Effects of grout and energy-dissipating bar properties on a Type III grouted seismic connection for precast concrete structures

摘要

This paper investigates the effects of grout properties and energy-dissipating steel reinforcing bar properties on the performance of a grouted Type III connection for gap-opening joints of precast concrete structures subjected to seismic displacements. This Type III connection offers the potential for a high-performance yet simple nonproprietary, low-cost system that allows Grade 60 (414 MPa) energy-dissipating ductile deformed reinforcing bars to reach close to their ultimate tensile strength and strain capacity under cyclic loading in a short grouted embedment length. The use of short grouted connections simplifies the construction of precast concrete structures because protruding bar lengths from precast concrete members can be minimized, and field-grouting lengths can be reduced. The test parameters investigated were the grout product, grout strength, energy-dissipating bar size, and energy-dissipating bar heat. It was found that the grout used in the connector sleeve and low-cycle fatigue fracture of the energy-dissipating bar can limit the deformation capacity of the connection. Additional requirements should be introduced in ASTM A706 to improve the low-cycle fatigue performance of reinforcing bars intended for seismic applications. Furthermore, it may be necessary to increase the bond length of the energy-dissipating bar for this nonproprietary connection to be used without the requirement for a specific grout product.