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Abstract— For a structural design the five major objectives utility, economy, efficiency, safety , aesthetic are need to be satisfied. This paper discusses the analysis and design of 10m span of three dimensional geometry of square based pyramid shape truss with the influence of removing purlin in the form of tubular and steel structure. This paper represents the comparison of tubular and steel structure in terms of economy, weight, efficiency. This analysis and design are performed step-by-step using STAA-PRO software considering all loads.This presents study on behavior and economical of roof truss by using spatial geometry. In this paper , the structure that is based on geometry as well as analytical and numerical representation of the relation between form and force.The results are
I. INTRODUCTION
Space structure is light in weight ,easy to manufacture and transport, flexible in workability, and requires short period for construction. Space truss is used to denote the structural system in which small linear members are arranged in three dimensions. The space truss structure as compared to plane is three-dimensional nature both in assembly and in load carrying behavior. These are used where there is need to avoid column. It consist of members joined together at their ends and form stable three dimensional structure. The advantage of space truss is their higher industrialized degree in production and construction , relative to other conventional system. Also their positive aesthetic quality and last is functional in that a space truss requires only the addition of light roofing system to enclose space. Also the collaboration between architects and engineers is being improved and simplified. Hence there are different spatial geometry developed for a roof truss. The geometry should be simple and statically determinate structure. This can be analyzed and design for angle section and hollow tubes. As the construction industry continues to evolve, innovative product and design techniques are being developed for increasing demands on both the efficiency and aesthetics of civil engineering structures. Hence, high strength, hot-rolled and cold-formed oval hollow sections called as tubular section are used.Tubular structure increases load carrying capacity , reduces the cost of maintenance , cost of painting . Tubes are of specialinterest to architect from an aesthetic point of view.The external surface of tube does not permit the collection of moisture and dust thus lack of corrosion.Steel is used for making structural steel shapes. Structural steel attributes compressive strength as well as tensile strength. It having high strength, stiffness, ductile properties, toughness.It can be developed into nearly any shape. Steel is inherently noncombustible material. Hence this geometry has been designed for both sections and compared for weight, economy , aesthetics. This is analyzed and designed considering dead load, live load, wind load.
II. SPACE TRUSS WITH SPECIAL GEOMETRY
As we defined space truss using different geometry, the simple geometry is pyramid with less members and designed with removing purlin. Hence it is economical as compared to others. In this, sheets are rest on members and load is transferred from members to joints. Also the load is equally distributed in three directions. This is analysed and designed for both tubular and angle section.The analysis and design of pyramid as a three dimensional geometry for space truss is for angle and tubular section with its economy and aesthetics. Pyramid roof is type of hip roof. In this, all four sides comes to a point at the top of roof. There are no vertical sides or gables. Square based pyramid is easy in cutting as compare to hip. A pyramid roof is extremely resistant to strong wind. This makes it an architectural choice for high-wind areas. The slope also provides extra space for ventilation or high ceilings.
With the industrialization and development of modern world there is demand for aesthetic and efficient structure. Hence the analysis and design of such special geometry is required. After the review of different shape formation, pyramid is simple geometry without using purlin. This is simple for analysis and design using STAAD-PRO software. The development of various three dimensional geometry used for space truss depends on their stability, erection, safety, efficiency , aesthetics.
LITERATURE REVIEW
Tom Van Mele, Lorenz Lachauer studied on Geometry-Based Understanding Of Structures. This paper presented the possibilities of using a geometry based approach to structural form finding the key principles of graphic statics and extends them to fully three dimensional problem using structural design. Then he conclude that the geometry or shape is important first to define the structure and then only we can analyze and design. It is also useful for both architecture and engineer.
Lau Wei Theng has analyzed and design effect of different truss shapes to the design of plane truss using angle section. In this the design of truss is to be carried out according to the the best geometrically layout of bars and nodes has to be determined and the most adequate cross section need to be calculated. Based on this study, some outcomes are defined the most effective shape in terms of weight and design of truss using steel angle section. He compared the cost of different materials normally used in the construction industry.
Rakesh R. Nora, Maske Ravi G. study on comparison between angular steel section and tubular steel section. This paper present about designing components of roof truss by conventional angle section and tubular section. The main purpose of this study is to regarding the economy, load carrying capacity of structural member. He conclude that the tubular sections proves to be economical. Structural members having larger unsupported length can be assigned tubular section will derive overall economy.
IVPROBLEM STATEMENT
The objective of the present work is to design and analyses the three dimensional pyramid shape geometry for roof truss. The development of structures with complex, curved geometry is a complicated process in which spatial and structural design are need to be separated and cost will be more. Therefore, the aim of this project is to develop the simple three dimensional geometry with less member for economy of roof truss. Compare analysis and design of square based pyramid for angular and tubular section regarding economy, aesthetics of structure. This square based pyramid is analyses and design by removing purlin. The stability of truss structure depends on its overall shape, number of members, arrangementof members.The Analysis and design will be performed in STAAD-PRO software.