The document provides minimum live load requirements according to ASCE 7 for different building occupancies ranging from 40 psf for residential to 100 psf for retail stores. It also gives the equation to calculate reduced live loads for influence areas greater than 400 square feet. Live load reduction factors are provided for different structural elements. Step-by-step calculations are shown for determining design loads, moments and axial forces for beams, girders and columns in a sample high-rise office building. The required moment is found to be 416 k-ft for girder BC1-1, 770.8 k-ft for girder CD2-2, and the required axial forces range from 49.2 kips for column A4 to 145

1. Load Calculations
According to ASCE 7:
Minimum Uniformly distributed Live Loads for Building Design:
40 PSF for Residential dwellings, appartments, hotel rooms, school classrooms
50 PSF for Offices
60 PSF for Auditoriums with fixed seats
73 – 100 PSF for Retail Stores
(For others see ASCE 7)
For influence area, AI > 400 Sq.ft., the live load may be reduced according to the live load reduction equation:
L = Lo {0.25 + (15 / √AI)}
Where
L = Reduced Live Load
Lo = Code specified design live load
AI =Influence Area =KLL (AT)
KLL = Live Load Element Factor
(See Table)
Table – Live load element factor, KLL
Element KLL
Interior columns 4
Exterior columns without cantilever slabs 4
Edge columns with cantilever slabs 3
Corner columns with cantilever slabs 2
Edge Beams without cantilever slabs 2
Interior Beams 2
All other members not identified above, including 1
Edge beams with cantilever slabs
Cantilever beams
One-way slabs
Two-way slabs
Dr. M.E. Haque, P.E. (Load Calculations) Page 1 of 6

2. A B C D E
AT for Edge Beam BC1-1
AT for Column B3
AT for Beam CD2-2
AT for Column C4
AT for
Column
A4
Dr. M.E. Haque, P.E. (Load Calculations) Page 2 of 6
1
2
3
4
40’-0” 40’-0” 40’-0” 40’-0”
30’-0”
30’-0”
30’-0”
Floor Plan of High-rise Office Building

3. Given:
Live Load, L=50 psf
Dead Load, D= 70 psf
1. Girder BC 1-1
Tributary area, AT = 40 x 15 = 600 sq ft
Influence area, AI = 2 AT = 2 x 600 = 1200 sq ft
Live load reduction = 0.25 + [15 / √ (AI) ] = 0.25 + [15 / √ (1200)] = 0.25 + 0.433 =0.683
Amplified loads per linear foot:
Dead Load = 1.2 (70 psf) (15 ft) = 1260 plf
Live Load = 1.6 (0.683)(50 psf) (15 ft) = 819.6 plf
Wu = 1.2 D + 1.6 L = 1260 + 819.6 = 2079.6 plf = 2.08 k/ft
2.08 k/ft
40 ft
Required Moment (LRFD), Mu = Wu L^2 /8 = 2.08 x 40^2 /8 = 416 k-ft
Dr. M.E. Haque, P.E. (Load Calculations) Page 3 of 6

4. 2. Girder CD 2-2
Tributary area, AT = 40 x 30 = 1200 sq ft
Influence area, AI = 2 AT = 2 x 1200 = 2400 sq ft
Live load reduction = 0.25 + [15 / √ (AI) ] = 0.25 + [15 / √ (2400)] = 0.25 + 0.306 =0.556
Amplified loads per linear foot:
Dead Load = 1.2 (70 psf) (30 ft) = 2520 plf
Live Load = 1.6 (0.556)(50 psf) (30 ft) = 1334.4 plf
Wu = 1.2 D + 1.6 L = 2520 + 1334.4 = 3854.4 plf = 3.854 k/ft
3.854 k/ft
40 ft
Required Moment (LRFD), Mu = Wu L^2 /8 = 3.854 x 40^2 /8 = 770.8 k-ft
Dr. M.E. Haque, P.E. (Load Calculations) Page 4 of 6

5. 3. Column A4
Tributary area, AT = 20 x 15 = 300 sq ft
Corner column without cantilever slab,
Influence area, AI = 1 AT = 1x 300 = 300 sq ft < 400, No live load reduction permitted.
Amplified load:
Dead Load = 1.2 (70 psf) (300 sqft) = 25200 lbs
Live Load = 1.6 (1)(50 psf) (300 sqft) = 24000 lbs
Wu = 1.2 D + 1.6 L = 25200 + 24000 = 49200 lbs = 49.2 kips
Required axial force (LRFD), Pu = 49.2 kips.
4. Column C4
Tributary area, AT = 40 x 15 = 600 sq ft
Influence area, AI = 4 AT = 4 x 600 = 2400 sq ft
Live load reduction = 0.25 + [15 / √ (AI) ] = 0.25 + [15 / √ (2400)] = 0.25 + 0..30618 =0.55618
Amplified load:
Dead Load = 1.2 (70 psf) (600 sqft) = 50400 lbs
Dr. M.E. Haque, P.E. (Load Calculations) Page 5 of 6

6. Live Load = 1.6 (0.55618)(50 psf) (600 sqft) = 26697 lbs
Wu = 1.2 D + 1.6 L = 50400 + 26697 = 77097 lbs = 77.1 kips
Required axial force (LRFD), Pu = 77.1 kips.
5. Column B3
Tributary area, AT = 40 x 30 = 1200 sq ft
Influence area, AI = 4 AT = 4 x 1200 = 4800 sq ft
Live load reduction = 0.25 + [15 / √ (AI) ] = 0.25 + [15 / √ (4800)] = 0.25 + 0.216506 =0.466506
Amplified load:
Dead Load = 1.2 (70 psf) (1200 sqft) = 100800 lbs
Live Load = 1.6 (0.466506)(50 psf) (1200 sqft) = 44784 lbs
Wu = 1.2 D + 1.6 L = 100800 + 44784 = 145584 lbs = 145.58 kips
Required axial force (LRFD), Pu = 145.58 kips.
Dr. M.E. Haque, P.E. (Load Calculations) Page 6 of 6