Technical Knowledge
MEP Seismic Basics
What is a seismic bracing system?
A seismic bracing system protects building MEP installations — pipes, ducts, cable trays and equipment — against horizontal seismic forces. It prevents lateral swinging, longitudinal displacement and falling of services, keeping fire protection, water supply and power systems operational after an earthquake.
Where is seismic bracing mandatory?
Per GB 50981, seismic bracing shall be provided for: suspended equipment heavier than 1.8 kN; domestic water and fire protection piping DN65 and above; rectangular ducts of 0.38 m² or larger (or round ducts ≥ 0.7 m in diameter); smoke exhaust and emergency ventilation ducts and related equipment (mandatory clause); and electrical conduits ≥ 60 mm or cable trays ≥ 150 N/m.
What types of seismic bracing exist?
By support direction: lateral braces (struts perpendicular to the pipe axis), longitudinal braces (struts parallel to the axis) and bi-directional braces (combination). By structure: single-pipe braces, multi-pipe combined braces, door-type frames and duct braces.
Which standards apply?
Key standards include GB 50981 Code for Seismic Design of Building MEP Engineering, CECS 420:2015 Code for Installation and Acceptance of Seismic Braces, and CJ/T 476-2015 General Technical Conditions for Seismic Braces.