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What is the moment strength for floor deck joists at Ultimate Limite State?

TonyC 2017-12-06 13:07:12

Here's an interesting technical support case put forward by an EdiLus user

What is the moment strength that the program specifies for the joist members used in prefabricated floors (precompressed joists, prefabricated panels)? Is it expressed per linear meter?

The moment value, as shown in the reinforcements table for prefabricated floors, represents the maximum acting moment on the single joist between all the load combinations at ULS (Ultimate Limit state) analyzed for floor calculations (see "Note!" at the bottom).

N.B.: Prefabricated floor deck manufacturers generally provide, according to the type of joist chosen, data sheets with the performance of the floor type per unit of width (one meter wide). In order to compare, in this case, the moment strength value, as provided by EdiLus, with the values shown in the manufacturer datasheets, simply multiply the moment value, provided in EdiLus, by a coefficient which is the ratio between 100 and the joist inter-axis (expressed in cm), as follows:

MULS (1m wide)=MULS,EdiLus· 100/i

where i is the interaxis between each joist expressed in centimeters.

NOTE! Remember that in the case of multi-span floor decks, stresses are calculated by assuming that the loads are arranged with a "chequered" pattern.