What does 2xL/480 mean? - The meaning of the "2xL/" deflection control when designing a member with a cantilever.

A Cantilever is one-half of a span. BC Calc® software uses the 2xL/_ formula to represent the 'span' ratio.  Therefore to report deflection in a consistent ratio, for example L/480, the length of the cantilever is multiplied by 2. If the cantilever controls in deflection the resulting control value is reported as 2xL/480.

This is in accordance with the IRC 2009, Table R301.7 Note(b):

For cantilever members L shall be taken as twice the length of the cantilever. 

In BC Framer® software the input property used is different. Instead of 2xL/480 the formula would be L/240.
Setting the correct deflection ratio for cantilevers.

Have more questions? Submit a request