Product(s):	RAM Structural System; Ram Steel
	Version(s):	Any
	Area:	Analysis; Design

Problem

Loads on beams from one-way deck are not calculated as expected when the deck changes along the length of the beam or between beams, (i.e. mid-bay).

Explanation

In Ram Structural System, loads from deck self-weight are calculated for each tributary area of framing or bay. The program performs this routine assuming that the deck within that bay is of constant type and orientation. Changes in the orientation or deck type in the middle of the bay effectively go unnoticed in this routine.

What the program does internally is to look at each beam-segment and at the mid-length of the segment it projects a vector towards adjacent framing and gets the deck properties at that mid-segment location. These are illustrated with orange arrows in the figure below.

This can affect the loads from the deck self-weight, where the deck weight changes, and the distribution of the loads, where the orientation changes. 

Avoidance

Always model beams (of any material) or walls along the transition lines where the deck type changes. 

This rule does not apply to surface loads which can change anywhere. Nor does it apply to 2-way decks which are free-form and changes can occur anywhere (beam are not even required). 

For more information about how changes in deck can effect composite beam design, refer to the Ram Steel Beam manual, starting in section 10.7 Composite Beam Design.

See Also

RAMSS Common Framing Table Errors

[[Missing or incorrect loads on perimeter beams]]