Shear Headed Anchors with Large Diameter and Deep Embedment in Concrete

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1 Shear Headed Anhors with Large Diameter and Deep Embedment in Conrete Namho Lee ), Kwang Ryun Park ) and Yong Pyo Suh 3) ) Atomi Energy of Canada Limited, Mississauga, Ontario, Canada ) Korea Power Engineering Company, Yongin, Kyeonggi, Korea 3) Korea Eletri Power Researh Institute, Daejeon, Korea. ABSTRACT This paper presents shear test results for large ast-in-plae anhor bolts in onrete. The tests were performed to evaluate the shear performane of large anhors, i.e. anhors with diameter greater than in. (5 mm) or embedment depth greater than 5 in. (635 mm), whih are not addressed by ACI 38, App. D and ACI 349, App. B. The tests were also intended to investigate the safety of suh anhors for use in nulear power plants. The test results are used to assess the appliability of existing design formulas valid for smaller anhors to large anhors. Suggestions are made for inorporating the effets of deep embedment or large diameter in existing design provisions for ast-in-plae shear anhor bolts under shear load. INTRODUCTION Current anhorage designs for nulear power plants frequently use large anhor bolts with diameters exeeding in. (5mm), embedment depths exeeding 5 in. (635mm), a speified yield strength of 4 ksi (98 MPa), and a speified ultimate strength of 55 ksi (85 MPa). While the shear behavior of smaller anhors has been studied extensively, large anhors have not been adequately addressed. In the researh desribed here, large anhors were tested in shear to develop design riteria for anhors whih are not addressed by ACI 38-5 Appendix D[] or ACI 349- Appendix B[], and to evaluate the appliability of apaity-predition methods developed for smaller anhors. To evaluate the shear behavior of anhors with large diameters, embedment depths and edge distanes, various anhors, with diameters from.5 in. (63.5 mm), 3. in. (76. mm) and 3.5 in. (88.9 mm), embedment depths from 5 in. (635 mm) and 3 in. (76 mm), and edge distane 5 in. (38 mm), in. (58 mm) and 3 in. (76 mm) were tested. EXISTING FORMULAS FOR PREDICTING THE SHEAR CAPACITY OF ANCHOR BOLTS IN CONCRETE The formulas used for omputation of shear apaities are given by Eq. () through (4). The breakout formulas of urrent US design provisions (ACI 38-5 and ACI 349-) are based on the Conrete Capaity Design Method (CCD-Method) (Fuhs et al. [3]). Eq. () and Eq. () valid for the Conrete Capaity Method and Modified Conrete Capaity Method [5] respetively are based on the mean of the onrete breakout apaity in unraked onrete. In ontrast ACI [4] and ACI 349- are based on the 5%-fratile of the expeted shear breakout apaities. Equation () (CCD-Method) and Equation () (Modified CCD-Method) were developed in SI units of N mm and thus onversions of the equations into lb-in were made for omparison with other methods. Capaities were also omputed by the 45-Degree Cone methods reommended by ACI and the CC methods as per ACI 349- onsidering 5%-fratile values. For ACI 349- the value k=7 is valid for raked onrete, but the tests were performed in unraked onrete. Therefore a k-value k=9.8 (k=7x.4) was used for alulations of predited apaity. The purpose of this omputation is to test the appliability of the formulas to large anhors. l Conrete Capaity Method (in US Customary Units (lbs)): n = 3( ) d o f ' () () d Modified CC Method (in SI Units (N)): o.. / ) (hef / ) (do n 3d o h ef f ' () ACI (45-Degree Cone Method in US Customary Units (lbs)): = () n = π f ' (3) l ACI 349- (in US Customary Units (lbs)): n = 9.8( ) d o f ' () (4) d where, f ' = speified onrete ompressive strength measured on ylinders in psi o

