Dimensions of seismic bracing for cable trays in the Philippines

Seismic bracing for cable trays in the Philippines typically uses either cable or rigid bracing systems, with cable braces having no length limitation and rigid braces designed for shorter spans, both compliant with ASCE 19 and local seismic codes.Cable BracingCable bracing is ideal for confined or crowded spaces where rigid bracing is difficult to install. Key points include:Brace Length: Cable bracing has no maximum length limitation, making it suitable for spans exceeding 3 meters (9 ft 7 in) or irregular layouts .Components: Uses steel cable assemblies, swaged oval sleeves, and pre-assembled kits to secure trays to threaded rods or structural elements .Attachment: Slotted fittings allow connection to existing threaded rods or trapeze supports, minimizing stress on fasteners and anchors .Compliance: Meets ASCE 19 requirements for seismic restraint of MEP systems . Cable bracing is particularly recommended for high-seismicity projects, where lateral and vertical accelerations can displace trays and cables .Rigid BracingRigid bracing is preferred when shorter spans and fewer stress points are desired:Brace Members: Typically use strut channels or pipes attached to the structure with patented yoke or clamp systems .Span Considerations: Rigid braces are generally used for spans where cable bracing is unnecessary; they require half the number of braces compared to cable systems .Attachment Hardware: Includes break-off bolts for torque verification, concentric attachment openings, and small-profile jaws for limited space .Compliance: Tested and UL-listed to UL203A standards, ensuring a 2.2 safety factor and improved load ratings . Rigid bracing is often used in combination with B-Line series cable trays for a fully engineered seismic solution .Design ConsiderationsWhen designing seismic bracing for cable trays:Seismic Design Basis: Confirm project-specific seismic criteria, including expected lateral and vertical accelerations, building drift, and vibration loads .Tray Type: Ladder trays are preferred for primary distribution due to structural stiffness; perforated or trough trays require careful evaluation .Brace Layout: Determine lateral and longitudinal brace locations based on tray span, load, and seismic forces .Attachment Points: Use threaded rods, trapeze supports, or structural members with approved fittings to secure braces .Inspection and Verification: Ensure visual verification of proper torque and installation, especially for rigid bracing systems .SummaryCable Bracing: Flexible, unlimited length, ideal for crowded spaces, fully compliant with ASCE 19 .Rigid Bracing: Shorter spans, fewer braces, UL-listed, suitable for structured layouts .Design: Must consider seismic loads, tray type, brace spacing, and attachment hardware . For projects in the Philippines, it is recommended to consult local seismic codes and work with suppliers like nVent CADDY or Eaton TOLCO to obtain engineered bracing layouts and pre-approved assembly drawings for compliance and safety .