International Journal of Earth Sciences and Engineering ISSN 0974-5904, Volume 04, No 06 SPL, October 2011, pp. 645-647
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Comparative Study of Supporting System of Elevated Ground Based Billboards K.A. Parmar Research Scholar, Applied Mechanics Department, L. D. College of Engineering, Gujarat Technological University, Ahmedabad, Gujarat (India) Email: kaparmar.19@gmail.
[email protected] com
M.G.Vanza Associate Professor, Applied Mechanics Department, L. D. College of Engineering, Gujarat Technological University, Ahmedabad, Gujarat (India) Email:
[email protected] [email protected] ABSTRACT: Billboard is recent trends for outdoor advertisement. At many places it is observed that the supporting system of billboards has been failed due to heavy wind load. This paper includes different types of supporting system having multi post back to back and multi post in single line with different configuration configuration for better selection and finally it compares deflection and cost of the system. As predominant failure is due to wind, Ahmedabad city is considered as location for comparative comparative study and the height of structure structure is taken 16.75 m.. Analysis and Design Design of supporting system system is as per STAAD. Pro which follows IS 800-2007. For wind consideration IS 875(part-3) -1987 is used. KEY WORDS: Hoarding, Billboard, Supporting system INTRODUCTION Billboard is the common term used to describe a type of outdoor advertising found along major highways. This name is most frequently given to large steel-framed signs, which are mounted on poles 20-100 ft (6.1-30.5 m) above the ground. Hoarding board and Advertisement board are also used for large steel frame signs. Main Components:Large billboards have three main components: 1) Steel used to construct and support the frame, 2) Artwork that conveys the advertising message, and 3) Electrical equipment for lighting and other special effects. Standard sizes for a large steel frame assembly are 6.1m x 18.3 m, 6.1 x 14.6 m or 3 x 11 m
General Consideration: 1. Size of billboard is 6.1 m x 12.2 m 2. All supports are fixed and joints are rigid 3. Foundation is 1.5 m below from ground base. 4. Effective length of the member is taken as per IS 8002007 by STAAD Pro. 5. Billboard is made up of 2 mm thick steel plate. OBJECTIVE The main objective of the present study is to select of two common types of configuration as supporting system of billboards for comparative study. 1) Multi post in single line 2) Multi post in double line
a) b) c)
Modelling each one in software (STAAD Pro) Wind analysis as per IS 875(part-3) 1987 Design as per IS:800(2007) using STAAD Pro
Wind force acting on billboard (F) is 0.8156 kN/m 2 as per IS 875, part-3, Sec.6.3. Wind load is generated only on billboard surface.
SCOPE The present study is carried out for supporting system of billboard with multi post back to back and in single line. The study will help to select better configuration of supporting system of billboard from multi post back to back and multi post in single line from economic and displacement criteria. LOADS AND LOADS COMBINATIONS Following loads are considered for analysis of supporting system. 1) Dead load 2) Wind load in +z direction 3) Wind load in in - z direction direction Following loading combinations are considered for analysis. 1) 1.5 D.L. + 1.5 W.L 2) 1.5 D.L. - 1.5 W.L
Wind Load Calculation: Calculation: Wind load is calculated as per IS 875(part-3)-1987 Location of Billboard is Ahmedabad for comparative study. External pressure coefficient Cf is considered as per IS 875, part-3,Sec.6.3.2.3 part-3,Sec.6.3.2.3 Wind force acting on billboard (F) F = Cf x Ae x pz (IS 875, part-3, Sec.6.3) Length of billboard is 12.2 m and height is 6.1 m so b/h = 2 and billboard is above ground. Cf = 1.2 (IS 875, part-3, Sec.6.3.2.3, Table 24) To allow for oblique winds, the design shall be checked for net pressure normal to the surface varying linearly from a maximum of 1.7 C f at the up wind to 0.44 C f at the downwind edge. Maximum Cf = 1.7 ANALYSIS AND DESIGN USING STAAD Pro Standard size of billboard:
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K.A. Parmar, M.G.Vanza
TOTAL WEIGHT OF STRUCTURE: Weight of structure = 64.461 kN MAXIMUM DISPLACEMENT: Maximum nodal displacement is at top centre node and it is 62.471 mm. Case 2: Supporting system with multi post back to back with second configuration
Fig.1 Standard size of billboard for study Case 1: Supporting system with multy post back to back with first configuration
Fig.3 Supporting system cross bracing
Fig.2 Supporting system with inclined members Member Properties : Vertical members (Members parallel to Y):- Built up member having size 65 x 45 x 8 with 80 mm spacing between each angle is selected as vertical members. Members parallel to x axis: - Single angle having size 90 x 90 x 8 mm is used as horizontal members. Members parallel to z axis: - 2 ISA 200 x 150 x 12 mm with longer leg connected back to back with 12 mm gusset plate is selected as members parallel to z axis at 3.05 m from ground level. Above 3.05 m from ground level, angles are 70 x 45 x 8 mm with longer leg connected back to back with 12 mm gusset plate. Inclined members: - ISA 100 x 100x 8 mm is used as inclined members.
Member Properties: Vertical members (Members parallel to Y):- 4 ISA 90 x 60 x 8 with 100 mm spacing between each angle is selected as vertical members Members parallel to x axis:- ISA 90 x 90 x 8 mm is selected as members parallel to x axis Inclined members:- ISA 110 x 110x 8 mm is selected as cross bracing for top two rows and for bottom last row ISA 130 x 130 x 8 mm is used. TOTAL WEIGHT OF STRUCTURE: Weight of structure = 76.565 kN MAXIMUM DISPLACEMENT: Maximum nodal displacement is at top centre node and it is 59.685 mm. Case 3 Supporting system of billboard with multi post in Single row:
International Journal of Earth Sciences and Engineering ISSN 0974-5904, Volume 04, No 06 SPL, October 2011, pp. 645-647
Comparative Study of Supporting System of Elevated Ground Based Billboards
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RESULTS AND DISCUSSION
Analysis is carried out on three different supporting system of billboard with multi post back to back and multi post in single line considering wind load in positive z direction and negative z direction. Final result of comparison is shown in concluding graph. CONCLUSION
Fig.4 Supporting system with multi post in single line Member Properties: Vertical members:- ISA 150 x 150 x 10 mm is used as vertical members Members parallel to x axis:- ISA 90 x 90 x 8 mm is selected as members parallel to x axis Members parallel to z axis:- ISA 60 x 60 x 8 mm is selected as members parallel to z axis Inclined Members:- ISA 90 x 90 x 8 mm is selected as inclined members within billboard height and single angle having size 125 x 125 x 6 mm is used from G.L to 7.6 m height. TOTAL WEIGHT OF STRUCTURE: Weight of structure = 56.177 kN MAXIMUM DISPLACEMENT: Maximum nodal displacement is at top centre node and it is 36.85 mm.
From the results of above all three cases a suggestion for the configuration of supporting system for the considered size of billboard is that the supporting system with multi post in single row shows better performance against wind load resistance and displacement and it is economical compared to other considered supporting system .
REFERENCES:
[1] [2]
[3]
[4]
IS: 800-2007, General construction in steel – code of practice, Bureau of Indian Standards. IS: 875 (part-3) – 1987 Code of practice for design loads (other than earthquake) for buildings and structures of Practice, Bureau of Indian Standards. An Explanatory handbook on IS: 875 (part-3) – 1987 wind loads on buildings and structures by Indian Institute of Technology Roorkee STAAD.Pro
International Journal of Earth Sciences and Engineering ISSN 0974-5904, Volume 04, No 06 SPL, October 2011, pp. 645-647
