Applies To
	Product(s):	STAAD.Pro
	Version(s):	All
	Environment:	N/A
	Area:	Modeling Solutions
	Subarea:	Loading
	Original Author:	Abhisek Mandal, Bentley technical Support Group

 I am trying to analyze a staad.pro model with IBC loading and getting an error message  “*** STAAD.Pro ERROR MESSAGE *** NO LOADING DEFINED FOR UBC LOAD. RUN TERMINATED.”

Although the error message says UBC but it is a generic message that is applicable to seismic load generations as per all other codes as well, including IBC.

The reason for getting the error is that, no seismic weight has been specified as part of the seismic definition and hence Staad is unable to calculate the Base Shear ( V = Cs x W ). As part of the seismic definition you need to specify various seismic parameters like Ss, S1, TL, I , SITE CLASS etc which are used to compute the coefficient Cs. In addition you need to define the seismic weights which will be used by the software to calculate the W term in the base shear equation. One can specify seismic weights in the form of selfweight , member weight , joint weight , element weight etc for. A sample input is provided below

DEFINE IBC 2006
SS 2.16 S1 0.80585 I 1 RX 3 RZ 4 SCLASS 4 TL 12
SELFWEIGHT 1
JOINT WEIGHT
50 51 54 55 WEIGHT 2
MEMBER WEIGHT
125 TO 127 UNI 1

An example problem EXAMP14.std is included with the software to explain the seismic load generation.