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Bundled Bars

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sometimes the required reinforcement bar will not fit for a given section of beam or girder, in this case, we resort to bundling a group of parallel bars, up to four bars can be bundled together,  ACI 7.6.6.2 stating that bundled bars should be enclosed within stirrups or ties, bundled bars should be tied, wired and fastened together to ensure remaining in position whether vertical or horizontal, ACI 7.6.6.3 stating that bars have diameter greater than 36 mm(#11) shall not be bundled in beams, the limitation of bundled bars size is for beam or girders in building, the small size of building members make it unpractical to bundle bars with size larger than 36mm(#11), in bridges the size of members are bigger and therefore it is allowed to bundle up to two bars with size greater than 36mm (#11). figure 1 showing bundle bar arrangements.

figure 1








when two or more of bars bundled deep vertically in bending plane, it is not practical to hook or bend all bundle at the same location, if the hook is required then individual bars shall be hooked staggered not at the same location. when the spacing limitation and cover requirements are based on bar size, fictitious bar diameter for bundled bars shall be derived from the equivalent area of the group of bars bundled together, ACI stating that for bundle bars terminated within the span of the flexural member(beam or girder), bars shall be terminated at a different location with a minimum of 40db stagger


                                     
                                                                                Figure 2





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