideration of snow load.

' Article 16. Shape of Gate Leaf, Gate Guide and Anchorage

Shapes of a gate leaf, gate guide, and anchorage shall properly be selected depending on the purpose of their use.

Description-.

A hydraulic gate, depending on its using method, is likely to be exposed J.o overflow from the leaf top and underflow from the gate bottom for hours, which may cause the gate to be vibrated excessively. These vibra­tions can be removed to some extent by improving the shapes of the leaf, guide and anchorage. It is better to decide the combination of these shapes based on past experiences, tests or hydraulic experiments. For example, for a long span hydraulic gate having overflow some measures should be provided, such as changing the shapd of the gate top so that no detrimen­tal vibrations are produced by the overflow, and a way to supply air per­fectly to the downstream of the gate should be devised.

As an example of an air supply device, as illustrated in Fig. 2.16-1, a deflector or a spoiler is installed on each side of the gate leaf top.

Fig. 2.16-1 Example of Air Supply Device

As for a hydraulic gate operated generally in a high head, the bottom pressure fluctuates unstably depending on how widely the gate is open with a large thickness of a gate lip, thus inducing vibrations of the gale leaf. Accordingly, it is better to minimize the thickness of the gate lip as much as permissible with a view to watertightness.

The same attention to the gate groove shape of a high pressure slide gate (Fig. 2.64-1 4) in Article 64. of this chapter is required to be paid to that of a gate which partially discharges for hours at a more than 10 .meter head. Generally, the offset is taken as 0.075 W to O.lOkF where W is the width of the gate groove, and the gradient downstream of the gate groove is required to be taken as 1/12 to 1/24 referring to Fig. 2.64-2, depending on the depth of water.

Fig. 2.16-2 Shape of Gate Groove

Article 17. Seal Part

Construction and seal materials for the seal part shall be of the proper shape and high durability appropriate to the purpose of its use.

Description:

The seal part of a hydraulic gate is often made of stainless steel plate, copper alloy plate and rubber.

It is necessary for the rubber seal to be easily replaceable, not to give too much friction force in operating the gate, to be watertight against some deflection and to have good durability. The rubber seal widely used is either a natural rubber or a synthetic rubber (chloroprene type). The former is very strong and the latter has an atmospheric corrosion resistance. Nor­mally such rubber seals as those which have a tensile strength more than 150kgf/cm², water absorption (weight ratio) max. 5%, breaking elonga­tion more than 300%, specific gravity 1.1 to 1.4, and Shore hardness 40 to 80° are used.

Fig. 2.17-1 Example of Seal

Part Using J

Seal

Gate guide

W///////

•'igr

Pressure water

Fig. 2.17-2

Example of Seal Part Using Cais­son Seal (Pres­sure Water Used)

The coefficient of friction between the rubber seal and stainless steel plate becomes 0.5 to 0.7 when wet and 0.9 to 1.2 when dry. Perfect adhe­sion is essential when attaching 4-ethylene resin fluoride, etc., to the seal’s contact face in order to reduce the coefficient of friction and at this time the coefficient of friction becomes about 0.1. It is necessary for the rub­ber seal to be properly protected from jet stream and running sediments, and the bolts and nuts to fix the rubber seal should be anti-corrosive with the use of stainless steel or by galvanizing. The tightening bolt pitch for the seal clamp plate is normally 10cm.

A proper hardness and shape should be selected for the rubber seal so as to be flexible enough to the movement and deflection Of the gate leaf due to hydraulic pressures.

As far as the shape of a rubber seal is concerned, there is a flat type, (plate rubber), an L-type, a J-type, a caisson type, etc. The shape is pro­perly selected and used depending on the gate leaf shape and hydraulic pressures. The flat type and L-type are used for the bottom or side seal­ing of a gate used under low hydraulic pressures, and the J-type is widely used from low to high hydraulic pressures. The caisson type is suitable for high hydraulic pressures and pressure water is injected to the seal back side in some cases.

In any case, watertightness should be obtained by utilizing the hydraulic pressure acting on the rubber seal,

The sliding coefficient of friction between metals at the seal part is about 0.3 to 0.6. The allowable bearing pressure in this case should be about 70 kgf/cm² during sliding, and about 200 kgf/cm² under static con­ditions.

