CHAPTER 1 GENERAL
1.1 Scope of Application
This Standard applies to the structural design of steel buildings. The
Standard, however, need not apply to structural designs based on special research studies.
1.2 Structural Safety Verification Tests
Where a design in involves connection and other structural details not
expressly prescribed in this Standard, the structural safe& of such details shall be proved by tests or by other appropriate means.
1.3 Enlargement of Section
Sections of various structural elements shall be enlarged as required, with due consideration for practical limitation in precision of structural designs, inadequacy in constructional workmanship, and such adverse factors as rusting, corrosion and wear of steel materials.
1.4 Nomenclature
A Gross sectional area; nominal body area of a high-strength bolt; or
sum of sectional areas of column components (mm 2)
A N Net section (mm 2)
A d Sectional area of lacing element; or total sectional area of a pair of
lacing elements in the case of double lacing (mm 2)
A f Cross-sectional area of compression flange; or cross-sectional area of
either flange (mm 2)
A p Sectional area of parts in contact (mm 2)
A s Cross-sectional area of vertical or horizontal stiffeners (mm 2)
A w Cross-sectional area of web plate (mm 2)
a Equivalent area loss due to rivet, bolt or high-strength bolt
holes(mm 2); or spacing of intermediate stiffeners (mm)
a 0 Net area loss due to rivet, bolt or high-strength bolt holes (mm 2)
b Width of compression element free at one edge and fixed at the other;
width of rocker or roller; or longitudinal spacing or pitch of consecutive
holes (mm)
21
212)(3.0)(05.175.1M M M M C +-= , but not larger than 2.3
Bending coefficient dependent upon moment gradient D
Nominal outside diameter of steel pipe; or outside diameter of main steel pipe (mm) d
Width of element stiffened along two edges; outside diameter of branch pipe; width of web plate; or diameter of pin (mm)
d1Minimum width of the portion of web plate divides by vertical or horizontal stiffener (mm)
E Modulus of elasticity (N/mm2)
e Distance between axes o
f gravity of components (mm)
F Basic value used in determining allowable stresses (N/mm2)
(N/mm2)
F
3
F
/
s
f Allowable stress in members subject to repeated stress variation
(N/mm2)
f b Allowable bendin
g stress (N/mm2)
f b1Allowable bendin
g stress in bearing plates and similar elements
subject to out-of-plane bending (N/mm2)
f b2Allowable bendin
g stress in pins subject to bending (N/mm2)
f c Allowable compressive stress (N/mm2)
f c’Allowable compressive stress in the toe of the web fillet of rolled
shapes or build-up I-shaped members (N/mm2)
f l Allowable bearin
g stress in plates in riveted or bolted joints (N/mm2) f p1Allowable bearing stress for contact area of pins and for other milled
surfaces (N/mm2)
f p2Allowable bearin
g stress for rockers or rollers(N/mm2)
f s Allowable shear stress (N/mm2)
f s0Allowable shear stress for high-strength bolts (N/mm2)
f st Allowable shear stress for high-strength bolts subject to combined
tension and shear (N/mm2)
f t Allowable tensile stress (N/mm2)
f t0Allowable tensile stress for rivets or bolts (N/mm2)
f ts Allowable tensile stress for rivets or bolts subject to combined tension
and shear (N/mm2)
g Transverse spacing between fastener gage lines (mm)
h Depth of beam (mm)
I0Moment of inertia of intermediate stiffeners (mm4)
I L Moment of inertia of horizontal or vertical stiffener (mm4)
I S Required moment of inertia of the stiffeners on compression flanges
(mm4)
i Radius of gyration, taken about an axis in the plane of web, of a tee
section comprising the compression flange plus one-sixth of beam
depth radius of gyration of a section with respect to axis subject to
buckling; or radius of gyration of horizontal or vertical stiffeners on
the web (mm)
i1The least radius of gyration of sectional elements of compression members (mm)
L Effective length of weld in branch connection of steel pipes (mm)
l Length of member; or length of distributed load (mm)
l b Unsupported length of compression flange (mm)
l d
Length of lacing element (mm) l k
Effective length of compression member subject to buckling (mm) l 1
Spacing of separators or tie plates; or length of hole in members with cover plates having holes (mm) l 2
Longitudinal component of the length of lacing of a built-up member (cm) M
