钢结构规范GB50017（英文版）

GB50017 ENGLISH VERSION 1 General 1.0.1 This Code intends to implement the technical-economic policy of the State in the design of steel structures, by using advanced technology and ensuring economy, reasonableness, safety, suitability for use and good quality of the structures. 1.0.2 This Code applies to the design of steel structures of industrial and civil buildings and allied engineering structures, among which members made of cold-formed steel shapes and their connections shall comply with the current national standard “Technical code of cold-formed thin wall steel structures” GB50018. 1.0.3 The design principles of this Code are based on the “Unified standard for reliability design of building structures” GB50068. Loadings and their combination values assumed in designing with this code shall comply with the current national standard “Load code for the design of building structures” GB50009. Buildings and engineering structures in seismic region shall furthermore comply with the current national standards “Code for seismic design of buildings” GB50011, “Seismic ground motion parameter zonation map of China” GB18306 and “Design code for antiseismic of special structures” GB50191. 1.0.4 In designing steel structures, designers shall consider the real situation of the project, select reasonably the material, the structural scheme and detailing measures. The requirements of strength, stability and stiffness of the structure during transportation, erection and service, as well as requirements of fire protection and corrosion resistance shall be fulfilled. Typical and standardized structures and structural members should be adopted in preference, the amount of fabrication and erection work should be reduced. 1.0.5 In the design documents of steel structures shall be indicated the design service life of the building structures, the steel grade, the category (or grade) of connection materials and mechanical properties, chemical composition and additional items of guarantee of the steel. Moreover, the weld type and the class of weld quality, the location of end planning for close fitting and its quality requirement shall also be indicated. 1.0.6 The design of steel structures with special requirements and those under special circumstances shall furthermore comply with the relevant current national codes. 2 Glossary and Symbols 2.1 Glossary 2.1.1 strength The capacity of resisting failure in member cross-section material or connection. Strength checking aims at preventing failure of structural members or connections from exceeding the material strength. 2.1.2 load-carrying capacity The largest internal force that a structure or member can bear without failure from strength, stability or fatigue, etc., or the largest internal force at the onset of failure mechanism in plastically analyzed structures; or the internal force generating a deformation that hinders further loading. 2.1.3 brittle fracture In general, the suddenly occurred brittle fracture of a steel structure subject to tensile stress without warning by plastic deformation. 2.1.4 characteristic value of strength The yield point (yield strength) or tensile strength of steel as specified by National Standard. 2.1.5 design value of strength The value obtained from division of the characteristic value of strength of steel or connection by corresponding partial factor of resistance. 2.1.6 first order elastic analysis The elastic analysis of structure internal forces and deformation, based on the equilibrium condition of undeformed structure, taking no account of the effect of the second order deformation on internal forces. 2.1.7 second order elastic analysis The elastic analysis of structure internal forces and deformation, based on the equilibrium condition of deformed structure, taking account of the effect of the second order deformation on internal forces. 2.1.8 buckling An abrupt large deformation, not conforming to the original configuration of members or plates subject to axial force, bending moment or shear force, and thereby causing loss of stability. 2.1.9 post-buckling strength of web plate The capacity of web plates to bear further loading after buckling. 2.1.10 normalized web slenderness Parameter, equal to the square root of the quotient of steel yield strength in flexion, shear or compression by corresponding elastic buckling stress of web plates in flexion, shear or local compression. 2.1.11 overall stability Assessment of the possibility of buckling or loss of stability of structures or structural numbers as a whole under the action of external loading. 2.1.12 effective width That part of plate width assumed effective in checking the section strength and the stability. 2.1.13 effective width factor Ratio of the effective width to the actual width of a plate element. 2.1.14 effective length The equivalent length of a member obtained by multiplying its geometrical length within adjacent effective restraining points by a coefficient taking account of end deformation condition and loading condition. The length of welds assumed in calculation of the strength of welded connections. 