1. Following books may be helpful in understanding plastic analysis and design of steel structures:
a. Plastic Analysis and Design of Steel Structures by Wong (http://www.amazon.com/Plastic-Analysis-Design-Steel-Structures/dp/0750682981)
b. Ductile Design of Steel Structures by Michael Bruneau et al. (http://www.amazon.com/Ductile-Design-Steel-Structures-Edition/dp/0071623957)
c. Plastic Design and Second-Order Analysis of Steel Frames by Chen & Sohal (http://www.springer.com/us/book/9781461384304)
2. In addition, documents at following links may also provide basic information about plastic analysis of steel structures:
a. http://digital.lib.lehigh.edu/fritz/pdf/205_32.pdf
b. https://www.google.com.pk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCUQFjACahUKEwi0hoa_orDIAhWDH44KHe95AU8&url=http%3A%2F%2Fwww.steel-insdag.org%2FTeachingMaterial%2Fchapter35.pdf&usg=AFQjCNE3VzmYRzdo9sPmd0IICUGLF3pBiQ
c. http://nptel.ac.in/courses/105106113/2_industrial_building/5_plastic_analysis.pdf
3. Following link provides information about various steel design guides, based on Eurocode:
http://www.steelconstruction.info/Eurocode_Design_Guides
Regards.