Rebar ties

[Mr. Inspector]

When does rebar need to be tied together? Plans never show or specify anything about ties.

 

[classicT]

Always.... shall be secured against movement during placement of concrete. Codes mandates that it be done, but will not provided the means or methods of how to do so.

ACI 318-14 via IBC Reference
26.6.2.2 Compliance requirements:
(a) Reinforcement, including bundled bars, shall be placed within required tolerances and supported to prevent displacement beyond required tolerances during concrete placement.
​

IRC R403.1.3.5.3 Support and Cover
Reinforcement shall be secured in the proper location in the forms with tie wire or other bar support system to prevent displacement during the concrete placement operation. Steel reinforcement in concrete cast against the earth shall have a minimum cover of 3 inches (75 mm). Minimum cover for reinforcement in concrete cast in removable forms that will be exposed to the earth or weather shall be 11/2 inches (38 mm) for No. 5 bars and smaller, and 2 inches (50 mm) for No. 6 bars and larger. For concrete cast in removable forms that will not be exposed to the earth or weather, and for concrete cast in stay-in-place forms, minimum cover shall be 3/4 inch (19 mm).​

 

[Mr. Inspector]

So if they are running horizontal rebar for a footing as long as pouring the concrete doesn't move them there is no requirement to tie the bars together?

 

[classicT]

Technically speaking, the lapped bar doesn't even have to be in contact. Non-contact lap splices are permitted under ACI-318.

25.5.1.3 For noncontact splices in flexural members, the transverse center-to-center spacing of spliced bars shall not exceed the lesser of one-fifth the required lap splice length and 6 in.​

 

[MT Florida]

so whats the requirement if movement is anticipated?

 

[MT Florida]

On a simple stem wall footing or in a bond beam of 1 #5 the inspectors required it to be tied every 8", so a 20" lap would require 3 ties. Could some reference where this could be found?

 

[Mark K]

So if they are running horizontal rebar for a footing as long as pouring the concrete doesn't move them there is no requirement to tie the bars together?

horizontal bars in footings are tied to cross bars to maintain separation and are tied together at splices. Vertical bars are tied to longitudinal bars.

 

[Mark K]

so whats the requirement if movement is anticipated?

If movement is anticipated, make it so the movement will not be a problem

 

[Mark K]

If there is a question of how much movement is acceptable and there is an engineer on the project ask him.

 

[Msradell]

The amount of lap at splices varies wildly depending on the engineer for the project. ACI normally calls for splices to be 48 Bar diameters but I've seen them as short as 30 Bar diameters and as long as 60 Bar diameters.

 

[Mark K]

According to ACI 318 the length of lap splices is dependent on a number of factors that depend on the strength of the reinforcement, strength of concrete, type of aggregate, size of reinforcement, spacing between bars being spliced, whether epoxy coated reinforcement is used, location of horizontal reinforcement with respect to start of pour, the forces being spliced, and the amount of reinforcing provided. In order to simplify things engineers will attempt to simplify the criteria. This simplified criteria may vary with the particular circumstances that may vary for different projects.

If the appropriateness of the criteria specified by the engineer is being questioned, I recommend that the plan check engineer be a licensed engineer.

 

[Paul Sweet]

The main function of typical wire ties is to keep bars from being displaced when the concrete is placed. There are special structural couplings, but they need to be detailed by an engineer.

 

[ICE]

According to ACI 318 the length of lap splices is dependent on a number of factors that depend on the strength of the reinforcement, strength of concrete, type of aggregate, size of reinforcement, spacing between bars being spliced, whether epoxy coated reinforcement is used, location of horizontal reinforcement with respect to start of pour, the forces being spliced, and the amount of reinforcing provided. In order to simplify things engineers will attempt to simplify the criteria. This simplified criteria may vary with the particular circumstances that may vary for different projects.

If the appropriateness of the criteria specified by the engineer is being questioned, I recommend that the plan check engineer be a licensed engineer.

Sounds like Mil Specs. Engineers tend to overthink everything. The season doesn’t factor in?