5.2 Member Design
5.2.1 For the design of structural member，the bending strength and axial compression strength shall be calculated，and the overall and local stabilities shall be checked based on stress state respectively.The specific calculation shall be done in accordance with relevant provisions set out in GB 50017-2003 Code for Design of Steel Structures，but the plastic development coefficients γx、γy shalltake 1.
5.2.2 The slenderness ratio A of member shall not be more than following specified value.
Major member：λ≤150；
Cross member and diagonal member：λ≤180.If the internal force is less than 50% of members bearing capacity，λ≤200；
Secondary member and horizontal cross member：λ≤200；
Tension member：λ≤350.
The slenderness ratio of member imposing prestress is unlimited.
The slenderness ratio of member between two guy nodes adjacent to mast shall comply with the following provisions：
Latticed mast（equivalent slenderness ratio）：λ0≤100；
Solid-web mast：λ0≤150.
5.2.3 The slenderness ratio λ of structural member for steel tower and mast shall be calculated according to the following provisions：
1 The slenderness ratio λ of major member is based on Table 5.2.3-1.
2 The slenderness ratio λ of diagonal member is based on Table 5.2.3-2.
3 The slenderness ratios λ of cross member and horizontal cross member are based on Table 5.2.3-3.
Table 5.2.3-1 Slenderness ratio λ of major members for tower and mast
Table 5.2.3-2 Slenderness ratio λ of diagonal member for tower and mast
Table 5.2.3-2（continued）
Table 5.2.3-3 Slenderness ratio λ of cross member and horizontal cross member for tower and mast
5.2.4 The slenderness ratio of latticed axial compression member for imaginary axis shall be based on equivalent slenderness ratio λ0 and λ0 is calculated based on Table 5.2.4.
Table 5.2.4 Equivalent slenderness ratio λ0 of latticed member
Notes：①The slenderness ratio of single limb of battened composite member shall be no more than 40；
②The slenderness ratio λ1 of single limb of battened axial compression member shall not be more than 0.7 times to bigger value of slenderness ratio λmax on two directions；The slenderness ratio λ1 of single limb of battened axial compression member shall not be more than 0.5 times than λmax（when λmax＜50，take λmax=50）；
③The angle of inclination between diagonal lacing bar and member axis shall remain at 40°-70°.
5.2.5 The local stability influences of tube wall shall be considered when the steel pole is bent and stressed.
1 The local stability influences of tube wall for circular steel pole shall be calculated according to the following formula：
1）For Q235 steel
2）For Q345 steel
Where，N——design value of axis stress acting on the section calculated（N）；
M——design value of bending moment acting on the section calculated（N·mm）；
W——section bending modulus（mm3）；
μd——correction coefficient of design strength；
D——outer diameter of circular steel pole（mm）；
t——wall thickness of circular steel pole（mm）.
2 The local stability influences of tube wall for polygonal steel pole shall be checked according to formula（5.2.5-1），in which is calculated according to the following formula：
1）Octagon
2）Dodecagon
3）Hexadecagon
Where，b——one-sided width of polygonal steel pole（mm）；
t——wall thickness of polygonal steel pole（mm）；
fy——yield strength of steels（MPa）.