Mechanical Splices
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There are three basic categories of mechanical splices:
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The designs of mechanical splices are proprietary. The splices are supplied by a number of manufacturers across the U.S.
The various types of mechanical splices available includes:
Coupler for Thread-Deformed Bar
This is a mechanical splice that requires special bars with threadlike rolled deformations over their entire length which meets ASTM A615. Splices are assembled with lock nuts and threaded couplers, then the nuts are tightened to a specified torque. Alternatively, the lock nuts can be omitted when the bars can be torqued together. Special hardware permits use for end anchorages in concrete or connection to structural steel members. Bars may be flame or saw-cut.
Grout-Filled Coupling Sleeve
The double-frustrum-shaped coupling sleeve is filled with a cement-based, non-shrink, high-early strength grout. Reinforcing bars to be spliced are inserted into the sleeve and butt at the center of the sleeve. The space between bar and sleeve is filled with non-shrink grout to transfer forces between the deformed surface of the bars and the deformed interior surface of the sleeve. No special end preparation of the bars is required except for normal cleaning. The relatively wide sleeves also can accommodate minor bar misalignments, and combinations of different size bars.
Combo Grout-Filled/Threaded Sleeve
Primarily used for precast construction, this type of mechanical splice combines two common mechanical splicing techniques. One end of the sleeve is attached and secured to a reinforcing bar by means of threading. The splice is then completed when the other bar end is inserted into the sleeve and the space between the bar and the sleeve is filled with high-strength grout. The wide mouth opening of the sleeve allows for minor bar misalignment during erection. The wide mouth also allows for transitioning between different bar sizes.
Steel-Filled Coupling Sleeve
The steel-filled coupling sleeve is a mechanical splice in which molten metal or “steel filler” interlocks the grooves inside the sleeve with the deformations on the reinforcing bar. Special details permit use as end anchorages or connections to structural steel members. Shear-cut, flame-cut, or saw-cut ends of the bar can be used as the “steel filler” fills the space between the ends of the bar. However, a bar-end check is recommended.
Non-Upset Straight Thread Coupler
This is a mechanical splice consisting of a coupler with internal straight threads at each end that joins two reinforcing bars with matching external threads. Because the cutting of threads reduces the net cross-sectional area of the reinforcing bar, some manufacturers use bars one size larger while other manufacturers use bars with tensile and yield strengths sufficient to overcome the loss of net area by thread cutting.
This type of splice is in three pieces (the two bar ends and the internally threaded coupler). These systems are also available as weld-on couplers, transitional couplers, and positional couplers.
Upset Straight Thread Coupler
This is a mechanical splice consisting of a coupler with internal straight threads at each end that joins two upset end reinforcing bars with matching external threads. Upsetting the bar ends permits the cross-sectional area in the threaded portion to be greater than the bar cross-sectional area.
This type of splice can either be in three pieces (the two bar ends and internally threaded coupler) or in two pieces with the coupler integrally forged or pre-assembled onto the bar end. These systems are also available as weld-on couplers, transitional couplers, positional couplers, and headed bars.
Cold-Swaged Threaded Coupler
The cold-swaged threaded coupler consists of pre-threaded male and female components, which are swaged onto the reinforcing bars using a swaging press with special dies. No threads are required on the bar ends. Splicing of the bars is completed by installing one pre-threaded component into the other. A three-piece position coupler is available for splicing bent bars that cannot be rotated. Optional details include transition couplers for splicing different bar sizes, couplers used to connect bars to structural steel members, and couplers with flanges having nail holes. Threads are sealed and protected for future extension applications.
Cold-Swaged Coupling Sleeve
The cold-swaged coupling sleeve uses a hydraulic swaging press with special dies to deform the sleeve around the ends of the spliced reinforcing bars. This produces a positive mechanical interlock with the reinforcing bars. Bars to be spliced are inserted equal distances into the sleeve. Bars may be shear-cut, flame-cut, or saw-cut, however, a bar-end check is recommended. Bars of different sizes can be spliced with this system. This mechanical splice can also be used for joining reinforcing bars to structural steel members. Longer sleeves are required for splicing epoxy-coated reinforcing bars.
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