EngDoc.ir. Page 1 of 51

Transcription

1 Page 1 of 51

2 1994 Northridge Earthquake Widespread failure of welded flange - bolted web moment connections Page 2 of 51

3 Damage Observations: Steel Moment Connections Pre-Northridge Welded Flange Bolted Web Moment Connection Weld Access Hole Beam Flange Stiffener Column Flange Backup Bar Page 3 of 51

4 Page 4 of 51

5 Page 5 of 51

6 Page 6 of 51

7 Page 7 of 51

8 Page 8 of 51

9 Page 9 of 51

10 Page 10 of 51

11 Page 11 of 51

12 Page 12 of 51

13 Stress Concentrations: Weld access hole Shear in flange Inadequate flexural participation of web connection Page 13 of 51

14 Page 14 of 51

15 Page 15 of 51

16 Improved Weld Access Hole See Figure 11-1 in the 2005 AISC Seismic Provisions for dimensions and finish requirements Page 16 of 51

17 Page 17 of 51

18 Page 18 of 51

19 Page 19 of 51

20 ANSI/ASIC Page 20 of 51

21 Refers to Relies on 39 ANSI/AISC 358 Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications SOME SPECIFICS Page 21 of 51

22 Connections Prequalified Including Supplement No. 1 Reduced Beam Section Connection Bolted Unstiffened and Stiffened Extended End- Plate Moment Connections Welded Unreinforced Flange Welded Web Bolted Flange Plate Kaiser Bolted Bracket ConXtech Moment Connection The Double Tee Stub is currently being balloted. Reduced Beam Section (RBS) Connection 42 Page 22 of 51

23 End Plate Moment Connections Unstiffened Stiffened Stiffened 4-Bolt: 4E 4-Bolt: 4ES 8-Bolt: 8ES 43 Bolted Flange Plate Connection 44 Page 23 of 51

24 Welded Unreinforced Flange Welded Web Connection 45 Prequalified Unique Requirements Provisions apply only to the prequalified connections. Beam and Column cross-section limitations based on specific test matrices Rolled and Built-up Members permitted Specific welding requirements for built-up members Page 24 of 51

25 Specific Prequalified Connections Reduced Beam Section (RBS) 47 Reduced Beam Section (RBS) RBS Concept: Trim Beam Flanges Near Connection Reduce Moment at Connection Force Plastic Hinge Away from Connection Page 25 of 51

26 Reduced Beam Section (RBS) 49 Connection was Prequalified at UT - Austin 50 Page 26 of 51

27 Whitewashed Connection Prior to Testing 51 Whitewashed Connection Prior to Testing 52 Page 27 of 51

28 Connection at 0.02 radian. 53 Connection at 0.02 radian. 54 Page 28 of 51

29 Connection at 0.03 radian. 55 Connection at 0.04 radian. 56 Page 29 of 51

30 Conformance Results 57 Reduced Beam Section (RBS) Prequalification Requirements for RBS in SMF Beam depth: Beam weight: Column depth: 58 Up to W36 Up to 300 lb/ft Up to W36 for wide-flange Up to 24-inches for box columns Beam connected to column flange (connections to column web not prequalified) RBS shape: RBS dimensions: Circular Per specified design procedure Page 30 of 51

31 Reduced Beam Section (RBS) Prequalification Requirements for RBS in SMF Beam flange welds: - CJP groove welds - Treat welds as Demand Critical - Remove bottom flange backing and provide reinforcing fillet weld - Leave top flange backing in-place; fillet weld backing to column flange - Remove weld tabs at top and bottom flanges Beam web to column connection: - Use fully welded web connection (CJP weld between beam web and column flange) See ANSI/AISC 358 for additional requirements (continuity plates, beam lateral bracing, RBS cut finish, etc.) 59 Reduced Beam Section (RBS) Reduced Section Geometry b f < a < 0.75b f 0.5d < b < 0.85d 0.1b f < c < 0.25b f Page 31 of 51

32 Reduced Beam Section (RBS) Protected Zone No Shear Studs. No welded, bolted, screwed or shot-in attachments for exterior facades, partitions, perimeter edge angles, piping or other construction. duct work, Decking arc-spot welds are permitted. 61 Lateral Brace Violates Protected Zone 62 Page 32 of 51

33 Lateral Brace Violates Protected Zone 63 Specific Prequalified Connections End-Plate Moment Connections Unstiffened Stiffened Stiffened 4-Bolt: 4E 4-Bolt: 4ES 8-Bolt: 8ES 64 Page 33 of 51

34 End-Plate Moment Connections End-Plate Concept: No Field Welding Simple Erection Connection is Stronger than Beam Special welding requirements Concrete slab requirements Connections 65 were prequalified at Virginia Tech End-Plate Moment Connections 66 Page 34 of 51

