HIGHLIGHTS OF TESTS OF STEEL BEAM-TO-COLUMN BOLTED CONNECTIONS (C6, C7, C8,C9)

Transcription

1 Beam-to-Column Connectons HGHLGHTS OF TESTS OF STEEL BEAM-TO-COLUMN BOLTED CONNECTONS (C6, C7, C8,C9) by' W. F. Chen K.F. Standig :G. P. Rentschler This work has been carried. out as part of an investigation sponsored jointly 'by the American ron and Steel nstitute and the Welding Research.Council. ffj'rz Ef\ Gi NEEF j\(::1 T()f?Y Department of Civil Engieering Fritz'Engineering Laboratory,Lehigh University, Bethlehem, Pennsylvania :l! ','1 ') 1 1 Ocober 1974 Fritz Engineerng Labor<atory Report No

2 333 (AS 137) 18 Oct 74 Highlights of Lehigh Connection Tests (Cp, C7, C8, C9) The test program consisting of twelve full-size momntresisting beam-to-column connections conducted at Fritz Engineering Laboratory, Lehigh University has recently been completed. The overall objective of this study is to dvelop 4esign procedures for safe, efficient, and economical,beam-to-column' connections. Primary attention 'wa focused upon the strength (plastic limit load), deformation,! 'capacity, and over-11,stiffness of" the connections. The tests result 'hghlights' presented herein are of 'the four, bolted s'pecimens tested in the twelve specimen program. They are 1 l J 1,j conections C6, C7, C8.and C9_ The experimental and referece lods along with a brief description of the joint and the failure mode are given in Table 1. C6 and C7 Connections C6 and C7 are shown respectively in Fig. 1 and Fig. 2.' Both connections were designed uing A572 Grade 55 steel with a WOx60 column section and a W14x74 beam section. Connection C6 is ;flange-bolted (8':'1"c.p A490 bolts in, l-1/6' round holes in each flange) utili..zing 1-l/8"xO", fnge connection "plates with the beam shear carried by a stiffened seat plate. 'Connection C7 has the same bolting cofiguration, olt diameter, and hol sizes in he flange asc6. The bolted parts of both specimens were 'designed as, bearing. type connections. However, in C7,_ the shear is

3 -2 carried by means of a shear plate welded to the column flange and bolted to the beam 'tv'eb by 3-1"tp A490 bols in 1-l/16' round holes. The load versus deflection curves for C6 and C7 are give in Fig. 3. Also sllown on the figure is a plot of CO which is "the control (fully welded) specimen using the same beam and column sections as C6 and C7. On this plot, as well as the plot of C8 and C9, the 'effects 'of slip are averaged b'y not plotting any of the horizontal slip plateaus. Note_that th load-deflection plots for both C6 and C7 have three -distinct phases (slopes). Photographs describing the failur of connection Co are shown in Fig. 4 through Fig-. 7. Fig.ure' 4 shows an overall view of: C6 a t failure depicting the extensive yielding in the beam web up to the end of the moment plates. Failure of this- connect1on occurred at a load -of kips when the eight bolts connetjng the tension flange sheared off simultaneous-ly.- Figue 5 presnts a closer look at the beam on which the eight bolts failed. Shown in Fig'. 6 is a view of the column panel zone adjacent to the beam tensio,d. flanges,.: Figure 7 show s the s hear 'failure: of fo.ur of the 'bolts and the extensive eformation of the bolts at failure. Photographs detailing the failure of connetion C7 are shown in Fig. 8 through Fig. 12". Figure 8 shows an overall view of C7 at,

