دراسة عملية ونظرية للاعمدة الحديدية الانبوبية المزدوجة المملوءة بالخرسانة و المعرضة الى احمال جانبية دورية

Experimental and Numerical Study of Concrete-Filled Double Skin Steel Tubular Columns Under Lateral Cyclic Loading

Abstract

The lateral cyclic behavior of composite concrete and double-skin steel tube columns is one of the construction methods used at the current time. The current study consists of two tubes outer and inner welded together perfectly and filled with two types of concrete: normal and high strength. Twelve composite columns represented the testing samples, six of them had square sections, and the other were circular. They were divided into six groups all subjected to cyclic lateral load: The first group consisted of two samples; circular and square. These samples were filled with normal concrete and subjected to cyclic lateral load only. The second group was the same construction as the previous group and was subjected to a scaled axial dead load of only about (40) kN. The third group also had the same construction and description as the 1st and 2nd groups and was subjected to an axial load (dead and live) scaled load of about (70) kN. The fourth group consists of two samples; circular and square. These samples were filled with high-strength concrete, and subjected to cyclic lateral load only. The fifth group was the same construction as the previous group and subjected to an axial dead load of only about (40) kN. The sixth group had the same construction and description as the 4th and 5th groups and was subjected to axial (dead plus live) loads of about (70) kN. The variables of experimental work and the numerical study included tube shape, type of concrete, and the value of axial load. The cyclic responses, including failure modes, the curves of lateral load –-displacement, the protocol of cyclic load with time, and validation between numerical study used (ABACUS program) and experimental work. The experimental and numerical study compared the effect of the type of concrete
that filled the composite columns and found that specimens filled with high–strength concrete(HSC) resisted the effects of lateral cyclic loading more than the same with normal concrete strength (NSC), for the circular section as a percentage of (6.68 %,9.20%,21.10%) respectively as the value of axial loads. For the square section, the resistance of lateral cyclic loading was increased as a percentage of (3.07%, 6.26%, and 9.53%) respectively according to the value of axial loads, compared with columns filled with normal concrete strength (NSC), which means the influence of high-strength concrete enhanced the performance of the resistance of composite columns to lateral cyclic loading. The shape’s effect, also considered in this study, the results show that circular sections have a resistance of lateral cyclic loads greater than the square section at the same conditions both for normal and high-strength concrete.