DESIGN OF Z PURLINS Purlin Designation P1
Created By: Madurai ES Consultancy Services Pvt Ltd. JOB No.: DATE :
Input Data: Purlin Geometry Span of the purlin Spacing of the purlin No. of Sag rods Slope of the Roof
= = = =
6.000 M 1.8 M 2 18 deg.
Number of Spans = (for 1 or 2 spans, Bending Moment Coefficient is 8, for 3 or more spans, it is 10) (in case of Bending about minor axis, (No of spans)x(No of sagrods+1) is used.
3
Input Data: Loads Dead Loads Weight of Sheeting Self Weight of Purlin Extra for cleats, as % of Purlin weight Additional Dead Loads to Consider
= = = =
6 kg/sqm Automatically Calculated from Section properties 10 % 0 kg/sqm
Live Loads Live load on Roof
= Automatically Calculated from Slope = 59 kg/sqm Additional Live Loads to be considered = 0 kg/sqm (For Design of Wall Girt (Cladding Runner), additional Live loads to be considered can be entered as -ve of LL on roof) (Live load will be 0 effectively) Wind Loads Basic Wind Speed 39 m/s Terrain Category 2 k1 1 Maximum Horizontal Dimension of Building 33.528 m k3 1 Hence, Bldg Class B Height of Top 10.3632 m Based on the data on right, k2 is obtained from the tables k2 0.98 Ht of building at eaves level, h Width of the building, w Length of the Building, l Hence, h/w and l/w
= =
= = =
5m 33.5 m 33.5 m 0.149 1.000
Based on the h/w and l/w, the values of Cpe is obtained from tables as noted below: Maximum Downward Cpe (include sign) -0.4 Maximum Upward Cpe (include sign) -0.7 Based on % of openings, Cpi is taken as +/-
0.5
y Services Pvt Ltd.
ion properties
of LL on roof) will be 0 effectively)
4786 16-08-2011
Input Data: Purlin Section Being Checked Try
Z 200x60x2.3
Yield stress of material Flange Width, b Depth of section d Thickness t Length of Lip lip_l Inner Bending Radius
2400 60 200 2.3 20 3
Area Zxx Zyy Ixx Iyy
8.07 47.72 10.22 477.18 61.34
Purlin Weight
KG/CM2 mm mm mm mm mm cm2 cm3 cm3 cm4 cm4
Section Modulus about Major Axis Section Modulus about Minor Axis Moment of Inertia about Major Axis Moment of Inertia about Minor Axis
3.519 kg/sqm
Output Summary Section Properties OK?
OK OK
Stresses Ok? Critical Stress Factor
OK 0.73
Deflection Check OK?
OK
Hence, Overall:
OK
Based on Section 9 of BS:5950 Part 5 – 1998 Based on IS 801 Clause 5.2.2.1
Notes:
1. Section Properties Check based on Section 9 of B:5950 Part 5 is a guideline and not mandatory Hence, Design is considered Safe even if above check only is not okay but all other che 2. Currently, this design only works if full width is effective. If full width is not effective, this spreadsheet will report Failure in Stress Check 3. Not suitable currently for curved roofs. 4. Design is not suitable for varying spans of purlins (varying truss spacing)
e and not mandatory okay but all other checks are okay effective,
Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd Z Purlin Design Report
Prepared By Madurai ES Consultancy Services Pvt Ltd. Code Author: S. Arunkumar, Managing Director.
