Ductility of Prestressed and Partially Prestressed Concrete Beam Sections

D analyses of structures responding elastically to ground motions recorded during severe earthquakes have shown that the theoretical response inertia loads are generally significantly greater than the static design lateral loads recommended by codes. Hence, structures designed for the lateral earthquake loads recommended by codes can only survive severe earthquakes if they have sufficient ductility to absorb and dissipate seismic energy by inelastic deformations.'-" Prestressed concrete has been widely used for structures carrying gravity loads but has not had the same acceptance for use in structural systems which resist seismic loading. Part of this caution in the use of prestressed concrete for earthquake resistant structures has been due to the paucity of experimental and theoretical studies of prestressed concrete structures subjected to seismic type loading. A survey of the research which has been conducted on the seismic resistance of prestressed concrete was published in 1970. 9 Parmeio and Hawkins" have published more recent reviews of the state of the art of seismic resistance of prestressed and precast concrete. There has been a lack of detailed building code provisions in the United States for the seismic design of prestressed and precast concrete. For example, the ACI Code,' the SEAOC recommendations, 2 the Uniform Building Code, 3 and the tentative provisions of the ATC 4 all contain special provisions for the seismic design of cast-in-place reinforced concrete structures, but do not have