Ordinance on Industrial Safety and Health
Ministry of Labour Ordinance No. 32 of September 30, 1972
Latest Amendments:
Ministry of Health, Labour and Welfare Ordinance No. 47 of March 30, 2007
In Japanese
Update : 2008.03.28
Part II Safety Standards
Chapter III Concrete Form Shoring
Section 1 Material, etc
Article 237 (Material)
- (1) The employer shall, as regards materials for concrete form shoring, not use those with extreme damage, deformation or corrosion.
Article 238 (Steel Used for Main Part)
- (1) The employer shall, as regards steel materials for main parts of supports, girders or supporting members for girders to be used for concrete form shoring, not use those materials unless otherwise conform to the Japanese Industrial Standard, G 3101 (Rolled Steel for General Structure), the Japanese Industrial Standard, G 3106 (Rolled Steel for Welded Structure), the Japanese Industrial Standard, G 3444 (Carbon Steel Tubes for General Structural Purposes), or the Japanese Industrial Standard, G 3350 (Cold-formed Light Gauge Steels for Construction Structure), or those materials of which the value of tensile strength is 330 N/mm2 or more in a test conducted by the method prescribed by the Japanese Industrial Standard, Z2241 (Method of Tensile Test for Metallic Materials), and which have elongation listed in the right column of the following table corresponding to the type of material and value of the tensile strength listed in the left column and the middle column of the same table respectively:
Type of material Tensile strength (N/mm2) Elongation (%) Steel pipe 330 or more but less than 400 25 or more 400 or more but less than 490 20 or more 490 or more 10 or more Steel plate, gauge steel, flat steel, or light gauge steel 330 or more but less than 400 21 or more 400 or more but less than 490 16 or more 490 or more but less than 590 12 or more 590 or more 8 or more Bar steel 330 or more but less than 400 25 or more 400 or more but less than 490 20 or more 490 or more 18 or more
Article 239 (Structure of Concrete Form Shoring)
- (1) The employer shall, as regards a concrete form shoring, not use unless the one with sound structure corresponding to the configuration of the concrete form, method of placing concrete, etc.
Section 2 Measures in the Case of Assembling, etc.
Article 240 (Erection Diagram)
- (1) The employer shall, when assembling concrete form shoring, prepare an erection diagram and assemble it under the said erection diagram.
- (2) The erection diagram set forth in the preceding paragraph shall describe the arrangement, method of connection and size of members such as supports, girders, ties and diagonal bracings.
- (3) The design of concrete form shoring pertaining to the erection diagram set forth in the paragraph (1) shall comply with the following provisions:
- (i) When a support, a girder or a supporting member of girder (hereinafter referred to as “support, etc.” in this Article) are not combined, the value of the stress produced on the said support, etc., by the design load (meaning the load equivalent to the weight of things supported by concrete form shoring plus load of 150 kg or more per 1 m2 of the concrete form; hereinafter the same shall apply in this Article) shall not exceed the value of the allowable stress of the materials of the said support, etc.
- (ii) When a support, etc., are combined, the design load shall not exceed the maximum working load designated by the manufacturer of the said support, etc.
- (iii) When a steel tubing frame for use as a support, the one shall have a safe structure even when the horizontal weight on top of the said concrete form shoring is equivalent to 2.5% of the design load.
- (iv) When something other than a steel tubing frame for use as a support, the one shall have a safe structure even when the horizontal weight on top of the said concrete form shoring is equivalent to 5% of the design load.
Article 241 (Value of Allowable Stress)
- (1) The value of allowable stress of materials set forth in item (i) of paragraph (3) of the preceding Article shall comply with the following provisions:
- (i) The value of allowable bending stress and allowable compressive stress of steel materials shall be two thirds or less of whichever is the smaller value of the value of yield strength of the steel materials or three quarters of the value of the tensile strength.
- (ii) The value of allowable shearing stress of steel materials shall be 38 % or less of whichever is the smaller value of the yield strength of said steel materials or three quarters of the value of the tensile strength.
- (iii) The value of allowable buckling stress of steel materials shall be the value obtained by calculation using the following formula or less:
Where,
, i, ∧, σc, ν and F in these formula designate each following values.
- : Length of the support (where the support is bound to prevent horizontal displacement, the maximum length between bound points) (cm)
- i: Minimum secondary radius of section of the support (cm)
- ∧: Critical slenderness ratio =
- where,
π: circumference ratio of - E: Young coefficient of said steel materials (N/cm2)
- σc: Value of allowable buckling stress, (N/cm2)
- ν: Safety factor = 1.5 + 0.57
- F: Whichever is the smaller value of the value of the yield strength or the value of three quarters of the tensile strength of the said steel materials (N/cm2)
- (iv) The value of allowable bending stress, allowable compressive stress and allowable shearing stress of timber in the direction of fibre shall be the value listed in the right column of the following table or less corresponding to the kind of timber listed in the left column of the same table.
Kind of timber Value of allowable stress (N/cm2) Bending Compressive Shearing Japanese red pine, Japanese black pine, Japanese larch, hiba, hinoki, Japanese hemlock, Oregon pine, or Port Oxford cedar 1,320 1,180 103 Japanese cedar, fir, silver fir, abies, red cedar or Western hemlock 1,030 880 74 Oak 1,910 1,320 210 Japanese chestnut, Japanese oak, Japanese beech, or keyaki 1,470 1,030 150 - (v) The value of allowable buckling stress of timber in the direction of fibre shall be the value obtained by calculation using the following formula or less:
Where,
, i, fc and fk in these formula designate each following values.