2 f ' = speified onrete ompressive strength measured on ubes with a side length of mm (=.8 h = effetive embedment depth in mm for Eq. () and inh for other Eqs. ef d = diameter of anhor in mm for Eq. () and inh for other Eqs.; and o l = load bearing length of anhor for shear in inh (l = h ef for anhors with headed stud) = anhor edge distane in mm for Eq. () and inh for other Eqs. DESCRIPTION OF EXPERIMENTAL PROGRAM f ' ) in MPa Test speimens To evaluate the effets of edge distane, embedment depth, anhor diameter and supplementary reinforement patterns on the shear apaity of large anhors, seven different test onfigurations were seleted. Five test repliates with eah of test speimens, S to S4, four repliates of speimen S6 and three repliates of speimen S7 were performed giving 7 speimens in total for un-reinfored anhors in shear. The speimen S5 with an embedment depth of 35 in. (889 mm) was planned to examine the effet of embedment depth. However, it was found the shear apaity of anhor with deep embedment depth relative to edge distane is not any more affeted by inreasing embedment depth omparing the tested apaities of the speimens having 5 in. (635 mm) and 3 in. (76 mm) of embedment depths and thus the speimen S5 having embedment depth of 35 in. (889 mm) was not tested. The test program is summarized in Table and the test speimens of unreinfored are shown in Fig.. Test group D and H are to examine the effet of anhor diameter and embedment depth on un-reinfored onrete shear breakout strength with an edge distane of in. (58 mm), respetively. Test speimens in a test group D have various diameters,.5 in. (63.5 mm), 3. in. (76. mm) and 3.5 in. (88.9 mm), with a fixed effetive embedment depth of 5 in. (635 mm). On the other hand, test speimens of a test group H have various embedment depths of 5 in. (635 mm), 3 in. (76 mm) and 35 in. (889 mm) with a onstant anhor diameter of 3 in. (76. mm). A test group E was planned to examine the effets of edge distane on unreinfored onrete shear breakout strength. All anhors were fabriated of ASTM A54 Gr. B3 Class steel (equivalent to ASME SA 549 GR. B3 Class used in Korean nulear power plants) with f y = 4 ksi (98 MPa) and f u = 55 ksi (85 MPa). The anhor head onsisted of a round thik plate whih was fixed to the bolt by lamping nuts (Fig. ). Table. Desription of Shear Test Speimens Test Group Speimen Reinforement Anhor Diameter, d b Effetive Embedment h ef Clear Distane d, in.(mm) in. (mm) in. (mm) ) D S None.5(63.5) 5(635) 8. (6.5) D D S None 3.(76.) 5(635) 8. (6.5) D3 S3 None 3.5(88.9) 5(635) 8. (6.5) H S None 3.(76.) 5(635) 8. (6.5) H H S4 None 3.(76.) 3(76) 8. (6.5) H3 S5 None 3.(76.) 35(889) NA E S6 None.5(63.5) 5(635) 63.8 (6) E E S7 None.5(63.5) 5(635) 5. (384.48) E3 S None.5(63.5) 5(635) 8. (6.5) Test Group Speimen Edge Distane, Test Blok Size, in. (m) No. of Ratio d/ in. (mm) (width x length x depth) Repliates D S.(58) 4.6 5(.6) x (.5) x 47(.) 5 D D S.(58) 4.6 5(.6) x (.5) x 47(.) 5 D3 S3.(58) 4.6 5(.6) x (.5) x 47(.) 5 H S.(58) H H S4.(58) 4.6 5(.6) x (.5) x 47(.) 5 H3 S5.(58) NA NA E S6 5.(38) (.) x 8(.7) x 73(.8) 4 E E S7 3.(76) (4.4) x 8(.7) x 73(.8) 3 E3 S.(58) Note ) Clear distane (d) is distane between the supports

3 The round plate would not diretly impat the anhor apaity in shear rather than in tension. The steel plate (ASTM A36) provides a minimum net bearing area satisfying the pullout strength requirement of Eq (B-) of ACI 349- App. B for eah anhor bolt. The nominal strength of the anhor bolt was onservatively used as the pullout strength N p for eah speimen. The size of the onrete test blok was large enough to avoid splitting failure. The onrete volume (width / length / depth) available for eah anhor is shown in Table. As shown in Fig., wooden and steel frames were onstruted to suspend the astin-plae anhors in the orret position and at the orret embedment depth. The onrete used in the test speimens was omparable to the onrete used in Korean nulear power plant, exept that % by weight of the Type I ement was substituted by fly ash and in. (5 mm) rushed aggregate was used instead of 3/4 in (9 mm). The target onrete strength at 8 days was f = 55 psi (37.9 MPa). The atual onrete strength at the time of testing is given in Table. The onrete for the speimens of one test series was poured from bath. Fig. Shemati Sketh and Photo of Unreinfored Shear Test Speimens (S to S7) Anhor Diameter db, in. (mm) Plate Diameter dh, in. (mm) Plate thikness th, in. (mm) Nut width F, in. (mm).5 (63.5) 6. (5.4).5 (63.5) (98.4) 3. (76.) 7. (77.8) 3. (76.) 