STUDIES ON CONCRETE FILLED CIRCULAR PVC TUBES AS COLUMNS

Abstract

Composite forms of constructions provide better utilization of the materials at hand. as they make use of the desired qualities of the constituent materials. Concrete Filled Tubes(CFTs) are gaining prominence as structural members all over the world, primarily for multi storey building construction due to their good seismic response and numerous other positive factors. Of course there are other less popular uses also which include the piers of bridges in the wet gaps and pile work for the foundation. As a result all the developed nations have come out with their building codes for this type of structural members. In addition there are a number of developing nations which are involved in developing the similar codes of practice. Steel is the most common material used for the tubular component of CFTs. GFRP wraps are also being used in a similar manner to generate confinement and increase of strength in structural members but their usage is limited to retrofitting and Re — Engineering purposes only. With the increase in the use of polymer based compounds in the construction industry there is a need to look for other suitable materials to combine with concrete. In addition there are cost factors involved with the use of steel. With this intent present work has been attempted to use UPVC tubes for CFTs. UPVC tubes are relatively very cheap in cost and are easily available in most common diameters and sizes. Present study focused on the studies of various parameters attached with the use of UPVC tubes as confining material for a CFT. Hereafter these are named as `Concrete Filled UPVC Tubes' or CFUTs. A total of 53 samples were casted and effects of different D/t ratios and L/D ratios were studied. As a result the study on both short columns and high slenderness columns was made possible. To study the effect of tube itself two different grades of tubes were used. The other parameters varied were the use of additional reinforcing material in concrete in addition to the tube and thereby generating more possibilities with the CFUTs. These materials were wire mesh, steel reinforcement of two different grades and types, GI pipe and the combination of wire mesh and steel reinforcement. Hence the study promised a wide range of possibilities with the CFUTs and brought out some very favorable conclusions. CFUT, being a complex concept. for the constructions, requires a high degree of quality control and supervision during the construction stage. Unlike normal RCC work, here, concrete once pored inside, is not visible for the natural inspection of the human eye. This aspect is also brought out as one of the result of the present study. Finally, the most pertinent point related to the study is suggesting the use of CFUT for the most common constructions of single and double storey constructions in semi urban and rural areas and thereby providing the cost saving benefits of CFUTs to the common masses