Experimental Study On The Axial Compression Of GRP-Concrete-PVC Tube Composite Column

GRP-Concrete-PVC composite column is a new type of composite column which is composed of GRP outer tube, PVC inner tube and reinforced concrete filled between them. A composite column with a moderate hollow ratio of 0.367, concrete strength grade C30, and reinforcement ratio of 0.9% is designed to investigate the failure phenomenon and loading capacity under axial pressure by static test. It is found that the appearance of the GRP tube has no obvious damage when the load is less than 30% of the ultimate bearing capacity, although some local cracks are initiated in GRP tube. As the load increases, the cracks propagate continuously. Occasionally the specimen has a crisp sound and a squeaking noise. When the load reaches 96% of the ultimate bearing capacity, the upper part of the GRP tube shows some damage character (tube colour turns to white), the outer parts of the tube are tore off, and the glass fiber bundle is layered off. When the load reaches the ultimate bearing capacity, the cracks developed look like an inclined Z-shaped band. The cracks propagate upto around one third of the specimen height from the bottom. The concrete inside the composite column is crushed. The relationship between the axial load and the strain of the GRP tube in different direction is analyzed.