4 -3 failure agin depicting the extensive yielding in the beam web (Fig. 9) up to the end of the moment connection plates. Failure'of this connection was due to the failure of five bolts in one of the tensin flange,connections. Two outside bolts in this flange failed at a load of 361 kips due to the prying action as shown in Fig. 10. Upon further loading three more bolts failed at the maximum load of 450 kips. Shown in Fig. 11 is a view of the panel. zon shoving yielding and '8 view of the beam web connection plate and the re'lative rotation of the beam web and the web 'connection plate. Figure 12 presents a view of the 'five bolts which failed. C8 and C9 'Connections a8 and C9 are shown respectively in Fig. 13 and Fig. 14. Both connections were designed using ASTM A572 Grade 55 steel,with a W14x136 column section and a: W2'4x1 beam section. Connection C8 is a flange.. bolted (14-l"q; A490 bolts in l1z;"tp. holes in each flange) and webbolted (7-3/4 t1 Cfj,.A325 bolts in slotted holea). The flange onnections were designed as fricton connections using aliowable bolt shearing stress values below those of a bearing type joint. The flange,connection'pates are 3/4 t1 x:ll". The web con nection.was designed as a bearing joint. ung A325 bolts in slotted holes perpendicular to the direction of loading. Connection C9 is identical to C8 except the design'of the bolted flange connection was b.ased on treating the "joint as a bearing connection. This l..ed to a 'flange connection rquiring 6-1"cp.A490 bolts in 1-1/16" round holes

5 -4 and flange connection plates of 3/4 x11". The load versus deflection curves for C8 and C9 are given in Fig. 15. Also shown on the'figure is a plot of ell which is the control (fully welded) specimen using the same beam and column sizes as C8 and C9. (;8 Photographs detailing, the failure of connection e8,are shown! / in Fig. 16 through Fig. 19. The maximum load reached on this connection was 516 kips. After reaching this level, the load dropped off due to column web buckling and the test was terminated for 'safety reasons. Figue 16 shows an overall view of C8 at the termination of test. Shown in Fig. 17- is a view of one of the beams where it is connected to the column. On this view the appearance of slip on the tension flange (top) can be detected, by the relative mqvement of the vertical lines. Slip n the compression-flange (bottom) was much less. Figure 18 shows the extensive yieiding which occurred in the column panel zone and Fig. 19 shows the extent of the uckling of the column web in the compression'region. Photographs showing he failure of connection C9 are given, in Fig. 20 through Fig. 22. The maximum load 'on this connection was 402 kips. - Failure occurred when the six bolts on one of the tension flange connections and one of the web bolts sheared off simultaneously.

6 -5 This can b seen clearly in Fig. 22. Shown in Fig. 20 is an overall view of the connection at -failure. Figure 21 presents a closer view of the column panel zone and beam ends showing-the yield pattern.

7 TABLE 1 TEST RESULTS OF CONNECTONS Test p p Joint Failure Bxperirnental Reference - m m Description Mode P P P P P m p pr p pr C6 Flange-bolted Shearing ai (bearing) with ure of eight seat(wlox60 col bolts on one 4x74 brn.) tension flange connection. C7 Flange-bolted Failure of five (bearing) web- bolts in one bolted(wlox60 tension flange col. W14x74 bm) connection. C8 Flange-bolted. Buckling of (friction) web- column web bolted(w14xl36.col. W24x6l bm) C9 Flange-bolted Shear failure (bearing) web- of six,bolts on bolted (W14x136 one of the tencol. W.24x61 bm) sien flange con nections.symbols P = maximum load of connection under tet m.p = plaitic limit load- p p. = pr plastic limit load assuming the area- of beam web is ero

8 Sym., WOx60 W4 x 74 (Fy=55k:j)-u---- {_Fy=55ksi) A Typ. Corner Clipped 5G 4 Yalix foux 15 3 /8 11 MO,ment Plate (F y =55ksi) Elevation Stiffener Plate lux 5 11 x (A36) Section lux 4 11 x 88" Stiffener fp.. (F y =55ksi) 3/ 12' '8 X x Backing Strip (A3"6) Y2- Clearance Sym A490-X Bolts 1'/16 11 Round Holes Section A--A Fig. 1 Connection C6 'Scale: o 5 loin.