Bending moment (N ?mm) M 1
Larger bending moment about the strong axis at the end of a member (N ?mm) M 2
Smaller bending moment about the strong axis at the end of a member (N ?mm) m
Number of components or groups of components connected by lacing or tie plates N
Compression (N) N 1
Larger compression (N) N 2
Smaller compression (N) n
Number of structural planes formed by lacing or tie plates in built-up members; or number of vertical or horizontal stiffeners P
Concentrated transverse load or reaction; or compression for computation of bearing stress (N) p
Spacing of holes (mm) Q
Shear (N) r
Radius of curvature of rocker or roller (mm) T
Tension (N) T 0
Design bolt tension for high-strength bolt (N) t
Thickness of plate; wall thickness of pipe; thickness of web plate; or plate thickness of pin (mm) t 0
Distance from edge of flange to toe of web fillet (mm) Z c
Section modulus of compression side of cross-section (mm 3) Z t
Section modulus of tension side of a cross-section (cm 3) α
Distribution factor for compressive stress γ
Fatigue factor θ
Intersecting angle between two pipes Λ
Critical slenderness ratio λ
Slenderness ratio of compression member (l k / i ) λy
Slenderness ratio of built-up compression member assumed to buckle as an integrated member λye
Effective slenderness ratio of built-up compression members σ
Maximum compressive stress in web plate (N/mm 2) σ0
Allowable compressive stress in plate subject to buckling (N/mm 2) c σb
Bending stress of extreme fiber in compression (M/Z c ) (N/mm 2) t σb
Bending stress of extreme fiber in tension (M/Z t ) (N/mm 2) σc
Mean compressive Stress (N/A ) (N/mm 2)
σP Bearing stress (N/mm2)
σt Mean tensile stress (T//A N); or tensile stress which is proportional to the force acting upon bolts (N/mm2)
σx,σy Normal stresses perpendicular to each other (N/mm2)
σ1,σ2 Larger absolute value and smaller absolute value of stresses at the upper and lower limits of stress range for members subject to repeated
stress variation (N/mm2)
τShear stress produced in rivets or bolts; or mean shear stress in web plate (N/mm2)
τ0 Allowable shear stress in plate subject to buckling (N/mm2)
τxy Shear stress in the plane of normal stresses, σx andσy(N/mm2)
CHAPTER 2 DRAWING PRACTICE
2.1 Rules of Representation
Drawings shall be prepared in compliance with JIS Z 8302 [General Rules for Technical Drawing], JIS A 0150 [Drawing Office Practice for Architects and Builders (General Rules)], JIS Z 8201 [Mathematical Symbols] and JIS Z 3021 [Graphical Symbols for Welding].
2.2 Items of Information to Be Given On Drawings
(1)Drawings shall give complete information on dimensions, sectional shapes
and relative positions of respective members. They shall also show, in
terms of dimensions, all floor levels, column centers, and joints and
connections of members. Drawings shall be prepared to scales large
enough to give the foregoing information with clarity.
(2)Where necessary, drawings shall show the qualities of steel materials to be
used.
(3)Where bolts or high-strength bolts are to be used, bolt qualities shall be
distinctly shown on the drawings as necessary.
(4)Cambers of trusses and beams shall be shown on the drawing as
necessary.
(5)Where parts are designed for metal-to-metal contact as in columns bearing
on base plates, in column splices or in stiffeners bearing on beam flanges, the extent of milling or machining required for ends of such parts shall be indicated on drawings as necessary.
CHAPTER 3 CALCULATION OF I.OADS AND STRESSES 3.1 General Loads
Loads to be used in structural calculation shall, as a rule, be those prescribed in the Enforcement Order of the Building Standard Law.
3.2 Impact
For structures carrying live loads which induce impact, the design loads shall be increased in accordance with the assessed effects of such impact. Where the effects of impact are not based on measurement, the design loads may be increased in accordance with the following:
(1)For structural supports of elevators :
100% of the elevator Weight
(2)For structural supports of overhead traveling cranes :
Where the speed is less than 60 m/minute
10% of the wheel load
Where the speed is 60 m/minute or over
20%of the wheel load
If jointless rail is used, "60 m/minute'' in the above requirement may be replaced by "90 m/minute.”
