what is the standard way to splice rebar to form a longer re

huangyhg

what is the standard way to splice rebar to form a longer re
in a tension concrete member, when the rebar is not long enough and need splice them to make a longer rebar, i have seen some contractor weld lap splice along overlap portion, some contractor use wire to tie the lap splice at overlap portion, some just let it overlap a development length and leave it. so what is the standard way in these overlap portion in practice?
also in a flexural beam, is it allowed to splice two (or more) short rebar to make up whole length rebar in tension?
thank you very much for your precious response.

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i generally just 'stretch' them... <g>
it is a matter of specifying a splice length, either tension or compression, that will permit the reinforcing steel stress to redistribute to the next bar.  there are several factors that determine the splice length and these are noted in aci or csa standards and likely other standards. try to provide splices in areas of reduced moments, etc.
dik
splices should be minimized, but are inevitable in reinforced concrete.  there are several ways splices can be made...the most common is to lap the required distance and tie the rebar together with tie wire.  welding can be done, but rebar has variable welding qualities, so it should be done in accordance with accepted welding procedures for rebar such as those given by the american welding society (aws).  mechanical splices using proprietary clamping devices can also be done.
lapping without tieing is not acceptable.
the general practice is to tie the splice bar with binding wire for required development/lap length ( to be worked out based on various factors stated in chapter 12 of aci). binding wires ties two bars together, keep them in plae so that they dont get displaced while concreting and ensure proper force transfer. welding of bars for splicing should generally be avoided.
it is allowed to to splice two bars in same beam. but the splice should be staggered and should be avoided in maximum bending moment area.