Rebar anchors

In order to install these devices, steel bolts are anchored in existing concrete pier/abutment by use of epoxy resin, as shown in Fig. 8. The minimum thickness of steel bracket is 22mm and the length of bore hole is 15 times more than diameter of anchoring rebar. Two types of epoxy resins, namely liquid resin and grease type resin, as shown in Table 1 are used for the anchoring. 

The Ufer approach also can be applied to guy-anchor points or a tower base, as illustrated in Fig. 10.228. Welded rebar or ground rods sledged in place after the rebar cage is in position can be used. By protruding... 

FIGURE 10.228 The Ufer ground system as applied to a transmission-tower base or guy-wire anchor point. When using this type of ground system, bond ail rebar securely to prevent arcing in the presence of large surge currents. (After... 

For nonsoil conditions, tower anchor points should have their own radial systems or be encapsulated in concrete. Configure the encapsulation to provide at least 3 in. of concrete on all sides around the embedded conductor. The length will depend on the size of the embedded conductor. Rebar should extend as far as possible into the concrete. The dynamic ground impedance measurements of the anchor grounds should each be less than 25. ... 

Each shortcrete layer has steel wire mesh and some strengthening rebar near the soil nail anchoring location providing the reinforcements. The whole system depends on the tension capacity of the soil nails and concrete face layers acting as a multiple span two-way slab system. Differential settlement is not a particularly sensitive issue for typical soil nail walls. 

When considering placement of reinforcing bars relative to the anchor, it may be necessary to explicitly consider the effect of the secondary moment caused by the couple between the anchor and the rebar. Alternatively, the reinforcing can be placed symmetrically around the anchor as shown in Figure 3.6. For typical cases where anchors are embedded in the tops of structural column pedestals it is generally not required that the reinforcing be placed symmetrically around the bolt, because the secondary moments can be accommodated within the section depth. 

Steel embedded plates are often used to transfer loads from structural members to concrete structures or foundations. Such plates are often cast-in-place for constructability and to provide a smooth surface for attachment. These plates are attached to the concrete with welded anchors, which typically consist of headed studs, headed anchors, weldable rebar, or shear lugs they can be designed to resist applied tension, shear, and moment. Welding should be compatible with the anchor type. 

Both rebar and headed anchor rods welded to an embedded plate can be cumbersome to handle since the lengths can be long. If this is undesirable for shipping or coating, a threaded coupler can be welded to the embedded plate and the rebar or anchor rods threaded to match. In this case the coupler weld would have to be sufficient to transfer the tension and shear loads. 

Fabbrocino, G., G. M. Verderame, and G. Manfredi (2005), Experimental Behavior of Anchored Smooth Rebars in Old Type Reinforced Concrete Buildings, Engineering Structures - Elsevier, Vol. 27, pp. 1575-1585 Amsterdam, Netherlands. 

Typically, optimal performance of adhesive anchors is achieved with a relatively thin bond line (that is, an annular gap of 1/16-1/8 in. [1.6-3.2 mm]). The hole diameter may be increased in order to facilitate installation of rebar and large diameter or deep anchors however, the use of larger hole diameters requires larger volumes of adhesive with attendant potential for excessive heat generation during the curing process and resultant shrinkage. Rebar is often substituted for threaded rod for concrete-to-concrete applications. 

The tension and the shear forces in the anchors are transfered to the longitudinal rebars and shear reinforcement, respectively, which will be designed as anchor reinforcement. Therefore, the concrete breakout strength in tension and shear (D.5.2 and D.6.2) is not checked. The concrete pryout strength in shear (D.6.3) is assumed OK by inspection because it is usuaiiy criticai for short and stiff anchors. 

Tranifar of Anchor Load to Vertical Rebars 4.1 Amount of vertical reinfordno steel... 

Tbe number of pedestal vertical rebars Ibat are effective for resisting anchor tension is 3 (See Figure... 

ALL REBARS THAT ARE LOCATED LESS THAN — FROM THE EDGE OF THE ANCHOR HEAD CAN BE EFFECTIVE FOR RESISTING ANCHOR TENSION... 

---