(3)For supports of motorized equipment:
Not less than 20% of the equipment weight
(4)For supports of equipment driven by reciprocating engines:
Not less than 50% of the equipment weight
(5)For hangers suspending floors or balconies:
30% of the live load thereon
3.3 Crane Runway Lateral Forces
(1)Braking Force in the Direction of Crane Travel
This shall be taken as 15% of each wheel load subject to braking force, as applied to the top of the crane rail.
(2)Horizontal Forces Normal to the Direction of Crane Travel
Crane supporting girders on both ends of a crane shall be considered as subjected simultaneously to 10% of the crane wheel loads acting normal to the direction of crane travel. For computation, the crane trolley and lifted load shall be assumed to be in the most unfavorable condition.
(3)Diagonal Tension
Where the load to be lifted is pulled by a crane in a diagonal direction, the stress induced in the structure by such operation shall be taken into
account.
(4)Earthquake Forces
Earthquake forces acting on cranes shall be assumed as applied at the top of the crane rail. Unless otherwise specified, the weight of lifted load may
be disregarded in computing the weight of a crane.
3.4 Repeated Variation of Stresses
For members subjected to repeated variation of stresses, the design stresses shall be increased to allow for the effects of material fatigue in accordance with Chap. 7.
3.5 Thermal Stresses
For structures subject to large variation of temperature, thermal effects shall be given due regard in structural design.
3.6 Combination of Stresses
Stresses in each structural component shall generally be combined in accordance with Table 3. 1, and further as specified below:
Symbols
G: Stress due to dead load as prescribed by the Enforcement Order of the Building Standard Law
P: Stress due to live load as prescribed by the aforesaid Order
S: Stress due to snow load as prescribed by the aforesaid Order
W : Stress due to wind load as prescribed by the aforesaid Order
K: Stress due to seismic load as prescribed by the aforesaid Order
(1)In combining stresses, the stress induced by cranes in structural supports
shall be regarded as stress due to live load.
(2)Where more than one crane simultaneously acts on structural supports,
the stresses due to cranes shall be combined for the most unfavorable case which is presumable in the course of actual crane operation.
(3)For design computation of column joints and column bases, stress
combinations in which storm or seismic load is involved shall also be
investigated for cases where live loads are disregarded.
CHAPTER 4 MATERIALS
4.1 Qualities
Unless otherwise provided, structural materials shall be of the qualities specified in the applicable standards listed in Table 4.1.
4.2 Shapes and Sizes
Unless otherwise provided, structural materials shall be of the shapes and sizes prescribed in Table 4.2.
4.3 Constants
Physical constants for structural materials shall, in general, be taken as the values given in Table 4.3.
CHAPTER 5 ALLOWABLE STRESSES
5.1 Structural Steel
Allowable stresses for structural steel under permanent loading shall be determined on the basis of the values of F given in Table 5.1.
2(1) Allowable T ensile Stress
On the net section as defined in 13.1
5.1F f t = (5.1)
where
f t : allowable bendin
g stress(N/mm 2)
(2) Allowable Shear Stress
3,5.1F F F f s s
s == (5.2)
where
f s : allowable shear stress(N/mm 2)
(3) Allowable Compressive Stress
(a) On the gross section :
When λ≤Λ
νλF f c ????????????? ??Λ-=24.01 (5.3)
When λ>Λ
2277.0??? ??Λ=λF
f c (5.4)
F E
6.02π=Λ (5.5)
where
f c : allowable compressive stress (N/mm 2)
λ : slenderness ratio of compression member ( see 11.1 )
E : modulus of elasticity (N/mm 2)
23223:??
? ??Λ+λν Λ : critical slenderness ratio
(b) On the web of rolled shapes or built-up I sections at the toe of the fillet :
Regardless of the requirement of (a) above, allowable compressive stress shall be as computed by Formula (5.6) below.
3.1F f c =' (5.6)
where
f c ’ : allowable compressive stress (N/mm 2)
(4) Allowable Bending Stress
(a) For flexural members such as rolled beams, plate girders and other
built-up members having symmetrical axis in the loaded plane
(except for box-type members), and meeting the width-thickness ratio
requirement of Chap. 8 and subjected to bending about the strong
axis, allowable bending stress on extreme fibers in compression shall
be taken as the larger value computed by Formula (5.7) or (5.8);
however, such stress shall not exceed f t on extreme fibers in compression or in tension.
t b b f C i l f ????
