Residual bond strength of corroded plain round bars

Abstract

This paper reports results of an experimental programme to measure changes in bond characteristics of plain round reinforcement as a result of corrosion. Principal parameters included in the investigation are the amount of corrosion, the presence of confining reinforcement in the form of links, cover thickness and the initial condition of the reinforcement. In the absence of confining links, bond strength of bars cast near the bottom of a pour is found to reduce with increasing corrosion. However, although top-cast bars were initially weaker, small amounts of corrosion were sufficient to raise bond strength to that of bottom-cast bars. With increasing corrosion, strength reduced in a similar manner to bottom-cast bars. Confining reinforcement had little influence on bond strength prior to the onset of corrosion, but plays an important role in maintaining strength once corrosion becomes established. Results from these tests suggest that surface crack width may provide a better parameter than section loss or corrosion penetration through which to assess residual bond strength. The reasons for this are explained, and empirical relationships for residual strength are derived.

Case studies on determination of load and resistance factors by method of moments

“…Figure 5 (taken from FIB (2000)) shows a linear relationship between the residual bond strength f bond and the corrosion penetration based on Rodriguez et al (1994aRodriguez et al ( ), (1994bRodriguez et al ( ), and (1996. The linear relation shown in figure 5 between the reduction of the bond strength In the paper by Cairns, Du & Law (2006) it is suggested that corroded plain bars the surface crack width may provide a better parameter than the corrosion penetration (0.5 ) in assessing the residual bond strength. figure 6 is shown some test data obtained by Cairns, Du & Law (2006).…”

“…The linear relation shown in figure 5 between the reduction of the bond strength In the paper by Cairns, Du & Law (2006) it is suggested that corroded plain bars the surface crack width may provide a better parameter than the corrosion penetration (0.5 ) in assessing the residual bond strength. figure 6 is shown some test data obtained by Cairns, Du & Law (2006). In the figure is the relationship between the bond strength and the surface crack width for bottom and top castings.…”

Modelización numérica del comportamiento adherente acero-hormigón en presencia de compresión transversal.

“…Se emplean en este caso "probetas largas", en los que la relación l/φ varía entre 10 y 20 (l/φ= [10][11][12][13][14][15][16][17][18][19][20], en las que ya no es posible asumir una distribución de tensiones tangenciales uniforme a lo largo de la longitud adherida. Mediante este tipo de ensayos se obtiene información muy valiosa acerca del comportamiento adherente en su conjunto y son típicos los ensayos tipo viga, anclaje o solape.…”

“…La resistencia de adherencia se incrementa inicialmente con la corrosión hasta un determinado límite, dado el carácter expansivo de los iones de cloro. A partir de este momento, el descenso en el comportamiento adherente es muy significativo [14,17].…”

“…Sin embargo, para cualquier situación de confinamiento, cuanto mayor sea el área relativa de las corrugas f R , menor es la reducción en la resistencia de adherencia [16,17,45,46,47,53].…”