Cold Formed Steel Tension Members with Two and Three Staggered Bolts

Transcription

1 Miouri Univerity of Science and Technoloy Scholar' Mine International Specialty Conference on Cold- Formed Steel Structure (2010) - 20th International Specialty Conference on Cold-Formed Steel Structure Nov 3rd Cold Formed Steel Tenion Member ith To and Three Staered Bolt D. M. Fox R. M. Schuter Follo thi and additional ork at: Part of the Structural Enineerin Common Recommended Citation Fox, D. M. and Schuter, R. M., "Cold Formed Steel Tenion Member ith To and Three Staered Bolt" (2010). International Specialty Conference on Cold-Formed Steel Structure Thi Article - Conference proceedin i brouht to you for free and open acce by Scholar' Mine. It ha been accepted for incluion in International Specialty Conference on Cold-Formed Steel Structure by an authorized adminitrator of Scholar' Mine. Thi ork i protected by U. S. Copyriht La. Unauthorized ue includin reproduction for reditribution require the permiion of the copyriht holder. For more information, pleae contact cholarmine@mt.edu.

2 Tentieth International Specialty Conference on Cold-Formed Steel Structure St. Loui, Miouri, U.S.A., November 3 & 4, 2010 Cold Formed Steel Tenion Member ith To and Three Staered Bolt Abtract D.M. Fox 1 and R.M. Schuter 2 The econd edition of the North American Specification for the Dein of Cold Formed Steel Structural Member a publihed in October of 2007 for ue in Canada, Mexico, and the United State. Thi Specification contain to country pecific appendice, namely Appendix A (ANSI/AISI S100-07) for ue in the US and Mexico and Appendix B (CSA S136-07) for ue in Canada. Both Appendix A and B require that a bolt taer reduction factor of 0.90 be ued hen calculatin the tearin failure trenth [reitance] of a cold formed teel member in tenion ith taered bolt. Thi 10% reduction a baed on limited tetin that a carried out by Dr. Roer LaBoube of the Univerity of Miouri-Rolla, hich ha no chaned it name to the "Miouri Univerity of Science & Technoloy". The objective of thi tudy a to etablih if thi bolt taer reduction factor i indeed neceary ince the taer term of [ 2 /4] ha been ued in the teel indutry for many year ithout uch a reduction. Experimental tetin of to and three taered bolt tenion member a carried out in the Structure Laboratory of the Department of Civil Enineerin at the Univerity of Waterloo. Baed on the tet reult of the 1.6 mm, 2.1 mm, 2.9 mm, 4 mm, 5 mm, and 6 mm thick teel heet, it can be concluded that the 0.90 bolt taer reduction factor i not neceary for the teel plate thicknee teted. 1 Enineerin Manaer, ispan Sytem, Richmond Hill, Ontario, Canada 2 Profeor Emeritu of Structural Enineerin and Director of the Canadian Cold Formed Steel Reearch Group, Department of Civil Enineerin, Univerity of Waterloo, Waterloo, Canada 575

