|
To obtain correct and competitive bids the specifying professional must show any special loading on the structural drawings. Special loadings could include concentrated loads and any non-uniform load distribution as illustrated. The load diagram shows a 20' span with non uniform loads combined with a concentrated load.
|
|
|
The maximum moment for this loading is 20267 lb. ft (243 kip inches). The equivalent uniform load to produce this moment would be 405 lbs. per ft.
|
|
The maximum end reaction is 3588 lbs, which is also the maximum shear. The equivalent uniform load to produce this reaction would be 359 lbs. per ft.*
|
| The K series joist tables show a 16K3 (with a 20' span) has a total load capacity of 410 lbs. per ft. The designer should show a 16K3SP on the drawings.
|
|
The SP indicates special requirements for the joist. The joist manufacturer will review the designated joist for its ability to carry the special load shown.
|
|
*For all standard K series joists the maximum end reaction is 8700 lbs. If more reaction capacity is needed, consider using two (or more) joists to share the load. For LH and DLH joists a conservative end reaction can be found by dividing the tabulated SAFE LOAD by two.
|
|
Another way to solve the problem is to use the tables for KCS joists.
The new KCS joists have constant moment and shear strengths -- in the
case of the illustrated example a 16KCS2 joist is found to resist a moment of 349 inch kips and a shear
of 4000 pounds. By specifying this joist it is not necessary to call for a SP joist or show the loading diagram.
|
|
Joist girders with unequal panel point loads must be defined by showing
the load diagram on the structural drawings.
|