Industry Technical Specification of the People’s Republic ofChinaTechnical Specification for Post-installedFastenings in Concrete StructuresJGJ145－20192019 BeijingContents1 General2 Terminology and symbols3 Materials3.1 Concrete base material3.2 Anchors3.3 Adhesive material of bonded anchors4 Basis of design4.1 Type and operating principles4.2 Design and safety concept5 Static analysis5.1 General5.2 Tension loads acting on anchor group5.3 Shear loads acting on anchor group6 Ultimate limit state6.1 Resistance to tension loads6.2 Resistance to shear loads6.3 Resistance to combined tension and shear loads7 Anti-seismic design8 Structural requirements9 Installation and acceptance9.1 General9.2 Drilling hole9.3 Installation and fastening9.4 Inspection and acceptance of installationAnnex A Testing method on site1 General1.0.1 This standard is compiled for post-installed anchoring technologyensuring reliable, safe and economical designs, construction and operation.1.0.2 This standard applies to the use of post-installed anchoring system innormal weight concrete. It does not cover anchorage to masonry and lightweight/gas concrete.1.0.3 Anchor design should be based on application (structural elements ornon-structural elements), load (tension, compression, moment, shear or combined tension and compression), action and safety level (important or normal), etc.1.0.4 The design, installation and acceptance of post-installed anchoringsystems should comply with this standard and relevant mandatory requirement of current national codes.1.0.5 In general, this standard is intended to address assessment and design ofadhesive anchoring systems where anchor theory applies (see Fig.below). It is not intended to address the assessment and design of post-installed 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).2 Terminology and symbols2.1 Terms2.1.1 Post-installed anchoring systemsAn assembly comprising drilling method, drill bit requirements, cleaning method (if specified by Manufacturer) base material, anchor or anchor group and component fixed to the concrete.2.1.2 AnchorA steel element post-installed into hardened concrete base material, usedto transmit applied loads. Steel elements for adhesive anchoring system may include threaded rods, deformed reinforcing bars, or internally threaded steel sleeves with external deformations.2.1.3 Expansion anchorsA post-installed anchor inserted into hardened concrete that transfersloads to or from the concrete by direct bearing or friction or both.Expansion anchors may be torque-controlled, where the expansion is achieved by a torque acting on the screw or bolt; or displacement-controlled, 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.2.1.3-1, Fig. 2.1.3-2).Fig 2.1.3-1 Torque-controlled expansion anchorsFig 2.1.3-2 Displacement-controlled expansion anchors2.1.4 Undercut anchorsA post-installed anchor that develops its tensile strength from themechanical 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. 2.1.4).Fig 2.1.4 Undercut anchors2.1.5 Adhesive anchorsFor the purposes of this standard, the adhesive anchor system is comprised of the following components:• Adhesive anchor;• Proprietary adhesive compounds in combination with a mixing and delivery system;• Acce ssories for cleaning the drilled hole including brushes, air nozzles, and other items needed to complete the cleaning process; and• Printed instructions for the adhesive anchor installation including holepreparation, injection, and cure for all environmental conditions permitteda) Load controlled anchor installed by tensioning anchor, causing sleeve to expandin predrilled undercutd) Displacement controlled anchor thatcuts its own undercut while set byhammering sleeve over coneb) Displacement controlled anchor set inpredrilled undercut by hammering sleeveover cone. e) Torque-controlled anchor set into pre drilled undercut by application of torqueforcing sleeve over conec) Displacement controlled anchor installed inpredrilled undercut and set by defineddisplacement, causing expansion sleeve toexpand into undercut. f) Torque-controlled anchor that cuts its own undercut by application of setting torque, forcing sleeve over cone.in the qualification .Fig 2.1.5 Adhesive anchor / rebar2.1.6 Base materialThe hardened material into which anchor is fastened. Normal weight concrete is defined to as the base material in this standard.2.1.7 Anchor GroupA number of anchors of approximately equal effective embedment depth with each anchor spaced at less than 3h ef from one adjacent anchor when subjected to tension, or 3c a1 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.2.1.8 FixtureComponent fixed to the concrete via the post-installed anchoring system.2.1.9 Anchor plate A steel plate fastened by anchors directly transfer loads onto anchors and base material.2.1.10 Failure modeThe failure mechanism observed of post-installed anchoring system post peak loads.2.1.11 Anchor steel failureThe steel failure of anchor rod or rebar under tension, shear or combinedtension and shear (see Fig 2.1.11).TensionShearFig. 