Project 2
ANS 1. WIDTH OF THE INDUSTRIAL BUILDING= 30 m.
LENGTH OF THE INDUSTRIAL BUIDING= 50m.
EAVE HEIGHT = 9 m.
BAY SPACING = 6 m.
SOIL TYPE = MEDIUM.
ROOF SLOPE= 1 in 12.
AREA OF THE BUILDING= 50*30
= 1500 M2.
NUMBER OF BAYS= 30/6 = 5 BAYS.
LOAD COMBINATION= DEAD LOAD + LIVE LOAD + WIND LOAD + CRANE LOAD.
AS THE LOCATION OF OUR BUILDING IS IN CHENNAI THE EARTHQUAKE LOAD WILL BE SIGNIFICANTLY LESS THAN THE EARTHQUAKE LOAD SO WE CAN IGNORE EARTHQUAKE LOAD.
DEAD LOAD= SELF WEIGHT OF THE STRUCTURE. IT INCLUDES THE WEIGHT OF ROOFING, GI SHEETS, GANTRY GIRDER, CRANE GIRDER, PURLIN, SAG BRACING.
DEAD LOAD DISTRIBUTED OVER ROOF= 0.438 KN/M.
TOTAL DEAD LOAD= 0.438*1500.
= 657 KN.
TOTAL LIVE LOAD = 0.75 KN/M2 (NO EXCESS TO ROOF IS PROVIDED).
= 075-0.04 = 0.71 KN/M2. (REDUCTION OF 0.02 FOR EVERY 1DEG SLOPE ABOVE 10 DEGREES).
= 0.71*1500.
= 1065 KN.
LIVE LOAD ACTING ON THE RAFTER= 4.5 KN/M.
AS WE HAVE BAY SPACING = 6M.
FROM HERE WE WILL GET LENGTH OF ONE RAFTER= 4.245 M.
NOW IN ONE BAY SPACING WE ARE USING 2 RAFTERS.
THEN OUR TOTAL LENGTH OF RAFTERS WILL BE 42.43 METRES.
LIVE LOAD DUE TO RAFTERS = 42.43*4.5
= 190.9 KN = 191 KN.
CRANE LOAD-
THE DEAD LOAD OF CRANE SYSTEM ALONG WITH GANTRY GIRDER = 7KN. (OVER COLUMN BRACKETS)
CASE VERTICAL CRANE LIVE LOAD(KN) HORIZONTAL CRANE LIVE LOAD(KN)
LEFT CORBEL RIGHT CORBEL
CL1 124.33 47.61 16.50
CL2 47.61 124.33 16.50
CL3 124.33 47.61 -16.50
CL4 47.61 124.33 -16.50
WIND LOAD-
BASIC WIND SPEED = 39m/sec.
WIND LOAD OVER THE ROOF AND SIDE WALLS COMES IN DIFFERENT COMBINATIONS-
CASE SIDE WALL(KN/M) PEB RAFTER(KN/M)
LEFT RIGHT
WIND ANGLE= 0+ 2.61 -2.35 5.74
WIND ANGLE= 90+ -3.65 -3.65 5.74
WIND ANGLE=0 4.70 -0.26 3.65
WIND ANGLE=90- -1.57 -1.57 3.65.
NOW THERE ARE 16 LOAD COMBINATIONS THAT CAN BE CREATED.LET US HAVE A LOOK AT THEM-
1. 1.5 DL +1.5 LL + 1.5CL1.
2. 1.5DL + 1.5 LL + 1.5 CL2.
3. 1.5 DL+ 1.5 LL + 1.5 CL3
4. 1.5DL + 1.5 LL + 1.5 CL4
5. 1.5 DL+ 1.5 WL (ANGLE= 0+)
6. 1.5 DL+ 1.5 WL (ANGLE= 90+)
7. 1.5 DL + 1.5WL(ANGLE= 0-)
8. 1.5 DL+ 1.5 WL(ANGLE = 90-) CONTD....
WE WILL TAKE FIRST ONE AS IT WILL GIVE THE MAXIMUM VALUE OF THE LOAD COMBINATIONS.
LIVE VERTICAL LOAD IN THE RIGHT AND LEFT CORBEL= 124.33+47.61
= 171.9 KN.
HORIZONTAL LIVE LOAD= 16.50 KN.
TOTAL DEAD + LIVE LOAD DUE TO CRANE LOAD= 7+ 171.9
= 179 KN.
TOTAL LOAD IF WE WERE TO TAKE THE COMBINATION NUMBER 1.
= 1.5 DL+ 1.5 LL+ 1.5 CL1.
= 1.5*657+ 1.5*1256+ 1.5*179.
= 985.5+ 1884+268.5
= 3138 KN.
DESIGN FOR FOOTING-
AXIAL LOAD= 3138 KN.
MOMENT LOAD= 16.5*9
= 148.5 KNM.
WE WILL BE USING M20 GRADE OF CONCRETE AND STRENGTH OF REINFORCEMENT= 500N/MM2.
BEARING CAPACITY OF SOIL= 200KN/M2.
FOR SAFETY PURPOSES WE WILL ASSUME IT AT 250 KN/M2.
TOTAL LOAD= 1.5*3138
= 3451.8 KN.
AREA OF FOOTING= 3451.8/250
= 13.8M2.
TAKING 10PERCENT INCREASE IN AREA, WE GET AREA= 15.1879 M2.
TAKING IT TO BE SQUARE FOOTING , SIDE OF FOOTING= 3.8972M
= 4.5M.
Pmax= 3451.8/4.5*4.5+ 148.5/(4.5*4.5)
= 178 KN <200KN/M2. HENCE SAFE.
ANS 2. DESIGN FOR GANTRY GIRDER-
UNIFORMLY DISTRIBUTED LOAD ON CRANE GIRDER= 100/9
= 11.11KN.
CONCENTRATED LOAD = 250+40= 290KN.
MINIMUM HOOK APPROACH = 1M.
LOAD ON EACH WHEEL= 145 KN.
IMPACT LOAD FOR AN ELECTRIC GIRDER= 25 PERCENT OF MAX LOAD.
= 36.25KN.
WE CAN TAKE IT TO BE 50 KN.
WAYS TO CALCULATE THE MAXIMUM BENDING MOMENT-
UNIFORMLY DISTRIBUTED LOAD ON GANTRY GIRDER= 100+0.2
= 100.2 KN.
MAXIMUM BENDING MOMENT= 100.2*1.5
= 150.3 KNM.
THIS BM WILL OCCUR AT THE WHEEL WHICH IS NEARER TO THE CENTRE OF TROLLEY.
SHEER FORCE IS MAXIMUM WHEN ONE OF THE WHEELS IS AT THE SUPPORT-
DRAG FORCE= 5 PERCENT OF 50.1
= 2.5 KN.
TRANSVERSE FORCE ON EACH WHEEL= 10 PERCENT OF (290/4).
= 7.25 KN.
GENERALLY I SECTION IS CHOSEN FOR THE DESIGN OF GANTRY GIRDER.
ECONOMIC DEPTH OF I SECTION= L/12 = 583.3 MM.
WIDTH OF FLANGE= L/35= 200MM.
Zp req. = 1.40*Mu/fy.
= 0.507 mm4.
CHECK FOR DEFLECTION-
MAXIMUM DEFLECTION= L/750.
= 9.3MM.
THE MAXIMUM DEFLECTION OF THE GANTRY GIRDER CANNOT EXCEED 9.3MM.
WE CAN LOOK UP FOR THE VALUES OF I SECTION IN THE STEEL TABLE AND THEN DETERMINE THE SHEER FORCE ACTING ON THE GIRDER.