A Fundamental Research onCrackDetection ofBasePiles ofBridge Piers UsinganAcceleration Pickup

Thisfundamental research isconcerned withthecrack detection ofaconcrete pillar combined withaconcrete hexahedron, whichisamodelofthebasepile ofabridge pier. Stationary wavesaregenerated inthepillar byhitting the headoftheconcrete hexahedron withahammer. Anacceleration pickup onthehexahedron observes thestationary waves generated inside theconcrete pillar through theconcrete hexahedron. Theproposed method measures thedepth ofthe crack inthepillar bymodeling thesensor output asanoutput ofalinear dynamic system withunknown parameters and applying amaximumlikelihood method. Experiments will showthat thelength ofthepillar isaccurately measured fora pillar withnocracks. Bycombining theresult withourprevious reports, wecaneasily expect that thelocation ofcracks will also beaccurately measured ifthepillar hascracks.