2.1.15 slenderness ratio The ratio of member effective length to the radius of gyration of its cross-section. 2.1.16 equivalent slenderness ratio The slenderness ratio transforming a lattice or battened column into solid-web one according to the principle of equal critical force for checking the overall stability of axially compressed members. The slenderness ratio transforming a flexural-torsional buckling and torsional buckling into flexural buckling. 2.1.17 nodal bracing force Force to be applied at the location of lateral support installed for reducing the unsupported length of a compression member (or compression flange of a member).This force acts in the direction of member buckling at the shear center of the member section. 2.1.18 unbraced frame Frames resisting lateral load by bending resistance of members and their connections. 2.1.19 frame braced with strong bracing system A frame braced with bracing system of large stiffness against lateral displacement (bracing truss, shear wall, elevator well, etc.), adequate to be regarded as frame without sidesway 2.1.20 frame braced with weak bracing system A frame braced with bracing system of weak stiffness against lateral displacement, inadequate to be regarded as frame without sidesway. 2.1.21 leaning column A column hinged at both ends and not capable of resisting lateral load in a framed structure. 2.1.22 panel zone of column web The zone of column web within the beam depth at a rigid joint of frame. 2.1.23 spherical steel bearing A hinged or movable support transmitting force through a spheric surface allowing the structure to rotate in any direction at the support. 2.1.24 composite rubber and steel support A support transmitting end reaction through a composite product of rubber and thin steel plates satisfying the displacement requirement at the support. 2.1.25 chord member Members continuous through panel points in tubular structures, similar to chord members in regular trusses. 2.1.26 bracing member Members cut short and connected to the chord members at panel points in tubular structures, similar to web members in regular trusses. 2.1.27 gap joint Joints of tubular structures where the toes of two bracing members are distant from each other by a gap. 2.1.28 overlap joint Joints of tubular structures where the two bracing members are overlaping. 2.1.29 uniplanar joint Joints where chord member is connected to bracing members in a same plane. 2.1.30 multiplannar joint Tubular joints where chord member is connected to bracing members in different planes. 2.1.31 built-up member Members fabricated by joining more than one plate members (or rolled shapes), such as built-up beams or columns of I- or box-section. 2.1.32 composite steel and concrete beam A beam composed of steel beam and concrete flange plate, acting as an integrated member by means of shear connectors. 2.2 Symbols 2.2.1 Actions and effects of actions F— concentrated load; H— horizontal force; M— bending moment; N— axial force; P— pretension of high-strength bolts; Q— gravity load; V— shear force; R— reaction of support. 2.2.2 Calculation indices E— modulus of elasticity of steel; Ec— modulus of elasticity of concrete; G — shear modulus of steel; — design value of tensile capacity of an anchor bolt; — design values of tensile, shear and bearing capacities of a bolt; — design values of tensile, shear and bearing capacities of a rivet; — design value of shear capacity of a connector in composite structures; — design values of capacities of bracing members in tension and in compression at a joint of tubular structures; Sb — lateral sway stiffness of bracing structures (horizontal force causing a leaning angle of unity) f — design value of tensile, compressive and bending strength of steel; fv — design value of shear strength of steel; fce— design value of end bearing strength of steel; fst — design value of tensile strength of reinforcing bars; fy — yield strength (or yield point) of steel; — design value of tensile strength of an anchor bolts; — design values of tensile, shear and bearing strengths of bolts; — design values of tensile, shear and bearing strengths of rivets; — design values of tensile, shear and compressive strengths of butt welds; — design value of tensile, shear and compressive strength of fillet welds; fc — design value of axial compressive strength of concrete; u — lateral inter-story deflection; [vQ] — allowable deflection taking into account solely the characteristic value of variable loads; [vT] — allowable deflection taking into account the characteristic value of permanent and variable loads simultaneously; — normal stress; c— local compressive stress; f— stress normal to the direction of the length of a fillet weld, calculated on its effective section; — stress range or reduced stress range for fatigue calculation; e— equivalent