خرسانة المساحیق الفعالة المالئة للاعمدة الحدیدیة مزدوجة التجویف والتي تخضع الى احمال متكررة

Rp_Reactive Powder Concrete- Filled Double Skin Tubular Column Subjected to Repeated Loading.pdf

Double skin concrete filled column consist of two-tube steel section filled with Reactive Powder Concrete is one of the methods that combine the properties of concrete and steel and faster in construction with better load carrying capacity. The present method consists of welding two tubes of steel of different sections concentrically, then filling the gap between them with reactive powder concrete in this study. The current study consists of practical part that relates to casting fourteen a composite column included seven sections for circular and square type with different variables to know their axial performance. They were divided into three groups, the first group was not filled, the second group was filled with ordinary concrete and the third group was filled with reactive powder concrete. All columns had dimensions of cross section (100 *100) and (50*50) mm for outer and inner square section and a diameter of (100) and (50) mm for outer and inner circular section with a thickness of 2.2 mm. Lengths of the samples were 800 mm but only two of the columns were 700mm. The properties of the tube were checked by AISC code, which achieves acceptable performance through local buckling. The steel tubes were connected doubly by welding the inner and outer tube concentrically. The variables of the practical part included: the percentage of steel fibers in the concrete mixture of about 0.5% and 1.5%, cross-sectional area of the concrete, length of the column, addition of shear ties by welding to the inner tube of the column and the type of concrete. The load was applied axially and concentrated on the column. The results of the work showed that the steel pipes filled with reactive powder concrete gave a high maximum resistance compared with normal concrete if used. Also, it was found the inner tubes of the columns that enhanced with shear connector along its overall length, led to increase the strength of columns filled with reactive powder concrete. The experimental results of the maximum strength were compared with the design strengths of the American Institute of Steel construction (AISC), American Concrete Institute (ACI), and the European Code (EN 2004). The mentioned design criteria gave a better and more conservative expectation for square steel sections than for circular sections.