Analysis and Design of Sump and Pump House

Abstract

Earthquake is one of the causes for damage of liquid containing structures. When liquid storage structure faces the earthquake, liquid is accelerated. Due to this acceleration liquid undergoes sloshing motion. This effect develops additional pressure on the wall and base of liquid containing structure. These types of behavior of liquid containing structure may become hazardous. Overturning of whole tank structure or cracking of tank wall may occur due to earthquake. So it is necessary to consider seismic forces during design of liquid containing structure.

IS:1893-1984 specific criteria for seismic analysis of various type of structures, including water tanks. But it has not sufficient provisions for ground supported water tanks (sump). In view of present international practice, the provisions of IS:1893-1984 are revised and published recently in different parts by Bureau of Indian Standards. IS:1893 (Part II) is published as draft criteria for Earthquake Resistant Design of Liquid Containing Structures.

This major project includes seismic analysis for several types of water tanks resting on ground like circular and rectangular water tanks, which are covered, or uncovered. Detail discussion on seismic provisions like time period, liquid mass, base shear, moment at base of tank wall, overturning moment, hydrodynamic forces is carried out considering both impulsive and convective mode. Analysis results are presented in graphical form for various capacity tanks. Comparative study of results of seismic forces and static forces is carried out for circular tanks with different height to diameter ratios. Similarly analysis results due to seismic forces and static forces for rectangular tank with different length to height ratio and length to width ratio is included. It is observed that hydrodynamic forces due to earthquake are beyond the permissible limit in higher earthquake zones. Finite element modeling of circular and rectangular tank with hydrostatic and hydrodynamic pressure is carried out in SAP2000 software. Step by step procedure for modeling of water tank in SAP2000 is included. Analysis results obtained by SAP2000 and analysis results as per IS:3370 (part IV) are compared for both circular and rectangular tanks.

Illustrative examples for analysis and design are included, considering provisions of IS:1893 (part II). Parametric study on design and estimation is carried out for IV different dimensions of tank and economic configuration is worked out. For analysis, design and quantity estimation of different component of tank like wall, base slab, footing, cover (dome or flat slab), internal columns and its footing computer programs are developed in C++.

Pumps are used to lift water from sump to the elevated water tank. For installation of pumps and electrical accessories pump house is required. This major project also includes analysis, design of pump house using STAAD/pro software. Program is prepared using C++ which generates input file for STAAD model of pump house for further analysis and design using STAAD/pro software.