Bond Strength in Battened Composite Columns

Abstract

Tests on 135 battened composite specimens are performed to investigate the bond between concrete and steel in battened composite columns. Several factors believed to affect the bond between the two materials are investigated, including age and size of specimen, curing, and temperature. The test results of this investigation show that the battened composite section offered less bond strength than the concrete‐filled tubes tested elsewhere. Experimental evidence also shows that age of concrete is a major factor of bond reduction. The strength of bond at the age of one year is about 30% of that at the age of three weeks. The size of the specimen, which affects the shrinkage and the confinement of the concrete, proves to be a significant factor of bond reduction. Curing of concrete also proves to be a contributing factor to the strength of bond. Increase in temperature reduces the strength of bond. The reduction is significantly higher for high temperatures. At 600° C the bond strength is less than 20% of that at room temperature.