2.1.11 Steel failure2.1.12 Concrete breakout failureFailures 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 2.1.12).Fig. 2.1.12 Concrete cone failure2.1.13 Concrete splittingA concrete failure mode characterized by the formation of planar crack inthe concrete parallel to and extending through the axis of the anchor(s) (see Fig 2.1.13).Fig. 2.1.13 Splitting failure2.1.14 Bond failureFailure mode characterized by the withdrawal of the anchor element from the concrete without rupture of the embedded part, for example the threaded rod or rebar, and without formation of a full-depth conical breakout surface. The formation of limited-depth conical breakout surfaces shall also be considered as bond/pullout failure. (see Fig.2.1.13).Fig. 2.1.13 Bond failure2.1.15 Concrete edge failureThe anchorage failure occurs at the lateral concrete surface with the shape of concrete cone in the fracture area as a half pyramid under shear loads (see Fig. 2.1.14).Fig. 2.1.14 Concrete edge failure2.1.16 Pryout failureThe anchorage failure occurs in concrete at the side opposite to shear load direction by short stiff anchors (see Fig. 2.1.15)Fig. 2.1.15 Pryout failure2.1.17 Pull-out failureThe anchorage failure of anchor pulled out from drilled hole completely (see Fig. 2.1.17)Fig 2.1.17 pull-out failure Fig. 2.1.18 pull-through failure 2.1.18 Pull-through failureThe anchorage failure of anchor expansion parts pulled out from anchor sleeve and the sleeve still keep inside the drilled hole (see Fig. 2.1.18).Similarly, for adhesive anchoring systems bond failure may occur between the anchor element and the adhesive or between the adhesive and the bore hole (see Fig. 2.1.19).Adhesive-element failure Adhesive bore hole failure2.1.21 Design working LifeThe period of time during which the performance of the anchoring system and structures will be maintained at a level compatible with the intended conditions of use.2.2 Symbols2.2.1 Action and ResistanceM=momentN=normal forceR=resistanceS=actionT=torsion momentV=shear forceN sd, V sd = design value of tensile (shear) loadN g sd, V g sd =design value of the sum of the tensile load (shear load) acting on the tensioned (sheared) anchors of a group.N h sd, V h sd = design value of tensile load (shear load) acting on the most stressed anchor of an anchor groupN Rk,s,V Rk,s=characteristic resistance of a single anchor (normal force, shear force) in case of steel failureN Rd,s, V Rd,s =design resistance of a single anchor (normal force, shear force) in case of steel failureN Rk,c, N Rd,c =characteristic (design) resistance of an anchor or a group of anchors, respectively, in case of concrete cone failure N Rk,sp, N Rd,sp =characteristic (design) resistance of an anchor or an anchor group in case of concrete splitting failureN Rk,p, N Rd,p =characteristic (design) resistance of an anchor in case ofpull-out failureT inst , N inst = installation torque moment and related pre-tightening torsion V Rk,c , V Rd,c =characteristic(design) resistance of an anchor or an anchor group in case of concrete cone failure at edgeV Rk,cp , V Rd,cp =characteristic (design) resistance of an anchor or an anchorgroup in case of concrete pryout failure2.2.2 Concrete and steelf yk =characteristic steel yield strengthf stk =characteristic steel ultimate tensile strengthf cu,k =characteristic concrete compression strength measured on cubes2.2.3 characteristic value of anchors (see Fig.2.2.3)a = spacing between outer anchors of adjoining groups or between single anchors.b = width of concrete memberc , c 1, c 2 = edge distance between anchors and the edge of concrete c cr,N = edge distance for ensuring the transmission of the characteristic tensile resistance of a single anchor without spacing and edge effects in case of concrete cone failure c min = minimum allowable edge distance for preventing concrete memberfrom the splitting failure due to installation d = diameter of anchor bolt, thread diameter or