ISSN 2319-8885
Vol.06,Issue.21
June-2017,
Pages:4197-4201
www.ijsetr.com
Design and Calculation of Dynamic Wind on 50m High Guyed Mast Tower
M. P. NAGA DURGA SRI RAMYA KRISHNA1, I. J. L. PRASANNA KUMARI2
1
PG Scholar, Dept of Civil Engineering, DJR College of Engineering &Technology, Vijayawada, AP, India,
Email: ramya.madireddy83@gmail.com.
2
Associate Professor, Dept of Civil Engineering, DJR College of Engineering &Technology, Vijayawada, AP, India,
Email: janaki102@gmail.com.
Abstract: The purpose of this study was to develop a new type of guyed mast tower. Guyed masts are a specialized type of
structure commonly used in the broadcasting industry to support equipment at substantial heights. The main purpose of this
tower it measures air quality surrounding areas. tower design must be tested for operational wind speed of 50m/sec. the design of
tower legs guys tie members bracings and guy joint at foundation level, bottom hinge for the tower, foundation for the tower
mast and guy support including finite element method (FEM) analysis. The static analysis of a one-level guyed mast has been
undertaken. The effects of geometrical and physical design parameters on the displacements of the mast were determined. With a
particular focus on the effect of static loading on the response mast behaviour. The wind effect on the structure is studied by
using the gust factor method and the seismic effect on the structure is studied by carrying out the modal analysis and response
spectrum analysis. The design of tower 50 m high guyed towers. All steel frames should be made of galvanized steel to
withstand harsh forest condition. tower installation should include necessary civil foundation work (tower base) for the
prescribed tower including guy foundation tension in the guy wires have to be adjusted by means of tension meter or by any
other standard method and the vertically of the assembled tower have to be assured within the tolerance specified. The results
obtained from the above analysis are tabulated, compared and conclusions are drawn.
Keywords: Guyed Masts, Bracings, Wind Analysis, Gust Factor Method, Structural Analysis.
I. INTRODUCTION
In our present study a linear static analysis of guyed mast
are considered for its structural response. Masts supported
laterally by guy cables usually provide a more economical
solution for taller towers. The cables are anchored to the
ground and are always pretension. Due to overall flexibility,
slenderness and lightweight, guyed masts are susceptible to
large deflections and also exhibit high dynamic sensitivity to
turbulent winds. As a result, dynamic analysis is considered
imperative for calculating the peak axial forces in the mast.
A suitable structural dimension of the model is identified and
the wind forces acting on the structure is calculated at
different guy levels. The standard approach for the
equivalent static analysis of line-like structures, based on the
gust factor, is reviewed, with special reference to the case of
systems with intermediate elastic supports, like cable-stayed
masts. A new analysis method, based on the definition of a
gust function variable along the height is proposed and
applied to a case study. The loads will be calculated as per IS
875-1987 (part3).The linear static analysis will be carried out
using SAP2000V14. The preliminary design is done. The
dimensions of mast is fixed by trial and error method. The
height of the mast is fixed as 100m. Base width of the mast
is 1m. pressurised cable diameter as 20mm. Most research
has been undertaken into the modelling of a guyed mast as
an equivalent beam element. The self-weight of a lattice
truss is substantially different to that of a beam element with
similar behavioural properties. In order to control the dead
load and mass of the mast, the self-weight and mass of the
mast (calculated from section properties of the equivalent
beam) were set to zero. The correct values, calculated from
the original lattice mast were then applied as additional
loadings and masses to the mast. The equivalent beam
stiffness for the masts used in this research had already been
calculated
A. Linear analysis
Any practical structure having mass and elasticity tends
to vibrate on application of external loading. Analysis of the
structure is conducted to determine the distribution of forces
and deformation induced in the structure by the ground
shaking. Linear procedure is applicable to the structure that
responds in an elastic manner. The linear static analysis is
done.
