|
|
|
|
|
Once we have an initial set of wall materials designed using the iteration to determine rigidity, the following steps are followed;
Anchorage vs. Hold-down Loop
For the entire shearline, the program performs the steps described below. If the Hold-down Configuration is set such that anchorages are allowed at either the wall ends or throughout the wall, such that there may be a Hold-downs Effect Factor Jhd causing the failure, the program resets the hold-down configuration to one that specifies hold-downs and tries again. It first tries hold-downs at ends, then tries hold-downs throughout the wall.
Deflection-based force distribution
If using deflection-based force distribution, once the wall materials are known, using the shear line forces from the iteration to determine rigidity the program iteratively distributes forces to each shear wall segments within the shear line, calculates the shear wall deflections, redistributes forces and recalculates deflections... until all the segments on the line have the same deflection.
Distribution to Shear Lines
For flexible diaphragm analysis, the same distribution of loads to the shear lines as for iteration 1 is used.
For rigid diaphragms, if using the capacity-based method of distributing forces, the rigidity of a shear line is estimated by the capacities of the designed walls on that shear line, in lbs/in, multiplied by the full-height segment lengths.
If using the deflection-based method, it is determined by
Σ Fi/DI,
where Fi and DI, are the forces and deflections on each segment. If forces have been distributed within the line such that the deflections of all segments are equalized, this is just F/D, the total force over the common deflection. Loads are then distributed to the shear lines using the torsional rigid diaphragm method.
Force Distribution with Shear Line
Using the new shear line forces, shear force is distributed to the full-height segments using either the capacity-based or deflection-based distribution method.
Wall Design
If all walls are forced to have the same material specification the program determines the critical shear wall segments on the line, that is the one with the highest force-per unit foot divided bythe Jhd factor. The program then designs the materials for the whole shear line to resist the force on that segment.
If walls can have different materials, the critical segment on each wall is determined. The program designs the materials on each wall to resist the forces on those segments.
Note that these walls may have different deflections or capacities than those used to distribute forces to design the walls; this is dealt with by the fInal design check of the structure.