diameter of rear d o ,D= drilled hole diameterd f = diameter of clearance hole in the fixtured nom = outside diameter of anchorh = thickness of concrete memberh 0 =depth of drilled holesh 1=depth between the sharp end of drilled hole and concrete surface h ef = effective anchorage depthh min = minimum thickness of concrete member to prevent from splitting Drilling hole Undercutting hole Undercut anchor I Undercut anchor II Torsion controlled anchor Displacement controlled anchor holeBonded rebarAnchor subjected to Tension loads Anchor subjected to shear loads Fig.2.2.3 anchor spacing and edge distancefailure due to installationh nom = embedment depth of anchors, s1, s2 = spacing of anchors in a group and spacing of anchors in a group in direction 1, direction 2s cr,N= spacing for ensuring the transmission of the characteristic tensile resistance of a single anchor without spacing and edge effects incase of concrete cone failures min = minimum allowable spacing for preventing from the splitting failure due to installationt fix = thickness of fixture or anchor plateA0c,N = area of concrete of an individual anchor with large spacing and edge distance at the concrete surface, idealizing the concrete cone as apyramid.A c,N= actual area of concrete cone of the anchorage at the concretesurface.A0c,v = area of concrete cone of an individual anchor at the lateral concrete surface not affected by edges parallel to assumed loading direction,member thickness or adjacent anchors, assuming the shape offailure area as a half pyramid.A c,v= actual area of concrete cone of anchorage at the lateral concretesurface.l f = effective length of anchor under shear loading2.2.4 Partial safety factors and calculating factorsγ =partial safety factor taking account of the safety level of anchorageAγ=partial safety factor for materialR*ψα,v = factor take account of the influence of the angle between the load and the direction perpendicular to the free edge of the concretemember on the shear resistance.ψec,N, ψec,v = factor take account of a group effect when different tension (shear) load are acting on the individual anchors of a group.ψh,v=factor take account of the fact that the shear resistance does not decrease proportionally to the member thickness.ψre,N=the shell spalling factor takes account of the effect of dense reinforcement.ψs,N ,ψs,v = the factor takes account of the disturbance of the distribution of stresses in concrete due to edge of the concrete member ontension (shear) resistance.ψucr,N, ψucr,v= the factor takes account of the position effect of the anchorage in cracked or non-cracked concrete on tension (shear) resistance.3 Materials of concrete and anchor elements3.1 Concrete base materials3.1.1 The concrete base material shall be solid and sufficiently large to resist and theintended loads. 3.1.2 Excessively air voided concrete, grout, grout layer and decorative mortar layersmay not be considered as sufficient base material. 3.1.3 Concrete strength for base material of post-installed fasteners shall be at leastC20. The concrete strength and modulus of elasticity should be obtained by on-site testing according to Code for Design of Concrete structures —GB50010.3.2 Anchor elements3.2.1 The materials of steel anchor elements shall be carbon steel, stainless steel oralloy 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 comply with Expansion and undercut building anchors for use in concrete Table 3.2.2 The material performance of carbon/alloy steel3.2.3 The performance grade of anchor made of stainless steel shall be defined bystk f and yk f (see Table 3.2.3). Note: the extension ratio δ is achieved from GB3098.6-86 criteria 7.13 3.2.4 The rebar and threaded rod of bonded anchors should be HRB 400 or HRB 335steel ribbed rebar and Q235 or Q345 steel threaded rod. The performance of ribbed rebar shall comply with Code for Design of Concrete structures—GB50010.3.2.5 Elastic modulus of anchors: E s=2.0 105Mpa.3.3 Adhesive material of adhesive anchoring systems3.3.1 The anchorage performance of the adhesive material of adhesive anchoringsystems shall be determined by special tests. Any extra filler and /or additives are forbidden to mix with an authorized bonding material on site except the committed dose filler and /or additives described in Manufacturer’s instruction.3.3.3 The performance of epoxy bonding material should comply with the requirementin Table 3.3.3 The performance of adhesive with component of epoxyNo. Performance Testing methodMechanical