Week 10 Challenge

1. Purlin & Girts number determination problem

Calculate total number of purlins and girts required for the building with following inputs

Rafter span = 50 m

Bay spacing = 8 m

Roof slope = 1 in 10

Height of column = 12 m

Brick wall height = 2 m

Purlin spacing = 1.2 m

Girt spacing = 1.5 m

ANS

RIDGE HIGHT = 1/10= X/25

X= 25/10= 2.5

LENGTH OF RAFTTER = `sqrt(25^2+2.5^2`

= 25.12 m

NO OF PURLIN = LENGTH OF RAFTER /SPACIG OF PURLIN +1

= 25.12/1.2 +1 =21.93 TAKE 22

= TAKE 22 NO OF PURLIN.

NO OF GRIT = LENGTH OF COLUMN (EXCLUDING BRICK WALL HEIGHT )/SPACING OF GRIT +1

= 10/1.5 +1 =7.66 TAKE 7 NUMBER OF GRIT

2. Taper the beam according to BMD envelope

For the STAAD file attached. For given loading taper the beam for the BMD envelope and check utility ratio within limit. (Design Parameter is already applied).

UTILIZTION RATIO WITHIN LIMIT.

3. Determining Wind load for certain category and condition as per IS 875 Part 3 :2015

An Industrial building of plan dimension 10m x 5m to be constructed (as in Figure below). Building is situated in Chennai. Find the wind pressure on the wall of the building. Assume wall opening as 15 %. Bay spacing = 2.5m.

BASIC WIND SPEED OF CHENNI Vb = 50 m/s

DESIGN WIND SPEED Vz= Vb*K1*K2*K3*K4

WHERE K1 ( RISK COEFFICIENT) = 1.0

K2 (TERRAIN ROUGHNESS AND HEIGHT )= TERRAIN CATEGORY 3 = 0.91

K3 (TOPOGRAPHY FACTOR) = 1.0

K4 (IMORTANCE FACTOR) = 1.15 ( FOR INDUSTRIAL BUILDING)

Vz = 50*1.0*0.91*1.0*1.15 = 52.32 m/s

WIND PRESSURE Pz= 0.6*Vz^2

= 0.6*52.32*52.32= 1642 .42 N/m^2 = 1.642 kN/m^2

AS THE OPENING IS 15%

CPi = +0.5 , -0.5

height of buildin = 6m

BULDING HEIGHT RATIO = h/w = 6/5 = 1.2

building plan ratio = l/w= 10/5 = 2

EXTERNAL WALL PRESSURE CO EFFICIENT CPe

FOR ROOF

for wall

						WIND LOAD CO EFFICIENT CALCULATION				PD =
	FOR WALL						for +vve	for -ve	FOR +VE			FOR -VE
	FOR 0		FOR	CPE	Cpi +ve	Cpi -ve	(Cpe -cpi)	(Cpe-cpi)	PD=(CPE-CPI)* A*F			PD=(CPE-CPI)* A*F
			A	0.7	0.5	-0.5	0.2	1.2	0.2*2.5*1.642=0.821 KN/M			1.2*2.5*1.642=4.9 KN/M
			B	-0.3	0.5	-0.5	-0.8	0.2	-3.284			0.821
			C	-0.7	0.5	-0.5	-1.2	-0.2	-4.9			-0.821
			D	-0.7	0.5	-0.5	-1.2	-0.2	-4.9			-0.821
		FOR WALL						for +vve	for -ve	FOR +VE			FOR -VE
		FOR 90		FOR	CPE	Cpi +ve	Cpi -ve	(Cpe -cpi)	(Cpe-cpi)	PD=(CPE-CPI)* A*F			PD=(CPE-CPI)* A*F
				A	-0.5	0.5	-0.5	-1	0	-4.105		0
				B	-0.5	0.5	-0.5	-1	0	-4.105		0
				C	0.7	0.5	-0.5	0.2	1.2	0.821		4.926
				D	-0.1	0.5	-0.5	-0.6	0.4	-2.463		1.642
	FOR ROOF				cpe	cpi -ve	cpi +ve	(cpe-cpi) +ve	( cpe-cpi) -ve	pd +ve		pd -ve
				EF	-0.7	0.5	-0.5	-1.2	-0.2	-4.926		-0.821
		0		GH	-0.5	0.5	-0.5	-1	0	-4.105		0
				EG	-0.8	0.5	-0.5	-1.3	-0.3	-5.33		-1.23
		90		FH	-0.6	0.5	-0.5	-1.1	-0.1	-4.51		-0.41

4. Find support reaction for given load. Static check problem

Mono sloped structure (20 degree) of width 10 m & length 30 m with bay spacing of 6 m having no wall sheeting (fully open all around) has following loads. Model the structure in STAAD. Apply Dead load, Live Load & Wind load on the structure and find the support reaction. Also perform static check if the total load applied on the structure is captured in support reaction for each load case.

Self Weight factor – 1.1

Roof Sheet loading = 0.5 kN/m²

Purlin load = 6 kN/m²

Live Load on Roof = 1.5 kN/m2

Wind Load on rafter (Pressure) = 2 kN/m²

ANS

LOADING CALCULATION

DEAD LOAD

ROOF SHEETING LOAD = 0.5 KN/M2

SAG AND BRACING = 0.5 KN/M2

PURLIN LOAD = 6 KN/M2

TOTAL DEAD LOAD = 7 KN/M2

BAY SPACING = 6 M

UDL DEAD ACTING ON THE RAFTER =7 KN/M2*6M = 63 KN/M

UDL DEAD ACTING ON THE END RAFTER = 31.5 KN/M

LIVE LOAD = 1.5 KN/M2

UDL LVE LOAD ACTING ON THE RAFTER = 1.5*6 = 9 KN/M

UDL LIVE ACTING ON THE END RAFTER = 4.5 KN/M

WIND LOAD ON THE RAFTER (PRESSURE)= 2 KN/M2

REACTIO AT SUPPORT

UTILIZATION RATIO.