Code Version: R1
Code Year: 2011
Revision History
R0: Basic Design with checks for Stresses and Deflection based on IS 800 only R1: Added Section property checks and Allowable Stress Calculations based on IS 801
JOB No.:
4786
DATE :
16/8/11
Input Data: Purlin Geometry Span of the purlin Spacing of the purlin No. of Sag rods Slope of the Roof
= = = =
5.500 M 1.2 M 0 10 deg.
Number of Spans
=
3
Bending Moment Coefficients: Use 8 for Single/Two spans, 10 for 3 or more spans Bending Moment Coefficient for Mxx(BMCX) For Bending About Minor Axis, Number of spans= number of spans x (number of sagrods+1) Number of Spans about Minor Axis = Bending Moment Coefficient for Myy(BMCY) TRY PURLIN SIZE C 150x50x3.15 Cross Sectional Area of Purlin = Purlin Weight
10 3 10
8.28 cm2 6.500 kg/m 5.417 kg/sqm
=
(Area in sqcm x 0.785 kg/sqcm/m) in kg/m (Weight in kg/m)/spacing
Design Calculations: Primary Load Cases DEAD LOAD Weight of Sheeting Self Weight of Purlin (calculated above) Extra load for weight Other Dead Loads
6.000 5.417 0.542 0.000
10 % of purlin weight
Total Dead Load =
kg/sqm kg/sqm kg/sqm kg/sqm
11.958 kg/sqm 0.120 kN/sqm
LIVE LOAD Live Load on Roof = 75 kg/sqm if slope is less than 10 degrees. If Slope is more than 10 degrees, LL = 75 – 2x(slope-10), subject to minimum of 40 kg/sqm Live load on Roof
=
75 KG/M2
Additional Live Loads to be considered = (For Design of Wall Girt (Cladding Runner), additional Live loads to be considered can be entered as -ve of LL on roof) Total Live Load =
0 KG/M2
75 kg/sqm 0.750 kN/sqm
WIND LOAD Basic Wind Speed Vb k1 k3
44 m/s 1 1
Terrain Category Maximum Horizontal Dimension of Building Hence, Building Class is Height of Top
3 44 m B 8.25 m
Based on the above data, k2 is obtained from the tables k2 0.88 Design Wind Speed Vz=k1.k2.k3.Vb Design Wind Pressure pz=0.6Vz^2 = Ht of building at eaves level, h
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38.72 m/s 899.543 N/sqm 0.900 kN/sqm =
6.35 m
Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd Width of the building, w Length of the Building, l Hence, h/w and l/w
= = = =
Based on the h/w and l/w, the values of Cpe is obtained from tables as noted below: Maximum Downward Cpe (including sign) Maximum Upward Cpe (including sign) Based on % of openings, Cpi is taken as +/-
24 m 44 m 0.265 1.833
-1.2 -0.8 0.7
Wind Load is included in two load combinations – DL+WL and DL+LL+WL Since, Dead Load and Live Load are downward, DL+WL will be critical for the maximum upward wind force Similarly, DL+LL+WL will be critical for the maximum downward wind force WL1: Maximum Upward Wind Force – To be used in combination DL+WL1 Maximum Upward Cpe (including sign) Cpi to use (for upward, use -)
-1.2 -0.7
Hence, Cpe+Cpi =
-1.9
Design Wind Pressure pz
0.900 kN/sqm
Wind pressure for Purlin Design
-1.709 kN/sqm
WL2: Maximum Downward Wind Force – To be used in combination DL+LL+WL2 Maximum Downward Cpe (including sign) Cpi to use (for upward, use -)
-0.8 0.7
Hence, Cpe+Cpi =
-0.1
Design Wind Pressure pz
0.900 kN/sqm
Wind pressure for Purlin Design
-0.090 kN/sqm
Design Calculations: Primary Load Cases – Conversion of forces to Normal And Tangential Components Spacing of the purlin Slope of the Roof
= =
1.2 m 10 degrees
Total Dead Load
=
0.120 kN/sqm