performance Viscosity strength (25℃)=4500～75000 MPa.sNormal cure is available under the installationtemperature -5℃～40℃, and the curing timecan be changed by changing the componentproportion.viscosity strength testmethod GB2794-81Strength and flexibility of bonding material Characteristic compression strengthf bc,k≥60N/mm2Characteristic tension strength f bt,k≥18 N/mm2Elastic modulus E≥5.2×103 N/mm2Ultimate deformation εu ≥0.01Compression Testmethod for plasticmaterial GB1041-79Tension Test method forplastic materialGB1040-79Steel-steel bonding strength Characteristic shear strength f bv,k≥14 N/mm2Characteristic tension strength f bt,k≥20 N/mm2Characteristic slit strength f bp,k≥20 kN/mTest method for shearstrength of bondingmaterial under tensileload GB7124-86Test method for tensionstrength of bondingmaterial GB6329-86Test method for slitstrength of bondingmaterial bonded metal tometal HB5166Steel-concret ebonding strengthThe bonding failure should occur in concreteinstead of in bonding materialTwo steel plate(50×50×5)with a steel rodrespectively, axessymmetrically bonded onthe bigger surface of a C50concrete cube(70×70×50). Tested undertension load after the Thread rodThread rodThread rodComponent 1 Component 2b) packed injectionc) Bulk mixed on sitea) capsuleadhesiveFig. 3.3.2 the types of adhesive4.1 Identification and application principal4.1.1 Types of anchor can be divided into expansion, undercut, adhesive, rebar andother types of fasteners. Besides validation of the performance of anchoring systems themselves, base material, the load on anchors, the type pf fixtures, requirements for anti-earthquake and other relevant influence factors shall be considered when selecting an anchoring system.4.1.2 Expansion anchor, undercut anchor may be used to the connection ofnon-structural elements, or the structural elements under tension, shear load(C 10 h ef) or combined of tension and shear. The limitation of the anchorapplication shall comply with the specification of clause 4.1.3 to clause 4.1.4.Note: non-structural elements include non-structural elements of structures (outer wall, partition wall, curtain wall, ceiling, ad board, cabinet frame) and the frame/bracket of equipments on the buildings (elevator, lightings and electric power, telecom equipments, pipe system, heating and air-condition system, fire and smoke alarm system) etc..4.1.3 Expansion anchor and undercut anchor can’t be used to connect thestructural elements or non-structural elements of lifeline structures under tension load, shear load perpendicular to edge (C<10 h ef), combined tension and shear loads.4.1.4 Adhesive anchoring systems or rebar can be applied on the structural elementsand non-structural elements under tension load, shear load perpendicular to edge, combined tension and shear loads while earthquake design level below seismic fortification intensity = 9 (see Fig. 2.15).4.2 Design safety and concept4.2.1 The design of anchorage in the ultimate limit state with partial safety factors,basing on data obtained from test and experience in construction, is defined to be design method of this standard.4.2.2 The intending design period of anchorage should be concord with the designperiod of connected structure.4.2.3 Anchorage is divided into two safe grades according to the severity degree of theanchorage failures. The safety grade in anchorage design should follow Table4.2.3, and should not be less than that of the main structure.Without earthquake action R S A ≤γ(4.2.4-1)With earthquake action RE kRS γ≤ (4.2.4-2)R kR R γ=(4.2.4-3)A γ= factor of safety grade, it will takes 1.2 and 1.1 respectively to theanchorage safe grade first grade and second grade;S = design combined loads of anchorage, calculating according to Code ofBuilding Structure Loads and Designing Code for Anti-earthquake .R ,k R = design(characteristic) resistance strength of anchorage;RE γ= partial safety factor of earthquake action R γ= partial safety factor for materialS A γ= design value of internal action (N ,M V ) in all chapters.4.2.5 Failure mode should be controlled in the design based on the type of fixtures,loads and the type of anchors. Steel failure of adhesive anchoring systems or rebar should be occurred instead of concrete failure for the structural elements or non-structural elements of lifeline structure under tension load, shear load perpendicular to edge or combined tension and shear loads. For expansion anchors and undercut anchors, whole anchor pull-out failure should be not adopted and sometimes the pull-through failure may not be adopted. For bonded anchor or rebar with the required anchorage depth, concrete failure or pull-out failure should not be adopted (including the failure on the interface of adhesive and anchor rod/rebar or adhesive and concrete.). 