Verma - Professor, structural Engineering Department, B.V.M.Engineering college, Vallabh Vidyanagar-۳۸۸۱۲۰. Gujarat, India
Darshana R. Bhatt - Research scholar, Birla Vishvakarma Mahavidyalaya, Vallabh Vidyanagar-۳۸۸۱۲۰, Gujarat, India

So far we have dealt with the management of static loads applied to soil. These loads are applied slowly and their magnitude increases gradually. They do not necessarily remain constant with time. Most structures, even ordinary ones, experience many changes in load during their lifetime. Ring foundations are usually provided for tall circular structures like smoke stacks, cement silos, water towers, etc. For such structures, the ring foundations are preferred because of full utilization of soil capacity and less or no tension conditions under the foundations. In water towers, the foundation is subjected to cyclic load due to variation in water level. The present investigation concerns the behaviour of ring foundation on reinforced granular soil in enhancing the damping characteristics. Model studies have been carried out using a steel ring footing having external diameter (B) = 130mm and internal diameter (h) = 50mm. Number of model cyclic plate load tests have been carried out on reinforced sand beds below the model footing. Load settlement curves for every test data have been plotted. The indicative of percentage damping capacities of un-reinforced sand has been determined and compared with that of the reinforced sand beds. From the study of the damping capacities of the sand beds at selected load levels, it may be stated that all the reinforced sand beds reinforced with different sizes of geo-grid and geo-jute have a higher percentage damping capacities than un-reinforced sand bed at a particular load level. For planer reinforcement the increase in damping capacity is found to be about three times greater than that of unreinforced soil. For three dimensional geo-cell reinforced condition the increase in damping capacity is about twice of the unreinforced sand. Therefore the reinforced sand beds will have a higher capacity for supporting machine foundations and foundations subjected to cyclic loading.