3 576 Introduction The North American Specification for the Dein of Cold Formed Steel Structural Member [1] (herein referred to a the NAS) applie for ue in Canada, Mexico, and the United State. Thi Specification contain to country-pecific appendice, namely Appendix A for ue in the US and Mexico and Appendix B for ue in Canada. Both Appendix A and B require that a bolt taer reduction factor of 0.9 be ued hen calculatin the nominal tenile reitance at the net ection. Thi 10% reduction factor a baed on limited tetin that a carried out by Dr. Roer LaBoube at the Univerity of Miouri-Rolla. The validity of thi reduction factor a firt brouht into quetion by a Canadian tructural enineer ho a deinin cold formed teel tenion member that had the ame thickne a hot rolled teel tenion member. In the Canadian hot rolled teel tandard Dein of Steel Structure (CAN/CSA-S16-09) [2] the procedure for determinin the tenile reitance of taered bolted tenion member doe not contain a reduction factor, reardle of thickne of the teel plate material. To invetiate thi difference in dein method, a tudy a initially carried out at the Univerity of Waterloo by Toutounchian et al [3] uin to bolt ith to different taer pattern and ix different teel plate thicknee. A follo-up tudy a carried out by Farahah [4] to complete the tetin of the to-bolt tudy by Toutounchian et al [3] and to alo include three-bolt taered tenion member. The objective of thi ork a to analye the to-bolt and three-bolt taered tet reult to etablih if the 0.90 reduction factor i required hen deinin tenion member connection ith taered bolt pattern. Current Dein Approache Appendix A Method The method in Appendix A of NAS-07 [1], hich applie to the US and Mexico, for calculatin the nominal tenile trenth of a member for failure due to rupture of the net ection involvin taer i: P n = A n F t A n = C r [A n b d h t + ( 2 /4)t] Where, F t Eq. E3.2-6 Eq. E3.2-7 = Nominal tenile tre in flat heet; in accordance ith Eq. E3.2-2 to E3.2-5 of the NAS [1]

4 577 C r = Bolt taer reduction factor = 0.90 = Sheet idth divided by number of bolt hole in cro ection bein analyzed = Tenile tre of material d = Nominal bolt diameter A n = Net area of the connected part A = Gro area of member t = Material thickne = Lonitudinal center-to-center pacin of any to conecutive hole = Tranvere center-to-center pacin beteen fatener aue line n b = Number of bolt hole in cro ection bein analyzed d h = Diameter of a tandard hole h = Bolt hole diameter, (bolt diameter + 1/16 in. (1.59 mm)) Appendix B Method The method in Appendix B of NAS-07 [1], hich applie to Canada, for calculatin the nominal tenile reitance of a member for failure due to rupture of the net ection involvin taer i: T n = A n A n = L c t L c = C r L Eq. C2.2-1 Eq. C2.2-2 Eq. C2.2-4 Where, A n = Critical net area of connected part (mm 2 ) = Tenile trenth of teel L c = Summation of critical path lenth of each ement alon a potential failure path of minimum trenth t = Material thickne C r = Bolt taer reduction factor = 0.90 L = Net failure path lenth inclined to force [includin ( 2 /4) alloance for taered hole] = Pitch, fatener pacin parallel to force = Gaue, fatener pacin perpendicular to force = Specimen idth h = Bolt hole diameter, (bolt diameter + 1 mm ( in.)

5 578 Tet Proram Shon in Table 1 and Table 2 are the thicknee and dimenion of the teel heet that ere provided by ArcelorMittal. Six teel heet thicknee ere choen for the to-bolt plate and five thicknee ere choen for the three-bolt plate; teel heet thicknee raned from approximately 1.6 mm [0.06in] to 6 mm [0.25in]. All pecimen ere prepared by Baumeier Corporation in Waterloo, Ontario. Specimen ere laer cut reultin in conitent orkmanhip ith precie plate dimenion and hole pattern. All pecimen dimenion ere elected in order to enure that fracture of the net ection a the overnin failure mode and that other mode, uch a bearin failure, ould not occur. The tet pecimen ere fabricated a rectanular plate ith a contant lenth of 200 mm for the to-bolt plate and a contant lenth of 240 mm for the three-bolt plate. Sinle hear and double hear connection ere teted. For double hear connection here pecimen ere deinated a havin the outide heet controllin, the inide heet thickne a elected in order to enure failure in the outide heet. Where pecimen ere deinated a havin the inide heet controllin, the outide heet of the double hear connection ere elected in order to enure failure in the inide heet. Shon in Fiure 1 and Fiure 2 are chematic diaram of the to-bolt and threebolt pecimen, repectively. For the cae of three-bolt connection, to different bolt taer orientation ere teted a hon in Fiure 2(a) and Fiure 2(b). The ultimate tenile tre,, of the pecimen ere obtained from coupon tet that ere carried out at the Univerity of Waterloo; reult of the coupon tet can be found in Table 1 and Table 2. All tet ere carried out in the Structure Laboratory of the Department of Civil Enineerin at the Univerity of Waterloo, the reult of hich are ummarized in Table 3 throuh Table 7. Shon in Fiure 3 i a photoraph of the tet frame that a ued ith all pecimen hich ere loaded quai-tatically until failure. Typical failure in both to-bolt and three-bolt pecimen occurred a fracture of the net ection alon the bolt hole a hon in Fiure 4. The failure load a recorded for each pecimen, a ummary of hich i included in Table 3 throuh Table 7.