- : Length of the support (when the support is bound to prevent horizontal displacement, the maximum length between bound points) (cm)
- i: Minimum secondary radius of section of the support (cm)
- fc: Value of allowable compressive stress (N/cm2)
- fk: Value of allowable buckling stress (N/cm2)
Article 242 (Measures, etc., to Be Taken for Concrete Form Shoring)
- (1) The employer shall, as regards a concrete form shoring, comply with the following provisions:
- (i) To take measures, such as the use of square timber, concrete placing, and use of posts in order to prevent settling of the supports.
- (ii) To take measures such as fixing of the legs, provision of bridge batten of foot post in order to prevent sliding of the legs of the supports.
- (iii) A butt joint or a bell-and-spigot joint shall be used for a joint of a support.
- (iv) To fasten connecting and intersecting portions of steel materials with fittings such as bolts and clamps.
- (v) When concrete forms have curved surfaces, to take measures such as use of stays in order to prevent floating of the concrete form.
- (v)-2 In the case that H-steel or I-steel (hereinafter referred to as “H-steel, etc.” in this item) is used as sleepers and other horizontal materials and when it is liable to cause deformation of the section of the said H-steel, etc., due to concentration of load on the point of connection between said H-steel, etc., and supports and jacks, etc., to attach reinforcing materials to the said points of connection.
- (vi) For those using steel pipes (excluding adjustable tubular pole shores; hereinafter the same shall apply in this Article) as supports, to conform the steel pipes to the following provisions:
- (a) To equip horizontal collar bracesin two directions for each height of 2 m or less, and prevent the horizontal collar braces from becoming displaced.
- (b) When putting girders or sleepers on the top of steel pipes, to fix an end plate of steel to the said top and fasten to the girders or sleepers.
- (vii) For those using adjustable tubular pole shores as supports, to conform the adjustable tubular pole shores to the following provisions:
- (a) No to connect three or more adjustable tubular pole shores .
- (b) When connecting adjustable tubular pole shores, to connect them using four or more bolts or specially designed fittings.
- (c) When the height exceeds 3.5 m, to take measures set forth in (a) of the preceding item.
- (viii) For those using tubular steel forms as supports, to conform the tubular steel forms to the following:
- (a) To equip cross bracings between tubular steel forms.
- (b) To equip horizontal collar braces each five frames or less in the direction of the side surface and the form surface of the concrete form shoring and in the direction of the cross bracings at the top layer and for each five layers or less, and prevent the horizontal collar braces from displacement.
- (c) To equip ledger formsin the direction of the cross bracings, as both ends of the concrete form shoring in the direction of the form surface and for each five frames or less at the top layer and for each five layers or less.
- (d) To take measures set forth in (b) of item (vi).
- (ix) For those using built-up steel propsas supports, the to conform built-up steel props to the following provisions:
- (a) To take measures set forth in (b) of item (vi).
- (b) When the height exceeds 4 m, to equip horizontal collar bracesin two directions for each 4 m or less, and prevent the horizontal collar braces from displacement.
- (ix)-2 For those using H-steel as supports, to take the measures set forth in (b) of item (vi) for the said H-steel sections.
- (x) For those using timber as supports, to conform the timber to the following provisions:
- (a) To take measures set forth in (a) of item (vi).
- (b) When connecting two or more timbers,to connect them with two or more reinforcements.
- (c) When putting girders or sleepers on the top of the timber, reinforcements to fix the top to the girders or sleepers.
- (xi) For those constructed with girders, to conform to the following provisions:
- (a) To fix both ends of the girders to supporting members in order to prevent the girders from sliding and coming off.
- (b) To equip collar braces between girders in order to prevent the girders from side buckling.
Article 243 (Step-Like Concrete Form Shoring)
- (1) The employer shall, as regards concrete form shoring assemble in the shape of steps using planking, square timber, etc., comply with the following provisions in addition to the provisions prescribed in each item of the preceding Article:
- (i) No to use planking, square timbers, etc., in two or more steps, excluding the unavoidable case due to configuration of the concrete form .
- (ii) When connecting planking, square timbers, etc.,to fasten the said planking, square timbers, etc..
- (iii) To fix supports to the planking, square timbers, etc.
Article 244 (Concrete Placing Work)
- (1) The employer shall, when carrying out concrete placing work, comply with the following provisions:
- (i) To check the concrete form shoring pertaining to the said work before commencing the work for the day, and repair when having found any abnormalities.
- (ii) To take in advance measures for suspending work when any abnormality is found on the concrete form shoring during work.
Article 245 (Work of Assembling, etc., of Concrete Form Shoring)
- (1) The employer shall, when carrying out assembling or dismantling work of concrete form shoring, take the following measures:
- (i) To prohibit workers other than those concerned from entering the area where the said work is carried out;
- (ii) To suspend the work when dangers regarding the implementation of the said work are forecast due to bad weather such as strong wind, heavy rain, and heavy snow;
- (iii) When raising or lowering materials, an instrument or a tool, to have worker use a lifting rope, lifting bag, etc.
Article 246 (Appointment of Operations Chief of Assembling, etc., of Concrete Form Shoring)
- (1) The employer shall, as regards the work set forth in item (xiv) of Article 6 of the Order, appoint an operations chief of assembling, etc., of concrete form shoring from the persons who have completed the skill training course for operations chief of assembling, etc., of concrete form shoring.
Article 247 (Duties of an Operations Chief of Assembling, etc., of Concrete Form Shoring)
- (1) The employer shall have an operations chief of assembling, etc., of concrete form shoring carry out the following matters:
- (i) To decide a work method and supervise the work directly.
- (ii) To check defects in material, an instrument and a tool, and remove defective ones.
- (iii) To monitor the use of a safety belt, etc., and a safety helmet during work.
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