This popular publication is the definitive source for information on development and splicing of reinforcing bars. Now in its sixth edition, the book features data on mechanical splices including load tests for Type 1 and Type 2 splices, Grades 40 to 80. Also included are extensive tables of development and lap splice lengths for Grade 60 uncoated and epoxy-coated reinforcing bars with 3,000 to 10,000 psi concrete compressive strengths. Additionally, development and lap splice length tables for welded wire reinforcement, expanded information on headed bars, and supporting formulas for all development and lap splice tables are presented. The new edition conforms to ACI 318-14 and AASHTO LRFD Bridge Design Specifications, 2016.
reinforcing bars anchorages and splices pdf download
As outlined above, the strength and/or deformation capacity of RC walls may be sensibly reduced by the presence of lap splices above the foundation level, where the seismic demand is maximum. Adequate detailing, i.e. providing appropriate lap-splice length and confining reinforcement, is crucial in order to attain the desired member ductility. The component presented in this subsection allows to account for the presence of lap splices in RC wall boundary elements and to estimate: (i) the steel strain distribution in the pair of spliced rebars; (ii) the crack width along the lap-splice length as well as the width contribution to the splice-end cracks originating from lap-splice deformation; (iii) the total lap-splice displacement and the failure point.
Results from a recently concluded experimental programme on RC wall boundary elements with lap splices (Tarquini et al. 2018) are used to validate the proposed mechanical model. The 24 test units (TUs), of which 22 with lap splices and two reference units with continuous reinforcement, shared the same geometry, illustrated in Fig. 8. They differed in terms of lap-splice length, confining reinforcement and loading history, which constituted the variable parameters of the test programme. The testing machine was a uniaxial press with a fixed top and a mobile bottom actuator to which the TUs were connected by means of rigid steel profiles. The instrumentation included load-cells as well as LVDTs and LED grids to evaluate global and local displacement values. Namely, LEDs were also directly glued on the pair of spliced rebars, allowing a direct monitoring of rebar strains.
Reinforcement can be developed by embedment length, hook, or mechanical anchoring device. The development of the reinforcing bars relies on mechanical interlock of the bar deformations, hook, and/or anchor along with sufficient masonry cover to prevent splitting of the masonry. Reinforcing bars may be spliced by lapping the reinforcement, by proprietary mechanical splices or by welding.
While the 2008 MSJC includes an equation to determine development and lap splice lengths, the 2009 IBC modifies the MSJC lap splice length. In accordance with the 2009 IBC, the minimum required lap length for spliced reinforcing bars is determined using Equation 1 (see Table 1).
Welded splices require the bars to be butted or shortly lapped and welded to develop in tension at least 125% of the specified yield strength of the bar. All welding is required to conform to AWS D1.4 (ref. 8), and steel for welded splices must conform to ASTM A706 (ref. 9). In practice, however, welding tends to be an expensive splicing option.
Mechanical splicing of reinforcement typically employs proprietary couplers specifically designed for this application. Mechanical splices are required to have the bars connected to develop in tension or compression, as required, at least 125% of the specified yield strength of the bar.
Reinforcing bars can also be spliced using end-bearing splices, but only in members containing closed ties, closed stirrups or spirals for bars subject to compression only. End-bearing splices rely on the transmission of compressive stress by bearing of square-cut ends held in concentric contact by a suitable device. The bar ends are required to terminate in flat surfaces within 1 degrees of a right angle to the axis of the bars and be fitted within 3 degrees of full bearing after assembly. 2ff7e9595c