DL Normal Component = DL x Spacing x cos(slope) = DL Tangential Component = DL x Spacing x sin(slope) =
0.141 kN/m 0.025 kN/m
Total Live Load
0.750 kN/sqm
=
LL Normal Component = LL x Spacing x cos(slope) = LL Tangential Component = LL x Spacing x sin(slope) = Total Wind Load in WL1
=
0.886 kN/m 0.156 kN/m -1.709 kN/sqm
WL is normal to roof Hence, WL1 normal component = WL1 x Spacing = And, WL1 Tangential component =
-2.051 kN/m 0.000 kN/m
Total Wind Load in WL2
-0.090 kN/sqm
=
WL is normal to roof Hence, WL2 normal component = WL2 x Spacing = And, WL2 Tangential component =
Design Calculations:Summary of Loads in Load Combinations
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-0.108 kN/m 0.000 kN/m
Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd From above calculations, the components of load in the various load combinations are tabulated DL+LL DL+WL1 DL+LL+WL2 Normal Load 1.028 -1.910 0.920 kN/m Tangential Load 0.181 0.025 0.181 kN/m For Strength Design, 0.75 factor is applicable for combinations with Wind Load since 33.33% extra stress is allowed Hence, the components of load in the various load combinations for Strength design are DL+LL 0.75(DL+WL1) 0.75(DL+LL+WL2) Normal Load 1.028 -1.433 0.690 kN/m Tangential Load 0.181 0.019 0.136 kN/m Maximum Normal Component =
1.028 kN/m
Purlin Section Selected: Section Name
C 150x50x3.15
Yield stress of material Flange Width, b Depth of section d Thickness t Length of Lip lip_l Internal Bending radius Total bending Radius, rad
2400 50 150 3.15 20 4.73 7.88
Flange Width w/o bend, w = b – 2 x rad
34.24 mm
Purlin Weight
kg/sqcm mm mm mm mm mm mm
Area
8.28 cm2
Zxx
35.40 cm3
Zyy
7.67 cm3
Ixx
266.00 cm4
Iyy
26.70 cm4
= =
6.500 kg/m 5.417 kg/sqm
(Area in sqcm x 0.785 kg/sqcm/m) in kg/m (Weight in kg/m)/spacing
Design Calculations: Checking Basic Section Properties based on Section 9 of BS:5950 Part 5 – 1998 Check No. 1 – Overall Depth <= 100t & >=L/45
Overall Depth 100t = L/45 =
150 mm 315 mm 122.222 mm
Hence
Ok
Check No. 2 – Overall Width of Compression Flange<=35t
Flange Width, b 35t =
50 mm 110.25 mm
Hence
Ok
Check No. 3 – Width of Lip >= b/5
Width of Lip B/5 =
20 mm 10 mm
Hence
OK
Check No. 4 – Total Width over both flanges >= L/60
Total Width over both flanges L/60 = Hence
96.85 mm 91.667 mm OK
Check No. 5 – Zxx of Purlin >= WL/1400 for Simply Supported Purlin and >=WL/1800 for Continuous Purlin
Zxx
=
35.40 cm3
W is normal component of unfactored distributed dead load plus imposed load in kN L is span of purlin in mm
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd W= L= Number of Spans = Hence, denominator =
5.652 kN 5500 mm 3 1800
WL/denominator
17.270
Hence
Ok
Result 1: Check for Section Properties Based on BS 5950 Part 5 Sec.9:
OK
Design Calculations: Checking Basic Section Properties based on IS 801 for Lip of Purlin Minimum Depth of Lip shall be 2.8 x t x ((w/t)^2-281200/Fy)^(1/6) and not less than 4.8t t= w= Fy= w/t= 2.8 x t x ((w/t)^2-281200/Fy)^(1/6) 4.8t=
2.3 49.4 2400 21.4782608696 17.048 11.04
Lip l=
mm mm kg/sqcm mm mm
20 mm
Hence
OK
Lip is Edge stiffener only if w/t<60 Here, w/t =
21.4782608696
Hence
OK
Result 2: Check for Section Properties Based on IS 801 Clause 5.2.2.1:
OK
Design Calculations: Stress Checks Check for w/t, lim = 1435/sqrt(f)
