Thursday, 21 June 2012

Vth-yr-working drawing-NBC-application-to-parts

dear all,

it is heartening to know u r keen to learn more and work hard to apply it in current WD package.

i m talking to other institutes hod's and they too agree w/me  that it is reqd by students to learn these matters (application of nbc, cibse,etc).

so for different parts i will tell u how it is done. 

basic rule to apply in design of facility is as follows:

1). if u r designing say for example a 5 hotel project, and you have banquet halls, it is always better to put such facilities like banquet hall etc, which are high people density on ground floor leading to safety.

because for exits you are only required to provide doors wide and sufficient in numbers leading to outside or to corridor which will lead to outside. again corridor width and numbers should be sufficient as per nbc (national building code). but u r saved the cost of stairways.

2). Municipal bye-laws will always insist to give minimum width of stairs, corridors, (passage ways) and door exits. but u must always add extra over minimum required as per occupant load as given in NBC. so for example if i have 1000 seats assembly facility like conferencing on second floor, then as per occupant load per exit unit i will get 1000/40 = 25. one exit unit = 500 mm. so total exit unit for stairway reqd is 25x 500 mm = 12500. now minimum width of stair for assembly building is 2000. so i will require 12500/2000 = 6.25 staircases to give quick exit time for 1000 ppl to go out to safety on ground level. 6.25 (below 0.5) can be rounded to 6 stairs. 

3). for same 1000 ppl doors reqd will be 1000/60 = 16.66 units of exits. so total door width reqd is 16.66 x 500 mm = 8333 mm. so u can give 4 doors of 2100 mm width on two sides of hall or on one side at sufficient intervals to avoid overcrowding near doors. please exit for assembly building shall not be less than 2000 mm width. for other facilities no door will be less than 1000 mm. 

4). for ramp for same 1000 ppl width reqd will be 1000/50 = 20 x 500 mm = 10000 mm. so u can give single ramp of above width or 2 ramps of 5000 mm width or 4 ramps of 2500 mm width.

5). for corridors: please keep this in mind: 
      NBC states as follows: Exit corridors and passage ways shall be of width not less than the aggregate required width of exit doorways leading from them in the direction of travel to exterior. 

the interpretation of above statement in our case of 1000 ppl assembly building will be as follows:

total aggregate width of doors = 8333 mm. so width of corridor will be 4200mm if 2 doors of 2100mm size open into it. it will be 2100 mm if one door open into it. it will be 6300 mm if 3 doors of 2100 mm open into it. 

hence i told u in the beginning that for high occupant load areas which ask for wider exits, please put them on ground floor. so u will at least save money on stairways. so stairs are always provided for less occupant facilities like residences / offices on upper floors.

please remind me to give you a copy of all necessary nbc tables like 20 for occupant load, 21 for occupants per unit exit width for stairways, ramps and doors for various group of occupancy like residential, educational, assembly, etc. also travel distance for the same. 

with best regards,

atule kedia 

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