COMPUTER AIDED DESIGN AND DRAFTING Of PRESTRESSED CONCRETE PIPES

Abstract

The application of Computers for specific and isolated purpose has gradually developed into a new branch of specilized knowledge, "Computer Aided Design" this can be defined as use of computer to assist in creation, modification, analysis and optimization of a design. The advantages of the application f.. the CAD to Civil Engineering have now' -been realised and move and/move design and research problems are being tackled using. CAD. The problem of prestressed concrete pipe• design and drafting using CAD has been (delt with in this dissertation. 'prestressed concrete pipes ate ideally suited for the pressure range 500 KN/m2 to 2000 KN/m2 . For this pressure range, - cast iron and steel pipes are not economical and reinforced. concrete pipes are not practicable due to their limited cracking strength. The various components of these pipes are designed and constructed to withstand the internal pressure and other external loads. Primarily, the design of prestressed concrete pipes, is concerned with the determination of core thickness and prestressing reinforcement-, which more or less involves trial procedure. Thus computer is' better suited for such work. A software package has been developed for analysis, design and drafting of prestressed concrete pipes. The design is based on' Indian Standard Specifications incorporating the changes and recommendation suggested by recent draft code. The• software package has been developed in FORTRAN-77 language for u'Pe in personal computer, but it can be run on any main frame gpmputer as well. Data input is possible either through screen or a file (specially for -0lander Coefficients). The screen mode is especially useful as it does not require the user to go through the input instructions for the data. The package has teen provided with certain built in corrections to meet the 4pecifications while leaving' a wide range of options so as to give to the designer enough Fexibility essential in the designs. The.package can thus said to be user f.rindly The package is made complete and effective by including crafting part through which three X-Sectional views of the pipe ind one view which shows the laying of pipe in trench or embankment are drawn. The drafting part of the package is also written in FORTRAN-77 and executed utilizing plot 88 graphics gacility. The working of the software package has been illustrated by solving few -design problems and based on it design chart has been formulated. Also, a study has been carried out to show the effect of various parameters on the cpst of the pipe. Based on above study following conclusions have been drawn. l`r Economy in the pipe design can be achieved by varying the core thickness, pitch of circumferentral prestressing wire and use of more ecomical dia of •circumferentral prestressing wire. (iv) 2. The cost/pipe volume reduces as the length increases, so it is recommended that the length of pipe should be 5m to 6m. 3 Cost of pipe per unit volume of pipe increases more or less linearly with internal pressure and internal diameter of the pipe.