a novel topology for lattice telecommunication towers ......2015/01/01  · which are more...

GLOBAL INSIGHTS OF THE STRUCTURE

DESCRIPTION: Fully tapered 2D designeddomain

HEIGHT: 19m (17m+2m Cap)BASE WIDTH: 4m

LOADING SCENARIO: Distributed load -changed while optimizing the topology

SUPPORTS : Full base fixedEDGE LINES SLOPE (17m from bottom to

the cap): 1:17FUNCTION OBJECTIVE: Weighted

complianceCONSTRAINT: Volume fraction

STO ANALYSIS DETAILS

Connection

column-beam

or column-

bracing

Bracing

members

orientation

and

intermediate

joint

Comparing tower OT with UA: 11% lighter, 4-5% higher fi in the two bending modes, 0.8%lower fi in the torsional mode (highly distortedshape), higher modal stiffness in all modes.

OptiStruct geometry transformed to 3D lineCAD model into Oasys GSA and embraced withEHS. Then compared against a conventionaltower model UA (comprised of RAS members).

Can we use computationalstructural topology optimization(STO) to create a new exoskeletonfor lattice self-supported towersthat will possess improvedstructural characteristics, highaesthetic value but at the sametime maintain its functionalutility?

Broadcasting television and radio systems, signal-transmission for the provision of wireless internet,telecommunication and two-radio services,necessitate the use of antennas and dish-reflectorswhich are more economically mounted on latticeguyed masts or self-supported (SS) towers. Thisstructures can be generally characterized as light,tall and flexible.

School of Civil Engineering

A Novel Topology For Lattice TelecommunicationTowers developed through a Computational

Morphogenesis Process

2 - THE CHALLENGE1 - INTRODUCTION

The lattice morphology has been a definingcharacteristic.

Almost as visually intrusive as they wereseveral decades ago.

Of course this depends on the solidity of thestructure.

Solidity will depend on the type of structuralmembers and the exoskeleton topology.

Such structures have obviously escaped theattention of Engineers and Architects.

AESTHETICS

The tool which enables SIMPalgorithm to produce skeletonstructures or members with improvedweight and stiffness characteristics aswell as high aesthetic value.

Achieve through optimum materialdistribution within a 2D or 3Ddesigned domain representing thecircumference geometry of astructure. (Altair’s OptiStruct)

Density plots: Red = 100% - Blue = 0%.

3 - STRUCTURAL TOPOLOGYOPTIMIZATION (STO)

Numerous optimization analyses wereperformed on 2D and 3D domains ofdifferent shapes. This provided the mostconsistent and realistic results was thefully tapered domain presented withinSection 5. Their validity was verifiedagainst the optimal cantilever bracing(OCB) of Stromberg et al. (2012). All anglesdeemed to these of Stromberg’s OCB.

4 - TAPERED 2D CONCEPTUALLAYOUT OF STO ANALYSIS

(a)2D domain (b)Analysis output: element-

density plot (c)Rendering plot (d)GSA model OT

Bracing panels: bottom-top OCB by

Stromberg

5 - MORPHOGENESIS PROCESS

(a) Bending mode 1

6 - Model OT VS Model UA

The new exoskeletonhas improved weight,stiffness and otherstructuralcharacteristics.

High aesthetic valuehas been achieveddue to the intriguingtopology, slenderform, use of EHS andnot being visuallydistracting with densemembers.

Antenna cap has beenproved effective forthe design.

STO is effectively usedto create exoskeletonstructures.

8 - CONCLUSIVEREMARKS

Typically use right angle sections (RAS) orcircular hollow sections (CHS).

RAS lead to high solidity and wind drag, pooraesthetic value and eccentric connections.

CHS lead to reduced solidity and wind drag,improved aesthetic value and concentricallyloaded connections.

Elliptical hollow sections (EHS) were rarelyor never used in the past.

EHS can significantly reduce the solidity ofthe structure in the along wind direction andcan improve the aesthetic value of the tower.

Supervised by Dr Konstantinos Daniel Tsavdaridis MEng (Hons) Civil, MSc, DIC, PhD, CEng, EUR ING, M.ASCE, M.IASSBy Andreas Nicolaou MEng Civil & Structural Engineering 2015/16 MSc

Research Grants

LOCAL INSIGHTS OF THE STRUCTURE

High solidity & poor aesthetic value

STRUCTURAL MEMBERS

(b) Bending mode 2 (c)Torsional mode

Test the tower underdynamic loadings(including windsimulation using CFD).

Wind performanceand local effects wheniced cross-sections.

Incorporate horizontalbracings into themodel to improve itstorsional response.

Apply the concept ofdeployable structures.

9 – FUTURE WORK

Nielsen, M.G and Støttrup-Andersen, U. 2006. Advantages of using tubular profiles for telecommunication structures. In: Tubular Structures XI Willibald, S. and Packer, J.A., 31 August/2 September, Quebec City. London: Taylor& Francis Group plc, pp. 45-51.Stromberg, L.L., Beghini, A., Baker, F.W. and Paulino, G.H. 2012. Topology optimization for braced frames: Combining continuum and beam/column elements. Engineering Structures. 37(No issue number), pp. 106-124.

REFERENCES

Model UA UA OT OT

Modefi

(Hz)ki

(N/m)fi

(Hz)ki

(N/m)

(a) 7.12 1.0E+6 7.41 1.9E+6

(b) 7.14 1.1E+6 7.52 1.6E+6

(c) 14.5 8.0E+6 14.4 9.5E+6