Experimental Research On Restraint Grouting-Anchoring Overlap-Joint Of Steel Bar

Precast concrete structure is a efficient path to realize housing industrialization, whereas precast concrete members joint is key. Restraint grouting-anchoring overlap-joint of steel bar method is brought forward for the first time by Harbin institute of technology, and researched and applied to the system built-concrete structure engineering field. The merit of this critical technology is safe joint, simple and convenient manipulation, low cost.This article used spiral hoop acting as restraint measure, researched the influencing of different match stirrup ratio to the bond length. By theoretical and experimental research, under the joint credibility, this article established the influence law of match stirrup ratio to bond length.Restraint grouting-anchoring overlap-joint of steel bar is the joint method build on bond anchorage theory. Code for design of concrete structures(GB50010)requires that when splicing of bars joint-area percentage is 100%,lap length ll is 1.6 times of anchorage length la. By theoretical analysis and advanced research conclusion,improving match stirrup ratioρsv could reduce the lap length ll .So this article designed a series of test specimen to verify it. The experiment design parameter set by theoretical analysis formula: bar diameter is 12mm,16mm and 20mm, lap length is 1.4la,1.2la and 1.0la,and spiral hoop match stirrup ratio. Experimentation referred to Technical specification for mechanical splicing of steel reinforcing bars (JGJ 107), proceed 123'Restraint grouting-anchoring overlap-joint of steel bar specimens'simply tensioned and heavily stressed repeat pull- press test. On trial, the specimens of 0% spiral hoop match stirrup ratio occurred portrait split destroyed phenomena at steel bar yield load round. Specimens of spiral hoop match stirrup ratio set by theoretical analysis, occurred specimens destroyed or steel bar snapped off at steel bar critical load round. Test indicate that on deploying spiral hoop restrain occasions,it could effectively reduce lap length. This article used experimental data as root, proceed in-depth theoretical analysis and finite element analysis, ascertained design calculation formula considering safety coefficient, supplied import gist for perfecting design specifications of system built-concrete structure and engineering practice.