The minimum thickness of a steel plate, which is directly exposed to weather and is not accessible for cleaning and repainting, should be___________________?

A. 10° to 30°
B. 30° to 40°
C. 40° to 70°
D. 90°

A. mean probable design life of structures
B. basic wind speed
C. both (A) and (B)
D. none of the above

A. lesser of 200 mm and 12 t
B. lesser of 200 mm and 161
C. lesser of 300 mm and 32 t
D. lesser of 3 00 mm and 24 t
where t is thickness of thinnest outside plate or angle

A. transfer load from top of end posts to bearings
B. keep the rectangular shape of the bridge cross-section
C. stiffen the structure laterally
D. prevent the sidesway buckling of top chord

A. 1/12 of strain at the initiation of strain hardening and about 1/120 of maxi-mum strain
B. 1/2 of strain at the initiation of strain hardening and about 1/12 of maxi-mum strain
C. 1/12 of strain at the initiation of strain hardening and 1/200 of maximum strain
D. 1/24 of strain at the initiation of strain hardening and about 1/200 of maximum strain

A. only on the ultimate stress of the material
B. only on the yield stress of the material
C. only on the geometry of the section
D. both on the yield stress and ultimate stress of material