Performance of UPVC Pipe Confined Concrete Columns in Compression

Abstract

Composite columns have been used in construction industry with great efficiency for a number of years. This is because composite column offers a superior column system as compared to the conventional column systems such as Reinforced concrete (RC), steel or timber columns. The reason in that composite column utilizes the combinedproperties of different individual materials. Steel and fiber reinforced polymer tubes have been the commonly used confining media in concrete encased columnconstruction. However, steel is faced with the problem of corrosion especially when used in corrosive environment while manufacture of fiber reinforced polymer involves arather expensive technology. This research proposed a novel-type concrete-filled composite column where unplasticized polyvinylchloride (UPVC) plastic tube was used toconfineconcrete.Concrete of varying class strengths namely; C30, C25, and C20 were used tofill UPVC tubes. The tubes had outer diameters of 55 mm, 83 mm and 110 mm andthicknesses of 2.5 mm, 3.0 mm and 2.5 mm respectively. The composite columns hadslenderness ratios of 2, 3 and 4. The columns were then tested on a universal testingmachine (UTM) to determine their behaviour under compressive load. Applied loads, deformation and strains on the specimen were monitored through in-built load cells, Linear Variable Displacement Transducers (LVDTs) and strain gauges respectively. Results showed that UPVC pipes are effective in confining concrete, since in all cases f' cc /f' >1. Confined strength values increased between 1.18 to 3.65 times the unconfinedstrength values. Columns filled with low strength concrete tended to be more ductile assince they underwent large deformations under load before failure. This great ductilityimplied more energy absorption capacity suggesting a potentially earthquake resistant composite column system. There is enormous potential of UPVC tubes for use in composite systems as illustratedby this research. The resultant is a cheap, more economical type of column for lightweight construction. The principal target audience for this project is individuals involved in application of building materials within the construction industry. Since the use ofUPVC in confining column is a relatively new area of research, limited literature wasavailable. Long term performance of these columns was also not studied. co