Study of Foundation Systems for High Rise Building on Soil with Different Characteristics

Abstract

Foundation is one of the most important part of the building as it affects the safety and stability of the building. For high rise building foundation is very important as it contribute to a huge cost of project. For buildings having similar dimensions and resting on different types of soil; size and types of foundation may get change. Foundation failure can create major problems to building and its also costs heavily for repair work. If the foundation is over designed it will cost huge amount of money. Thus the choice of appropriate type of foundation for high rise building is very important. Generally high rise building has different types of foundations like raft, pile and piled-raft. In this study G+40, G+50 and G+60 storey buildings are considered. Modelling and analysis of buildings are carried out in ETABS software. For all the buildings different foundation systems like pile, raft and piled-raft are considered. Three different types of soils like sandy, clayey and rock are considered for the study. Foundations for G+40, G+50 and G+60 storey buildings are designed for all three types of soils. For raft foundation, three different types of rafts are considered which are simple raft, column headed raft and slab beam raft. The raft foundations are designed for all the buildings in SAFE software. Pile and Pile cap are also designed for all buildings with different soil conditions. Spread sheets are developed for geotechnical and structural design of pile and pile cap. For analysis of piled-raft foundation Poulos-Davis-Randolph (PDR) method is used. Design of raft in piled-raft foundation is designed in SAFE software and piles are designed using developed spread sheet. A parametric study is made for piled raft foundation system. Length of pile, diameter of pile and numbers of pile are the parameters which are considered in study. From this parametric study, it is found that by increasing the length, diameter and numbers of pile, load taken by pile increases. Here feasibility is evaluated for all different types of foundation systems for buildings with different heights resting on different soils. From the study it is found that pile and piled-raft foundation is feasible for all the different types of soils considered in this study and raft foundation is feasible only for rock. Based on the economy point of view, the pile foundation is the most appropriate solution for the buildings resting on different types of soils.