Article 18. Hinged Support

A hinged support shall be so properly constructed as to operate the gate leaf smoothly and to provide easy maintenance and control by taking ac­count of the external force to be supported, rotating speed and frequency of use.

Such pins as those with rollers of a fixed wheel gate, those with trun­nion hubs of a radial gate, and those with bearings of a bottom hinge flap gate rotate while supporting hydraulic loads applied to the gate leaf, and safely transmit these loads to the anchorage. Thus, these pins should be strong enough and rigid enough and should be so constructed as to precisely rotate even if the turning angle is small and so as not to produce any uneven contact due to deflection of the gate.

In general, the hinged support of a hydraulic gate is subject to a large load, and its rotating speed is very low. In many cases, it rotates within limited angles, as in the case of a rotating support for a hinged type gate. In addition, it is often difficult to lubricate it. As for the bearing used for these hinged supports of the gate leaf, a plain bearing of an externally lubricating type, plain bearing of an oil-less type, and roller bearing are used.

Such materials as B.C, LBC, and PBC are used for the bush of an ex­ternally lubricating type plain bearing which is oiled with a grease gun or by a centralized lubricating system through oil grooves. In this case, if a lubricant having a good anti-pressure nature to the load is used, about 150 kgf/cm² to 200 kgf/cm² of an allowable rotary face pressure can be taken to the projected area, and its coefficient of sliding friction is ap­proximately 0.2.

Recently, an oil-less bearing with a solid lubricant incorporated in its bush has been widely used at the support because of its convenience. This bearing originally does not need to be lubricated, however rust may gener­ate depending on the pin’s material and water quality and thus it is prefer­able to lubricate it with view to rust prevention. Use of a grease suitable for solid lubricant is.desirable for lubrication.

For a solid lubricant, molybdenum bisulfide, graphite, fluorine resin, etc., are used, however these lubricants change the performances of the bearing. It is also necessary for the bearing in water not to generate a gal­vanic’ action between the lubricant and the bush.

The material for an oil-less bearing should be JIS H5102-HBsC4 (more than BHN 210) or the equivalent. Its allowable rotary bearing pressure can be taken up to about 250 kgf/cm² and its coefficient of sliding friq- tion is approximately 0.1 to 0.2.

The allowable static bearing pressure can be within twice the allowable rotary face pressure.

A roller bearing can be used for the fixed wheel of a high pressure gate which does not have sufficient down-pull force and for the trunnion bear­ing of a radial gate. In these cases, it is desirable to use a spherical roller , bearing having an automatic adjusting effect and it is necessary to pro­vide a sealing device with grease inserted inside to prevent the water from flowing in.

The coefficient of rolling friction of a roller bearing is about 0.01 to 0.02, and the load factor should be about 1.2 to 1.5 times the basic static rating load.

^z Article 19. Skin Plate

The bending stress generated in a flat plate by hydraulic pressure shall be calculated from the following formula:

ioo ^kat²

where a: Stress (kgf/cm²)

k: Factors in Table 2.19-1

a: Short side of a rectangle (cm) b: Long side of a rectangle (cm) p: Hydraulic pressure (kgf/cm²) Plate thickness (cm)

b/a
1.00	30.9	13.7	13.7	30.9
1.25	40.3	18.8	13.5	33.9
1.50	45.5	22.1	12.2	34.3
1.75	48.4	23.9	10.8	34.3
2.00	49.9	24.7	9.5	34.3
2.50	50.0	25.0	8.0	34.3
3.00	50.0	25.0	7.5	34.3 .
CO	50.0	25.0	7.5	34.3

Table 2.19-1 k value

Fig. 2.19-1 Stress of

Skin Plate

If a skin plate is welded to a girder as a mono-structure, it is permissi-* ble to have the plate work together with its effective width.

Description:

It has been decided to determine the bending stress of a flat plate from the DIN 19704 (Design Standard for Hydraulic Structures) formula. The short side (a) and the long side (Z>) of a block usually mean the distance between weld lines in case of a welded structure, and the distance between the rivet centers in case of a riveted structure.

Compressive side 241

Tensile side 30t

Fig. 2.19-2 Effective Width

When a skin plate works together with a girder, the effective width of the flange plate on the compressive side should be less than 24 times the plate thickness and the flange plate on the tensile side less than 30 times the plate thickness.

