how to design a shallow foundation
CE451 - Foundations
A factory building is required in an area where the soil profile from bore hole data is as shown in Fig. 1. One part of the factory. isolated from other buildings. has a building with a crane. also called a gantry (Fig. 2) to load raw materials. The span of the building is 40 m ( 120ft). The area is a marsh with organic top soil layer. Below this layer are layers of sands and gravels as shown in Fig. 1. The USCS description for each layer is given. The topsoil up to an elevation of – 10 m ( - 30ft) was removed and replaced with compacted fill. After the fill was compacted at approximately 90% maximum dry unit weight (average). further boreholes were made with SPT conducted to ascertain the level of compaction. The SPT results for two boreholes BH2 and BH5, near two of the outer columns (column A and column B) are shown in Fig. 3. On each column, the total dead load is 650 kN ( 150 kips).Live load except crane is 1300 kN (300 kips), and the dynamic (live) load from the crane is 2000 kN (400 kips). Assume that the equivalent static live load from the crane is 125% of the dynamic ( live) load. Design suitable shallow foundations for columns A and B. The total settlement is limited to 25 mm ( I in.) and the differential settlement cannot exceed 6 mm (1/4 in.). The minimum embedment depth is 1.5 m
Write a report describing and justifying your design. Clearly state all design assumptions. limitations (e.g. uncertainty of design data from the tests conducted) and criteria used. Describe how the foundation should be constructed and provide any necessary information to the contractor. Your report must contain a design summary about one-half page long. All drawings should be neatly drawn by hand or preferably by a CAD program. (Hint: One of the cases you should consider is when the crane is fully loaded and is near each of the columns.