9307843 Naaman This proposal aims at pursuing the development of a high energy absorbing joint for precast concrete structures in seismic zones. The joint is made from high performance fiber reinforced cement based composites (HPFRC) such as high fiber content fiber reinforced concrete and SIFCON (Slurry Infiltrated Fiber Concrete). The joint is designed to act as an energy dissipating connector between the beam and the column elements. The use of high fiber content in the matrix of the joint is meant to insure high ductility, increased energy absorption, reduced spalling, and superior shear resistance during load reversals. The immediate objective of the research is to understand the fundamental mechanisms that control the properties of the joint and its response under monotonic and cyclic loads. An experimental and an analytical programs are planned. In the experimental program, two types of tests are proposed. The first is designed to identify the bond shear stress versus slip characteristics of reinforcing bars embedded in HPFRC; the other is to clarify the response of these composites, under monotonic and cyclic shear loading, with and without dowel reinforcement. The analytical program aims at developing a model to predict the hysteretic moment rotation response of the joint using the constitutive properties of the two main component materials and their interface. This study should eventually lead to designing joints with optimized ductility and energy absorbing properties. ***
