Steel members have the advantages of high tensile strength and ductility, while
concrete members have the advantages of high compressive strength and stiffness.
Composite members combine steel and concrete, resulting in a member that has the
beneficial qualities of both materials. In this paper, an attempt was made with steel tubular beams filled with different types of concrete using waste materials under cyclic loading for effective recycling of waste materials in construction works. It is widely recognized that the innovative use of two or more material in structures generally leads to more efficient economical systems for resisting seismic forces. In this area utilizing of concrete filled steel tubes are new idea which increasingly finding application in design practice. Current design codes and standards provide little information on the flexural behaviour of square concrete filled steel tubes (CFT) as there have been few experimental studies. There are significant differences in d/t limits recommended in various codes for CFT under bending.
This paper presents an experimental investigation of the flexural behaviour of square CFT subjected to pure bending where d/t ratio 23.6 & 25.4. The paper compares the behavior of empty and void-filled, hot rolled square hollow sections under pure plastic bending. The behaviour of square concrete filled steel tubular beams with partial replacement of fine aggregate by fly-ash & quarry dust and partial replacement of coarse aggregate by granite, construction & demolition debris, rubber, steel slag, tiles and marbles under cyclic loading is presented. The effects of steel tubes, compressive strength of concrete and the confinement of concrete are examined. 20 specimens were tested with strength of
concrete as 20 MPa. The beams were 91.5x91.5 and 113.5x113.5 mm in size is 1200 mm in length. From the test results it was observed that the ultimate load carrying capacity of steel tubular beams filled with different waste materials concrete is almost same as that of conventional concrete. In general, void filling of the steel tube enhances strength, ductility and energy absorption especially for thinner sections. The model is implemented to analyze several concrete filled steel tubular beams under cyclic loading. The steel shell provides confinement for concrete core thus increases the ductility and strength of core. The experimental results show good seismic characteristics and energy absorption. The use of concrete filled steel tubular sections in structural frames has increased in United States, Japan, China and Australia during the past ten years. Hence this research would give a solution for effective solid waste management as well as cost effective. The proposed composite inelastic element proves to be very reliable under cyclic loading, and it traces the experimental results with good accuracy. The versatility is due to the fact that no predefined phenomenological rules are involved in dictating the overall hysteretic
behaviour of any cross-section.