Design of Steel Structure
Generally the purlins are placed at the panel points so as to avoid

Axial force in rafter
Deflection of rafter
Bending moment in rafter
Shear force in rafter

ANSWER DOWNLOAD EXAMIANS APP

Design of Steel Structure
The elastic strain for steel is about

1/12 of strain at the initiation of strain hardening and 1/200 of maximum strain
1/24 of strain at the initiation of strain hardening and about 1/200 of maximum strain
1/2 of strain at the initiation of strain hardening and about 1/12 of maximum strain
1/12 of strain at the initiation of strain hardening and about 1/120 of maximum strain

ANSWER DOWNLOAD EXAMIANS APP