Qhov kev tsim lub kaum ntse ntse yog hais txog lub ntse kaum ntawm uas lub nruab nrab ntawm cov yeeb nkab steel ntawm cov steel sawb, feem ntau qhia nyob rau hauv. Daim qauv tsim yog qhov tseem ceeb tshaj plaws hauv cov txheej txheem ntawm cov yeeb nkab ntawm cov kab hlau welded, uas tsis yog qhov sib txuam ntawm lub cheeb ntawm cov yeeb nkab ntawm cov yeeb nkab ntawm cov yeeb nkab ntawm cov hlau thiab lwm yam Sawb. Thaum tus tsim lub ntsej muag <90 tus kauv txoj kev sib hlub tuaj yeem tsim tau, thiab muab kauv txoj kev sib raug zoo ntawm B, D, thiab:
D=b / π cos
