evaluation of the pile group under vertical harmonic vibration in layered soil

 in general, piles are used as pile groups in foundations of structures. in this paper, an analytical model is presented for evaluation of response of pile-pile interaction in pile groups under vertical harmonic vibration. it is assumed that no slip occurs between soil and pile and the pile is vertical and elastic, and the soil behavior is linear visco-elastic with hysteric type damping. interaction of pile-soil and pile-pile obtained from studies of nogami and novak and then pile group interaction is evaluated. while the stiffness and damping of the pile group subjected to harmonic vertical vibration in stratified soils are obtained through extension of equations. it should be noted that (ssm) method which was initiated for single pile by second author and then developed is used for evaluation of pile group interaction in stratified soils.