Chapter 12 Riveted, Bolted & Welded Connections

Riveted, bolted and welded connections Bearing type connections Ordinary bolt (or rivet) Friction type connections High strength bolt

Lab joints (ต่อทาบ) Butt joints (ต่อชน) cover plate main plate

Boiler joints (pressure joints) Repeating group Boiler joints (pressure joints) Repeating group outer cover plate Inner cover plate Structural joints

Multiple rows

long pitch intermediate pitch back pitch short pitch diagonal pitch

Efficiency: compares the strength of the joint with that of solids plates P0 ถ้าชิ้นส่วนที่ไม่มีรอยต่อรับแรงได้ไม่เกิน P0 ประสิทธิภาพของรอยต่อหมายถึง: รอยต่อรับแรงดึงได้เป็นกี่ % ของกำลังของชิ้นส่วนเดิม ( ที่ไม่มีรอยต่อ ) Efficiency = P1/P0 P1 และชิ้นส่วนที่มีรอยต่อรับแรงได้ไม่เกิน P1

t (1) Shearing (at connector) (2) Tearing (of plate) st

sb (3) Bearing (of plate) (4) Unlikely to occur if the distance from the edge of the plate to the connector is large enough (1.75-2 times the diameter of the connector)

(1) Rivet capacity (shearing of rivet and bearing failure)

(1) Rivet capacity (shearing of rivet and bearing failure) (cont’) sb = 19 ksi (2) Tearing capacity (tension failure of plate) st = 11 ksi tearing: 3.25” Hence the strength of the repeating section is 6533.5 lb per 3.25 in.

Internal pressure

(1) Preliminary calculation: load that can transmitted by one rivet (shear or bearing) (2) Possible method of failure

d = 20.5 mm

P-19.8 kN Row 1 (has 1-rivet) single shear 19.8 kN 19.8 kN main plate cover plate 19.8 kN

P P Hence strength of row-1 is 19.8 kN P-37.3 kN P-26.7 kN Row 1 (has 1-rivet) main plate cover plate crash in the main plate 37.3 kN P P-37.3 kN 37.3 kN crash in the cover plate 26.7 kN P main plate cover plate P-26.7 kN Hence strength of row-1 is 19.8 kN 26.7 kN

Row 2 (has 2-rivets) double shear 39.6 kN 2 x 19.8 kN 2 x 19.8 kN Shear strength at row-2 is 2 x 19.8 kN P-99 kN 2 x 19.8 kN 19.8 kN 19.8 kN 2 x 19.8 kN 59.4 kN

Hence strength of row 2 is 74.6 kN Row 2 (has 2-rivets) crushing at main plate 37.3 kN One possible bearing strength at row-2 is 19.8 kN P-94.4 kN 2 x 37.3 kN 57.1 kN One possible bearing strength at row-2 is crushing at cover plate 53.4 kN 2 x 26.7 kN 19.8 kN P-126.6 kN 4 x 26.7 kN Hence strength of row 2 is 74.6 kN 2 x 26.7 kN 73.2 kN

Hence strength of row 3 is also 74.6 kN Row 3 (has 2-rivets) 2 x 19.8 kN double shear 2 x 37.3 kN 37.3 kN crushing at main plate 4 x 26.7 kN 2 x 26.7 kN crushing at cover plate Hence strength of row 3 is also 74.6 kN

Total rivet capacity 74.6 kN 74.6 kN 19.8 kN

Tearing at row 1 of main plate

Tearing capacity of main plate Row 2 Row 1 Row 3 74.6 kN 19.8 kN 74.6 kN main plate main plate 19.8 kN main plate 19.8 kN 37.3 kN

Tearing capacity of cover plate Row 1 Row 3 Row 2 19.8 kN

79.2 kN outer cover plate inner cover plate Row 2 Row 1 Row 3 19.8 kN

Rivets failure: 169.0 kN Tearing of main plate: 175.5 kN Tearing of cover plate: 190.4 kN

12-5 STRESSES IN BEARING-TYPE CONNECTIONS Assume each rivet carries a load proportional to its resisting shear area the average load transmitted by 1 shear area is Totally 9 shear areas: 1/2 1 2 2 2 1/2 1

the average shearing stress is Row1 Row2 Row3 4 kips 4 kips the maximum average bearing stress is

main plate (Row 1) main plate (Row 2) main plate (Row 3) 8 kips 2 kips

Upper cover plate 4 kips 2 kips Lower cover plate 4 kips 2 kips

Lower cover plate 4 kips 2 kips

Lab joints (ต่อทาบ) Butt joints (ต่อชน)

shearing capacity of 1-rivet bearing capacity of 1-rivet Row1 upper plate Total rivets capacity

Hence the joint capacity is Efficiency = upper plate 26.94 kN Row2 Row3 26.94 kN

Twisting moment (-4.5,0) (-4.5,4) (-4.5,-4) (-1.5,0) (-1.5,4) (-1.5,-4) (1.5,4) (1.5,0) (1.5,-4) (4.5,4) (4.5,0) (4.5,-4) Twisting moment

ให้นิสิตพยายามทำโจทย์ข้อ 1220 ถึงข้อ 1240 ให้ได้นะครับ

สำหรับรอยต่อแบบ friction type ให้คิดแบบเดียวกับรอยต่อแบบ bearing type ยกเว้นไม่ต้องคำนวณค่าหน่วยแรงแบกทาน (Bearing stress) ที่เกิดขึ้นระหว่าง bolt และ plate

Butt Weld (เชื่อมแบบต่อชน)

Fillet Weld (เชื่อมแบบพอก) base on AISC, for E70 electrodes, A36 steel

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Torsional couple: Centroid: Polar moment of inertia: