OPTIMAL DESIGN OF WATER TOWER STAGING

Abstract

Considering the diversity of opinion among the various research workers and designers regarding the economical pro- portions, of Intze tank and the scarcity of guidelines for designing the staging made up of columns 'and braces economically under the, action of various wind and seismic forces, the problem of their optimal design is taken up for investigations in the present study. The economical proportions of Intze type containers have been worked out in the light of its minimum weight besides having minimum hoop tension in the bottom ring beam, smaller projected surface area and a suitable diameter for staging for the economical design of staging and foundation. To achieve this objective, the proportions of various parameters of the container have been varied to a wide , range. In all, seven capacities of the container ranging between /x.50 ' to 1800 KL have been investigated. The design is carried out by working stress method and on no. crack basis for the forces obtained from the membrane analysis. The recommended proportion for the container are given in the last chapter. The configuration of staging, selected for investigation is the frame work of upright circular colwans and horizontal braces of rectangular section. The stu-cly covers the above range of capacities and a number of heights of the water towers. The staging is analysed by equivalent tube analogy for the v horizonal forces. To achie-.e the economy i the design of staging, bottom ring beam of the container and columns and braces of the staging have been optimized by varying the breadth' and depth of the ring beam and the number of panels, the number and size of columns in the staging. Twenty combinations of five capacities ranging between 450 to 1800 KL and four heights between 12 to 21 m have been considered for all the three wind and five seismic zones in which the country is classified for the determination of wind and seismic forces. Thus in all 160 cases have been investigated. For each case 12-18 combinations have been designed by varying the different parameters of the staging namely number of panels, number of columns and the column size. The final recommendations and guidelines for the economical design of staging are given in the last chapter.