Post-Installed Reinforcing Bar Guide
6.0 WHAT ’ S THE BACK STORY ?
D-regions are parts of a structure with a complex variation in strain . They include portions near abrupt changes in geometry ( geometrical discontinuities ) or concentrated forces ( statistical discontinuities ). D-regions are assumed to extend a distance h from the force or geometric discontinuity ( see Figure 47 ).
B-region D-region B-regionD -region
Nodes are represented by extended nodal zones , which are in turn classified according to the sense and orientation of intersecting the ties and struts ( Figure 49 ). The proper modeling and assessment of extended nodal zones requires a thorough understanding of the limits of the strut-and-tie model approach .
Most post-installed reinforcing bar problems can be expressed with some variant of a C-C-T node , as shown in Figure 50 . h 2h h
Figure 47 — Idealized D- and B-regions in a concrete beam .
Post-installed reinforcing bar
The design of D-regions is complex and requires a clear understanding of force flow . In strut-and-tie modeling , the complex state of internal forces is idealized as a truss . The compression ( struts ) and tension ( ties ) members are identified in the region . The points of equilibrium where struts , ties , and concentrated forces intersect are denoted as nodes ( Figure 48 ).
Effective bond length
Figure 49 — Strut-and-tie model for a post-installed reinforcing bar connection .
Tie Strut Node
Figure 50 — Extended nodal zone .
Figure 48 — Strut-and-tie model of a corbel .
Note : A detailed description of strut-and-tie modeling of a post-installed reinforcing bar connection in a column foundation joint subject to overturning moment is provided in Hamad , B ., et al ., " Evaluation of Bond Strength of Bonded-In or Post-Installed Reinforcement ," ACI Structural Journal V . 103 , No . 2 , pp . 207-218 [ 8 ]. Additional experimental verification of this connection is described in Kupfer , et al . [ 11 ].