Live Load Reduction Examples
- Ömer Can Sagbas (Unlicensed)
Calculation of the live load reduction is explained in four examples which are LiveLoadReductionToType_Example, LiveLoadMaxReduction_Example and LiveLoadReductionDLTest_Example, LiveLoadReductionTransferColumn_Example respectively.
Figure 1. LiveLoadReductionToType_Example
Dimensions : 20ft x 20ft in plan
In this example, live load reduction rates are calculated using 5 different live load class.
Live Load Classes
Live Load Type | Magnitude, psf |
|---|---|
Live Load | 50 |
Heavy Live Load | 150 |
Group A LL | 50 |
Passenger Vehicle Garage LL | 50 |
Live Load Reducted | 50 |
Reducible Area / Supported Floors
Columns/Reducible Area | Third Story, inch^2 | Second Story, inch^2 | First Story, inch^2 |
|---|---|---|---|
C1 | 14400 | 28800 | 43200 |
C2 | 14400 | 28800 | 43200 |
C3 | 14400 | 28800 | 43200 |
C4 | 14400 | 28800 | 43200 |
Supported Floors | 1 | 2 | 3 |
Reduction Factor
Factor / Value | Third Story Column | Second Story Column | First Story Column |
|---|---|---|---|
LFactorGeneral | 1 | 0.96 | 0.88 |
LFactorHeavy | 1 | 0.96 | 0.88 |
LFactorGroupA | 1 | 1 | 1 |
LFactorPassengerVehicleGarages | 1 | 0.96 | 0.88 |
C1 is loaded Group A class.
C2 is loaded Live Load class.
C3 is loaded Heavy Live Load class.
C4 is loaded Passenger Vehicle Garages class.
Live Load
Column | Fx, kips - Hand Calculation | Fx, kips - Building Design Suite | ||||
|---|---|---|---|---|---|---|
Third Story | Second Story | First Story | Third Story | Second Story | First Story | |
C1 | -5 | -10 | -15 | -5 | -10 | -15 |
C2 | -5 | -10 | -15 | -5 | -10 | -15 |
C3 | -15 | -30 | -45 | -15 | -30 | -45 |
C4 | -5 | -10 | -15 | -5 | -10 | -15 |
Reducted Live Load
Column | Fx, kips - Hand Calculation | Fx, kips - Building Design Suite | ||||
|---|---|---|---|---|---|---|
Third Story | Second Story | First Story | Third Story | Second Story | First Story | |
C1 | -5 | -10 | -15 | -5 | -10 | -15 |
C2 | -5 | -9.80 | -14.20 | -5 | -9.80 | -14.20 |
C3 | -15 | -29.40 | -42.60 | -15 | -29.40 | -42.60 |
C4 | -5 | -10 | -15 | -5 | -9.80 | -14.20 |
Figure 2. LiveLoadMaxReduction_Example
Dimensions : 28ft x 28ft in plan
In this example, live load reduction rates are calculated with maximum reduction values.
