Horizontal support frames (commonly known as perforated frames or perforated frames) are indispensable lateral connecting components in Bailey bridge systems. Their core function is to connect multiple rows of trusses, combining independent sheet trusses into a stable, integrated spatial structure. Through rigid connections, the support frames effectively resist lateral deformation, ensuring uniform stress distribution on bridge truss units under load and preventing twisting or overturning of single-row trusses due to lateral instability. In terms of installation location, the support frames are flexible in design; they can be installed at the top of the upper chord of the truss to enhance horizontal stiffness, or at the vertical members to provide vertical support.