Question

Problem(s) 1. Determine the reduced roof live load given the following information: a. Tributary Area = 320 ft b. Typical Pitched Roof with Slope 6:12 2. Determine the snow load for the following structure: a. Building location is Rochester New York b. Warm Roof c. Fully Exposed in a building site category C d. Slope is 4/12 e. Importance Category is II Spread Sheet 1. Add a new tab to your already created Timber Spread Sheet. Label that tab "Horizontal Load Conversion" or (HLC). This tab will be able to convert quickly the horizontal projected plan to the sloped roof. Follow the example in the class note and use the problem statement below to check your spreadsheet. Print the results and turn in with the rest of the assignment. a. Snow Load = 85 psf b. Dead Load = 60 psf c. Roof Slone 4:12

Answer 1

ROOF LOADS Live Load Slope of roof Method of Design Lo = F = : 20 psf (as per ASCE7) 6 inches of rise per foot ASD CALCULATIONS Tributary area of structural member A = 320 ft Reduction Factors R = As per ASCE7, 0.88 R = 1 for A, <=200 ft 1.2-0.001A, for 200 ft <At<600ft? 0.6 for A, >=600 ft? R = As per ASCE7, 0.9 R2 = 1 1.2-0.05F for F4 for 4<F<12 for F> =12 Reduced roof live load L = LORR = 20 X = 15.84 psf where 12 <=lrs=20 0.9 x 0.9

GIVEN DATA Location Ground Snow Load, Roof Slope Terrain Category Exposure Rochester, NY P,= 25 psf · 18.43° (4 in 12) : 1 (1-Fully Exposed, 2- Partially Exposed 3- Sheltered) Heating of building : Warm CALCULATIONS Flat Roof Snow Load, ei Importance Category Exposure Factor, Thermal Factor, Importance Factor, Risk Cat Ce= Ct = 0.8 1 1.2 Flat Roof Snow Load, P = 0.7CCID = 14.0 psf Sloped Roof Snow Load, p. Roof Slope Factor CS = 1 (obstructed surface) Sloped roof snow load, P = CSP = 14.0 psf

Roof Slope = 4 in 12 ROOF LOADS Dead load Snow load 60 psf 85 psf Roof Angle 0 = tan 4/12) 18.43 Hence, dead load on horizonatl plane, 60.00 /cose 63.25 psf