How Side members of frame undergo lateral bending due to?

Side members of a frame undergo lateral bending primarily due to lateral loads, such as wind or seismic forces, which create moments along the frame. These loads cause deflections that induce bending stresses in the side members, leading to potential structural failure if not adequately designed. Additionally, the geometry and boundary conditions of the frame influence how these lateral loads are distributed among the members. Proper analysis and reinforcement are crucial to ensure stability and integrity under such loading conditions.