4.65 (7.5) 3.5 (88.9) 9. (8.6) 4. (.6) (36.5) Fig. Details of Anhor Head Table Conrete Strength at the Time of Testing Test speimen Curing ages (days) Compressive strength in psi (MPa) S-A/B/C/D/E 75/79/88/89/9 5959(4) / 68(4) / 64(4) / 654(4) / 69(43) S-A/B/C/D/E 99/95//6/7 63(43) / 67(43) / 687(43) / 6358(44) / 6358(44) S3-A/B/C/D/E 99/98/95/94/93 67(43) / 658(43) / 63(43) / 66(43) / 6(43) S4-A/B/C/D/E 87/87/9/9//93 63(4) / 63(4) / 673(43) / 687(43) / 6(43) S5-A/B/C/D/E 39/4/37/35/4 5(36) / 54(36) / 55(36) / 549(35) / 568(36) S6-A/B/C/D 56/57/57/58 565(39) / 5645(39) / 5645(39) / 5665(39) S7-A/B/C 44/54/55 5(35) / 534(36) / 548(36) Test Setup The test setup onsisted of a loading frame, loading plate, jak assembly, load ell and other items, shown in shemati and photo in Fig. 3. The load was applied to the anhor under fore-ontrol in inrement as a perentage of the target maximum test load for eah test speimen, i.e. 5% at st step and every % of the target maximum from nd step to failure load. It was reated by shear test frames in parallel on the onrete surfae of anhor speimen blok. The lear distane between the supports was 4. h ef for speimen S through S7 and thus allowing for an unrestrited formation of a onrete one. The applied load was measured by a load ell. Additionally, the strains along the embedment length of the anhor bolt were measured. Furthermore, the lateral displaement of the anhor at the level of onrete top surfae was measured by LDT loated at the enter of jig plate (Fig. 3). 3

4 (a) Shemati (b) Photo Fig. 3 Shear Test Setup TEST RESULTS Failure loads, failure modes and load displaement behavior The average failure loads for the unreinfored shear test speimens are summarized by edge distanes, anhor diameter and effetive embedment depths in Table 3. The values given in the tables are normalized to f = 55 psi (37.9 MPa) by multiplying the measured peak load of eah test with the fator (55/f,test ). ACI and ACI 349- predit the lower bound (5%-fratile) of the apaity, while the CCD-Method and the modified CCD-Method predit the mean shear apaity. Therefore, the measured mean apaities are ompared with the values predited by the CCD-Method and the Modified CCD-Method, and the 5%-fratiles apaities are ompared with the predition aording to ACI and 349- as shown in Table 3. The 5%-fratile was alulated assuming an unknown standard deviation and a 9% probability. In test series S to S7 failure was aused by onrete one breakout below the onrete shear breakout apaities alulated with the available formulae, Eqs. () to (4) (see Table 3). The typial raking patterns on the front fae (edge fae) and top fae of S speimen are depited in Fig. 4. The general rak pattern omprised of one major longitudinal rak entered approximately on the front fae of the blok with inlined raks on the sides of the front fae (edge fae). Some of large anhors loaded in shear typially exhibit rushing of the onrete in front of anhor similarly to small anhors in shear. However, the embedment depths are relatively large ompared with the diameters of the anhor and the rushing of the onrete in front of anhor were judged not to ause failure of the shear test speimens. On the top surfae, the raks formed generally one failure pattern with a breakout prism angle of around 5 to 5 degrees initiating at the anhor bolt. Some repliates of the unreinfored speimens (S3, S4 and S7) show raks, normal to the edge, emanating from the anhor and this sort of rak was judged to have developed due to flexural behavior of a part of a one (partly separated from main test blok by one failure) having two end supports. To physially identify the internal rak propagation defining the breakout failure one, one repliate of speimen S type was seleted, and onrete was ored from front fae as shown in Fig Fig. 4 Typial Crak Patterns of Five (5) Repliates and Internal Crak Profile in Speimen S 4

