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	Applies To
	Product(s):	STAAD.Pro
	Version(s):	ALL
	Environment:	ALL
	Area:	Modeling Solutions
	Subarea:	Geometry
	Original Author:	Biswatosh Purkayastha, Bentley Technical Support Group

communities.bentley.com/.../culvert.zip

Question: How to model the box culvert on which the vehicle would move in Staad?

Answer:  The following steps with illustration explains the procedures to model and simulate the analysis of the box culvert in Staad.

We encourage to use the PARAMETRIC Modelling as this will ensure the proper meshing maintaining the well connectivity between the element nodes or with any other control points.

There are two types of imposed loading to be considered.

(1) The moving load due to the vehicle movement

(2) The Active Earth pressure load.

For the moving load one may place set of dummy beams with negligible stiffness and selfweight whose purpose would be only for transferring the vehicular loads as the moving load cannot be applied directly on the plate element.

For adding the active earth pressure on the side wall one can use the Rankine's earth pressure formula and use the hydro-static loading feature in Staad.pro.

Following are the illustrations of the "Compression Only" and "Tension Only" spring support to idealize the soil spring action. Accordingly, assign the Tension Only and Compression Only supports to the respective side walls. The resistance imparted by these spring supports would represent the Passive Earth Pressure.

Following are the post-processing results after the analysis.