??Λ-=22)/(4.01 (5.7) )(89000f b b A h l f = (5.8)
where
f b : allowable bendin
g stress(N/mm 2)
l b : unbraced length of compression flange(mm)
i : radius of gyration, taken about an axis in the plane of web, of a
tee section comprising the compression flange plus one-sixth of the depth of beam(mm)
2
12123.005.175.1???? ??+???? ??-=M M M M C , but not more than 2.3 M 2 and M 1 are the smaller bending moment and the larger
bending moment, respectively , about the strong axis at the
ends of a member subject to buckling. (M 2 / M 1)takes a positive
value in the case of single curvature and a negative value in
the case of double curvature. Where moment on the center of
the portion subject to buckling is larger than M 1 , C is taken as
unity .
h : depth of beam(mm)
A f : cross-sectional area of compression flange(mm 2)
Λ : (see Formula 5.5)
(b) For tubular and box-type steel members, for members having axes of
symmetry in the loaded plane, subjected to bending about the weak
axis and meeting the width-thickness ratio giving in Chap. 8,and for
gusset plates loaded within their plane, allowable bending stresses on
extreme fibers in tension and compression shall be taken as ft.
(c) Allowable bending stress on extreme fibers in compression for
channels and members not having axes of symmetry in the loaded
plane and meeting the width-thickness requirement of Chap. 8 shall
be as obtained from Formula(5.8), but not greater than f t .
(d) Allowable bending stress in bearing plates and similar elements
subject to bending outside their plane shall be as obtained from Formula (5.9).
3.11F f b = (5.9)
where
f b1 : allowable bendin
g stress(N/mm 2)
(e) Allowable bending stress in pins subjected to bending shall be taken as the value computed by Formula(5.10).
1.12F f b = (5.10)
where
f b2 : allowable bendin
g stress(N/mm 2)
(5) Allowable Bearing Stress
(a) For contact area of pins and bearing stiffeners and for other milled
surfaces, the allowable bearing stress shall be obtained from Formula (5.11).
1.11F f p = (5.11)
When parts in contact area different in quality. F shall be taken as the
smaller value, and bearing stress op shall be obtained by Formula (5. 12).
P p A P
=σ (5.12)
where
f p1 : allowable bearin
g stress (N/mm 2)
P : compression (N)
A p : generally, sectional area of parts in contact (mm 2); for
pin/connections, A p =td where t = plate thickness of pin (mm)
and d = diameter of pin (mm)
σp : bearing stress (N/mm 2) '
(b) For rockers or rollers, allowable bearing stress shall be computed by
Formula (5.13).
F f p 9.12= (5.13)
When parts in contact are different in quality , F shall be taken as the
smaller value, and bearing stress op shall be obtained by Formula (5.14).
br PE P 42.0=σ (5.14)
where
f p2 : allowable bearin
g stress (N/mm 2)
P : compression(N)
E : modulus of elasticity (N/mm 2)
b : width of rocker or roller (mm)
r : radius of curvature of rocker or roller (mm)
σp : bearing stress (N/mm 2)
5.2 Rivets, Bolts and High-Strength Bolts
(1) Allowable tensile and shear stresses of rivets, bolts and high-strength bolts
under permanent loading shall be as given in Table 5.2. Allowable stresses shall be computed for the body area of fasteners.
Table 5.2 Allowable Stresses on Rivets, Bolts and High-Strength Bolts (N/mm 2)
5.3, and they shall be so arranged as to transmit shear by friction.
(2) Allowable bearing stress in plates connected by rivets Or bolts shall be as
computed by Formula (5.15) for the projected area obtained by multiplying rivet or bolt diameter by thickness of connected plates. Where
countersunk rivets or bolts are used, the thickness of connected plates shall be taken as the actual thickness of such plates less one-half the depth of rivet or bolt head sunk in the plates.
F f l 25.1
(5.15)
where
f l : allowable bearin
g stress (N/mm 2)
High-strength bolted connections need not be restricted by the allowable bearing stress.
