Abstract
This paper discusses the behavior of grouted noncontact lap splices under monotonic tension load. Deformed bars lapped through a grout-filled corrugated duct, and a spiral reinforcement was preembedded in the connection to improve tensile strength of the splice. The experimental results show that bond failure splices are always failed by the pullout of the preembedded bar other than the grouted bar. As the spiral pitch distance is not greater than 75 mm, the tensile strength generally improves with the increment of volumetric spiral reinforcement ratio due to the higher confinement provided by the spiral bar. Compared with the spiral bar diameter, the spiral pitch distance provides more dominant effect on the tensile strength of the connection. Based on the experimental results and the development length specified in ACI 318-14, a revised equation with a reduction factor of 0.76 was proposed to predict the required minimum lap length of spirally confined lap splice.
Highlights
Rebar lapping in grout-filled conduit is enormously used in construction of precast concrete structures. e connection system (Figure 1) is based on the use of consecutive column segments provided each with longitudinal bars protruding from the upper end and corrugated steel conduits encased in the lower end. e steel conduits are positioned adjacent to the embedded longitudinal bars. e continuity of the longitudinal reinforcement is achieved through the noncontact lapping when the lower projecting bars are inserted and grouted into the corrugated duct
ACI 318-14 [2] specifies that application of such splices in plastic hinge requires demonstration through laboratory testing that the spliced precast structural element shows an equivalent response to its cast-in-place counterpart
Research studies to address the aforementioned concerns and the use of grouted noncontact lap splices in plastic hinge regions of structural elements have been completed in recent years
Summary
Rebar lapping in grout-filled conduit is enormously used in construction of precast concrete structures. e connection system (Figure 1) is based on the use of consecutive column segments provided each with longitudinal bars protruding from the upper end and corrugated steel conduits encased in the lower end. e steel conduits are positioned adjacent to the embedded longitudinal bars. e continuity of the longitudinal reinforcement is achieved through the noncontact lapping when the lower projecting bars are inserted and grouted into the corrugated duct. ACI 318-14 [2] specifies that application of such splices in plastic hinge requires demonstration through laboratory testing that the spliced precast structural element shows an equivalent response to its cast-in-place counterpart. Research studies to address the aforementioned concerns and the use of grouted noncontact lap splices in plastic hinge regions of structural elements have been completed in recent years. Eir results indicate that the precast specimens have similar hysteretic response and energy dissipation capacity as the reference monolithic units, and the grouted corrugated ducts are suitable to be used in seismic regions. For the time being, fewer references exist dealing with the lap length of grouted corrugated duct connection and a calculation method for the required lap length which can promise sufficient strength in plastic hinge region, and is economical, reasonable, and urgently needed. 30 sets of 90 lap splices were prepared, and spiral reinforcement was preembedded in the connected region to improve the bond behavior of the splice. rough monotonic tension test, the effects of spiral configuration on tensile strength were investigated as well as the calculation of the required lap length
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