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Module 1: Column Bases

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Introduction to Design of Slab Base
The main function of a column base is to transfer the loads from the column to its foundation. They are of two types of column base: Slab base and gusset base.A base plate is a medium through which concentrated load from the column will be spread to the soil.
A slab base basically consists of a thick plate of steel material and this thick plate is connected with the column through some angle that is called cleat angle.
The steps in DESIGNING SLAB BASES are:
Assume a suitable grade of concrete and determine the bearing strength of concreteCompute the area of the slab base and select the size of the base plateDetermine the intensity of pressure from the concrete pedestalFind the minimum thickness required as per codal provisionsProvide two to four nominal boltsCheck the weld length connecting the base plate with the column
Introduction to Design of Gusset Base
In a gusset base, the column is connected to the base plate through gusset plates. The load is transferred to the base partly through bearing and partly through the gusset plate.
Gusset bases are for columns carrying heavy loads (including moments).
The steps in DESIGNING A GUSSET BASE are:
Assume a suitable grade of concrete and determine the bearing strength of the concreteCompute the area of the concreteFind the size of the gusset plateDetermine the dimension of the base plateDetermine the intensity of pressure from the concrete to the base plateCompute the thickness of the base plate by flexural strength at the critical sectionProvide a hold-down bolts 2 to 4 numbers of 20-mm diameter