EXPERIMENTAL INVESTIGATION INTO THE BEHAVIOUR OF CONCRETE FILLED PVC TUBES

Abstract

Steel columns are extensively used in high-rise buildings wherein very high axial loads and moments are to be transferred. These steel sections have traditionally been open sections such as I-section or H-section. During the past decade or so, however, tubular sections in high strength steel have facilitated the use of steel in high-rise buildings much to its advantages. The hollow space within the tube has been further used to advantage by filling it with concrete. This has given rise to a composite section for column which primarily is in steel and supplemented by concrete with a minor amount of reinforcement to take care of problems related to creep and shrinkage. This type composite section has been popularly used in developed countries wherein availability of steel and welding technology is no problem. In the present thesis work, columns are required to transfer small amount of axial load and moment arising in low cost housing units. Single or 2-storey buildings as dwelling units for low income groups of people needs appropriate kind of technology so as to make the buildings durable and cost-effective. PVC pipes. readily available for piping work, is intended to be studied for its effectiveness in being used as columns. This type of columns is generally referred to as Concrete-Filled Tube (CFT). Performance of such CFT's is the main stay of study in this thesis. In this experiment 24 samples 16 samples of diameter 140mm &200mm of three grades M20, M30 &M40 were tested for axial load behaviour after 28 days of dry curing. In these 16 samples, 4 samples are of M20 grade- 140mm,4 samples are of M30 grade 140mm,4 samples are of M20 grade-200,and 4 samples are of M40 grade- 200mm. Out these 4 samples 2 were tested for concrete loaded and 2 are tested for both loaded Remaining 8 samples of diameter 140mm &200mm of M20 & M40 are tested for durability after keeping them in artificially prepared sea water for 28days. In these 4 samples are of M20 grade 140mm out of which 2 samples are normal Reinforced concrete and 2 are composite. Remaining 4 samples are of M40 grade 200mm out of which 2 samples are normal Reinforced concrete and 2 are composite. .The ductile behaviour of the specimens was observed for all grades of concrete and upvc tubes of different diameters. The percentage reduction in strength of samples are calculated after keeping them in artificially prepared sea water for 28 days with that of normally cured concrete. The results have shown that there is practically no loss in the strength of specimen which are confined by UPVC. The failure patterns of different specimens were also compared. 11