Skewed　bridges　are　more　vulnerable　to　earthquake-induced　failure　than　straight　bridges　due　to　pounding　at　expansion　joints　between　the　bridge　superstructure　and　abutments.　This　study　focuses　on　analyzing　pounding　effect　and　rotation　mechanism　of　highway　bridges　with　prestressed　concrete　box　girder　and　seat-type　abutments　when　subjected　to　bi-directional　near-fault　ground　motions,　especially　seismic　response　with　respect　to　abutment　skew　angle.　These　analytical　models　include　nonlinear　characteristics　of　skewed　bridge　components,　especially　pounding　effect　between　the　superstructure　and　abutment　in　both　longitudinal　and　transverse　directions.　Nonlinear　time　history　analyses　were　performed　to　predict　the　pounding　force　and　its　effect　on　the　seismic　response　of　skewed　highway　bridges　using　the　Kelvin　model.　The　analytical　results　indicate　that　the　pounding　of　skewed　bridge　causes　significant　seismic　displacement　response　and　local　damage　of　superstructure.　In　addition,　the　pounding　in　the　transverse　initial　gap　reduced　the　rotation　response　of　the　skewed　bridge,　and　the　skew　angle　has　significant　effect　on　the　seismic　behavior　of　skewed　highway　bridges.　The　pounding　force　and　back-fill　response　decreased　with　an　increasing　skew　angle,　but　deck　displacement　in　longitudinal　direction　and　torsion　response　increased　apparently.　Bridges　with　skew　angle　increased　demand　on　shear　keys　under　the　strong　earthquake　excitation.