Steel Bar Splicing

Splicing in an inevitable practice in construction of reinforced concrete structures. as you know steel bars are produced with a limited length, so engineers have to cut them in an appropriate way to minimized the waste and meet the requirement of structural design. To do this we connect smaller bars to reach the desirable length. There are 18 methods to splice 2 pieces of steel bar. Each method comes with different cost and technical considerations.
Simple Lap Splice
This method is usually the most popular one due to its simplicity and low cost. In this method, two bars are wired together to secure in concrete mixture. If the bars are connected it is called a contact lap. But sometimes there is distance between bars and we call it a non-contact splice. According to codes the distance between bars should not be more than one-fifth the lap splice length nor 6 inches.
Another important thing is the length of a lap splice to provide enough friction. This length is a function of concrete strength, type of concrete, the yield strength of the reinforcing bars, bar size, bar spacing, concrete cover, and the amount of ties or stirrups.
According to ACI 318 Code, bars with diameter of 14 and 18 are not allowed to be connected by lap splicing unless the designer can make sure the interaction is only compressive.
Welded Lap Splice
However field-welding is not recommended in general, it can be used as a method to splice steel bars. Since welding inspection will definitely increase the overall cost of this method. CRSI provides comprehensive recommendations for welded splices.
Using a threaded Coupler to Splice
Using a coupler as a third member for splicing is another approach which must be done under special considerations. This method is usually used for cases that limitations do not allow usage of other methods. For example if the free length of rebar is not enough for welding or lap splicing, we have to connect the bars by using a coupler.
ASTM A615 has some requirements for the type and size of rebar which are suitable in this method. Moreover, the assembly of this connection must be carried out by applying an specific torque. The coupler can be designed in various shapes and functions as it is shown in the figure.
Using a grouted Coupler to Splice
In this method a coupling sleeve is filled with grout that provides sufficient cohesiveness to connect the parts. This grout must be cement-based and non-shrinkable to remain secure and transfer the forces. a simple cleaning of rebar ends is all needed in this method. This connection needs to be aligned and centric, otherwise load transfer can cause a degree of stress concentration that undermine the overall strength of the splice.
Using Grout-Filled/Threaded sleeves
In this method, the sleeve is both threaded and grouted to provide a more reliable connection. Actually this technic is a combination of previous methods.HUtu

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