Taking　a　spandrel　stone　arch　bridge　as　the　engineering　background,　two　FE　models　are　selected　with　unilateral　contact-friction　interfaces　based　on　considering　effect　of　spandrel　structure　or　not　Ultimate　load-carrying　capacity　under　concentrated　load　on　L/4　or　L/2　section　is　analyzed.　The　results　show　that　failure　mode　of　the　two　FE　models　is　same.　It　is　a　four-hinge　failure　mode　under　concentrated　load　on　L/4　section　and,　whilst,　a　five-hinge　failure　mode　when　loaded　on　L/2　section.　The　FEA　results　considering　effect　of　spandrel　structure　show　that　hinges　appear　not　only　in　the　spandrel　arch　ring　and　spandrel　arch　pier,　but　also　in　the　main　arch　ring.　The　spandrel　structure　could　strongly　affect　the　bridge＇s　collapse　behavior　by　increasing　its　load　carrying　capacity.