How to model a Sway Brace pipe support in AutoPIPE?
Sway Brace has a rigid stiffness up to load limit of 1800lb, then stiffness changes to 1800lb/in. The full sway brace resistance load is exerted in the colde condition = free thermal movement * spring + preload
Note: There are 2 styles - Mechanical and hydraulic (viscous) sway brace. AutoPIPE models a mechanical.
The pipe moves 1.215" under thermal case T1 at node A01 (with inclined support removed), the sway brace load would exert a total 1800 lb/in x 1.215" plus 1800 lb preload = 3987 lbs in the Gravity case. When the pipe fully expands in the thermal T1 case there is zero resisting load in the operating condition
Sample model: Sway_Brace_6.dat
Insert a inclined support at A01, with 1800 lb /in spring rate
Insert > xtra data > concentrated force. Add 2 forces, +ve preload = 1800 in GR and –ve preload in T1 case i.e. gravity case force in same direction as thermal movment and force in T1 case in the opposite direction
Add a imposed displacement in the gravity case = the free thermal movement = 1.215”
Results show expected full preload = 3982lb exerted on anchor A00 by the sway brace. In the operating case – no load in seen in GT1 at both anchor A00 and A01 support
AutoPIPE cannot simulate the arc or pendulum movement of a rigid strut. Typically good design practice limits angulation of struts or hangers to +/- 4 deg
One workaround is calculate the lateral restoring force for the angulation for each loading and apply this force at the pipe connection point.
Different Types of Supports