TR.32.13 Notional Loads
A notional load is a lateral load (horizontal load) which is derived from an existing vertical load case. This load type has been introduced to accommodate a requirement in design codes. The AISC 360-05 specification for example defines notional loads as lateral loads that are applied at each framing level and are specified in terms of gravity loads.
Description
Both Principal and Reference load cases can be selected and moved into the Notional Load Definition where the required factor and direction can be specified. The notional loads are calculated and applied as joint loads.
General Format
LOAD nLoad LOADTYPE type TITLE title
…
Load items
…
NOTIONAL LOAD
n { X | Z } (f1)
Where:
| Parameter | Default Value | Description |
|---|---|---|
| n | - | Load case number of the primary load case or reference load case which contains the vertical load items. |
| f1 | 0.002 (or user-specified) |
Factor by which the contents of LN are to be multiplied. Typically, codes recommend 0.2 to 0.3 % (0.002 to 0.003). The default is 0.002 or the factor specified in DIRECT ANALYSIS definition block. |
Multiple load items can be specified under any NOTIONAL LOAD and there can be one or more blocks of NOTIONAL LOAD command(s) in any load case.
Example 1
LOAD 1 : DEAD JOINT LOAD 13 TO 16 29 TO 32 45 TO 48 61 TO 64 FY -100 LOAD 2: DEAD NOTIONAL LOAD NOTIONAL LOAD 1 X 0.002 … LOAD 10: IMPOSED JOINT LOAD 13 TO 16 29 TO 32 45 TO 48 61 TO 64 FY -50 LOAD 11:IMPOSED NOTIONAL LOAD NOTIONAL LOAD 10 X 0.002
Example 2
If we want to combine the load cases in Example 1, two methods are available:
LOAD 3 : DEAD LOAD + IMPOSED LOAD + Notional Loads REPEAT LOAD 1 1.0 10 1.0 NOTIONAL LOAD 1 X 0.002 10 X 0.002
As an alternative, the following could be used:
LOAD 3 : DEAD LOAD + IMPOSED LOAD + Notional Loads REPEAT LOAD 1 1.0 2 1.0 10 1.0 11 1.0
Example 3
Similarly,
Load 1 LOADTYPE None TITLE DEAD SELFWEIGHT Y -1.15 MEMBER LOAD 143 145 CON GY -16 * Load 2 LOADTYPE None TITLE DEAD-NOTIONAL NOTIONAL LOAD 1 X 1.0 * Load 3 LOADTYPE None TITLE DEAD AND NOTIONAL REPEAT LOAD 1 1.0 NOTIONAL LOAD 1 X 1.0
Alternatively the following could be used to define load case 3:
Load 3 LOADTYPE None TITLE DEAD AND NOTIONAL REPEAT LOAD 1 1.0 2 1.0
Example 4
Using Notional loads with REFERENCE loads
DEFINE REFERENCE LOADS LOAD R1 LOADTYPE Dead TITLE REF DEAD LOAD SELFWEIGHT Y -1 LIST 1 TO 120 FLOOR LOAD YRANGE 19 21 FLOAD -0.05 GY YRANGE 39 41 FLOAD -0.05 GY LOAD R2 LOADTYPE Live TITLE REF LIVE LOAD FLOOR LOAD YRANGE 19 21 FLOAD -0.03 GY YRANGE 39 41 FLOAD -0.03 GY END DEFINE REFERENCE LOADS ********************************************** * LOAD COMBINATIONS INCLUDING NOTIONAL LOADS * ********************************************** * *DEAD + LIVE +/- NOTIONAL LOAD * LOAD 1 REFERENCE LOAD R1 1.2 R2 1.6 NOTIONAL LOAD R1 X 0.0024 R2 X 0.0032 LOAD 2 REFERENCE LOAD R1 1.2 R2 1.6 NOTIONAL LOAD R1 X -0.0024 R2 X -0.0032 LOAD 3 REFERENCE LOAD R1 1.2 R2 1.6 NOTIONAL LOAD R1 Z 0.0024 R2 Z 0.0032 LOAD 4 REFERENCE LOAD R1 1.2 R2 1.6 NOTIONAL LOAD R1 Z -0.0024 R2 Z -0.0032
If a PRINT STATIC CHECK or PRINT LOAD DATA command is added with any analysis specification in the input file, the generated NOTIONAL LOADs would be printed as in the following:
NOTIONAL LOAD - (POUN,FEET) LOADING 4 DL+NDLX JOINT DIRECTION LOAD … 6117 X -0.00200 X 74124.266 = -148.249 6118 X -0.00200 X 115504.569 = -231.009 6119 X -0.00200 X 38397.157 = -76.794 6120 X -0.00200 X 15551.155 = -31.102 6121 X -0.00200 X 17347.718 = -34.695 6122 X -0.00200 X 29341.723 = -58.683 6123 X -0.00200 X 39771.147 = -79.542 6124 X -0.00200 X 39712.750 = -79.426 6125 X -0.00200 X 34006.254 = -68.013 ============================================== 48554642.872 -97109.290