Document 8RmDGjkKJ04VzXZbVV6oKazBa

TABLE 47--N STRENGTH OF ICE Load Ice Thickness Inches (mm ) One person on skis One person on foot Group, single file or Snowmobile Passenger car, 2 ton gross Light truck, 2'h ton gross Medium truck, 3'/2 ton gross Heavy truck, 7-8 ton gross IV4 2 3 7>/a 8 10 12 Courtesy Snow, Ice and Permafrost Research Establishment, Corps of Engineers, U S Army Snowmobile data from A Snowmobile Accident Study," R W McLay and S Chism, 1969 NOTES 1) This table is for clear sound ice 2) Thickness must be increased and extreme caution used after spnng melt starts 3) Snow ice-use 50% of thickness of snow ice as effective for table given Example 10 in snow ice plus 6 in clear ice gives 11 in thickness Medium truck all right, but not heavy truck 4) Table does not apply to parked loads 5) Key to safety on ice is to disperse the weight over a large area, do not run vehicles within 50 ft of each other TABLE 47-0 DESIGN WIND PRESSURES FOR VARIOUS HEIGHT ZONES OF BUILDINGS OR OTHER STRUCTURES (From Minimum Design Loads in Buildings and Other Structures, American Standards Institute A58 1) Height Zone, feet Wind Pressure pounds per sq ft Less than 50 50 to 99 100 to 199 200 to 299 300 to 399 400 to 499 500 to 599 600 to 799 800 to 999 1.000 to 1,199 1,200 to 1,399 1,400 to 1,599 1,600 and over 20 24 28 30 32 33 34 35 36 37 38 39 40 From Kent's Mechanical Engineers' Handbook (John Wiley is Sons) WIND LOADS A minimum pressure in pounds per square foot is specified by all building codes as an allowance for the effect of wind pressure against exposed surfaces of buildings The figures given are recommended in this report as mimmums These requirements do not provide for tornadoes because they are based on a design wind velocity of 75 mph, corresponding roughly to a 5-min average of 50 mph (indicated 63 by a 4-cup anemometer) at 30 ft from the ground Special provision for wind bracing is required for narrow buildings of even medium height and for all high buildings In towertike structures wind bracing should be planned in the early stages of design The overturning moment due to wind pressure should not exceed two-thirds of the moment of stability, disregarding live loads, except where foundations are securely anchored The possibility of a structure sliding on its foundation bed should also be considered In computing the wind load no allowance should be made for the shielding effect of other buildings All roofs should be designed to resist wind suction as well as wind pressure 1605