Effective Seismic Input

When in­cor­po­rat­ing earth­quake ex­ci­ta­tion in­to the soil-struc­ture mod­el, we not on­ly have to ap­ply ef­fec­tive forces that are equiv­a­lent to the in­com­ing earth­quake, but we al­so have to ac­count for the non-lin­ear­i­ty of the struc­ture, or in oth­er words, start the tran­sient earth­quake analy­sis from a sta­t­ic state of the struc­ture.

The ef­fec­tive forces to be ap­plied to the mod­el are de­rived from the scat­ter­ing analy­sis frame­work de­scribed ear­li­er, where­in we con­sid­er the dif­fer­ence  be­tween the ground mo­tion with the struc­ture and with­out, and this scat­tered mo­tion – en­tire­ly out­go­ing from the struc­ture – is ab­sorbed by a PML bound­ary.

The non-lin­ear analy­sis of the struc­ture can al­so be in­cor­po­rat­ed in the same con­text, as de­scribed lat­er.