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Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 10.0 and may not reflect current behavior
ASCE 7 Commentary C27.4.6 states that the 15% eccentricity and 75% for All Heights Case 2 loads may not cover all cases, and said for certain buildings, 5% eccentricity at full loading is more appropriate. Therefore, we now allow you to control the eccentricity and percent loading to be used, with the default being 15% and 75%.
The inputs added for this are in the existing are in a new data group called Directional (All heights) Method
In a new data group called Directional (All heights) Method there are data fields called Applied to enter the percentage of load used, defaulting to 75%, for each building direction.
The existing Eccentricity inputs that previously were for dynamic analysis (flexible structures) only, are now also enabled for the usual static analysis case. For static analysis, you enter a percentage of building width; for rigid analysis, and absolute value in feet.
The load generation process creates Case 1 loads according to the ASCE standard, and case 2 loads by multiplying the Case 1 magnitudes by the percentage entered. When shearline forces are created with Case 2 loads, torsional analysis is applied for both rigid and flexible diaphragms, with an accidental eccentricity equal to the percentage entered multiplied by the building width for rigid structures, and the entered eccentricity for flexible structures.
The eccentricities entered and the percent loading is echoed in the Site Information section of the Design Results.
The eccentricities and load percentage appear in the input echo.
The proportion of building width B is given on the line showing the actual eccentricity in each direction.
The source of the eccentricity is given in an explanatory note - either entered by user due to C27.4.6 or from Figure 27.4-8 for 15%. This is followed by the percentage of load.
For flexible diaphragms, the eccentricities and load percentage also appear in the explanation at the top of the torsional analysis procedure.