5.3 Welds
Allowable stress under permanent loading on effective throat of arc weld may be taken as the values prescribed below provided that welding electrode used is appropriate for the type of steel to be welded and that welding is performed under satisfactory control. Welds in SS 490 and SS 540 steels, however, shall not be allowed to carry any stress.
(1) Allowable stresses for fillet weld, plug weld, slot weld, flare weld,
partial-penetration weld and those on effective area of welds described in Chap. 16 and for welds of branch connection of tubular steel members shall be the same as allowable shear stress for base metal.
(2) Allowable stress for complete penetration butt welds shall be the same as
that for base metal to be welded.
(3) Where steels of different qualities are welded, allowable stress for welds
shall be taken as the smaller value of the allowable stresses for base
metals.
5.4 Cast Steel and Forged Steel
Allowable stresses for cast steel and forged steel may, where applicable, be considered the same as those for corresponding rolled steels.
5.5 Allowable Stresses for Steel Members Subject to Combined Stresses
Allowable stresses for members subject to both normal and shear stress
shall satisfy Formula (5.16).
22223xy y x y x t f τσσσσ+-+≥ (5.16)
where
σx and σy : two normal stresses perpendicular to each other (N/mm 2)
xy : shear stress in the plane of σx and σy (N/mm 2)
5.6 Allowable Stresses under Temporary Loading
In checking members for temporary loading by the combination of stresses described in Chap. 3, allowable stresses specified in this chapter may be increased by 50%.
CHAPTER 6 COMBINED STRESS
6.1 Axial Compression and Bending Moment
Members subjected to both axial compression and bending moment shall be proportioned to satisfy Formulas (6.1) and (6.2) given below, in which σc , c σb and t σb shall take absolute values.
1≤+b b c c
c
f f σσ (6.1) and
1≤-t c
b t f σσ (6.2)
where
f c : allowable compressive stress, as appropriate, prescribed in 5.1, (3)
(N/mm 2)
f b : allowable bendin
g stress, as appropriate, prescribed in 5.1. (4)
(N/mm 2)
f t : allowable tensile stress prescribed in 5.1, (1), (N/mm 2)
σc . : N /A = mean compressive stress (N/mm 2)
c σb : M/Z c = bending stress on extreme fiber in compression (N/mm 2)
t σb : M/Z t = bending stress on extreme fiber in tension (N/mm 2)
N : compression (N)
M : bending moment (N ?mm)
A : gross sectional area (mm 2)
Z c : section modulus of compression side of a cross-section (mm 3)
Z t : section modulus of tension side of a cross-section (mm 3)
6.2 Tension and Bending Moment
Members subjected to both tension and bending moment shall be
proportioned to satisfy Formulas (6.3) and (6.4) given below, in which σt , c σb and , t σb shall take absolute Values.
1≤+t
b
t t f σσ (6.3) and
1≤-b t
b c f σσ (6.4)
where
σt = T/A N : mean tensile stress (N/mm 2)
T : tension (N)
A N : net section as prescribed in 13.1 (mm 2)
Other symbols have the same meanings as in 6.1 above.
6.3 Shear and Tension
(1) Rivets and bolts subject to combined shear and tension shall be so
proportioned that the tensile stress produced by forces applied to the
connected parts shall not exceed the value of f ts obtained from Formula
(6.5).
τ6.14.1-=to ts f f
(6.3)
and to ts f f ≤ (6.4)
where
f ts : allowable tensile stress for rivets or bolts subject to combined tension
and shear (N/mm 2)
f to : allowable tensile stress for rivets or bolts described in 5.2, (1) (N/mm 2) τ : shear stress which is produced in rivets or bolts and which shall not
exceed the allowable shear stress given in 5.2, (1) (N/mm 2)
(2) For high-strength bolts subject to combined shear and tension, shear stress
shall not exceed the value of f st as determined from Formula (6.6).
