Connections are established between reinforcing steel and concrete in construction using mechanical splices. First, the rebars are aligned and then secured by a splicing system linking them in a way that suits appropriate splicing standards. This process effectively transfers force from one bar to another while being separated by at least two bar diameters. These attachments are highly reliable, primarily because the structure does not entirely depend on the concrete for weight transfer. Splices allow structural designers to satisfy several building code regulations while achieving an optimal balance between steel and concrete and removing additional rebar lap zone.
Types of mechanical splices
Various splices are available, categorised under tension-compression, tension only or compression only.
Tension and compression mechanical splices
Deformed coupler bars
Unique bars with thread-like formations are assembled with locknuts and couplers and tightened to the required torque.
These couplers are attached to the reinforcement bars' ends and formulated with stainless-steel sleeves. To provide a mechanical overlock, these are moulded onto the contours of the rebar. A swaging press and special dyes create pre-threaded parts and achieve the connection. Installing one pre-threaded component into the other completes the splicing.
Upset Straight Threads
Upset Straight thread couplers are ideal for providing full-length mechanical joints between reinforcing bars with upsetting ends. You can connect rebars with different or similar diameters laterally, vertically or slant. The two upset end reinforcement bars are joined by a coupler comprising internal straight thread and matching exterior threads at either end.
These couplers connect reinforcing bars with corresponding exterior threads using internal straight threads at each end. The splice lessens the net cross-sectional area of the reinforcing bar and comprises three components, the internally threaded coupler and two bar ends.
Upset rebar ends with straight threads.
Heads are formed to attach to the bars' ends using a hydraulic device. The coupler is made to fit between closely spaced bars.
These couplers are made for applications where linking the reinforcing bars is imperative. Each coupler comes with a small shape and is suitable for use in cramped spaces with little room or in situations where you must keep the loss of cover to a minimum. Since these couplers are produced and delivered attached to the threaded bar, all that is needed on-site is to engage and tighten the bars.
End-bearing or compression-only mechanical splices
This only bears the compression stress, where a vertical bearing transfers the stress between bars. Compression-only mechanical splices are advisable when tension stress has not been developed. Alternatively, compression-only splices are not advisable across other situations where conditions are not guaranteed.
Mechanical lap or tension-only splices
Appropriate only when tension forces are present; these are shorter than lap splices. Reinforcing bars are connected by coupling sleeves instead of lap splices. However, mechanical lap splices are better suited for restoring structures because they require less concrete area to be removed. Some examples of mechanical lap splices are double-edge coupling sleeves and shear screws.