【正文】 – 1 – e6df22647cf739a1b774602efe92fd46 Thursday, December 10, 2020 05:34 Industry Technical Specification of the People’s Republic of China Technical Specification for Postinstalled Fastenings in Concrete Structures JGJ145－ 2020 – 2 – 1 General This standard is piled for postinstalled anchoring technology ensuring reliable, safe and economical designs, construction and operation. This standard applies to the use of postinstalled anchoring system in normal weight concrete. It does not cover anchorage to masonry and lightweight/gas concrete. Anchor design should be based on application (structural elements or nonstructural elements), load (tension, pression, moment, shear or bined tension and pression), action and safety level (important or normal), etc. The design, installation and acceptance of postinstalled anchoring systems should ply with this standard and relevant mandatory requirement of current national codes. In general, this standard is intended to address assessment and design of adhesive anchoring systems where anchor theory applies (see Fig. below). It is not intended to address the assessment and design of postinstalled reinforcing bars proportioned according to the concept of reinforcement development (see Fig. below). I) Reinforcement designed according to anchor theory (covered in this standard). II) Reinforcement designed according to rebar theory (not covered in this standard). – 3 – 2 Terminology and symbols Terms Postinstalled anchoring systems An assembly prising drilling method, drill bit requirements, cleaning method (if specified by Manufacturer) base material, anchor or anchor group and ponent fixed to the concrete. Anchor A steel element postinstalled into hardened concrete base material, used to transmit applied loads. Steel elements for adhesive anchoring system may include threaded rods, deformed reinforcing bars, or internally threaded steel sleeves with external deformations. Expansion anchors A postinstalled anchor inserted into hardened concrete that transfers loads to or from the concrete by direct bearing or friction or both. Expansion anchors may be torquecontrolled, where the expansion is achieved by a torque acting on the screw or bolt。 or displacementcontrolled, where the expansion is achieved by impact forces acting on a sleeve or plug and the expansion is controlled by the length of travel of the sleeve or plug (, Fig. ). Fig Torquecontrolled expansion anchors – 4 – Fig Displacementcontrolled expansion anchors Undercut anchors A postinstalled anchor that develops its tensile strength from the mechanical interlock provided by undercutting of the concrete at the embedded end of the anchor. The undercutting is achieved with a special drill bit prior to installation of the anchor or alternatively by the anchor itself during the installation procedure (Fig. ). – 5 – Fig Undercut anchors Adhesive anchors For the purposes of this standard, the adhesive anchor system is prised of the following ponents: ? Adhesive anchor。 ? Proprietary adhesive pounds in bination with a mixing and delivery system。 ? Accessories for cleaning the drilled hole including brushes, air nozzles, and other items needed to plete the cleaning process。 and a) Load controlled anchor installed by tensioning anchor, causing sleeve to expand in predrilled undercut d) Displacement controlled anchor that cuts its own undercut while set by hammering sleeve over cone b) Displacement controlled anchor set in predrilled undercut by hammering sleeve over cone. e) Torquecontrolled anchor set into pre drilled undercut by application of torque forcing sleeve over cone c) Displacement controlled anchor installed in predrilled undercut and set by defined displacement, causing expansion sleeve to expand into undercut. f) Torquecontrolled anchor that cuts its own undercut by application of setting torque, forcing sleeve over cone. – 6 – ? Printed instructions for the adhesive anchor installation including hole preparation, injection, and cure for all environmental conditions permitted in the qualification. Fig Adhesive anchor / rebar Base material The hardened material into which anchor is fastened. Normal weight concrete is defined to as the base material in this standard. Anchor Group A number of anchors of approximately equal effective embedment depth with each anchor spaced at less than 3hef from one adjacent anchor when subjected to tension, or 3ca1 from one or more adjacent anchors when subjected to shear. Only those anchors susceptible to the particular failure mode under investigation shall be included in the group. Fixture Component fixed to the concrete via the postinstalled anchoring system. Anchor plate A steel plate fastened by anchors directly transfer loads onto anchors and base material. Failure mode The failure mechanism observed of postinstalled anchoring system post peak loads. – 7 – Anchor steel failure The steel failure of anchor rod or rebar under tension, shear or bined tension and shear (see Fig ). Tension Shear Fig. Steel failure Concrete breakout failure Failures of the anchor in an unconfined tension test, characterized by the formation of a conical fracture surface originating at or near the embedded end of the anchor element and projecting to the surface of the concrete test member (see Fig ). Fig. Concrete cone failure Concrete splitting A concrete failure mode characterized by the formation of planar crack in the concrete parallel to and extending through the axis of the anchor(s) (see Fig ).