165　distinct　pulse　records　are　quantitatively　indentified　by　considering　the　uncertainty　of　pulse　orientation　and　using　wavelet　method　from　3661　groups　of　strong　motion　records　in　175　earthquake　events　from　Wenchuan　and　Ludian　earthquake　in　China　and　the　NGA　(Next　Generation　Attenuation)　database　of　the　US　to　form　a　database　for　this　study.　The　long-period　pulses　are　extracted　from　the　original　pulse　record.　We　compare　the　response　spectra　of　the　original　records　with　the　residual　ground　motion　after　the　pulse　extraction.　The　results　show　that　the　response　spectra　at　the　period　rang　near　the　pulse　period,　Tp,　are　highly　amplified　due　to　the　presence　of　large　velocity　pulses,　and　shown　as　a　narrow-band　effect.　Based　on　a　quantitative　analysis　of　the　epsilon　parameter,　we　find　that　median　amplification　curves　vary　with　period　and　show　distinct　peak　values　near　the　pulse　period,　Tp,　with　strongest　amplification　of　approximately　3.5,　and　decrease　when　departing　from　Tp.　The　most　significant　period　range　with　amplification　effects　is　from　0.5Tp　to　2Tp.　Quantitative　empirical　models　of　amplification　factor　Af　and　pulse　period　Tp　are　proposed　based　on　least-squared　fitting　of　the　results.　We　further　investigate　the　effects　of　earthquake　magnitude　and　site　shear　wave　velocity　on　the　amplification　factor　curves.　With　the　increase　of　the　magnitude,　the　affected　period　band　due　to　pulse　amplification　becomes　broader,　and　the　peak　period　moves　towards　the　long　period　direction.　Both　the　affected　period　band　and　the　peak　period　moves　towards　the　short　period　direction　with　the　increasing　of　shear　wave　velocity.　The　empirical　model　of　pulse　amplification　factor　obtained　in　this　study　can　be　used　as　a　modification　of　the　response　spectra　for　a　specific　earthquake　and　site　condition　in　near-fault　cases.　©　2017,　Engineering　Mechanics　Press.　All　right　reserved.