3.2 Load and Seismic Action
3.2.1 The load acting on the structure for mobile communication engineering tower and mast is generally divided into two categories：
1 Permanent load：self-weight of structure and fixed equipment，initial stress of guy，soil weight，soil stress，etc.
2 Variable load：wind load，ice load，seismic action，snow load，live load（including the load for platform installation and maintenance），temperature variation，foundation deformation，etc.
3.2.2 The wind load shall be calculated in accordance with the following provisions：
1 The wind load acting on the structure for steel tower and mast shall be calculated in accordance with the provisions set out in GB 50009-2001 Load Code for the Design of Building Structures.The recurrence interval of reference wind pressure is taken as 50 years，which shall not be less than 0.35kN/m2.
2 The wind areas of tower and mast members，platforms，antennas and other attachments shall be taken into account for the calculation of wind load.The wind area of mobile communication antenna shall be calculated based on actual angle.If the specific direction of antenna at the same height is undetermined，the antenna may be assumed as evenly and symmetrically distributed.
3 The shape coefficient μs of mobile communication antenna is as shown in Table 3.2.2-1.
Table 3.2.2-1 Shape coefficient μs of mobile communication antenna
Notes：①The height-width ratio is the ratio between height and diameter of antenna on the vertical wind direction；
②The interpolation method is adopted for intermediate value.
4 The shape coefficient μs of steel pole is as shown in Table 3.2.2-2.
Table 3.2.2-2 Member shape coefficient μs of steel pole
3.2.3 Snow load：The snow load of platform shall be calculated according to GB 50009-2001 Load Code for the Design of Building Structures.And the recurrence interval of reference snow pressure shall be 50 years.
3.2.4 The ice load shall be calculated based on the following principles：
1 The influences of additional gravity and wind area acting on the surfaces such as structure member，guy and antenna after icing shall be taken into account for the structure design for mobile communication engineering steel tower and mast.
2 The basic ice thickness shall be in accordance with local observational data collected at a place 10m high，and the statistical-based once-in-50-year maximum ice thickness shall be the standard.Where there is no observational data，the maximum ice thickness shall be determined through field survey，or based on following empirical values upon analysis：
1）Heavily iced zones：Daliang Mountains，Northeast Sichuan，Yunnan，Qinling Mountains，Hunan，Guizhou，Fujian，Jiangxi and other regions；the reference ice thickness may take 10mm-30mm；
2）Lightly iced zones：Northeastern China（part），North China（part），Huaihe River Basin and other regions；the reference ice thickness may take 5mm-10mm.
Note：The ice is also affected by terrain and local climate，so there may be heavy ice or no ice in some places of the lightly iced zone.Similarly，there may be light ice or extra heavy ice in some places of the heavily iced zone.
3 The ice load acting on the pipeline and structural member shall be calculated in accordance with the following provisions：
1）The ice load acting on the circular-section member and guy per unit length may be calculated according to the following formula：
Where，qI——ice load per unit length（kN/m）；
b——basic ice thickness（mm）which is adopted in accordance with the provisions of this article；
d——diameters of circular section member and guy（mm）；
α1——adjustment coefficient of ice thickness related to member diameter，which is adopted based on Table 3.2.4-1；
α2——height variation coefficient of ice thickness，which is adopted based on Table 3.2.4-2；
γ——ice weight，generally take 9kN/m3.
Table 3.2.4-1 Adjustment coefficient α1 of ice thickness related to member diameter
Table 3.2.4-2 Height variation coefficient α2 of ice thickness
2）The ice load q（kN/m2）acting on non-circular member per unit surface area may be calculated according to the following formula：
Where，qa——ice load per unit area（kN/m2）.
3.2.5 The seismic action may be determined in accordance with the following provisions：
1 The seismic fortification intensity of the structure for steel tower and mast shall be based on local basic intensity，but the intensity of buildings may be adopted for the structure for steel tower and mast constructed on the buildings；
2 The seismic action of the structure for steel tower and mast shall be calculated with modesuperposition response spectrum method，and the calculation method shall be executed in accordance with GB 50011-2001 Code for Seismic Design of Buildings；
3 No seismic checking calculation is required for cross section providing the seismic fortification intensity of the structure for steel tower and mast is 8 degrees or below.In this case，only the aseismic structure requirements need to be met；
4 The adverse combination of vertical and horizontal seismic actions shall be simultaneously taken into account providing the seismic fortification intensity of the structure for steel tower and mast is 9 degrees.
3.2.6 The live load acting on the platform shall be determined based on actual technological conditions.The vertical live load generally is 2kN/m2.The horizontal load action of antenna shall also be considered.The horizontal load acting on the top handrail shall not be less than 1.0kN/m.