MONOPOLES FOR MONOPOLES FOR TRANSMISSION & DISTRIBUTION TRANSRAIL LIGHTING LTD Gammon Group Office: Boo ang, 20 /209 Boomrang,A-201/209 Chandivali farm road, Near chandivali studio, Andheri East,Mumbai 400072 M h Maharashtra, h India I di Tel: +91 (22) 40889696 Fax: +91(22) 40889666 Email:
[email protected] q@ URL: www.transraillighting.com Manufacturing Divn: Survey No. No 227/1 ,Khanvel Khanvel kherdi rd; Silvassa -396230 (U.T. Of D & N.H)`
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INTRODUCTION Nowadays most of the transmission utilities are facing problems in laying the transmission lines in urban areas due to severe Right of Way problems. This is in view of non availability of adequate land for installation of conventional lattice type towers.
To overcome these practical difficulties, new concept of
I being Is b i used d world ld wide id
MAJOR PRJECTS & CLIENTS
USE OF MONOPOLES IN TRANSMISSION & DISTRIBUTION Transmission Monopoles are Pole Structure used as replacement of Lattice Type Towers. Towers This structure helps countering the constraints as Right of Way or Corridor width. Also for hilly terrains, a Monopole can be conveniently used against a Lattice Tower. The Monopoles adds to the aesthetics of the city too. The Transmission line using a Monopole can be accommodated on Highway Curbs. These Monopole based lines can give handy solutions to ROW based problems, few of them are mentioned below: ¾Up gradation of line within the existing Corridor can be done using the Transmission line Monopole.
¾ These Monopole based lines can be constructed to feed Power to new industry from existing sub-stations, both situated in city areas, where the problem off right bl i ht off way is i severe. ¾ Relocate lines to take care of new railways / metros etc. In almost all metro cities, major work on new trains / Flyover is going on and the existing lines are required to be diverted. Use of Monopole towers can take care of such requirements. ¾ These Monopoles can be used, used where the Transmission Line is Parallel to road. ¾These Monopoles can be used, where the Transmission Line is Passing through thick forest area, thus minimize the loss to environment. Above are jjust few cases where Monopole p installation can be the solution.
DESIGN METHODOLOGY Approach to the Design of Transmission line is Similar to the Lattice type structure. etc. is carried in accordance with structure Load Calculation & Line Clearance etc the Standards / as per the Customer Specification.
REFERENCE STANDARDS IS -875 (Part-III) 1987
: Code for Wind Loads on Structure.
IS-802 (Part1/sec1) 1995
: Code for Transmission Line tower ( Material Loads & Permissible stresses. : Code for design & Maintenance of Overhead Power Lines. Lines : Code for Design of Tubular pole for Transmission Line.
IS-5613 -1985 ASCE 48-05
INPUT DATA : For Transmission Monopole Design input data is the forces i.e. ¾
Transverse load – Load on EW & Conductor due to the wind pressure & component of Mechanical tension due to line angle deviation.
¾
Longitudinal load – Unbalanced force due to broken wire condition/ Stringing.
¾
Vertical Load – Dead weight of EW, EW Conductor & other Accessories. Accessories
g parameters All these values varies with respect to the following 1.
Type of line & Deviation angle.
2.
Properties of Conductor / Ground wire.
3.
Normal Span
4.
Wind Pressure Or wind zone.
5.
Specific height requirement / Terrain.
STEPS INVOLED FOR DESIGN OF TRANSMISSION MONOPOLE Step-1
- Decide the Geometry of the Structure & Its Approximate Height.
Step-2
- Wind Pressure Calculation.
Pr cal
Step-3
- Sag Tension Calculation
sag
Step-4
- Prepare Line Clearance Diagram
diagram
Step-5
- Load Calculations ( For Reliability, Security & safety Condition)
Step-6
- Analysis of Monopole structure.
Analysis
Load Calc
DIFFERENT PROFILES OF TUBULAR MONOPOLES
DIFFERENT PROFILES OF TUBULAR MONOPOLES
BASIS OF DESIGN: BASIS OF DESIGN: Approach to the calculation is based on the Elastic Limit Principles, Where load effects are compared with ultimate resistance of the structure.
In Elastic limit state, strength or Capacity of the pole is assessed by moment of resistance at Elastic Limit & the dimensions are decided. The maximum bending stresses arising out of the calculated bending moments are maintained i t i d below b l th yield the i ld stress t off Pole. P l
Stability & Stress analysis should be carried for each structural element. Consideration should be Given to the Load effect Resulting out of deflected shape of Structure.
Finite element Model of the Structure shall be developed & Entire pole structure shall be Generated. Member
in the deflected shape shall be adequately
represented and the point of maximum Stress is adequately defined.
ANALYSIS : ANALYSIS : Analysis of structure is carried using Power line software PLS-Pole. This software allows generating the finite element model of the Monopole by selecting the component & assembling them in to the finished structure.
I can perform It f Li Linear & non linear li A l i With Analysis. Wi h the h linear li option i secondary d effect of structure displacement (i.e. P-Delta effect) is ignored, whereas in Non linear analysis P P-Delta Delta effect is considered.
PLS POLE can be run in two modes, Design g Check Mode or allowable span p Mode.
MANUFACTURING UNIT
MAXIMUM USAGE FOR EACH LOAD CASE FOR EACH ELEMENT TYPE
DESIGN CHECK DESIGN CHECK •
PLS -POLE can be run in two modes, Design Check Mode or allowable span Mode. STRENGTH CHECK: PLS-POLE checks the section strength as per following standards. ¾ ASCE /SEI ¾ TIA / EIA -222F ¾ ANSI / TIA 222-G
Design checks For each design load case, the analysis produces axial, bending, shear, and torsional stresses at the ends of each tubular element or at every Nodal point. Then Combine effect of these Stresses is Checked with the allowable stresses at that particular section. section Utility shall be less than 100%. 100%
ASCE STRENGTH CHECK For transmission poles designed according to ASCE/ SEI Standard 48-05 (ASCE, 2006) the strength usage is calculated at each of the Nodal points as: SQRT { (fa + fb )2 + 3 (fv + ft )2 } / ( fall x S.F.) Where:
fa =normal stress due to axial load fb =normall stress t d tto bending due b di fv =shear stress due to shear force ft =shear stress due to torsion fall =allowable (permitted) combined stress defined in ASCE
Standard 48-05. It is based on w/t ((multiple p flats). ) To calculate the unsupported pp flat width "w", it is assumed that a steel plate bending radius of 4 times the plate thickness is used. For a corner point, w/t is the largest of the values for the two adjacent flat faces. S.F. = Strength Factor for steel poles
Combine Allowable Bending & Axial Stresses for Polygonal Tubular Steel Pole Structures are as follows. For 16 Sided
565< √ Fy *w/t
