DESIGN PROCEDURES FOR A BUILDING FOUNDATION (STEP BY STEP)

DESIGN PROCEDURES FOR A BUILDING FOUNDATION (STEP BY STEP)

Good design must not only be safe but must aim to save lots of construction costs, time and materials. the subsequent procedures should help to realize this and an ‘educated’ client will recognize the importance of funding this work with a sensible fee.

     Design Procedure of foundation

 1. DECIDE the situation OF COLUMNS & FOUNDATION and sort OF LOADS working on THEM.(E.X DEAL LOAD, superload OR WIND LOAD) 
On the building plan, the position of columns and loadbearing walls should be marked, and the other induced loadings and bending moments. the hundreds should be classified into a dead, imposed and wind loadings, giving the acceptable partial safety factors for these loads.
 2. ESTIMATE ALLOWABLE BEARING PRESSURE OF SOIL USING GROUND INVESTIGATION REPORT. 
From a study of the location ground investigation (if available), the strength of the soil at various depths or strata below the foundation level should be studied, to work out the safe bearing capacity at various levels. These values – or presumed bearing values (from any standards or codes) within the absence of a site investigation – are wont to estimate the allowable bearing pressure.
 3. DECIDE DEPTH OF FOUNDATION 
The invert level (underside) of the inspiration is decided by either the minimum depth below ground level unaffected by temperature, moisture content variation of erosion – this will be as low as 450 mm in granular soils but, counting on the location and ground conditions, can exceed 1 m – or by the depth of the basement, boiler house, service ducts or similar.
 4. CALCULATE FOUNDATION AREA 
The foundation area required is decided from the characteristic (working) loads and estimated allowable pressure. This determines the preliminary design of the kinds of combinations of sorts of foundations. the choice is typically supported by economics, speed, and buildability of construction. 
5. DETERMINE VARIATION IN VERTICAL STRESSES 
The variation of vertical stress w.r.t depth is decided, to see for possible over-stressing of any underlying weak strata.
 6. CALCULATE SETTLEMENT 
Settlement calculations should be administered to see that the entire and differential settlements are acceptable. If these are unacceptable then a revised allowable bearing pressure should be determined, and therefore the foundation design amended to extend its area, or the foundations should be taken right down to a deeper and stronger stratum.
 7. COST CONTROL
 Before finalizing the selection of foundation type, the preliminary costing of other superstructure designs should be made, to work out the economics of accelerating superstructure costs so as to scale back foundation costs.
 8. CONSIDER TIME 
Alternative safe designs should be checked for the economy, speed and ease of construction. Speed and economy can conflict in foundation construction – an initial low-cost solution may increase the development period. Time is usually of the essence for a client needing early return on capital investment. A fast-track program for superstructure construction are often negated by slow foundation construction. 
9. VARIATION IN GROUND CONDITION 
The design office should be prepared to amend the planning if excavation shows the variation in ground conditions from those predicted from the location soil survey and investigation.

Er.SP.ASWINPALANIAPPAN., M.E.,(Strut/.,)

Structural Engineer

Madras Terrace Architectural Works

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