![]() ![]() However, for the splices under rare earthquakes, the stress level of the splices generally can go beyond the bar’s yield strength and large plastic strain could occur. ![]() Commonly, the stress level of the splices under frequent earthquakes did not exceed the bar’s yield strength. The third and fourth loading schemes (CH and CL) are of special interest because they involve splices under frequent and rare earthquakes, respectively. The second loading scheme (RT) relates to a splice under service loads with a stress level of generally no more than 60 % of the yield strength of the spliced bars. Stress–strain relationships were presented for splices under various loadings.įour loading schemes were used in this study, i.e., incremental tensile (IT) loadings and repeated tensile (RT) loadings as well as cyclic loadings at high stress (CH) and at large strain (CL). Special attention was paid to the deformation capacities of the splices and the association of the mechanical performance of the splices under different loadings. In this regard, tests on a total of 36 specimens were conducted in this study to gain new knowledge on the characteristics of the splices under tensile and cyclic loadings. In fact, most of the technical details for this type of product are private and proprietary with restricted access. Moreover, stress–strain relationships for splices under various loading schemes have not been available, which has made it difficult to build accurate models to simulate and to understand the behavior of structural components and structures (Ren et al. They found that the mechanical performance of the splices improved with an increase in embedded length of bars and compressive strength of grout.ĭespite these efforts, data are still scarce on the mechanical performance of splices, especially those involved in cyclic loadings when the splices are considered for use in earthquake-prone areas. The loading reversed 20 loops and ranged from 0.95 F ys in tension to −0.5 F ys in compression, where F ys denotes the force corresponding to the yield strength of the connected bars. ( 1997) studied strength, rigidity, capacity of elongation, and the bond stress-slip relationship of splices under cyclic loading. On the other hand, limited information is available for the behavior of splices under cyclic loading. In general, appropriate geometrical configuration of coupling sleeves, adequate embedded length of bars, and high compressive strength of grout help to enhance the grout-bar bond and, therefore, improve the mechanical performance of the splices. ( 2014) averaged 95 and 62 % of those of the connected bars, respectively. 2014 Henin and Morcous 2015), e.g., the ultimate strengths and ultimate strains of 24 specimens appropriately fabricated by Ling et al. ![]() For example, the tensile strengths and deformation capacities of the splices were lower than those of the connected bars (Einea et al. Test results have indicated that the mechanical performance of the splices is generally not as strong as that of the connected bars. In these circumstances, the mechanical performance of the splices essentially depends on the bond behavior between grout and bars. In general, the most common failure modes for splices under incremental tensile loading have been bar fracture and bar pull-out due to grout-bar bond failure (Einea et al. By doing this, lateral confinement to the bars was generated to enhance the grout-bar bond, resulting in a transfer of axial force between discontinued bars.Įfforts have been conducted to investigate the mechanical performance of splices with coupling sleeves of various geometrical and mechanical configurations, mostly under incremental tensile loading. On construction sites, high-strength and non-shrink cementitious grout was cast into the sleeve and around the bars using a low-pressure grout pump. A stop located in the sleeve’s midsection ensures appropriate positioning of the two embedded bars. Ribs were produced on the sleeve’s interior surface to increase the resistance force of the bond between the sleeve and grout. The grout-filled coupling sleeve came in different sizes to splice reinforcing bars of the adjacent precast members. Figure 1 illustrates a splice of typical configuration. This type of splice can provide continuity of reinforcement between precast elements and develop quality connections maintaining structural integrity. Since the 1970s when grouted splices (to be referred to as splices from this point forward) were invented (Yee 1973), they have been used as a preferred technology to splice bars particularly in precast concrete elements. The most commonly used methods to splice reinforcing steel bars are lap splices, welded splices and mechanical connections.
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