STUDY ON RATIONALIZATION OF PRECAST JOINT CONSTRUCTION USING RESTRAINT LAP JOINT

Abstract

 We propose restrained lap joints with spiral reinforcement bars surrounding an lap joint to rationalize the joining of precast members; for this purpose, we conducted 5 series tensile tests of the joint with the diameters of D13, D16, D19, D22, and D25. Consequently, the performance of an SD345 steel joint could be achieved by setting the overlapping length of the main reinforcement bar to 8 times diameter that of the main reinforcement bar for the D13 type, and 9 times diameter for the other types, and setting the reinforcing bar ratio of the spiral bars to 6.2% for each. The structural performance of members joined using the smallest and biggest diameter joints were then subject to tests (bending, shear, and ductility), and results showed that the structural performance was similar to that of materials without joints. Moreover, a comparison of this junction to the present coupler-type joint revealed that the precast members material cost might be reduced by approximately 20% and the construction cost by approximately 10%.