Experimental investigation on blast furnace slag aggregate concrete filled double skin tubular (CFDST) stub columns under sustained loading

As significant growth of iron production in China in recent decades, plenty of blast furnace slag is generated. Meanwhile, the policies on the natural aggregate exploitation has been getting more restricted as it threats the environmental conditions. There is an alternative solution to the above issues that furnace slag aggregate concrete is filled in middle between double-skin tubular (DST) columns with external stainless steel tubes. This study conducted a series of tests on furnace slag aggregate concrete filled double-skin tubular (CFDST) stub columns under sustained loading condition. The experimental investigations were conducted on circular specimens with furnace slag aggregate replacement ratio of 100%. The hollow ratio of the specimens ranged from 0.5 to 0.75. A total of 8 specimens were tested to capture the behaviours of the creep, shrinkage, ultimate strength before and after 6 months sustained loading. The results indicated that the shrinkage strain of the sandwiched furnace slag aggregate concrete tended to stabilise after 30 days and the creep developed constantly throughout the 180 days of the test. The furnace slag aggregate CFDST specimens with stainless steel tubes have demonstrated well load carrying capacity and ductility under sustained loading. The existing design methods were evaluated on the applicability on the stainless steel-furnace slag aggregate specimens under sustained loading and reasonable predictions were obtained.