stress rage of variable amplitude fatigue; [] — allowable stress range of fatigue; — critical stresses of plate under individual action of bending stress, local compressive stress and shear stress receptively; — shear stress; f — shear stress of a fillet weld along the direction of its length calculated on its effective section; — density of mass; 2.2.3 Geometric parameters A — gross sectional area; An — net sectional area; H — column height; H1, H2, H3 — heights of the upper, middle (or lower) and lower portions of stepped columns; I — moment of inertia of gross section; It​— Torsional moment of inertia (St. Venent torsion constant) of gross section; I​— sectorial moment of inertia (warping constant) of gross section; In​— moment of inertia of net section; S— static moment of gross section; W—gross section modulus; Wn— net section modulus; Wp—plastic gross section modulus; Wpn—plastic net section modulus; a, g— spacing; gap; b— plate width or free outstand of plate; b0— flange unsupported width between webs of a box-section; width of the top surface of the concrete haunch; bs— outstand of stiffeners; be— effective width of plate; d— diameter; de— effective diameter; d0— hole diameter; e— eccentricity; h—full height of a section(section depth); story height; hc1— thickness of concrete slab; hc2— thickness of concrete haunch; he— effective thickness of fillet welds; hf— leg size of fillet welds; hw— web height (web depth); h0— effective web height; i— radius of gyration of a section; l— length or span length; l1— spacing of lateral supports in the compression flange of a beam; connecting length of bolted (riveted) joints in the direction of force; l0— effective length for flexural buckling; l— effective length for torsional buckling; lw— effective length of welds; lz— assumed distribution length of a concentrated load on the edge of effective web depth; s— shortest distance from the root of the groove to weld surface in an incomplete penetration butt weld; t— plate thickness; wall thickness of (tubular)chord members; ts— stiffener thickness; tw— web thickness; — angle; —angle; angle of stress dispersal; b— normalized depth-thickness ratio in calculating girder web subject to bending moment; s— normalized depth-thickness ratio in calculating girder web subject to shear force; c— normalized depth-thickness ratio in calculating girder web subject to local compressive force; — slenderness ratio; 0, yz, z, uz— equivalent slenderness ratio; 2.2.4 Coefficients of calculation and others C— dimensional parameter for fatigue calculation; K1, K2 — ratios of linear stiffness of members; ks— shear buckling factor of members; Ov— overlap ratio of bracing members in tubular joints; n— number of bolts, rivets or connectors; number of stress cycles; n1— number of bolts (or rivets) on a calculated section; nf— number of frictional force transferring surfaces in a high-strength bolted connection; nv— number of shear planes of bolts or rivets; — coefficient of linear expansion; coefficient for calculating transverse force generated by crane sway; E—modular ratio of steel to concrete; e—reduction factor of girder section modulus taking account of web effective depth; f —equivalent factor of underloading effect for fatigue calculation; 0 —stress gradient factor of column web; y —factor of steel strength effect; 1 —factor for planed and closely fitted web edge; 2i —amplification coefficient for bending moment of the i-th story members due to lateral translation of a frame, taking account of second order effect; —ratio of outside diameter of bracing member to that of chord member; parameter for fatigue calculation; b—factor of equivalent critical moment for overall stability of beams; f—amplification coefficient for design value of the transverse fillet weld strength; m, t—factors of equivalent moment for beam-column stability; 1 —amplification coefficient of design value of strength for reduced stress; —strength-yielding ratio of stud steel; 0—importance factor of structures; x, y —plasticity adaptation factor of cross-sections about principal axes x, y; —modification factor; b—factor of unsymmetry of a beam section; 1, 2—parameters for calculation the effective length of stepped columns; —slip coefficient for friction surfaces in a high-strength bolted connection; effective length factor of columns; 1, 2 , 3 —effective length factors for the upper, middle (or lower) and lower portions of stepped columns; —parameter for checking overall stability of beams; —effective width factor of web compressive zone; —stability factor of axially loaded compression members; — overall stability factors of beams; —amplification coefficient of a concentrated load; n, a, d—parameters for capacity calculation of directly welded tubular joints. 3 Basic design requirements 3.1 Design principles 3.1.1 For all calculations except fatigue calculation, the limit state design method based on probabilistic theory is adopted, using design expressions with partial safety factors. 