As per clause 5.2.1.1 of IS 801, f is the actual stress in compression element computed based on effective width Compression stress based on full width = Max (Mxx/Zxx+Myy/Zyy) for all three unfactored combinations
Span for major axis bending = Span of purlin = 6.000 m Span for minor axis bending = Span of purlin / (no. of sagrods + 1) = 2m Bending Moment Coefficient for Mxx(BMCX) Bending Moment Coefficient for Myy(BMCY) Note: Calculation for the above is at the top of the report DL+LL Normal Load Tangential Load
1.179 0.383
-1.724 0.055
DL+LL+WL2 1.337 kN/m 0.383 kN/m
Mxx Myy
4.244 0.153
6.207 0.022
4.812 KN-m 0.153 KN-m
88.947 14.988
130.077 2.148
100.849 N/sqmm 14.988 N/sqmm
103.935
132.225
115.837 N/sqmm
Mxx/Zxx Myy/Zyy Mxx/Zxx+Myy/Zyy Max. Compression Stress = f
= =
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DL+WL1
10 10
132.225 N/sqmm 132.225 N/sqmm 1322.249 kg/sqcm
Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
https://www.youtube.com/watch?v=OBXsA1vuKR0 https://www.483scaffolddesign.com/design-calculations
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
1435/sqrt(f) = w/t =
39.463 21.4782608696
Hence
Design is restricted to Fully Effective Section
OK
Maximum Compressive Stress based on Lateral Buckling of Flange, as per Clause 6.3 of IS 801
Calculate X=L2Sxc/(dIyc) and Y = Pi2ECb/Fy Fb, the Allowable Compressive Stress based on Lateral Buckling of Flange is calculated as X<0.18Y implies, Fb = 0.6 Fy - CASE (i) X>0.18Y but X<0.9Y implies, Fb= 0.667 Fy – Fy . X / (2.7 Y) - CASE (ii) X>0.9Y implies Fb = 0.3 Fy . Y / X - CASE (iii) L = Unbraced Length of member = Span / (Number of sagrods+1) Sxc = Compression Section Modulus of section about major axis = Zxx d = Depth of Section = Iyc = Moment of Inertia of the compression portion = Iyy/2
200 47.72 20 30.6708864958
Hence, X =
cm Cm^3 cm Cm^4
3111.639 (unitless)
Pi = E = Modulus of Elasticity, as per IS 801 is taken as Cb as per IS 801 can be taken conservatively assuming M1=0 (end span) Fy =
3.1415926536 2074000 kgf/sqcm 1.75 2400 kg/sqcm
Hence Y =
14925.720 (unitless)
Hence, 0.18 Y = And, 0.9 Y =
2686.630 13433.148
Comparing X with 0.18Y and 0.9Y, the applicable case is
2
Hence, Fb = = =
0.667Fy-Fy.X/(2.7Y) 1414.688929635 kg/sqcm 141.469 N/sqmm
=
1440 kg/sqcm 144 N/sqmm
=
141.469 N/sqmm
Basic Allowable Design Stress = 0.6Fy
Hence, allowable stress is calculated as lower of the two DL+LL Mxx/Zxx+Myy/Zyy Allowed
DL+WL1 103.935 141.469
132.225 188.154
Safety Ratio
0.735
0.703
Max. Safety Ratio
0.735
DL+LL+WL2 115.837 N/sqmm, calculated above 188.154 0.616 OK
Shear Stress in Web
As per clause 6.4.1 of IS 801,allowed maximum average shear stress Fv in kgf/sqcm is calculated as Case 1: If h/t is less than 4590/sqrt(Fy), Fv=1275 x sqrt(Fy) / (h/t) Case 2: If h/t is more than 4590/sqrt(Fy), Fv=5850000 / (h/t)^2 Both are subject to maximum 0.4Fy h t Hence, h/t =
195.400 mm 2.300 84.957
4590/sqrt(Fy) =
93.693
Hence, Case is :
1
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1275 x sqrt(Fy)/(h/t) = 5850000/(h/t)^2 = 0.4Fy =
735.223 810.518 960
(Clear Depth between flanges = Depth – 2 x thickness)
Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
Hence, Fv =
to maximum of 0.4Fy = 735.223 kgf/sqcm
Actual Shear
'=wl/2
Here, w = SQRT(Wn^2+Wt^2)
DL+LL