4.2.6 Partial safety factor of material,R γ, should be taken as Table 4.2.6 based on thetype of fixture and the failure mode of fixture. It may be adjusted if the reasonable test results and reliable construction experiences are approved by national authorized institute.authorized institute or designers approvals.5 Static analysis5.1 GeneralInternal force of anchor group should be calculated according to the following assumptions:1. The anchor plate and the interface of concrete do not deform under designaction (plain sections remain plain). The anchor plate should be sufficiently stiff in the plain, such that the bending deformation of the anchor plate can be ignored; 2. The anchors do not contribute to the transmission of compression force (exceptfor bonded anchors and rebar), so the compression force is transmitted by anchor plate to the concrete directly. 3. Internal force of anchor shall be calculated according to the theory of elasticity.If the anchorage failure of anchors or bonded anchor/rebar is steel failure and the strength of the steel is low (≤5.8 grade), the internal force shall be calculated according to the theory of elasticity-plastic theory considering stress redistribution. 5.1.2 If the condition in Equation 5.1.2 is fulfilled, then non-cracked concrete shall beassumed, otherwise cracked concrete shall be assumed, and the width of crack shall be calculated according to Code for Design of Concrete Structures :0≤+R L σσ (5.1.2)L σ=characteristic value of stress produced by external actions andpre-stressed force in concrete member. The positive is tension, negative is compression;Rσ=characteristic value of tensile stress produced in concrete memberbecause of constrained contraction of concrete, changing of temperature and displacement of support, if the precise calculation is not checked, it can be approximately taken as 3=R σMPa.5.2 Tension loads acting on Anchor group5.2.1 The design tension acting on each anchor of anchor group shall be calculated bythe following formulas under the concentric tension load (see Fig.5.2.1):Sd N = design value of tension load acting on the individual anchor;N = design value tension load resisted by an anchorage group; n= amount of anchors in an anchor group.5.2.2 The design value of tension load acting on the most stressed anchor of an anchorgroup under the combined tension and moment loads in the analysis of elastic theory (see Fig. 5.2.2):1. ifthen2. ifthenM =design value of moment;h sd N =design value of tension load acting on the most stressed anchor in ananchor group.1y ,i y =perpendicular distance from anchor l (anchor i) to geometrical center ofan anchor group'1y ,'i y = perpendicular distance from anchor 1(anchor i) to the outermost edgeanchorsL =distance from the acted point of normal force N to the outermost anchors inthe compressed area.5.3 Tension loads acting on Anchor group5.3.1 For the distribution of shear loads and torsion moments acting on the fixture to the anchors of a group anchor the following case shall be distinguished based on thediameter of drilled holes of anchor plate,f d , and the diameter of anchors,d , the distance c from anchors to the edge of concrete member.1. All anchors take up shear loads if the hole clearance between anchor stud anddrilled holes on anchor plate, d d f -=∆, or the clearance between the drilled holes and sleeve of anchors nom f d d -=∆, is not greater than the acceptable value []∆ in Table 5.3.1 and the edge distance is larger than 10 ef h (see Fig.2. Only the most unfavorable anchors take up shear loads if the edge distance issmaller than 10 ef h (ef h c 10<) or the hole clearance is larger than the value given in Table 5.3.1([]∆>∆)(see Fig. 5.3.1-2);3. Slotted holes in direction of the shear load prevent anchors to take up shearloads (see Fig. 5.3.1-3).Fig. 5.2.1 centralized tension load Fig. 5.2.2 combined tension and shear loadsa) Shear loadb) Torsion moment Fig. 5.3.1-1 the shear loads acting on anchors5.3.2 The design value of shear loads acting on an individual anchor of an anchor groupunder shear load V shall calculated by the following formulas:V Si h Sd V V max ,=(5.3.2-4)V x Si V ,Vy Si V ,=the shear loads in x (y) direction acting on anchor i of an anchorgroup