Foundation Engineering Question: heat 1- FS Shallow Foundation Design Project Yo

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Foundation Engineering Question:
heat 1- FS Shallow Foundation Design Project Your firm has been retained to design a suitable shallow foundation for two ecreaes columns (column A and column B) in a factory building. The building will be located in an area with a soil profile from borehole data as shown in Figure 1 One part of the factory, isolated from all the other buildings, has a building with a crane, also called a gantry (Figure 2), to load raw materials. The span ncrea ) of the building is 40 m. The area is a marsh with organic matter in the topsoil layer. Below this layer are layers of sands and gravels as shown in Figure 1. The USCS description las for each layer is given. The topsoil up to an elevation of -10 m was removed Sse 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 Figure 3. Te On each column, the total dead load is 650 kN, live load except crane is 1300 kN, and the dynamic (live) load from the crane is 2000 kN. Assume that the equivalent static live load from the crane is 125% of the dynamic live load. The total settlement is limited to 25 mm and the differential settlement cannot exceed 6 mm. The minimum embedment depth is 1.5 m. Use FS 3. The client has requested a written report describing and justifying your design. Clearly state all design assumptions, limitations (eg, uncertainty of design data from the test conducted) and criteria use. Describe how the foundation should be constructed and provide any necessary information to the contractor. Your report must contain a design summary about 1/2 page long. Provide accurate, neat drawings drawn by hand or preferably by a CAD program (Hint: You should consider cases with varied realistic loading conditions. One of the cases should be when the crane is fully loaded and is near each of the columns.] You have agreed to provide your report by 9:30 am on Tuesday, November 14, 2017. Foundation Engineering Shallow foundation design project

Explanation / Answer

Hi,

Please find guidelines/procedure for your design.

Foundation type is shallow only, try square foundation, if there is any moment load due to gantry you can think of rectangular foundation also.

Axial load on foundation is 650 + 1300 + 1.25 X (2000) = kN

I feels that your prof. do not want to consider any moment load here.

Consider depth of foundation min. 1.5 m. Assume some foundation size.

Calculate contact pressure based on above load and then bearing capacity.

Please check you are getting factor of safety of 3 otherwise increase size of foundation. Soil properties (phy)need to be evaluated based on SPT N vs depth curve.

Once this is done proceed with settlement calculation. Based on N values using empirical corelations determine modulus of elasticity.

Please ensure that total settlement is less than 25 mm. If it is, foundation size is ok or otherwise increase foundation size. Consolidation settlement is not applicable.

Regarding differential settlement, it can occur only if there are different loads on foundation or soil geology below 2 foundations are different.

Min 2 foundation load cases need to be considered:

1. Dead load + live load +crane load one one foundation only. For other foundation only dead load + live load.

Consider variation in geology in your calculations means 2 different calculations based on BH02 & BH05

Ensure that differential settlement is less than 6 mm otherwise revise foundation sizes.

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