In this case, the stresses should be checked by the formula below: Same directional stress:

^abS ~ °S + °b

- \ -

*

where a_bS: Same directional stress (kgf/cm²)

a₅(0.3a,or 0.3a]): Stress of the skin plate in the same direction as the girder (kgf/cm²) Stress of a tensile (compressive) edge of a girder (kgf/cm²)

up Allowable stress (kgf/cm²)

Resultant stress of 2 axial directions:

°_x = M “ <Wbs +

where op Combined stress (kgf/cm²)

a_bS: Sum of girder’s tensile (compressive) edge stress and the stress on the skin, plate in the same direction as the girder. (kgf/cm²)

crs?**Stress of the skin plate at a rigM^ngle to the girder * (kgf/cm²)

r: Shearing stress of the skin plate as a flange of a girder (kgf/cm²) (To be considered only when the flange is sub­ject to a shearing force.)

Article 20. Corrosion Allowance

'i. As for a member of a hydraulic gate either to be submerged or to be worn, more than the values in Table 2.20-1 shall be added to the calcu­lated plate thicknesses.

Table 2.20-1 Corrosion Allowance (unit: mm)

■ Place ■	Skin plate		Other main members
Water contact face or abrasion face	One face	Both faces	Both faces
Hydraulic gate always used in fresh	1 (1)	2 (1)	2
water
Hydraulic gate always used in sea water	1.5	3	2
Note: Figure in ( ) indicates corrosion allowance for abrasion. If there is a			'ear of abrasion,

this value should be added to the corrosion allowance.

2. As for the corrosion allowance of a hydraulic gate which is not always in contact with water, a decrease by 0.5mm from the above value foe one side shall be permissible.

Description'.

Since corrosion of a hydraulic gate develops most seriously around the water line, the corrosion allowance should cover both the water-contact- face and one meter above the water surface.

It is preferable that even a hydraulic gate not in full-time use but sub­merged often should be treated exactly as a gate in full-time use. How­ever, for a hydraulic gate, such as a stoplog, used less frequently, the corrosion allowance does not need to be included.

It is desirable that an allowance of more than 1.5 times the values in this Article (maximum about 4mm) should be added to a gate leaf having difficult access and incapable of being cleaned after installation. The cor­rosion allowance has been set separately for sea water and fresh water by taking account of a hydraulic gate used in sea water which aggravates the corrosion more seriously.

However, when such a special material as stainless steel is used or such a special surface treatment as metalikon plating is conducted, the corro­sion allowance may be alleviated.

Article 21. Rigidity, Minimum Plate Thickness and Slender­ness Ratio of Gate Leaf

1. Each part of the gate leaf shall be placed in the position required and shall be provided with enough rigidity.

2. The minimum steel thickness of primary members used for a gate leaf shall be more than 6mm for steel plates and more than 5mm Tor steel shapes and shall include a corrosion allowance.

3. The slenderness ratio shall be less than the value shown in Table 2.21-1.

Table 2.21-1 Slenderness Ratio
Members		Slenderness ratio
Compressive member	Main member Secondary member	120 150
Tensile member	Main member Secondary member	200 240

... - . 1.84 -

Description:

Steel materials are used as primary members of a hydraulic gate and they are subject to a dynamic load of vibrations caused by flowing water, impact by drifting debris and trees or other unexpected loads, and thus each member should be so constructed as to maintain the rigidity and stability not only in the loading direction but also in the perpendicular direction.

There are a variety of hydraulic gates ranging from small to large sized ones, from 5 - 6mm to 50 — 60mm thick steel materials used for the gate leaf, and thus it is difficult to uniformly regulate the minimum thick­ness. But, the gate is commonly installed in a high humidity location, i.e. in an environment where it is easily corroded and worn, and taking ac­count of manufacturing and handling during transportation, the minimum, thickness has been set as specified in paragraph two of this Article even though based on computations a thin and slender member could be used.

For more than a medium sized gate, it is preferable to use more than 8mm as the minimum thickness.

With an excessive slenderness ratio, the rigidity of the leaf becomes in­sufficient even though allowance can be obtained from calculation, and . thus the maximum slenderness ratio was set, with the exception of the eyebar sections and the round bars.