9 8 "<P A490-X Bolts in l'/g'round Holes W4x74 Sym. WOx (F y =55ksi) --+-f-(fy=55ksi )-+-lil1-o-l A ' /2 X 5i'4 X9'2 Shear t (Fy =55ksi) ", 3 -_ 't' A490.-X Bolts in YG Round Holes Ye" xoux15 3 /8 11 Moment Plote (F y =55ksi) Elevation. X 4 X 8 7/ 8 " Stiffener t(fy =55ksi) 3/ 8 11 X oj,t"x 12" Backing 'Strip ( A36). :t2 Clearance Sy.. Section A-A Scale: L o 5 -loin.. Fig. 2 Connection-C7

10 \ \ \ \ \ \ \ \ \ (Y) t., \J) '\ " \1 _. - C\...l r-:. "" n et r- u """0 {. (:$ --, cj -l '(''1\J =,..L <)1 CJ, '"' +=. "- U (j) V1 \) ""J- 0 "'':': <::J \J t - 0 el- <q QJ 0 (f) :> -0 CS b --J f") <5J 1..

11 Fig. 4 Overall View of C6 Fig. 5 View of C6 Beam

12 '? _i:i}1,,-:". (,J ",':..a."',l".."' '",\" '/\.\" \:tilt;,,:,j.'::,' )(it.l:l, ", '.:..., '; A OT'.: '\...',.;11:)f :;..;. Y::;'i:=\"o:p -J1>: f', - _ ()J u...l,"'_,:.t'_j'...,,':.' ).' >.J. i:.: Bm!l!;mi11lr! 'Jtit" :- -e,;: J 5'" -; J,4,',,1 <..0 0 O' ;1 1--:; -. ' - ',:1 ';:S":'. - Fig. 6 Tension Panel, Zone of C6 Fig. 7 Sheared Bolts of Connection C6

13 Fig. 8 Overall View of C7 Fig. 9 View of C7 Beam

14 Fig. 10 Prying Action of C7 Flange Bolts. ':;2:,,_...,c. "V L :...J... +,.t Fig. 11 Panel Zone of Connection C7

15 Fig. 12 Bolts at'failure of C7

16 14 - A490- F Bolts in Y4 11 Round Holes 3/8 Strip Shims Sym. 5 J " rig x2 x 20Y 2... Plate With 13/16, Round Holes (A36) W4xl36 ( Fy= 55ksi). 16,LJ::::;::.:;..r--.3@3 11 = /4 11 A325-X Bons in Slotted Holes -- W24x Cf. H--_9u (F:y=55ksi) 3@3 d=23 oj /4 '2, ve x5 1'4 X 20 V2 Shear t (F y =55ksi) Elevation. Sym. rf ,-==--=--;::.=:::.=- :L-$--" -$-_-$- -$-_-$- -$- -$- J 32l1Gage r-$-- -$-$---$-- -$---$-.1,LL ,'-'-' : _ Plan View 13" U " 16 xll V 4 x24v2 - Moment Plate ( Fy.=50ksi) Scale:, o 5' 'loin. Fig. 13 Connection'C8

17 ,/ \f' A490-X Bolts in Yls" Round Holes Sym. 5 " :t16 X 2 X 20V2 Plate 'with 13/16 Round Holes '(A 36) W4x 136 ( F y =55 ksi) Elevation W24x61 <F y = 55ksi) :3 ' ',". 1'8 X 5Y'4'X 20/2 Shear e. (F y =55ksi) 3@ 3 11 =9 11 -_3/allxllf x 13 u Backing Strip (A36) ( Typ.) 7-3 /4 11 cp A325-X Bolts in,slotted Holes Sym. 3/8 " Strip Shims., Plan View f " 6 )t 10 '4. X 12 V2 Mome'nt Plate (Fy=50ksi) Scale:, o 5 10 in. Fig. 14 Connection,C9

18 ' /\..,}J..\... \ 1 \. ) - \l t\j '-l, tj, C(, Q.,.0 0 <1 C0 fyj', 0- '-'.;. tj ex> f..j V] \) \} () '", t.l- i, u '-...-.sz \'J -1 '-"..-J...; \\.1 "1 0 til > -.. lr) ""'- n [' '" S. J )<1 '-J "'" l \)1 LC (.J -1.. () \.::),.

19 Fig. 16 Overall View of C8 Fig. 17 View of C8 Beam

20 Fig. 18 Panel Zone of C8

21 Fig. 19 View Showing Buckling-of C8 Column Web

22 Fig. 20 Overall View of C9 Fig. 21 Panel Zone of Connection C9

23 ,F,-ig., 22 -,View of.c9 Beam a-t Connection