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What does the Equivalent Lateral Force Spreadsheet Solve?
This spreadsheet will find your seismic coefficient for structural building (Chapter 12) and non-building (Chapter 15) systems. It only finds your base shear forces, you will still need to plug any seismic shear forces into either your ASD? or LRFD? load combinations to solve for the variety of structural solutions.
This spreadsheet solves for:
- Your Seismic Response Coefficient
- Your Seismic Base Shear Force
How to Understand this Spreadsheet | |||||||||||||
Where to download?
How to use this Spreadsheet:
This spreadsheet works in Microsoft Excel 2003 and later. This spreadsheet will solve for your Seismic Response Coefficient and your Seismic Base Shear.
The portions of the spreadsheet highlighted in yellow are the variables. The portions highlighted in blue are your results:
Equations
The top portion of the spreadsheet shows you all of the Seismic Response Coefficient equations. There are multiple equations that determine: the calculated seismic response coefficient, the minimum allowable seismic response coeff, and the maximum allowable seismic response coeff.
Fig. 1: Spreadsheet Equations
where:
S_{DS} = The short period design spectral response acceleration parameter
S_{D1} = The 1 second design spectral response acceleration parameter
T = The fundamental period of the structure
R = The Response Modification Factor of the structure (this factor is based off of the structural system being used; higher R values react better to earthquakes then lower R values)
I = The Importance Factor of the Structure
T_{L} = The Long-period transition period parameter
S_{1} = The M.C.E (Maximum Considered Earthquake or Maximum Credible Event) spectral acceleration parameter
Site Specific Variables
The next portion of the excel sheet covers all of the site specific variables. These are variables are determined by the location of the building.
Fig. 2: Site Specific Equations/Variables
where:
S_{S} = The parameter for the 0.2 second spectral response acceleration
S_{1} = The MCE (Maximum Considered Earthquake or Maximum Credible Event) spectral acceleration parameter
S_{MS} = The MCE, 5 percent damped, spectral response acceleration at short periods adjusted for site class effects
S_{M1} = The MCE, 5 percent damped, spectral response acceleration at 1 second adjusted for site class effects
S_{DS} = The design, 5 percent damped, spectral response acceleration at short periods adjusted for site class effects
S_{D1} = The design, 5 percent damped, spectral response acceleration at 1 second adjusted for site class effects
Structure Specific Variables
The next portion of the excel sheet covers all of the structure specific variables. These are variables are determined by the structural system used in the building, the occupancy, and importance.
Fig. 3: Structure Specific Equations/Variables
where:
h_{n} = the height of the building from the base to level n respectively (conservatively you can use the height of the building)
Results
The final section sums everything up.
Fig. 4: Spreadsheet Results/Summary
where:
V = The shear force at the base of your structure.
Note: Don't forget that you still need to plug these values into your load combinations to properly analyze the structure.
Notes:
The following notes must be considered when using this spreadsheet:
- Designed using the ASCE 7-05 edition.
- See Chapter 12 for Buildings and Chapter 15 for Non-Building structures.
- If checking Non-Building Structures not similar to buildings (Table 15.4-2), C_{S-Min} will change to not be less that 0.03 or \left(\frac{0.8S_1}{\frac{R}{I}}\right) .
Addendum
- V1.0: This is the original version of the Equivalent Lateral Force Spreadsheet