under the shear load V acting on the fixture;V Si V =the combined shear loads acting on anchor i of an anchor group undershear load V on the fixture;x V ,y V =the design value of shear load V in x (y) direction, x n ,y n =the amount of anchors take up the shear loads x V (y V )h Sd V =the design value of shear loads acting on the most stressed anchor of ananchor group.5.3.3 The design value of shear loads acting on an individual anchor of an anchor group under torsion moment T shall calculated by the following formulas in basis of elastic analysis (see Fig. 5.3.3):∑∑+=22,ii ix y x Ty (5.3.3-1) ∑∑+=22,ii iy y x Tx (5.3.3-2) ()22,)(T siy T x si V V += (5.3.3-3) T si h Sd V V max ,= (5.3.3-4)T =design value of torsion moment;T x Si V ,, Ty Si V ,= the shear loads in x (y) direction acting on anchor i of an anchorgroup under the torsion moment acting on the fixture;T Si V =the combined shear loads acting on anchor i of an anchor group undertorsion moment T on the fixture;i x , i y =coordinate x (y) distance from anchor i to the center of the anchorgroup.The design value of shear loads acting on an individual group under the combined shear load V and torsion moment Fig. 5.3.2 shear loadby the following formulas (see Fig. 5.3.4):max ,si hSd V V = (5.3.4-2)Si V =the design value of shear load acting on anchor i6Ultimate limit state6.1Resistance to tension loads6.1.1 The resistance to tension loads shall be checked according to Table 6.1.1:g Sd N =design value of the sum of the tensile loads acting on the tensioned anchor ofan anchor group,s Rd N ,=design value of resistance of a single anchor or an anchor group in case ofsteel failure;c Rd N ,=design value of resistance of a single anchor or an anchor group in case ofsteel failure;p Rd N ,=design value of resistance of a single or group expansion anchors orundercut anchors in case of pull through failure;sp Rd N ,= design value of resistance of a single anchor or an anchor group in case ofsplitting failure.6.1.2 Design resistance of an anchor in case of steel failure,s Rd N , is obtained fromthe following formulas:stk s s Rk f A N ⋅=,(6.1.2-2)s Rk N ,=characteristic resistance of anchor or bonded rebar in case of steelfailureN Rs ,γ=partial safety factor of anchor or bonded rebar in case of steel failure(see Table.4.2.6).s A =stressed cross-section of anchor or rebar;stk f = characteristic steel ultimate tensile strength of anchor.6.1.3 The design resistance of an anchor or an anchor group, respectively, in case of concrete cone failure,c Rd N ,, should be calculated by following formula:(6.1.3-1)(6.1.3-2)c Rk N ,=characteristic resistance of an anchor or an anchor group,respectively, in case of concrete cone failure;N Rc ,γ=partial safety factor in case of concrete cone failure take as Table4.2.6;0,c Rk N =the initial value of the characteristic resistance of an anchor placed incracked concrete calculated according to clause 6.1.4;0,N c A =area of concrete cone of an individual anchor with a large spacing andedge distance at the concrete surface, idealizing the concrete cone asa pyramid according to clause 6.1.5.N c A ,=actual area of concrete cone of the anchorage at the concrete surfaceof a single anchor or an anchor group, calculated according to clause 6.1.6.N s ,ψ=the factor takes account of the disturbance of the distribution ofstresses in the concrete due to edge of the concrete member, calculated according to clause 6.1.7.N re ,ψ=the shell spalling factor takes account of the effect of reinforcements,calculated according to clause 6.1.8.N ec ,ψ=the factor takes account of a group effect when different tension loadsare acting, calculated according to clause 6.1.9.N urc ,ψ=the factor takes account of the position of anchorage in cracked ornon-cracked concrete, calculated according to clause 6.1.10.6.1.4 The initial value of the characteristic resistance of a single anchor placed incracked concrete, 0,c Rk N , is obtained by test. It may be obtained by the followingformula or Table 6.1.4 if the anchors comply with the relevant specification of this code and product code:k cu f ,=characteristic concrete compression strength measured on cubes(N/mm 2), when 60~45,=k cu f MPa, it shall be decreased by a factor0.95.ef h =effective embedment depth (mm), it is measured from concrete surface tothe most stressed point between expansion component of anchor and drilled concrete hole for expansion anchors and undercut anchors.6.1.5 The area of concrete cone of an individual anchor with a large spacing and edge。