B. Finite Element Analysis
For analysis of guyed mast the mast is modelled as frame
element and cables are modelled as truss element. The Fig.3
shows the plan view of guyed mast. FEA consists of a
computer model of a material or design that is stressed and
analysed for specific results. It is used in new product
design, and existing product refinement. A company is able
Copyright @ 2017 IJSETR. All rights reserved.
M. P. NAGA DURGA SRI RAMYA KRISHNA, I. J. L. PRASANNA KUMARI
to verify a proposed design will be able to perform to the
consideration of their interaction with isolators chains,
client's specifications prior to manufacturing or construction.
hardware and cables. In their study, they analyzed
In case of structural failure, FEA may be used to help
dynamic characteristics of wind loads acting on support
determine the design modifications to meet the new
towers, considering their interaction with isolator’s
condition.
chains, hardware and cables. The main aim of their
study is to analyze the dynamic
4. effects produced by the accessories on the support
C. Design of steel mast :
1. Steel mast anchored at different heights, is loaded in
towers. For their study in order to obtain the cable
bending due to wind, and compression from vertical
breakage, they developed a method. The analysis is
loads (dead load, live load, pretension forces in the
carried out on two support tower, with different
cables).
foundation conditions and the dynamic effects were
2. Pretension force in cables is determined so that in case
evaluated by using time dependant function.
the cable is unloaded due to wind action, the cable
5. Srikanth L and Neelima Satyam D, [15]studied about
should still be subjected to a tension force.
the dynamic analysis of tower. The dynamic analysis of
3. As a rule, if the guy is attached in the top of the tower
tower is carried out using numerical time stepping finite
(100% ),the tension should be 8% of the tensile strength.
difference method. The important parameters in
4. For 80% of the tower's height, 10% tension should be
designing the tower include acceleration, frEQuency,
applied.
and velocity. From the study of tower it is clear that
5. If the anchor point is at 65% of tower height, 15%
breaking load is the critical combination among the
tension can be applied as you loose a lot of wind load in
forces developed in the structure. It is also clear that the
this last type of installation.
maximum axial force in the leg members is 1600kN
6. The breaking strength will improve the control of the
including the breaking load combination and it is
flexibility and still not cut down on the cable strength.
reduced to 522.382kN without considering breaking
Normally, a tower has 2-3 levels of guys (depending on
load.
the height of the tower/mast) and four guys on each
level. It is recommendable to use turnbuckles as it will
III. METHOD OF ANALYSIS
allow you to fine tune your adjustments later on.
The internal forces in the members of a statically
7. After the internal efforts in members is determined
determinate pin jointed frame are only axial forces. These
(legs, straight), they are designed using relevant
can be determined by using
verifications.
1. Method of sections
8. For one segment of the mast, members of the same type
2. Method of Joints
have similar sections.
A. Method of Joints:
In this method, the free bodies of the joints are
II. LITERATURE REVIEW
1. Marcel I. R. et.al. [20]had proposed an alternative
considered one by one and the equations of Equilibrium are
structural analysis modeling strategy for guyed steel
written for each joint in terms of ∑Fx and ∑Fy. Assuming
towers design, considering all the actual structural
the support reactions have been computed from the overall
forces and moments, by using three-dimensional beam
Equilibrium of the structure. In this method there are 2/3
and truss finite elements because in the usual structural
numbers of unknown reactions at a joint if it is a plane/space
analysis, models assumed as simple truss where all the
truss. In the plane truss analysis, the analysis will be start
steel connections are considered hinged. Initially the
from the support where only two members will meet. This
comparisons are based on static and dynamic structural
analysis is continued by finding the member forces from one
behavior of the towers. Later the linear buckling
joint to another joint.
analysis is carried out to determine the influence of the
various modeling strategies on the tower stability
B. Method of Sections:
behavior.
