3.0 ANCHORING SYSTEMS
3.1 ANCHOR PRINCIPLES AND DESIGN
3.1.1 DEFINITIONS
Adhesive anchor is a post-installed anchor that is inserted into a drilled hole in hardened concrete , masonry or stone . Loads are transferred to the base material by the bond between the anchor and the adhesive and the adhesive and the base material .
Anchor category is an assigned rating that corresponds to a specific strength reduction factor for concrete failure modes associated with anchors in tension . The anchor category is established based on the performance of the anchor in reliability tests .
Anchor group is a group of anchors of approximately equal effective embedment and stiffness where the maximum anchor spacing is less than the critical spacing .
Anchor reinforcement is reinforcement used to transfer the full design load from the anchors into the structural member .
Anchor spacing is centerline-to-centerline distance between loaded anchors .
Attachment is the structural assembly , external to the surface of the concrete , that transmits loads to or receives loads from the anchor .
Cast-in-place anchor is traditionally a headed bolt , headed stud or hooked bolt installed before placing concrete . Additionally , cast-in-place internally threaded inserts are a form of cast-in-place anchors .
Characteristic capacity is a statistical term indicating 90 percent confidence that there is 95 percent probability of the actual strength exceeding the nominal strength . This is also called the 5 % fractile capacity .
Concrete breakout is a concrete failure mode that develops a cone or edge failure of the test member due to setting of the anchor or applied loads .
Concrete splitting failure is a concrete failure mode in which the concrete fractures along a plane passing through the axis of the anchor or anchors .
Cracked concrete is condition of concrete in which the anchor is located . See Section 2.1.2 .
Critical spacing is minimum required spacing between loaded anchors to achieve full capacity .
Critical edge distance is minimum required edge distance to achieve full capacity .
Cure time is the elapsed time after mixing of the adhesive material components to achieve a state of hardening of the adhesive material in the drilled hole corresponding to the design mechanical properties and resistances . After the full cure time has elapsed , loads can be applied .
Displacement controlled expansion anchor is a postinstalled anchor that is set by expansion against the side of the drilled hole through movement of an internal plug in the sleeve or through movement of the sleeve over an expansion element ( plug ). Once set , no further expansion can occur .
Ductile steel element are anchors designed to be governed by ductile yielding of the steel . This is determined by performing tension testing on coupons machined from the finished anchors . The minimum requirements are 14 % elongation and 30 % reduction of area .
Expansion anchor is a post-installed anchor that is inserted into a drilled hole in hardened concrete or masonry . Loads are transferred to and from the base material by bearing , friction or both .
Edge distance is distance from centerline of anchor to the free edge of base material in which the anchor is installed .
Effective embedment depth is the overall depth through which the anchor transfers force to or from the surrounding concrete . The effective embedment depth will normally be the depth of the concrete failure surface in tension applications . For cast-in headed anchor bolts and headed studs , the effective embedment depth is measured from the bearing contact surface of the head . For expansion anchors , it is taken as the distance from surface of base material to tip of expansion element ( s ).
Gel time is the elapsed time after mixing of the adhesive material components to onset of significant chemical reaction as characterized by an increase in viscosity . After the gel time has elapsed , the anchors must not be disturbed .
Minimum edge distance is the spacing from the centerline of the anchor to the edge of the base material required to minimize the likelihood of splitting of the base material during anchor installation .
Minimum spacing is distance between the centerlines of adjacent loaded anchors to minimize the likelihood of splitting of the base material during anchor installation .
Minimum member thickness is minimum required thickness of member in which anchor is embedded to minimize the likelihood of splitting of the base material .
Post-installed anchor is an anchor installed in hardened concrete and masonry . Expansion , undercut , and adhesive anchors are examples of post-installed anchors .
Projected area is the area on the free surface of the concrete member that is used to represent the larger base of the assumed rectilinear failure surface .
Anchor Fastening Technical Guide Edition 22 | 3.0 ANCHORING SYSTEMS | 3.1 ANCHOR PRINCIPLES AND DESIGN Hilti , Inc . 1-800-879-8000 | en español 1-800-879-5000 | www . hilti . com | Hilti ( Canada ) Corporation | www . hilti . ca | 1-800-363-4458
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