【正文】 ion, member thickness or adjacent anchors, assuming the shape of failure area as a half pyramid. Ac,v = actual area of concrete cone of anchorage at the lateral concrete surface. lf = effective length of anchor under shear loading Partial safety factors and calculating factors – 14 – A? =partial safety factor taking account of the safety level of anchorage *R? =partial safety factor for material ??,v = factor take account of the influence of the angle between the load and the direction perpendicular to the free edge of the concrete member on the shear resistance. ?ec,N, ?ec,v = factor take account of a group effect when different tension (shear) load are acting on the individual anchors of a group. ?h,v =factor take account of the fact that the shear resistance does not decrease proportionally to the member thickness. ?re,N =the shell spalling factor takes account of the effect of dense reinforcement. ?s,N ,?s,v = the factor takes account of the disturbance of the distribution of stresses in concrete due to edge of the concrete member on tension (shear) resistance. ?ucr,N, ?ucr,v = the factor takes account of the position effect of the anchorage in cracked or noncracked concrete on tension (shear) resistance. – 15 – 3 Materials of concrete and anchor elements Concrete base materials The concrete base material shall be solid and sufficiently large to resist and the intended loads. Excessively air voided concrete, grout, grout layer and decorative mortar layers may not be considered as sufficient base material. Concrete strength for base material of postinstalled fasteners shall be at least C20. The concrete strength and modulus of elasticity should be obtained by onsite testing according to Code for Design of Concrete structures— GB50010. Anchor elements The materials of steel anchor elements shall be carbon steel, stainless steel or alloy steel. The selection of the anchor element shall be based on the environment condition and durability requirement of the application. The performance of anchors should ply with Expansion and undercut building anchors for use in concrete The materials performance of anchor made of carbon steel or alloy steel shall be defined by stkf and stkykff (see Table ). Table The material performance of carbon/alloy steel performance grade Characteristic tension strength stkf (MPa) 300 400 500 600 800 Characteristic yield strength ykfor ksof 2, (MPa) 180 240 320 300 400 480 640 Extension ratio 5? (%) 25 22 14 20 10 8 12 Note: the performance grade means 300?stkf (MPa), ?stkyk ff 。 ? Proprietary adhesive pounds in bination with a mixing and delivery system。 – 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