This document discusses the seismic behavior of beam-column joints in reinforced concrete moment frames. It begins by introducing beam-column joints and their importance. It then explains that joints have limited strength and are vulnerable to damage during earthquakes. To prevent this, joints must be designed to resist earthquake effects. The document outlines how beams apply moments to joints during quakes and how this can cause diagonal cracking if the joint is not reinforced properly. It concludes that providing large column sizes or steel ties in the joint can prevent such cracking and damage.