6 h h 579 e h Fiure 1 Schematic Diaram of To-Bolt Specimen e (a) With Staer Pattern 1 e (b) With Staer Pattern 2 Fiure 2 Schematic Diaram of Three-Bolt Specimen

7 580 Fiure 3 Photoraph of Tet Specimen in Tenile Tet Machine (a) To-bolt Specimen Failure (b) Three-bolt Specimen Failure Fiure 4 Photoraph of Typical Oberved Failure Mode

8 581 Analyi of Tet Reult In order to acertain hether a reduction factor i required for taered bolt, the predicted nominal trenth [reitance] a calculated ithout the reduction factor a follo: = A n Eq. 1 A n, NR = L c t Eq. 2 L c, NR = L Eq. 3 Where, A n, NR L c, NR L = Critical net area of connected part ithout a reduction factor for taered bolt (mm 2 ) = Tenile trenth of teel = Summation of critical path lenth of each ement alon a potential failure path of minimum trenth ithout a reduction factor for taered bolt = Net failure path lenth inclined to force [includin ( 2 /4) alloance for taered hole] = Pitch, fatener pacin parallel to force = Gaue, fatener pacin perpendicular to force Since the pecimen ere fabricated uch that fracture of the net ection a the controllin failure mode, only fracture of the net ection a conidered in the calculation ith the alloance for taered hole. The reult of the calculation for each tet pecimen are included in Table 3 throuh Table 7. Alo included i the ratio of teted trenth [reitance] to predicted nominal trenth [reitance] for each tet pecimen. A reduction factor ould be required if, on averae, pecimen tended to have the ratio of teted trenth to predicted nominal trenth belo 1.0. A hon in Table 3 throuh Table 7, the averae ratio raned from 1.09 to Further, the tandard deviation raned from 0.03 to 0.11, meanin that the mot of the tet pecimen predicted nominal trenth [reitance], calculated by Eq. 1 ithout a hole taer reduction factor, proved to be accurate or conervative. Thi can alo be oberved from Fiure 5 and Fiure 6. Since the lare majority of the tet to calculated trenth [reitance] ratio are above the ideal line of 1.0, it can be tated that a reduction factor i not required in order to accurately predict the nominal trenth [reitance] of tenion member ith taered bolt hole for the teel thicknee teted.

9 582 / Double Shear Connection, Inide Sheet Controllin Double Shear Connection, Outide Sheet Controllin Sinle Shear Connection Specimen Thickne Fiure 5 Teted trenth to predicted nominal trenth of to-bolt pecimen / Double Shear Connection, Inide Sheet Controllin Sinle Shear Connection Specimen Thickne Fiure 6 Teted trenth to predicted nominal trenth of three-bolt pecimen