In this method, the structure is intersected by suitable
section and the Equilibrium of the free body of the structure
2. Shakeel Ahmad and Md. Ehtesham Ansari [1]
studied about the tower failures due to High Intensity
on either side of the section is considered. The forces in the
Winds (HIW) associated with tornadoes and micro
members intersected by the section are treated as external
bursts. They conclude that the towers are highly affected
forces in writing the Equations of Equilibrium. Since the
by the tornadoes and the study shows that the maximum
conditions of Equilibrium provide only three independent
displacement occurs at the top of the tower in both X
Equations in the case of plane structure, it is preferable to
and Y direction. They also conclude that the maximum
select a section which interests not more than three members
displacement at nodal increases rapidly from 12m height
unless the forces in some of the intersected members are
to the top of the tower in both X and Y directions. All
already known. When the section intersects only three
the analysis of tower is carried out using STAAD-PRO.
members, the axial forces in the member may be determined
3. N. R. Cuevas and R.M. Hernández, [2]analyzed that
by taking moments about the same points at which two other
in the study of support towers, the support towers are
points meet. This method is much helpful in quickly
considered as isolated structures, without any
accessing particular member force in the overall structure.
International Journal of Scientific Engineering and Technology Research
Volume.06, IssueNo.21, June-2017, Pages: 4197-4201
Design and Calculation of Dynamic Wind on 50m High Guyed Mast Tower
Fig 3. 3-dimensional view of the Guyed mast tower.
Fig 1.Seismic load parameters.
IV. MODELLING AND ANALYSIS OF GUYED MAST
SYSTEM
A. Tower modelling :
The towers are modelled in Staad.Pro. The towers are
separated into panels consisting of various members and trial
sections for analysis are assigned. Positioning Of Guy Wires
As we know that the guy tower relies on the guy wires to
safely dissipate the forces that are acting on the tower. So the
attachment point of guy wire on the tower and the angle in
which it is attached to the horizontal plane plays an
important role in dissipating the forces on the tower
The masts of most guyed towers include three planar
tmsses of equal width joined to each other along the edges,
as shown in Figure 3. The general tmss arrangements are Xbraced and Warren with verticals. Tmsses comprise of onedimensional bar elements and are assumed to be connected
forming a frictionless pin joint at the common nodes. Each
node has three degrees of freedom, making a total of six
degrees of freedom per element.
B. Static Analysis of Guyed Masts
For the static analysis of guyed masts, cables and the
mast are analyzed separately to maintain tight handedness of
the system matrices. The solution is obtained iteratively, and
displacement compatibility is ensured between the top end of
the cables and the mast. In each iteration, the reactive guy
forces at the top end are added to the global force vector and
the global stiffness matrix of the mast is augmented by the
stiffness of the cables.
Fig 2. Elevation Along X – Axis.
International Journal of Scientific Engineering and Technology Research
Volume.06, IssueNo.21, June-2017, Pages: 4197-4201
M. P. NAGA DURGA SRI RAMYA KRISHNA, I. J. L. PRASANNA KUMARI
Table 2. Displacement Result.
At ground level Above 30m level
Fig 4. Nodal Numbering for Tightly Banded System
Matrices.
V. RESULTS AND DISCUSSION
A. Staad.pro Analysis
The Analysis of guyed mast tower section properties
members is carried out as per staad.pro analysis, all the
tower members are safe.
B. Designed Structure
The selected members and their uses are tabulated in Table
2.All beams in the moment frame use reduced beam sections
the reduced beam sections lead to larger story drifts, but
members were not designed for strength corresponding to
their reduced beam sections, as instructed. These members
are capable of satisfying both strength and serviceability
requirements. Some constructability difficulty is likely from
some of the differences in member sizes, but connections are
beyond the scope of this project.
Table 1. Structural Shapes Used
Fig 5. Results of 50m mast subjected linear transient
analysis (at top guy level).
VI. CONCLUSION
 After the study of tower with base width, it is clear that
height of tower is directly proportional to the base
width.
 The study of different loading conditions on structures is
very important to recognize the case that will cause the
larger deflection in tower model and exceed the yield
stress to decide which case will be optimized.
