设计指南21全面概述了与结构焊接相关的主题，包括焊接类型的选择、焊接设计、冶金、焊接修复、焊接工艺规范、质量、检验、经济性和安全性。第二版参考了AISC 360-16、AISC 341-16和AWS D1中的规定。1:2015，包含了新的章节，涉及应用于焊接连接的地震考虑和断裂力学，关于疲劳的章节已经扩展。流行的第一版“特殊焊接应用”一章已被划分和扩展:更多的特殊应用得到解决，新的一章“问题和修复”以解决问题的实际建议解决了常见问题。

Design Guide 21 provides a complete overview of topics related to structural welding, including selection of weld types, weld design, metallurgy, weld repair, weld procedure specifications, quality, inspection, economy and safety. The second edition references provisions in AISC 360-16, AISC 341-16 and AWS D1.1:2015, and contains new chapters dealing with seismic considerations and fracture mechanics as applied to welded connections, and the chapter on fatigue has been expanded. The popular first edition chapter on "special welding applications" has been divided and expanded: more special applications are addressed and a new chapter on "problems and fixes" addresses commonly encountered problems with practical advice to solve the problem.