Ef­fects of Blast Load­ing on Engi­neer­ing Struc­tures – An Over­view

NBM&CW - - BLAST LOADING IMPACT - Ak­shayku­mar Sanaki, Rak­shitha J, San­ket De­sai, N. Mu­niru­drappa,

Post Grad­u­aƟon Student, Pro­fes­sor, De­part­ment of Civil Engi­neer­ing, Dayananda Sa­gar College of Engi­neer­ing, Shav­ige Mallesh­wara Hills, Ku­mar­swamy Lay­out, Ben­galuru, In­dia.

The present study aims at pro­vid­ing an over­view on the blast load­ing and blast ef­fects on engi­neer­ing struc­tures. The use of ve­hi­cle bombs to aƩack city cen­ters has been a fea­ture of cam­paigns by ter­ror­ist or­ga­ni­za­Ɵons around the world. A bomb ex­plo­sion within or im­me­di­ately nearby a build­ing can cause cat­a­strophic dam­age on the build­ing’s ex­ter­nal and in­ter­nal struc­tural frames, col­laps­ing of walls, blow­ing out of large ex­panses of win­dows, and shuƫng down of criƟ­cal life-safety sys­tems. Loss of life and in­juries to oc­cu­pants can re­sult from many causes, in­clud­ing di­rect blast-ef­fects, struc­tural col­lapse, de­bris im­pact, fire, and smoke. The in­di­rect ef­fects can com­bine to in­hibit or pre­vent Ɵmely evac­uaƟon, thereby con­tribuƟng to ad­diƟonal ca­su­alƟes. In ad­diƟon, ma­jor catas­tro­phes re­sulƟng from gas-chem­i­cal ex­plo­sions re­sult in large dy­namic loads, greater than the orig­i­nal de­sign loads of many struc­tures. Due to the threat from such ex­treme load­ing condiƟons, ef­forts have been made dur­ing the past three decades to de­velop meth­ods of struc­tural anal­y­sis and de­sign to re­sist blast loads. The anal­y­sis and de­sign of struc­tures sub­jected to blast loads re­quire a de­tailed un­der­stand­ing of blast phe­nom­ena and the dy­namic re­sponse of var­i­ous struc­tural el­e­ments. This pa­per presents a com­pre­hen­sive over­view of the ef­fects of ex­plo­sion on struc­tures. An ex­planaƟon of the na­ture of ex­plo­sions and the mech­a­nism of blast waves has been high­lighted.

tech­nol­ogy, blast mag­ni­tudes have in­creased [12]. Ex­plo­sion within the struc­ture or nearby struc­tures can cause sud­den or cat­a­strophic dam­age to the build­ing’s ex­ter­nal and in­ter­nal struc­tural frames, col­laps­ing of walls, blow­ing out large win­dows, loss of life and in­juries to oc­cu­pants, etc. There­fore, the struc­tures are to be de­signed for an ad­e­quate level of blast re­sis­tance. How­ever, de­sign­ing of struc­tures to be fully blast re­sis­tance is not re­al­is­tic and eco­nom­i­cal [14]. But with the help of cur­rent engi­neer­ing and ar­chi­tec­tural knowl­edge one can en­hance the new and ex­ist­ing struc­tures to mit­i­gate the ef­fects of an ex­plo­sion re­sult­ing due to blast.

It can be de­fined as the sud­den con­ver­sion of po­ten­tial energy into ki­netic energy with the pro­duc­tion and re­lease of gas un­der pres­sure. The sud­den lib­er­a­tion of energy causes in­crease in tem­per­a­ture and pres­sure so that the ma­te­ri­als present are con­verted into hot com­pressed gases. Since these gases are at high tem­per­a­ture and pres­sure, they ex­pand rapidly cre­at­ing a pres­sure wave which is known as shock waves. It is a thin tran­si­tive area prop­a­gat­ing with su­per­sonic speed in which there is a sharp in­crease of den­sity, pres­sure, and speed of the sub­stance. They arise when the speed of the source wave is greater than the sound wave. A shock wave in air is gen­er­ally re­ferred to as blast wave [11].

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