ANALYSIS OF STAGING OF WATER TOWER AS A RIGID JOINTED SPACE FRAME

Abstract

The comparison of forces by 3D analysis and Approximate Method of analysis was carried out for six different cases of the overhead tanks. Stagings had either circular or square shapes in plan. Amongst these six cases, two have square overhead tanks with square shape of stagings and the remaining four have circular overhead tanks with circular shape of stagings. The total weight of the tank as well as the height of the staging remained constant. The six cases were modeled and named as model A to model F. The main objectives of the study are (i) Comparison of fundamental time periods and seismic coefficients of the models. (ii) Comparison of forces in the members Based on the foregoing study it is found that the Approximate Method of analysis overestimates the forces as compared to 3D analysis. It is found that the point of contraflexure in the columns does not occur in the middle of the columns until unless the braces are very stiff. Hence 3D analysis is being recommended particularly when the relative stiffness of the brace as compared to the column is less than 14.U. Further, the forces worked out from 3D analysis are lesser than that obtained from Approximate Method.