The primary members herein are those which directly support hydrau­lic pressure force, own weight and gate operating force, etc., and the sec­ondary members are those which execute secondary functions to the main structural functions, e.g. back side bracings and extra members and sub­vertical members for main structural members.

f

Article 22. Deflection by Gate Leaf

Deflection by the gate leaf shall be within 1/800 of a span with the ex­ception of special cases.

Description:

Deflection by the gate leaf has been set at less than 1/800 by consider­ing the rigidity required by the structure and safety during the operation. The span means the distance between the supports for a fixed wheel gate, and the clear span for a radial gate and a bottom hinge flap gate.

For a hydraulic gate for which elastic water sealing material is used at the seal part, sufficient watertightness can be obtained under the above deflection, however special cases should be considered separately. It is desirable for the deflection of a metal-contact-type (at the seal part) gate to be 1/1000 to 1/2000 in order to ensure watertightness. For a long span gate, the maximum deflection allowed can be 1/600.

For a gate in which it is permissible for the watertightness to be less than that of ordinary gates, such as a stoplog gate, a value greater than 1/600 is permissible.

Article 23. Plate Girder

Design of a plate girder, web plate, stiffener and flange plate shall be as follows:

1. Minimum thickness of web plate

SS41.SM41.SMA41 SM50 SMA50 without vertical stiffener 6/70 b/60 b/51 -

with vertical stiffener 6/152 Z?/130 6/123

where b: Space between fixed edges of a flange (cm)

2. Width of flange plate

Compressive flange within 24t

Tensile flange ‘ within 30t

where t: Flange plate thickness (cm)

3 . Space between vertical stiffeners

d-^ 3,200 -^=

S_ N A

where d’. Max. space of vertical stiffeners (cm)

tj. Web plate thickness (cm)

S’: Shearing force acting on web plate (kgf) • At Total section area of web plate (cm²)

4. Dimension of vertical stiffener

(1) General

where b_s: Width of vertical stiffener (cm)

where t_s: Thickness of vertical stiffener (cm) Generally attached to both sides of a web plate.

(2) Vertical stiffener at a load concentration point

Generally, a stiffener shall be attached to both sides of the web plate after determining that the cross section will not be buckled by the load. The total effective section area must be less than 1.7 times the section area of the stiffeners.

The effective buckling length shall be d/2 (a half of the girder height), and the effective width of the web plate shall be up to 12 times the thickness of the web plate on each side of the vertical stiffener.

Description:

It is desirable for the dimensions of each part of the plate girder to be well-balanced, i.e. if the web plates are too thin, buckling would take place due to a bending moment and shearing force, or if the flange plates and vertical stiffeners are of improper dimensions they will not work in cooper­ation with the web plate.

Buckling of the web plate can be avoided by the addition of horizontal and vertical stiffeners.

Generally, horizontal stiffeners are used less frequently for a hydraulic gate, and so only the dimensions for a vertical stiffener have been specified.

It is necessary to study the buckling of the web plate by shearing or bending moment when a particularly large shearing force or bending mo­ment occurs in the girder. The stiffeners should be provided at load con­centration points such as the supports of a main girder.

If the clear space between the upper and lower flanges exceeds 70 t_u (where is the web plate thickness) for SS41, SM41, and SMA41, 60.t_{u t}- for SM50 and 57 for SMA50, vertical stiffeners as specified in para­graphs 3 and 4 of this Article should be provided.

Article 24. Web.Plate Thickness of Members Subjected to Com­pressive Force

1. The web plate thickness of a member subjected to compressive force shall be in accordance with the following standards, provided that both ends of the plate are sufficiently restrained.

SS41, SM41, SMA41 thickness G =

SM50 thickness

^u- 34

SMA50

thickness t> —

^u- 32

where b: Space between fixed edges of a flange (cm)

2. Width and thickness of the flange plate shall be in accordance with paragraph 2, Article 23. of this Chapter.

Description:

Even though a member subjected to compressive force such as the arm of a radial gate has sufficient section area, local buckling may take place if the plates constituting the arm are too thin. Thus, the plate thickness of a compressive member has been delimited. The leaf of a shell type gate is exempt from application of this Article provided that stresses and buck­ling are properly studied and safety is confirmed.