5 Table 3 Shear Test Results and Preditions for Un-reinfored Speimens Classifiation Preditions Tests Conrete Shear Breakout Capaities in kips (kn)-(d/h ef /) Referene S S S3 S4 S6 S7.5/5/ 3./5/ 3.5/5/ 3./3/.5/5/5.5/5/3 CCD-Method Eq. () 6 (96) 8 (4) 39 (63) 37 (54) 4 (63) 397 (766) Modified CCD Eq. () 6 (56) 3 (578) 35 () 38 (64) 9 () 5 (9) ACI Eq. (3) 86 (87) 86 (87) 86 (87) 86 (87) 5 (467) 49 (864) ACI 349- Eq. (4) 63 (75) 7 (765) 8 (8) 78(79.8) 6(47) 99 (33) Mean 7.6(479) 98.9 (44) 3.5(46) 99.9 (444) 6. (67) 4 (77) CO (%) %-fratile.8(448) 83.3 (37) 83.4 (37) 84.9 (378) 48.8 (7) 9.7(933) 5% fratile/mean Classifiation Symbol in Ratio of Observed to Preditions Comparison Fig. 6 S S S3 S4 S6 S7 Mean Mean of Test Results (I) Mean / Eq.() (II) Mean / Eq.() %-Fratile of Test (III) Nu, 5% / Eq.(3) Results (I) Nu, 5% / Eq.(4) The load-displaement urves for unreinfored speimens S through S7 are shown in Fig. 5(a) through 5(f), using the displaement measured at the enter of jig plate. The load-displaement relationship for eah test repliate varied based on the onrete strength at time of testing. Sine all of shear test speimens were failed by onrete breakout, the total deformation onsists mainly of onrete deformation with little steel deformation. The anhor displaements were rather large after some large raks in the onrete due to shear break out failure were observed S-A S-B S-C S-D S-E Load (kips) S-A S-B S-C S-D S-E Load (kips ) S3-A S3-B S3-C S3-D S3-E (a) S-A to S-E (b) S-A to S-E () S3-A to S3-E 8 4 Load (kips )..3.4 S4-A S4-B S4-C S4-D S4-E Load (kips ) 3. S6-A S6-B S6-C S6-D Load (kips ) (d) S4-A to S4-E (e) S6-A to S6-D (f) S7-A to S7-C S7-A S7-B S7-C 3 Load (kip s ) Fig. 5 Measured Load - Displaement Relationships (Un-reinfored speimens) Comparison of predited and tested shear breakout apaities Shear test results are presented in graphial (Fig. 6) and tabular form (Table 3). The predited apaities and the mean and 5% fratile of the tested apaities are ompared for eah type of investigated anhors. Five repliates of eah speimen 5

6 were tested for Speimen S through S4 exept for four repliates of speimen S6 and three repliates of speimens.. S7. Sine eah repliate was tested at a different uring. stage, the shear test results were normalized to a.9.8 ompressive strength of 55 psi (37.9 MPa) as shown in I.7 Table 3 to failitate omparison. The formula for omputing.6 II shear apaities of anhors in onrete proposed by ACI III are based on 5% fratile while those for CCD-.3 I Methods are based on the mean of test results. Therefore, it. is reasonable to ompare the mean and 5% fratile values of. test results to the values predited by CCD-Methods and S S S3 S4 S6 S7 ACI 349-, respetively. The ratios of measured apaities Fig. 6 Ratios of Test Results (5% fratile and to predited values are plotted in Fig. 6. The observed mean) to Predited failure loads ompared to the values predited aording to Eq. () and Eq. () are also illustrated as a funtion of various parameters (see Fig. 7). EALUATION OF TEST RESULTS FOR SPECIMENS (S to S7) The test results for large anhors show that the shear breakout apaities appeared not to be influened signifiantly by the embedment depth and the anhor diameter (Fig. 7(a)~7(d)), while the failure loads are influened by edge distane (Fig. 7(e), 7(f)). That is, the apaity of large sized anhor with relatively limited edge distane and deep embedment depth does not inrease signifiantly with an inrease in the embedment depth. This means that the load bearing length (l) should be limited in the equation to predit the shear breakout apaity to some depth instead of full embedment depth depending on the ratio of embedment depth to edge distane. Furthermore, in the performed tests the failure load is not muh influened by the anhor diameter. Therefore the diameter of the anhor to be inserted in the predition equation should also be limited. Most of the ratios of the test results to predited apaities are less than.. On average, the measured failure loads are only about 5% of the failure loads predited by ACI (45-degree one model). The ratios appear to be almost onstant with the varied parameters (see Table 3). This predition equation is very unonservative for large anhors. Also the failure loads predited aording to the CCD-Method are on average only about 5% of the measured failure loads (see Table 3). The ratios inrease with inreasing edge distane (see Fig. 7(a)). This predition equation is also unsuitable for large anhors. The main reason for this is, that aording to Eq. () the failure loads inrease for a onstant ratio embedment depth to anhor diameter in proportion to d, while the tests show no suh inrease. Note that in the original proposal (Eligehausen, Mallee and Rehm[6]), the values