Topic 4: Basic equation in determining Pile capacity

Notes:

Steps in pile capacity check

6)By examining the formula, if the pile is in excessive compression ( normally the case), we can either: i.Add more piles without changing the pile spacing,  This will reduce the (P/A) but may increase construction cost (especially in the case of bored/ micro piles). ii.Adjust, the pile spacing,  This method may be useful if there is no site constraint (working space)  This may reduce the M(y)/Ixx component.  Pile cap plan size will increase so the cost (framework, concrete, and reinforcement). iii.In an extreme case, both components may need to be adjusted.  Note:  The abbreviation (yi) refers to the appropriate lever arm between the ith Row of pile considered and C.G. of piles.

Example 1: (Tow Rows Pile Arrangement) (Single load –vertical load) –not Raked  Consider a 2PG pile cap subjected to a column load of 1400 kN. If the column position offset value is 100mm from its original position as shown in figure below, perform pile capacity check. Take allowable pile working load to be 800 kN/pile. column Pile

Example 2: Four Rows Pile Arrangement (Single load-Vertical load)  Consider a 12PG pile cap subjected to a column load of 6000 kN. If the column position offset value is 75mm from its original position as shown in figure below, perform pile capacity check. Take allowable pile working load to be 620kN/pile.

Example 3: Multiple load (Vertical and Horizontal)  Consider a 7PG pile cap subjected to a column loads as shown in figure below, perform pile capacity check. Take allowable pile working load to be 820 kN/pile. Raked pile P2 P1 A 2000 kN3000kN 550kN 1500mm y1y2

Thank you