Structural Assessment of RCC Elevated Service Reservoir For Different Capacity

Elevated service reservoir is one of the maximum important infrastructures that is utilized by society. Our every day existence relies upon at the water supply, that is procured through an elevated service reservoir. Therefore, the safety of the service reservoir is of utmost importance. Most of the damage on elevated service reservoirs is caused by an earthquake, as the horizontal forces acting on the structure make the service reservoir vulnerable. Our predominantly study is based on extracting the dynamic forces mainly to determine critical condition of the structure. In this paper, different capacities of elevated service reservoir are taken and the design and analysis are done according to Indian standards. Dynamic analysis of the service reservoir is done and parameters such as time period, hydrodynamic pressure, base shear, base moment are compared with different capacities. Hence, the capabilities of the structure are substantially necessary to examine within the sub-continent region.

IOP Publishing doi:10.1088/1757-899X/1197/1/012065 2 2.METHODOLOGY When elevated service reservoir are subjected to earthquake, a strong lateral forces are generated, causing the reservoir to oscillate. These fluids are comprises two parts, the container and the fluid kept in it. When lateral forces are induced, the bottom portion of the fluids undergoes oscillations along with container walls. This portion is called impulsive fluids mass (mi) and creates impulsive hydrodynamic pressure. Similarly, the top portion goes under sloshing phenomena. This portion is called as convective fluids mass (mc) and it creates convective hydrodynamic pressure. [3] To analyze their effect, model mass system is used. Since this system contain both container and fluid, two mass system are more effective than one mass system. A two mass system means it has two degrees of freedom, but these are obtained as two single degrees of freedom because of their difference in time period. Following figure 1 shows idealization of two mass system. The structural mass (ms) within the system is that the container mass additionally to atleast one third mass of staging and (ks) being lateral stiffness of staging.

3.PROBLEM STATEMENT
For the analysis of the elevated service reservoir, four different capacities of the tank are taken in such a way that h/D ratio was maintained in an increase of 0.05 . Where h is the depth of water and D is the inner diameter of the tank. [4] The design of the ESR is done by using staad pro in accordance with IS 456 [5] & IS 3370 [[6]- [7]] , figure 2 demonstrate staad model of 500 m3 capacity and seismic design is executed via way of means of the usage of Indian Standards 1893 Part2 [8], design statistics are taken as M25, Fe500, EC=25000 Mpa. [9]. Following Table 1. provides design constant values while Table 2 provides calculation of component of water tank, Table 3 gives data of load acting on component in ESR.

4.1.Time period
Time Period of impulsive mode and convective mode are analysed with respect to empty and full condition. Figure 3 gives H/D vs Time Period for full tank and Figure 4 gives H/D ratio for Empty tank.

4.2.Base Shear
Base shear determines maximum dynamic force acting on base of body. Figure 5 gives base shear for both full and empty condition.

4.3.Base Moment
Overturning moment is extracted in accordance with empty and full condition of tank. Figure 6 provides base moment for impulsive and convective mode.

4.4.Hydrodynamic Pressure
It acts on surface of ESR during horizontal excitation of structure. In given below Figure 7, hydrodynamic pressure is the resultant of convective and impulsive pressure on wall and pressure due to inertia and excitation of wall.

CONCLUSIONS
• Time period of convective mode is larger compared to impulsive mode and the tank in full condition has more time period compared to empty condition. • Tank fully condition has additional base shear compared to tank in empty condition and because the capability will increase the distinction between them increases. • Base moment in full tank condition increases rapidly compared to base moment in empty tank condition, but the increase is linear.