of d and of the ratio h ef / d o to be inserted in Eq. () are limited to d=5 mm and h ef / d o = 8 respetively. When observing these limits, the average ratio of test to predition inreases to about.8. However, even when observing the limitations the predition equation is slightly unonservative. When prediting the failure loads using ACI 349- whih is based on the CCD-Method without limiting d and h ef, the ratios of test to predition inrease by about 5% ompared to the CCD-Method, beause in ACI 349- a ratio of 5%-fratile to mean value of.75 is assumed, while in the test this ratio is on average.85. This predition equation is also not suitable for large anhors. The failure loads predited by the modified CCD-Method agree muh better with the test results than the other proposals. On average the ratio of test to predition is.83 (see Table 3). The ratios inrease with inreasing edge distane (Fig. 7(f)). They are almost independent of the embedment depth and the anhor diameter (Fig. 7(a)~7(d)). They derease with inreasing ratio of embedment depth to edge distane (Fig. 7(i)) and inreasing ratio of anhor diameter to edge distane (Fig. 7(j)). However, this is mainly due to the fat, that the failure load is underestimated for a large edge distane (small ratio diameter to edge distane) and overestimated for small edge distanes (large ratio diameter to edge distane). All together, aording to the test results the influene of these parameters is overestimated in the predition equation. With some proper modifiations, Equation () an be used to design large anhor bolts. The CC-method developed for small anhor overestimates the apaity of large anhors. The formula (Eq. ()) modified from the CC-method appears to overestimate the apaity of large anhors with relatively small edge distane to a lesser degree than CC-method, but underestimates the apaity of large anhor with an inreased edge distane relative to those for S through S6 (see S7 in Table 3). Aording to the test results, in the range =5 in (38 mm) to =3 in (76 mm) the onrete edge failure loads inrease approximately in proportion with. However, tests and numerial alulation at the University of Stuttgart[5] with anhors up to a diameter d o =5 mm show, that due to the size effet, the onrete edge failure load inreases approximately in proportion to. Therefore, Equation () is modified by limiting d o to in (5 mm) and h to 8d o = 6 in ( mm). This results for =5 in (38 mm) in ef Ratio 6

7 n.5 = 6.7 f in SI Unit (N) (a) In the modified CC-Method it is assumed that the 5%-fratile of the failure loads are.75-times the mean value. In the present tests the ratio between the 5%-fratiles and the mean value is.8 to.94, on average.85. In pratial appliations this ratio might be somewhat lower. Therefore a ratio =.8 is assumed. With this assumption we get n, m Assuming f =.8 f one gets = 5.4 f in SI Unit (N) (b) n = 7.3 f in SI Units (N), n.5 = 7.4 f in US Customary Units (lbs) (a-) = 5.9 f in SI Units (N), = 4. f in US Customary Units (lbs) (b-) MODIFIED METHOD MODIFIED METHOD Mean =.43.8 CO = Mean = CO = y=-.x y=-.7x y=-.65x Embedment Depth, inh Embedment Depth, inh Diameter, inh Mean =.45.8 CO = Mean =.8.8 CO = y=-.868x Diameter, inh (a) CCD w/ Emb. Depth (b) Modified w/ Emb. Depth () CCD with Diameter (d) Modified w/ Diameter Mean =.8 CO = y=.x Edge Distane, inh MODIFIED METHOD Mean = CO = y=.343x Edge Distane, inh Mean =.46.8 CO = y=-69x Embedment Depth/Edge Distane(h ef /) (e) CCD with Edge Distane (f) Modified w/ Edge Distane (g) CCD w/ Ratio (h ef / ) Mean =.46.8 CO = y=-.4x Anhor Diameter/Edge Distane(d/) Mean =.8.8 CO = y=-674x Embedment Depth/Edge Distane(h ef /) Mean =.8.8 CO = y=-4.759x Anhor Diameter/Edge Distane(d/) (h) CCD w/ Ratio (d/ ) (i) Modified w/ Ratio (h ef / ) (j) Modified w/ Ratio (d/ ) Fig. 7 Ratios of Observed to Predited as a Funtion of arious Parameters Table 4 ontains a omparison of the measured average failure loads (onverted to f = 55 psi (38 MPa)) with the values alulated aording to Eq. (a). Furthermore a omparison of the 5%-fratiles is given. The omparison shows, that for an edge distane in (58 mm) the proposed Eq. (b) in the predition is a little unonservative while for an edge distane =3 in the predition aording to Eq. (b) is onservative. The ratio of the predited failure loads and the measured values in 5% fratile are.8 and.3 for the speimen (S) with 6d o of edge distane (edge distane 5 in (38 mm) and diameter.5 in (63.5 mm)) and the speimen (S7) with d o of edge distane (edge distane 3 in (76 mm) and diameter.5 in (63.5 mm)), respetively. Therefore, the proposed formula for large anhor bolts with diameters exeeding 7

