%0 Journal Article %T EVALUACION DEL COMPORTAMIENTO DE BARRAS DE ACERO CON BAJO CONTENIDO DE CARBONO SOLDADAS A TOPE Y SOMETIDAS A CICLOS SEVEROS DE CARGA AXIAL EVALUATION OF THE BEHAVIOR OF BUTT-WELDT LOW-CARBON BARS OF STEEL AND SUBJECTED TO SEVERE CYCLES OF AXIAL LOAD %A Enrique Castilla C %A Aim¨¦ Guerrero %A Norberto Fern¨¢ndez %J Bolet¨ªn T¨¦cnico %D 2001 %I Scientific Electronic Library Online %X RESUMEN El presente estudio eval¨²a el comportamiento de barras para refuerzo con bajo contenido de carbono (ASTM A-706) soldadas a tope y sometidas a ciclos severos de carga pulsante. En tal sentido, se ensayaron 95 barras para todos los di¨¢metros comerciales entre y 1 pulgada soldadas seg¨²n lo establecido por la norma AWS D1.4. Un total de 55 barras eran de acero termotratado y las restantes 40 de acero microaleado. Una vez alcanzado el agotamiento de algunas muestras ensayadas, se determinaron a trav¨¦s de las t¨¦cnicas de microscop¨ªa electr¨®nica de barrido (M.E.B.) y espectrometr¨ªa de energ¨ªa dispersiva por rayos X (E.D.X.), las caracter¨ªsticas microestructurales y fractogr¨¢ficas de las uniones soldadas del refuerzo estructural. Los resultados sugieren que las barras de acero microaleado son soldables a temperatura ambiente sin comprometer sus propiedades sismorresistentes. Para el caso de las barras de acero termotratado, los di¨¢metros grandes (mayores o iguales a de pulgada) presentan restricciones en cuanto a su soldabilidad con fines sismorresistentes, por ser ellos posiblemente m¨¢s sensibles al agrietamiento por hidr¨®geno. Se concluye tambi¨¦n sobre la profundidad de temple para barras de acero termotratado que garanticen su comportamiento d¨²ctil al ser soldadas a temperatura ambiente ABSTRACT This study evaluates the behavior of butt-welded low-carbon reinforcing bars (ASTM A-706) subjected to severe cycles of pulsating load. The tests covered 95 bars of all commercial diameters between #4 and #8, welded according to specifications set forth in AWS D1.4. Of these, a total of 55 were of thermo-treated steel and the remaining 40 were of micro-alloy steel. Once failure was reached in some of the tested specimens, the micro-structural and fractographic characteristics of the welded joints were determined using electronic microscope scanning and X-ray dispersive energy. The results suggest that micro-alloy steel bars can be welded at room-temperature without affecting their earthquake-resistant properties. In the case of thermo-treated steel bars, larger diameters (equal or greater than #6) show undesired behavior for earthquake-resistant use, perhaps because they are more sensitive to hydrogen cracking. Conclusions are also drawn as to the quench depth for thermo-treated steel bars which will guarantee ductile behavior when welded at room temperature %K Acero %K termotratado %K microaleado %K soldadura %K barras %K tren de carga %K falla fr¨¢gil %K falla d¨²ctil %K Steel %K thermo-treated %K micro-alloy %K welding %K bars %K freight train %K brittle failure %K ductile failure %U http://wwww.scielo.org.ve/scielo.php?script=sci_arttext&pid=S0376-723X2001000300001