10 583 Summary Preented in thi paper i a tudy conducted at the Univerity of Waterloo in order to acertain the need for a reduction factor currently included in the NAS [1] for taered bolted connection. An experimental tet proram a conducted to collect data to either ubtantiate the need for or the poible elimination of the reduction factor. Baed on the tet reult, it a hon that the majority of the teted connection trenth are conervatively predicted uin the current NAS [1] equation ithout the taered bolt hole reduction factor for the teel thicknee teted. A uch, it i recommended that conideration be iven to remove the reduction factor from both Appendix A and Appendix B of the NAS [1], hich ould brin tenion member in line ith proviion contained in other current teel dein tandard. Reference [1] AISI (2007). North American Specification for the Dein of Cold-Formed Steel Structural Member. American Iron and Steel Intitute: Wahinton, D.C. [2] CSA (2009). CAN/CSA-S16-09: Dein of Steel Structure. Canadian Standard Aociation: Toronto, ON [3] Toutounchian, A., Canete, D., Mazhar, S., and Guermon, T. (2007). Cold Formed Steel Tenion Member Connection ith Staered Bolt. 4 th Year Civil Enineerin Project, Department of Civil Enineerin, Univerity of Waterloo: Waterloo, ON [4] Farahah, M. (2009). Cold Formed Steel Tenion Member Connection ith To and Three Staered Bolt. Co-operative Education Report, Department of Civil Enineerin, Univerity of Waterloo: Waterloo, ON

11 584 Table 1 Mechanical Propertie of Sheet Steel ued in 2 Bolt Specimen Material ID t F y % Elon 2B n/a % 2B-1.6-S1-O 1.61 n/a % 2B n/a % 2B-2.1-S1-O 2.11 n/a % 2B n/a % 2B n/a % 2B-5.0-S n/a % 2B-5.0-S0/S n/a % 2B-6.0-S0/S n/a % 2B-6.0-S n/a % Table 2 Mechanical Propertie of Sheet Steel ued in 3 Bolt Specimen Material ID t F y % Elon 3B % 3B % 3B % 3B % 3B %

12 585 Table 3 Summary of Tet Reult, 2 Bolt Tet, Sinle Shear Connection Specimen ID t d h O-2.9t-0.5S O-4t-0.5S O-5t-0.5S O-5t-1.0S O-6t-0.5S O-6t-1.0S Averae 1.10 Standard Deviation 0.11 Table 4 Summary of Tet Reult, 2 Bolt Tet, Double Shear Connection, Outide Sheet Controllin Specimen ID t d h O t S O t S O t S O t - 1 S O t - 1 S O t - 1 S O t S O t S O t S Averae 1.09 Standard Deviation 0.11

13 586 Table 5 Summary of Tet Reult, 2 Bolt Tet, Double Shear Connection, Inide Sheet Controllin Specimen ID t d h I t S I t S I t S I t S I t S I t - 1 S I t - 1 S I t S I t S I t S I t - 1 S I t - 1 S I t - 1 S I-2.9t-0.5S I-2.9t-0.5S I-4t-0.5S I-4t-0.5S I-4t-0.5S I-4t-1.0S I-4t-1.0S I-4t-1.0S Averae 1.10 Standard Deviation 0.10

14 587 Table 6 Summary of Tet Reult, 3 Bolt Tet, Sinle Shear Connection Specimen ID t d h O-1.6t-0.5S O-1.6t-1.0S O-1.6t-1.0S O-2.1t-0.5S O-2.1t-0.5S O-2.1t-1.0S O-2.1t-1.0S O-4t-0.5S O-4t-0.5S O-4t-1.0S O-4t-1.0S O-5t-0.5S O-5t-0.5S O-5t-1.0S O-6t-0.5S O-6t-0.5S O-6t-1.0S Averae 1.11 Standard Deviation 0.04

15 588 Table 7 Summary of Tet Reult, 3 Bolt Tet, Double Shear Connection, Inide Sheet Controllin Specimen ID t d h I-1.6t-0.5S I-2.1t-0.5S I-2.1t-0.5S I-2.1t-0.5S I-2.1t-1.0S I-2.1t-1.0S I-2.1t-1.0S I-4t-0.5S I-4t-0.5S I-4t-1.0S I-4t-1.0S I-6t-0.5S I-6t-0.5S I-6t-1.0S I-6t-1.0S Averae 1.10 Standard Deviation 0.03