【正文】 cted according to application requirements, and the classification of crack control grades shall ply with the following provisions:Grade I – members with strict requirements that no crack is allowed, and no tensile stress shall produce in the concrete at the tensile edge of the member when it is calculated according to shortterm effect bination of loads。II. Structural members for which no cracking is allowed. The safety grade of all members must not be lower than Grade III in all phases.Notes: ① The safety grade of trusses and brackets shall be increased by one grade。 the corresponding load characteristic values shall be used for the proof calculation on fatigue, deformation, anticracking and cracking width。③ When the strength standard values of carbon steel wires, indented steel wires and strand steel wires do not ply with the provisions in Table , proof calculation shall be performed for their strength design values。 Grade B cold drawn low carbon wires can be inspected by batches, and should be used for welded skeletons, welded meshes, erecting stand bars, stirrups and structural reinforcement。③ The tensile strength design value of Grade LL550 cold drawn reinforcement with ribs supplied in coils shall reduce by 20 N/mm2 after mechanical straightening, and the pression strength design value shall not be greater than the corresponding tensile strength design value。 for Grade I reinforcement with a diameter greater than 12mm, the strength after cold drawing must not be used if it is cold drawn。w0—Basic wind pressure, kN/m2. The basic wind pressure shall be determined on the basis of maximum wind speed averaged in 10 min. v0 (m/s) at 10m above ground once in 30 years on a fairly empty and flat ground in the local area, at a value of w0=v02/1600.The basic wind pressure shall not be less than kN/m2.For highrise buildings, the basic wind pressure shall be taken as the basic wind pressure value multiplied by a coefficient of 。ms—Wind load body shape coefficient。III. The even distribution of accumulated snow over the whole span for frames and columns. The standard value of wind load vertical to the surface of a building shall be calculated according to the following formula:wk=b zmzw0 ()Where wk—Standard value of wind load, kN/m2。S0—Basic snow pressure, kN/m2. The basic snow pressure shall be determined as the self weight of the maximum accumulated snow once in 30 years on empty and flat ground in the local area. In the design of load bearing members of building structures and roofing, the distribution of accumulated snow shall be taken into consideration according to the following provisions:I. The most unfavorable condition of uneven distribution of accumulated snow for roofing plates and purlins。II. It shall be taken as , canteen, theater, cinema, station, auditorium, exhibition hall or stadium. For the dynamic calculation in the design of architectural structures, it can be performed as for static calculation by multiplying the weight or equipment load with a dynamic coefficient when there is sufficient basis. The standard value of snow load on the horizontal projection plane of roofing shall be calculated according to the following formula:sk=m rs0 ()Where sk—Standard value of snow load, kN/m2。II. It is taken as for reinforced concrete canopies.Notes: ① For light members or members with large breadth, when the construction load might exceed the above load, proof calculation shall be performed according to actual conditions, or temporary supports and padding plates shall be provided.② In the calculation of the strength of cornices and canopies, one concentrated load shall be taken into account for every along the width of the plate。 for some special cases, it shall be determined according to the provisions in relevant design specifications for architectural structures. Under normal conditions, the load bination value coefficient is taken as when the wind load is included in the bination, and as when no wind load is included in the bination.For ordinary bent and frame structures, the load bination coefficient is taken as when two or more variable loads, including wind load, are included in the bination。It shall be taken as when its effect is favorable to the structure.II. Partial safety factor for variable load:It is taken as under normal conditions。R—Design value of resistance of structural members, and shall be determined according to the provisions in relevant design specifications for architectural structures。 the safety grade of structural members shall be determined according to the provisions in relevant design specifications for architectural structures。Section V Structure Design1. Basic Provisions Safety Grades for StructuresUnified Standard for Architectural Structure Design GBJ 68 – 84 Different safety grades shall be applied in the design of architectural structures according to the seriousness of possible consequences (endangering the lives of people, causing economic losses, producing social impact, etc.) that might be resulted from damage to structure. The classification of safety grades for architectural structures shall ply with the requirements in Table .Safety grades for architectural structures Table Safety gradeConsequence of damageType of buildingsIIIIIIVery seriousSeriousNot seriousImportant industrial and civilian buildingsOrdinary industrial and civilian buildingsSecondary buildingsNotes: ① The safety grade for special buildings shall be determined separately according to actual conditions。② When the design is performed according to antiseismic requirements, the safety grade of architectural structures shall ply with the provisions in “Specification for antiseismic design for buildings” Structure Load and CombinationsSpecification on Loading for Architectural Structures GBJ 9 –