...
Live load reduction is performed according to NYCBC - 2014 Chapter 16 Section 1607.9.2.
Live loads which are classified as “L,L_Heavy or L_Passenger” are permitted to be reduced in alternative method.
...
Figure 4
L
Live loads not exceeding 100 psf and are other than public assembly or parking vehicle garages are classified as “L” live load.
The design live load of any structural member supporting 150 square feet or more is permitted to be reduced.
Live load reduction along column design line is calculated as follows;
→ The tributary area of each column at column design line is determined.
→ The live load area/ tributary area ratio of each live load class (if any) at each column is determined.
→ Each tributary area is multiplied by the live load area ratio of each live load class (if any) to determine the reducible live load area at each floor along the column design line.
→ Cumulative reducible area of live load classes(if any) at each column is determined along the column design line.
→ Reduction in percent is a function of cumulative tributary area where;
R= 0.08*(At -150)
→ For one way slabs, tributary area, At, shall not exceed the product of slab span and a width normal to slab span of 0.5 times slab span.
→ Maximum reduction in percent for columns can not be more than %60 or %23.1*(1+D/L) where D is dead load per square foot of area supported and L is unreduced live load per square foot of area supported.
→ Live load reduction factor is equal to (100-Rmax)/100
L_Heavy
Live loads exceeding 100 psf are considered to be heavy live loads. Live load reduction for L_Heavy is calculated as follows;
→ If column supports 1 floor, live load reduction factor is 1.0
→ If column supports two or more floors, live load reduction factor is 0.8
L_AssemblyGroupA
Live Loads which are classified as “L_AssemblyGroupA “ are not permitted to be reduced in alternative method. Thus live load reduction factor for L_AssemblyGroupA is always 1.0.
L_ParkingVehicleGarages
Live loads which are classified as “L_ParkingVehicleGarages” are permitted to be reduced as following;
→ If column supports 1 floor, live load reduction factor is 1.0
→ If column supports 2 or more floors, live load reduction factor is the maximum of live load reduction factor explained in “L” class live loads and 0.8.
Lr
Roof live loads which are classified as ”Lr” is considered to be unreducible live loads.
...
Figure 4
| Show if | ||
|---|---|---|
| ||
Figure 4’de görülen “Run Tributary Analysis” butonuna tıklanarak tributary analizi gerçekleştirilir. |
...
If there is discontinuity in vertical memberscolum design lines, a red point is created on the cell in dahasheetspreadsheet. Move cursor over the red point to see load distribution factors to near of vertical members near to discontinuous column as illustrated in Figure 6.
The distribution factors are calculated as by assuming the lumped total force of supported by the column as point load.
...