3.1.2 Load-carrying structures shall be designed according to the following ultimate limit states and serviceability limit states: 1. The ultimate limit states include: strength failure of members and connections, fatigue failure and excessive deformation no longer suitable for carrying load, loss of stability of structures and members, formation of mechanism and overturning of the structure. 2. The serviceability limit states include: deformations affecting normal use and appearance of a structure, structural and non-structural components, vibration affecting normal use, local damage (including concrete cracks) affecting normal use or durability. 3.1.3 In the design of steel structures, different classes of safety shall be adopted according to the consequence of damage which may be caused by a structural failure. Steel structures of industrial and civil buildings, in general, shall be taken as safety class 2, whereas for a special building structure the safety class shall be dealt with individually in conformity to its actual condition. 3.1.4 In designing a steel structure according to the ultimate limit state, the basic combination of load effects shall be considered and, if necessary, the accidental combination of load effects shall also be considered. In designing a steel structure according to the serviceability limit state, the normal combination of load effects shall be considered, whereas for composite steel and concrete beams, the quasi-permanent combination shall also be considered. 3.1.5 In checking the strength and stability of structures or structural members and also the strength of connections, the design value of loads shall be used (i.e. the characteristic value of loads multiplied by partial safety factor for loads), whereas in checking fatigue, the characteristic value of loads shall be used. 3.1.6 For checking the strength and stability of structures subjected to direct dynamic loading, the design value of the dynamic load shall be multiplied by an impact factor, whereas the characteristic value of the dynamic load without impact factor shall be used in checking fatigue and deformation. In the calculation of fatigue and deflection of crane girders or crane trusses together with their surge girders, the crane load shall be determined by one of the cranes of largest loading effect in the bay. 3.2 Load and calculation of load effects 3.2.1 In the design of steel structures, the characteristic value of loads, the partial safety factor for loads, the load combination coefficient, the impact factor of dynamic loads shall comply with the requirements of the current national standard “Load code for the design of building structures” GB50009. The importance factor of structures 0 shall comply with the current national standard “Unified standard for reliability design of building structures” GB50068. Among others, 0 for structural members with design service life of 25 years shall not be less than 0.95. Note: For members or structures supporting light roofing (purlins, roof trusses, frames, etc), the characteristic value of uniform roof live load shall be taken as 0.3 kN/m2 when only one variable load is acting and that the horizontal projection of the loaded area exceeds 60 m2. 3.2.2 In checking the strength and stability of crane girders (or trusses) for heavy duty cranes and the associated surge girders, and also in checking the strength of their connections (mutual connections between crane girders or trusses, surge girders and columns), a horizontal transverse force generated by sway of cranes shall be taken into account. The characteristic value of this horizontal force acting at each wheel of the crane should be the following Hk=αPk,max (3.2.2) where Pk,max—characteristic value of maximum wheel load from the crane; α— coefficient, α=0.1 for regular cranes with flexible hook, α=0.15 for grab cranes and magnetic disc cranes and α=0.2 for cranes with rigid hook. Note: The current national standard “Code for design of cranes” GB/T3811 classifies cranes into A1 through A8 categories according to their service grade. Generally speaking, light duty regime in this Code corresponds to categories A1~A3; medium duty regime corresponds to categories A4 and A5; heavy duty regime corresponds to categories A6~A8, while A8 belongs to extra-heavy duty. 3.2.3 In checking roof trusses with suspended cranes and electric hoisting tackles, the number of hoisting equipment on each operation route in one bay should not be more than two for girder crane and not more than one for electric tackle. 3.2.4 In calculating working platform structures of metallurgical workshop or of similar workshops, the loading caused by repairing materials may be multiplied by a reduction factor: 0.85 for main girders 0.75 for columns (including foundation) 3.2.5 The structure calculation model and basic assumptions shall comply with the actual behavior of members and connections as far as possible. 3.2.6 The int