Abstract: results and its advantage to the industry.

Abstract:

In present
world of rising infrastructure development, trusses of different size and shape
are used on a large scale at many places. Demand for resisting heavy structural
loads and longer spans results in large and heavy trusses. Hence need for
optimization of resulting heavy and bulky trusses have been increasing. This
paper describes the use of programming language in performing optimization of
plane & space truss structures to obtain minimum weight. The algorithm uses
fixed length as vector and design variables is the c/s areas of the members.
The objective considered here is to minimizing the weight of the truss
structure. The constrictions in this problem are the stress in the member and
nodal deflection, in no member of the structure should exceed this allowable
stress and deflection of the material. As a case study, this method is applied
to a bench mark example of 10 bar truss and the results provided show that the
minimum weight obtained is further reduced by the methodology adopted.

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Keywords: Optimization, FEM, MATLAB.

                                                                                                                                                                                                                                                               
                                                                                                                                                                                     

1.      Introduction

Optimization of steel structures has a wide scope in structural
engineering due to their own complication, reliability of results and its
advantage to the industry. Weight optimization of truss structure plays a vital
role in economic and sustainability consideration. The analysis part and
optimization process is very complex and less reliable for manual calculation
hence nowadays powerful computing systems are used to solve huge data set of
structure and gives desired results with accuracy.

 

A.   
Structural optimization

It involves the challenge of providing the most efficient
design: i.e. the least expensive design which will satisfy all the design
criteria for the entire life span of the structure. The cost of the structure
is reduced by optimizing the use of materials (By reducing weight of the
structure) and labor productivity (which involves fabrication, construction
time & and complex topological configuration of the structure). Since,
shape and topological optimization are practically impossible to conduct using
existing design and methods, only size optimization is usually attempted in
conventional structural design. Topology and shape optimization are, thus
active research fields in structural optimization now-a-days. The introduction
of different algorithms and computational techniques into the field of
structural optimization has paved a way for research because they have been
successfully used where conventional methods have failed.

 

B.     Methods of optimization

The design of truss structure is based
on the results of the size, topology, and geometry optimization, as shown
in   Fig. 1.

1.     
Size Optimization is deals with the provision of
minimum c/s area for members by considering that the node connectivity and
coordinates are fixed.

2.     
Topology Optimization is deals with the connectivity
between of member between nodes.

3.      Geometry Optimization is deals with
the determination of the optimum node 
coordinates by assuming that the topology of the truss structure is
fixed.