Question

Consider the office building shown below. The building is located in New Orleans, LA, at ground level near the coast. The structure is a reinforced concrete frame. 3@30 ft = 90 ft 6th floor 5th floor 4th floor 3rd floor 2nd floor 1st floor 5@12 ft = 60 ft D4 Elevation 4@25 ft = 100 ft Plan View Assume the following values for dead and live loads: Dead load from slab: Ws = 70 lb/ft Self-weight of beams: Wb = 45 lb/ft Self-weight of columns: We = 70 lb/ft Live loads: W, = 30 lb/ft Compute the loads transferred to the bottom of (A) column D4 at the first floor, (B) column B3 at the third floor, and (C) column C3 at the fifth floor (see figures) for the following load cases: 1) Dead loads, D (including own weights of the structural system components) [2 points for each column] 2) Live loads, L [3 points for each column]

Answer 1

Dead load from slab=Ws=70 lb/ft? Self weight of beam=Wb=45 lb/ft Self weight of columns=Wc=70 lb/ft Live load W1=30 lb/ft? Floor height =12 ft

12.5" 12.5" ...... 3@ 30 ft = 90 ft an 12.5 12.5' D4E 15' 4@25 ft = 100 ft Plan View

Tributary area for column 1)B3 and C3 AT=(15+15)*(12.5+12.5)=750 ft? Length of beam =(12.5+12.5+15+15)=55 ft 2)D4 Ar=15*(12.5+12.5)=375 ft? Length of beam =(12.5+12.5+15)=40 ft Since the load on each storey and storey height are same let us analyze a typical storey first

Since the load on each storey and storey height are same let us analyze a typical storey first

TYPICAL STOREY(along B3,C3) DEAD LOAD OF SLAB SELF WEIGHT OF BEAM SELF WEGHT OF COLUMN TOTAL DEAD LOAD 750X70 52500 45+55 2475 70*12 840 55815 LIVE LOAD 750*30 22500 TYPICAL STOREY(along D4 ) DEAD LOAD OF SLAB SELF WEIGHT OF BEAM SELF WEGHT OF COLUMN TOTAL DEAD LOAD lb 375X70 45*40 70*12 26250 1800 840 28890 LIVE LOAD 375*30 11250

Total load at bottom of column =No stories above* typical load for storey A) D4 -First floor(have 5 stories above) 1) Dead load =5*28.89==144.45 k 2) Live load =5*11.25=56.25 k B) B3 Third floor (have 3 stories above) 1) Dead load =3*55.815=167.445 k 3) Live load =3*22.5=67.5 k C) C3 -Fifth floor 1) Dead load =1*55.815=555.815 k 2) Live load =1*22.500=22.5k