Live Load Class
Live Load Type | Magnitude, psf |
|---|---|
Live Load | 50 |
Reducible Area / Supported Floors
Columns/Reducible Area | Second Story, inch^2 | First Story, inch^2 |
|---|---|---|
C1 | 176400 | 352800 |
C2 | 176400 | 352800 |
C3 | 176400 | 352800 |
C4 | 176400 | 352800 |
Supported Floors | 1 | 2 |
Reduction Factor
Factor / Value | Second Story Column | First Story Column |
|---|---|---|
LFactorGeneral | 0.4 | 0.4 |
LFactorHeavy | 1 | 0.8 |
LFactorGroupA | 1 | 1 |
LFactorPassengerVehicleGarages | 1 | 0.8 |
Live Load
Column | Fx, kips - Hand Calculation | Fx, kips - Building Design Suite | ||
|---|---|---|---|---|
Second Story | First Story | Second Story | First Story | |
C1 | -61.21 | -122.43 | -61.21 | -122.43 |
C2 | -61.26 | -122.51 | -61.26 | -122.51 |
C3 | -61.25 | -122.50 | -61.25 | -122.50 |
C4 | -61.28 | -122.56 | -61.28 | -122.56 |
Reducted Live Load
Column | Fx, kips - Hand Calculation | Fx, kips - Building Design Suite | ||
|---|---|---|---|---|
Second Story | First Story | Second Story | First Story | |
C1 | -24.49 | -48.97 | -24.49 | -48.97 |
C2 | -24.50 | -49.01 | -24.50 | -49.01 |
C3 | -24.50 | -49.00 | -24.50 | -49.00 |
C4 | -24.51 | -49.02 | -24.51 | -49.02 |
Figure 3. LiveLoadReductionDLTest_Example
Dimensions : 20ft x 20ft in plan
In this example, D/L ratio is calculated for maximum reduction.
Live Load Classes
Live Load Type | Magnitude, psf |
|---|---|
Live Load | 50 |
Heavy Live Load | 150 |
Live Load | 100 |
Heavy Live Load | 200 |
Reducible Area / Supported Floors
Columns/Reducible Area | Third Story, inch^2 | Second Story, inch^2 | First Story, inch^2 |
|---|---|---|---|
C1 | 28800 | 79200 | 136800 |
Supported Floors | 1 | 2 | 3 |
Reduction Factor
Factor / Value | Third Story Column | Second Story Column | First Story Column |
|---|---|---|---|
LFactorGeneral | 0.96 | 0.68 | 0.538 |
LFactorHeavy | 1 | 0.8 | 0.8 |
LFactorGroupA | 1 | 1 | 1 |
LFactorPassengerVehicleGarages | 1 | 0.8 | 0.8 |
Live Load
Column Load Class | Fx, kips - Hand Calculation | Fx, kips - Building Design Suite | ||||
|---|---|---|---|---|---|---|
Third Story | Second Story | First Story | Third Story | Second Story | First Story | |
C1 LL | -10 | -22.5 | -37.50 | -10 | -22.5 | -37.50 |
C1 HLL | -15 | -50 | -85 | -15 | -50 | -85 |
Reducted Live Load
Column | Fx, kips - Hand Calculation | Fx, kips - Building Design Suite | ||||
|---|---|---|---|---|---|---|
Third Story | Second Story | First Story | Third Story | Second Story | First Story | |
C1 LL | -9.60 | -21.1 | -32.5 | -9.60 | -17.30 | -26.06 |
C1 HLL | -15 | -45.8 | -71 | -15 | -43 | -73.8 |
Figure 4. LiveLoadReductionTransferColumn_Example
Dimensions : 20ft x 20ft in plan
In this example, column’s tributary area not continuing bottom floors transfers other column’s tributary area.
Live Load Class
Live Load Type | Magnitude, psf |
|---|---|
Live Load | 75 |
Reducible Area / Supported Floors
Columns/Reducible Area | Second Story, inch^2 | First Story, inch^2 |
|---|---|---|
C1 | 8640 | 23040 |
C2 | 8640 | 23040 |
C3 | 8640 | 23040 |
C4 | 8640 | 23040 |
C5 | 11520 | 11520 |
C6 | 11520 | 11520 |
Supported Floors | 1 | 2 |
Live Load
Column | Fx, kips - Hand Calculation | Fx, kips - Building Design Suite | ||
|---|---|---|---|---|
Second Story | First Story | Second Story | First Story | |
C1 | -4.5 | -15 | -4.5 | -15 |
C2 | -4.5 | -15 | -4.5 | -15 |
C3 | -4.5 | -15 | -4.5 | -15 |
C4 | -4.5 | -15 | -4.5 | -15 |
C5 | -6 | 0 | -6 | 0 |
C6 | -6 | 0 | -6 | 0 |
Verification object link