P-Delta Loads

Two sources of loads that are used in P-Delta effects are considered in the program:

Setting	Description
Mass Loads	This option uses building mass to calculate P-Delta effects. It is briefly related to mass associated with diaphragms (including member mass as well as any mass load defined with surface\line and point loads). This is the default method used in the program. RAM Frame provides users with an option for specifying factors for magnifying the P-Delta effects. To account for P-Delta effects due to live loads and/or factored loads, users may want to specify values larger than unity for the P-Delta factor. The program puts a maximum limit of 10.0 for the P-Delta factor. However, it needs to be remembered that the P-Delta modification scheme adopted in RAM Frame assumes small deflections in the building. Deflections within the range allowed by Code would generally be considered small
Use Gravity	Instead of using building mass, this option uses applied dead, live, roof and snow loads to calculate P-Delta effects. Note that different scale factors can be defined for dead, live, roof, and snow load components. Live load reduction factors are also applied for live loads.

Setting

Description

Mass Loads

This option uses building mass to calculate P-Delta effects. It is briefly related to mass associated with diaphragms (including member mass as well as any mass load defined with surface\line and point loads). This is the default method used in the program. RAM Frame provides users with an option for specifying factors for magnifying the P-Delta effects. To account for P-Delta effects due to live loads and/or factored loads, users may want to specify values larger than unity for the P-Delta factor. The program puts a maximum limit of 10.0 for the P-Delta factor. However, it needs to be remembered that the P-Delta modification scheme adopted in RAM Frame assumes small deflections in the building. Deflections within the range allowed by Code would generally be considered small

Use Gravity

Instead of using building mass, this option uses applied dead, live, roof and snow loads to calculate P-Delta effects. Note that different scale factors can be defined for dead, live, roof, and snow load components. Live load reduction factors are also applied for live loads.

If the Mass Loads option is chosen, the mass is converted to weights to be used in P-Delta calculations.

When gravity loads are chosen for P-Delta calculations, the program uses the gravity loads as summarized in the Diaphragm Gravity Loads dialog. Note that user defined gravity loads can be also used for P-Delta calculates for diaphragms with one-way decks.