CYCLIC LOAD TESTS ON PRESTRESSED CONCRETE MODEL FRAMES

Prestressed concrete frames are commonly used in bridge design. Howeve r, very little is known about their behaviour under reversed cyclic lo ads, particularly when subjected to severe earthquakes, and most bridg e codes do not provide the required design guidelines. Results from sm all-scale models of eight prestressed concrete frames, tested under va rious load histories simulating earthquake forces are presented. The e xperimental primary curves (horizontal force-displacement relationship s) are compared with the theoretical results, and the experimental hys teretic loops are compared with those calculated from Tadeka's rules. The concrete strength is approximately 40 MPa, and the effective prest ress varied between 36% and 51% of the ultimate strength of the prestr essing steel. It was found that the ductility and energy dissipation i ncreased with decreasing effective prestress. The effect of the load h istory on the reversed cyclic behaviour is also significant.