# Scaling Design Values of Combined Response per ASCE 7-16 §12.9.1.4

**How does ideCAD scale design values of combined response according to ASCE 7-16?**

The combined response for the modal base shear (V

_{t}) iscompared with the calculated base shear (V) using the equivalent lateral force procedure automatically. If it isusing the equivalent lateral force procedure, the forces are**less than 100% of the calculated base shear (V)**automatically.**multiplied by V∕V**_{t}

Where the combined response for the

, drifts are**modal base shear (V**_{t}) is less than C_{s}Wautomatically.**multiplied by C**_{s}W∕V_{t}

**Symbols**

**V** = The equivalent lateral force procedure base shear**V _{t}** = The base shear from the required modal combination

*The seismic response coefficient*

**C**_{s}=*The effective seismic weight*

**W =***The response modification factor in Table 12.2-1*

**R =***The Importance Factor*

**I**_{e}=*the design spectral response acceleration parameter at a period of 1.0 s*

**S**_{D1}=*The fundamental period of the structure(s)*

**T =**A base shear (V) is calculated in each of the two orthogonal horizontal directions using the calculated fundamental period of the structure T in each direction and the procedures of Section 12.8.

The seismic base shear, V, in the earthquake direction considered, is determined by the following equation.

**Scaling of Forces per ASCE 12.9.1.4.1**

If the calculated fundamental period exceeds C_{u}T_{a} in a given direction, C_{u}T_{a} is used in lieu of T in that direction. Where the combined response for the modal base shear (V_{t}) is* less than 100% of the calculated base shear (V)* using the equivalent lateral force procedure, the forces is

*.*

**multiplied by V∕V**_{t}**Scaling of Drifts per ASCE 12.9.1.4.2 **

If the combined response for the * modal base shear (V_{t}) is less than C_{s}W*, and where C

_{s}is determined with Eq. (12.8-6), drifts are

*.*

**multiplied by C**_{s}W∕V_{t}

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