0.75(DL+WL1) 0.75(DL+LL+WL2) -1.293 1.003 kN/m 0.041 0.287 kN/m
Normal Load Tangential Load
1.179 0.383
w= Hence, Shear= Shear Stress fv=V/dt
1.240 3.719 8.275
1.294 3.881 8.636
1.043 kN/m 3.129 kN 6.962
Stress Ratio
0.113
0.117
0.095
Max. Shear Stress Ratio in Web
Hence
0.117
OK
Bending Stress in Web
As per clause 6.4.2of IS 801 for the design check of allowable stress in combined shear and bending Fbw = 36560000/(h/t)^2 Here, h/t already calculated above as 84.957 Hence, Fbw =
5065.388 kg/sqcm 506.539 N/sqmm Basic Allowable Design Stress calculated earlier = 0.6Fy 144 N/sqmm Hence, governing value for Fbw =
144 N/sqmm
Already calculated fbw = Mxx/Zxx since Zyy at web is very high (x=t/2, Z=I/x) DL+LL DL+WL1 DL+LL+WL2 Mxx/Zxx 88.947 130.077 100.849 N/sqmm Fbw 144 191.52 191.52 Safety Ratio 0.618 Max. Safety Ratio 0.679 In summary, Bending stresses in Web is:
0.679
0.527 OK
Combined Shear and Bending Stresses in Web
As per clause 6.4.3 of IS 801 for the design check of allowable stress in combined shear and bending SQRT((fbw/Fbw)^2+(fv/Fv)^2) must be less than 1 In this clause, Fbw is not restricted by 0.6Fy and Fv is not restricted by 0.4Fy
DL+LL 506.539 735.223
673.697 977.847
DL+LL+WL2 673.697 977.847
Actual stresses already calculated are fbw 88.947 fv= 8.275
130.077 8.636
100.849 6.962
Hence, Fbw = And Fv =
DL+WL1
fbw/Fbw fv/Fv
0.176 0.011
0.193 0.009
0.150 0.007
SQRT of sum of squar
0.176
0.193
0.150
Maximum Combined Stress Ratio in Web is In summary, Combined stresses in Web is:
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0.193 OK
Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
Result 3: Check for Stresses:
OK
Overall Safety Ratio
0.735
Design Calculations: Deflection Check Theoretical Deflection is calculated as (5/384) (wl^4/EI) for Simply Supported beam and (3/384) (wl^4/EI) for multiple spans Here, number of spans =
3
Hence, formula to use =
(3/384) (wl^4/EI)
w is normal component of unfactored distributed load in kN/m, max. of all load combinations = 1.724 kN/m L = Span of the Purlin
6.000 m
E = Modulus of Elasticity, as per IS 801 is taken as =
2074000 kg/sqcm 207400 N/sqmm
I = Ixx
477.18 Cm^4
Hence, Theoretical Deflection =
17.64 mm
Allowable Deflection as IS codes is Span/180:
33.33 mm
Hence
OK
As per MBMA, allowed deflection from Live load component must be within Span/240 Span
6.000 m 6000 mm
or Span/240 =
25.00 mm
Normal Component of Live Load Hence, deflection from Live Load =
1.01 kN/m 10.3331229651
Hence
OK
Result 4: Check for Deflection:
OK
Results Summary
Section Properties OK?
OK OK
Stresses Ok? Critical Stress Factor
OK 0.73
Deflection Check OK?
OK
Hence, Overall:
OK
Based on Section 9 of BS:5950 Part 5 – 1998 Based on IS 801 Clause 5.2.2.1
Notes:
1. Section Properties Check based on Section 9 of B:5950 Part 5 is a guideline and not mandatory 2. Currently, this design only works if full width is effective. If full width is not effective, this spreadsheet will report Failure in Stress Check 3. Not suitable currently for curved roofs. 4. Design is not suitable for varying spans of purlins (varying truss spacing)
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Z Purlin Design Created Report by Madurai ES Consultancy Services Pvt Ltd
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