Allowable compression limits in prestressed concrete members.

摘要

The allowable compressive stress limits in the ACI 318 Building Code and AASHTO Specifications were based principally on historical justification when prestressed concrete was first introduced in the United States about 50 years ago. As a new material, it was thought to be important to double-check its adequacy with both “working stress” and “strength design”. Both the ACI 318 Building Code and AASHTO Specifications that strength design be performed for flexural prestressed concrete members.; Strength design was first permitted as an alternate design method for nonprestressed concrete member in the 1956 ACI Code and later became a substantial part of the 1963 ACI Code to replace working stress design. The researcher proposed that the compressive stresses in flexural pretensioned prestressed concrete members should be solely based on strength design criteria. The proposed strength design method will frequently allow for higher prestress level than the current empirical allowable compressive stress limits given in the ACI 318-99 Building Code and AASHTO Specifications for Highway Bridges.; This research included theoretical study and experimental results of two simply supported inverted tee specimens, with cast-in-place deck, subjected to very high compressive stress induced by prestress. These specimens were designed, produced and tested at the University of Nebraska Structures Laboratory.