35 AISC Design Guide 4 For High Seismic and Wind Applications 67 End-Plate Welding Weld access hole not permitted because of ruptures that occurred during testing. Rupture 68 Page 35 of 51

36 End-Plate Welding Weld access hole not permitted because of ruptures that occurred during testing. Rupture End-Plate Welding Recommended welding procedure: No weld access holes Surface Preparation: All surfaces ground clean Flanges beveled 45º full depth Minimum root opening Typical Beam 70 Page 36 of 51

37 End-Plate Welding Recommended welding procedure: Welding Sequence: 1. Fillet welds on both sides of web installed. 2. Fillet welds on inside of flanges installed Backgouge 3. Flange groove weld root backgouged and flange groove welds installed. Note: Welds over webs are not CJP. 3 Backgouge 71 Detailing Requirements Effective end-plate width in calculations Beam flange width + 1 in. Bolt gage < beam flange width Bolt spacing and pitch Provide adequate tightening clearances Finger shims Used to correct beam length variations 72 Page 37 of 51

38 4ES and 8ES Stiffener Detailing 1"± Length of Stiffener L st = h st / tan 30º 30 ± 1"± h st L st 73 8-Bolt Stiffened Moment End-Plate, 8ES 74 Page 38 of 51

39 8-Bolt Stiffened Moment End-Plate, 8ES 75 End-Plate Moment Connections Prequalification Requirements: Beam depth: Min. and max. in Table 6.1 Beam weight: Column depth: No limit Up to W36 Beam connected to column flange (connections to column web not prequalified) Bolts: Finger Shims: A325 or A490 Permitted 76 Page 39 of 51

40 Connection Test with Concrete Slab Test Frame Test Column Lateral Support Typ. W24x68 Composite Slab W24x68 Actuator Rigid Link Pin Support W14x257 Rigid Link Reaction Frame 77 Test 1 with Concrete Slab 78 Page 40 of 51

41 Test 1 with Concrete Slab 79 Test 1 with Concrete Slab Premature Bolt Rupture 80 Page 41 of 51

42 Test 2 with Concrete Slab 10'-0" 1'-11 1/4" 4'-8 1/4" 3'-4 1/2" NO STUDS HINGE ZONE 10'-0" 1'-11 1/4" 3'-4 1/2" 4'-8 1/4" NO STUDS HINGE ZONE 3'-0" END OF STIFFENER END OF STIFFENER 3'-0" 5" COMPOSITE SLAB (3" COVER ON 2 COMPOSITE METAL DECK) REINFORCED W/ 4x4-W2.9xW2.9 WWF 1/2" MIN. GAP FORMED W/ NEOPRENE FILLED W/ FOAM INSUL. 3/4"Ø X 4" SHEAR 1'-0" MAX. 81 Test 2 with Concrete Slab 82 Page 42 of 51

43 Test 2 with Concrete Slab Column Tip Load (kips) Total Rotation (rad.) Column Tip Load (kips) Beam Rotation (rad.) Column Tip Load vs. Total Rotation Column Tip Load vs. Beam Rotation 83 Requirement for All Prequalified Bolted Connections Compressible expansion joint material, at least 1 in. thick, shall be installed to isolate the column/connection from the concrete slab. 84 Page 43 of 51

44 Specific Prequalified Connections Bolted Flange Plate (BFP) 85 BFP Concept: Bolted Flange Plate (BFP) Shop Welded/Field Bolted A325 or A490 bolts plates must be identical Top and bottom flange Hinge at end of flange plates 86 Page 44 of 51

45 Bolted Flange Plate (BFP) Prequalified at U. of California at San Diego 87 Bolted Flange Plate (BFP) 88 Page 45 of 51

46 Bolted Flange Plate (BFP) 89 Bolted Flange Plate (BFP) 90 Page 46 of 51

47 Bolted Flange Plate (BFP) 91 Bolted Flange Plate (BFP) 92 Page 47 of 51

48 Bolted Flange Plate (BFP) 93 Bolted Flange Plate (BFP) 94 Page 48 of 51

49 Bolted Flange Plate (BFP) Fracture Location Close-up of Fracture Location 95 Specific Prequalified Connections Welded Unreinforced Flange - Welded Web (WUF W) 96 Page 49 of 51

50 Welded Unreinforced Flange- Welded Web (WUF-W) WUF-W Concept: Full beam strength Shop welded single plate with bolts for erection Field welded beam flange to column flange Field welded single plate to beam web Similar to pre-northridge connection 97 Welded Unreinforced Flange- Welded Web (WUF-W) Erection Bolts 98 Page 50 of 51

51 Link d. Alireza rezaeian با تشکر از توجه حضار گرامی Page 51 of 51