8 in. (5mm), embedment depths exeeding 5 in. (635mm) would be more aurate with an minimum edge distane of 8d o ~9d o for pratial purposes. The angle of the failure one observed in test series S to S7 was rather low ( 5 degrees). This means, that the harateristi spaing would be about s r, = 4, larger than the value assumed in the CC-Method ( sr, = 3 ). However, in the tests with supplemental reinforement, the angle of the failure one was on average about 35 degrees. Beause in nulear strutures strutural supplemental reinforement will always be present, the value sr, = 3 should be used in the design. It is, therefore, proposed to verify large anhors in nulear power plants without supplemental reinforement loaded by shear fores for onrete edge failure aording to ACI 349-; however replae Eq. (4) by Eq. (b- ) with minimum edge distane at 8d o ~9d o. Table 4 Comparison of Failure Loads (Measured vs. Predited by Eq. (a) or Eq. (b)) Mean values Eq. (a) 5%-fratiles Eq. (b) Edge distane, in (mm) 5 (38) (58) 3 (76) n,test kips (kn) 6. (66.9) ().5 (455.9) () 4. (76.) (3) n,al kips (kn) 74.9 (333.3) 5.3 (53.).9 (94.7) / n,test n,al n,test kips (kn) 48.8 (7.) 87. (387.9) (4) 9.7 (93.8) n,al kips (kn) 6.4 (68.6) 93. (43.6) 7.8 (759.8) / n,test n,al Note: () Test series S6, () Test series S, S, S3 and S4, (3) Test series S7, (4) SUMMARY AND CONCLUSIONS =.85 The test results show that most of available formulas for small sized anhor overestimate the shear breakout apaity of large anhors with diameters exeeding in. (5mm), embedment depths exeeding 5 in. (635mm). The shear breakout apaities of large anhors appeared not to be influened signifiantly by the embedment depth and the anhor diameter, while the failure loads are influened by edge distane. Therefore, the load bearing length should be limited in the equation to predit the shear breakout apaity to some depth instead of full embedment depth depending on the ratio of embedment depth to edge distane and the diameter of the anhor to be inserted in the predition equation should also be limited. The proposed formula, Eq. (b) or (b-)) for large anhor bolts with diameters exeeding in. (5mm), embedment depths exeeding 5 in. (635mm) an be reommended for use with 8d o ~9d o of minimum edge distane for pratial purpose. The angle of the failure one was rather low ( 5 degrees) and thus the harateristi spaing would be about sr, = 4, larger than the value assumed in the CC-Method ( sr, = 3 ). However, in the tests with supplemental reinforement, the angle of the failure one was on average about 35 degrees. Beause in most of strutures adopting large anhors strutural supplemental reinforement will always be present, the value sr, = 3 should be used in the design. REFERENCES n, mean. ACI Committee 38, Building Code Requirements for Strutural Conrete (ACI 38-5) and Commentary (ACI 38R- 5), Amerian Conrete Institute, Farmington Hills, Mihigan, 5.. ACI Committee 349, Code Requirements for Nulear Safety Related Conrete Strutures," Amerian Conrete Institute, Farmington Hills, Mihigan,. 3. Fuhs, W., Eligehausen, R. and Breen, J.E., Conrete Capaity Design (CCD) Approah for Fastening to Conrete, ACI Strutural Journal,. 9. No.. Jan.-Feb. 995, pp ACI , Code Requirements for Nulear Safety Related Conrete Strutures, Amerian Conrete Institute, Farmington Hill, Mihigan, Hofmann, J., Tragverhalten und Bemessung von Befestigungen am Bauteilrand unter Querlasten mit beliebigem Winkel zur Bauteilkante (Laod-bearing behaviour and design of fasteners lose to an edge under shear laoding with an arbitrary angle to the edge) Dotor thesis, Institut für Werkstoffe im Bauwesen, Universität Stuttgart, 4 (in German). 6. Eligehausen, R., Mallée, R., and Rehm G., Befestigungstehnik (fastening tehnique) Betonkalender 997, Part II, Ernst Sohn, Berlin 977, p