 The geometry parameters of the tower can efficiently be
treated as design variables, and considerable weight
reduction can often be achieved as a result of geometric
changes
 The tower with different steel section decides the weight
of Tower. And the Tower structure with least weight is
directly associated in reduction of the foundation cost.
 The mast tower with X-bracing is lighter than that with
Y-bracing with tabular sections under wind and seismic
load conditions.
 The tower with steel section and X-bracing has the
greater reduction in weight after optimization
International Journal of Scientific Engineering and Technology Research
Volume.06, IssueNo.21, June-2017, Pages: 4197-4201
Design and Calculation of Dynamic Wind on 50m High Guyed Mast Tower
[12] Chien, C. W. and Jang, J. J., “Wind-resistant design of
 Optimization of tower geometry with respect to member
high mast structures,” Asia Pacific of Engineering Science
forces. The tower with base width 2.8m is concluded as
and Technology, Vol. 3, No. 2, (2005).
the optimum tower configuration with respect to
geometry.
Author's Profile:
 This Study analytically examined the seismic behaviour
M P Naga Durga Sri Ramya Krishna,
of guyed masts that incorporate synthetic ropes as guys.
received herB.Tech degree in Civil
Much research has been performed on the behaviour of
Engineering and pursuing M.Tech degree in
guyed masts under wind loads, as this generally controls
Civil Engineering(structural) from DJR
the design
College of Engineering & Technology.
 Geometric nonlinearities and cable-mast interaction are
important and should be simulated properly by using
appropriate type and number of elements in the cable
model, suitable formulation, and also the correct
I J L Prasanna Kumari, received her
modelling of inertia properties of both the mast and the
M.Tech degree and B.Tech degree in Civil
guy cables.
Engineering. He is currently working as an
 Cable-mast interaction and local resonance of the cables
Assoc Professor in DJR College of
sets at the upper levels which are connected to the outer
Engineering & Technology.
anchor contribute to the response.
VII. REFERENCES
[1] Helin Zhou “On estimation of the effective height of
towers on mountaintops in lightning incidence
studies”,Journal of Electrostatics, vol.68, 2010, 415-418.
[2] PiaRepetto, “Dynamic along wind fatigue of slender
vertical structures”, International Journal on engineering
structures, vol.23, 2001, 1622-1623.
[3] P. Harikrishna, A Annadurai, A. Gomathinayagam, N
Lakshamanan, “Full scale measurements of the structural
response of a 50 m guyed mast under wind loading”,
Research paper, vol.25, Dec 2002, 859-867.
[4] Gregory M. Hensley,Raymond H. Plaut, “Threedimensional analysis of the seismic response of guyed
masts”, International Journal on engineering structures,
vol.29, 2007, 2254-2261.
[5] M. Belloli,“Wind loads on a high slender tower:
Numerical and experimental comparison”, International
Journal of engineering structures, vol.68, 2014, 24-32.
[6] Lasse M konen, Pertti Lehtone, Mika Hirviniemi
,“Determining ice loads for tower structure design”,
International Journal of engineering structures, vol.74, 2014,
229-232.
[7] MassimilianoLucchesi, “A numerical model for nonlinear dynamic analysis of slender masonry structures”,
vol.68 , 2006 , 24-32.
[8] Neil I. Fox ,“A tall tower study of Missouri winds”,
International Journal of Renewable Energy, vol.36 ,
2011,330-337.
[9] Cello F.Carri “Experimental Study of The Wind Forces
on Rectangular Lattice Communication Towers with
Antennas" Journal of Wind Engineering and Industrial
Aerodynamics, vol. 91. 1007-1022.
[10] Simiu, E., Scanlan, R., “Wind Effects on Structures:
Fundamentals and Applications to Design”., John Third
Edition Wiley & Sons, New York, 1996
[11] Sockel, H.,” Wind-Excited Vibrations of Structures”.
CISM Courses and Lectures NO. 335, International Centre
for Mechanical Sciences, 1994.
International Journal of Scientific Engineering and Technology Research
Volume.06, IssueNo.21, June-2017, Pages: 4197-4201