Roof Truss Analysis 10f1v

ROOF TRUSS ANALYSIS Definitions: Span Pitch Bay length

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usually express in of length Height of truss over span. Most economical pitch is = ¼ Distance center to center of trusses

Deadloads:  Weight of roof covering ( GI sheets, ceramic roofings, etc. )  Weight of steel purlins Unit weight varies from 80 – 220 Pa of roof surface.The low values for light loads and short span between roof trusses.  Weight of roof trusses Weight of roof trusses is distributed equally to ts on TC and BC or weight is distributed 2/3 on TC ts and 1/3 on BC ts. Empirical Formula;

WT = 35.9 ( 1 + L/3.048 )

( Steel Truss )

Other Deadloads: o Weight of Bracings  Weight of bracings may be assumed to vary from 48 Pa to 100 Pa of roof surface. o Weight of ceiling if any o Weight of ceiling joist if any Miscellaneous loads  Balcony load if there is any  Shafting if there is any  Other ceiling loads if there is any Tributary AreaProjected area in a structure to which actual loadings are assumed to be distributed.

LOAD COMBINATIONS:  Deadload + Liveload  Deadload + Windload ( Left )  Deadload + Windload ( Right )  1.2Deadload + 1.3Windload ( Left ) + Liveload  1.2Deadload + 1.3Windload ( Right ) + Liveload  1.2Deadload + 0.5Liveload  Deadload + 0.75 [ Liveload + Windload ( Left ) ]  Deadload + 0.75 [ Liveload + Windload ( Right ) ]