???? ??-=O t so st T A f f σ1
(6.6)
where
f st : allowable shear stress for high-strength bolts subject to combined
tension and shear (Nt/mm 2)
f so : allowable shear stress for high-strength bolts as prescribed in 5.2,(1)
(N/mm 2)
σ t : tensile stress which is proportional to the force acting upon bolts and
which shall not exceed the allowable tensile stress for high-strength
bolts as specified in 5.2, (1) (N/mm 2)
T o : design bolt tension (N)
A : nominal body area of high-strength bo1t (mm 2)
CHAPTER 7 MEMBERS AND CONNECTIONS SUBJECT
TO REPEATED VARIATION OF STRESS
7.1 Fatigue Factor and Allowable Stresses
(1) Where the number of repeated stress variations is below 1×104 in the life
of a structure, the fatigue effects need not be considered.
(2) Where the number of stress variations is 1×104 or over, fatigue factor (γ)
and allowable stresses (f ) shall be determined in accordance with Table
7.1 and Formula (7.1). The upper and lower limits in the range of stress
variation, however, shall not exceed the stress permitted in Chaps. 5 and 6 for the type of steel and connection material used.
f ≤?1σγ (7.1)
Table 7.1 Fatigue Factor (γ) and Allowable Stresses (f )
(1) At the upper and lower limits of stress range, the stress having the larger
absolute value shall be expressed as σ1 (N/mm 2) and that having the smaller
absolute value as σ2 (N/mm 2). Value of σ2/σ1 shall, therefore, be positive if σ2
and σ1 have the same sign and negative if they have opposite signs.
(2) Increase of allowable stress as provided in 5.6 shall not be permitted for f .
7.2 Bolts
Bolts shall not be used in connections subject to repeated stress variation.
7.3 High-Strength Bolts
Effect of repeated stress variation need not be considered for high-strength bolts subject to shear only.
7.4 Notches
Parts with sharp notches shall be so designed that working stress in them will not exceed 75% of the value of f /γgiven in this chapter.
CHAPTER 8 WIDTH-TO-THICKNESS RATIO OF
PLATE ELEMENTS
8.1 Width-to-Thickness Ratio of Plate Elements
Such unstiffened plate elements of framework as are -subject to axial compression or compression due to in-plane bending shall meet the ratio of width to thickness given below.
(1) Projecting Plate Elements Free at One Edge and Fixed at the Other
(a) Single-angle struts and multiple-angle struts with separators:
F t b 200≤ (8.1)
where symbols have the same meanings as given in (b) below.
(b) Compression flanges of beams and columns; angles or plates
projecting from girders, columns or other compression members; stems of tees; stiffeners as specified in 9.3.
F t b 240≤ (8.2)
where
b : width of unstiffened plate element which, in built-up members,
shall be taken from the free edge to the first row of fasteners or
welds; the width of legs of angles, flanges of channels or zees,
stems of tees and cold-formed light-gauge sections shall be taken
as the full nominal dimension; the width of flanges of I- shape
members and tees shall be taken as one-half the full nominal
width. (mm)
t : thickness of plate element. For a uniformly sloping flange, its
average thickness may be regarded as the thickness. (mm)
(2) Element Stiffened along Both Edges
(a) Web plates of columns or other compression members. flanges of
square and rectangular sections of uniform thickness; cover plates; and all other stiffened compression flanges:
F t d 735≤ (8.3)
Moment of inertia of the stiffeners on the stiffened compression
flanges shall not be smaller than I s (mm 4) obtained from Formula
(8.4).
1509.124-??
? ??=t d t I s (8.4)
where
d : th
e width o
f elements stiffened alon
g two edges taken as: the
distance between nearest lines of rivets, bolts, high-strength
bolts or welds in the case of built-up elements; the distance
between the fillets in the case of rolled sections; or the length of
flat plate in the case of cold-formed light-gauge sections (mm)
t : the thickness of plate elements (mm)
(b) Web plates of beams
F t d 100,1= (8.5)
where symbols have the same meanings as in (a) above.
(3) Where the actual width-to-thickness ratio exceeds the values prescribed
in (1) and (2), stress analysis may be made by disregarding the portion in excess of the prescribed value.
(4) The design of the stiffened web plates may be based on the provisions of
Appendix ''Buckling Calculations for Web Plates and Design of Stiffeners. "
8.2 Diameter-to-Thickness Ratio of Tubular Steel
Diameter-to-thickness ratio of tubular steel elements shall satisfy the value obtained from Formula (8.6).
F t D 500,23= (8.6)
where
D : nominal outside diameter of tube (mm)
t : wall thickness of tube (mm)