ดาวน์โหลดงานนำเสนอ
งานนำเสนอกำลังจะดาวน์โหลด โปรดรอ
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Chapter 12 Riveted, Bolted & Welded Connections
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Riveted, bolted and welded connections
Bearing type connections Ordinary bolt (or rivet) Friction type connections High strength bolt
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Lab joints (ต่อทาบ) Butt joints (ต่อชน) cover plate main plate
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Boiler joints (pressure joints)
Repeating group Boiler joints (pressure joints) Repeating group outer cover plate Inner cover plate Structural joints
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Multiple rows
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long pitch intermediate pitch back pitch short pitch diagonal pitch
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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
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t (1) Shearing (at connector) (2) Tearing (of plate) st
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sb (3) Bearing (of plate) (4) Unlikely to occur
if the distance from the edge of the plate to the connector is large enough ( times the diameter of the connector)
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(1) Rivet capacity (shearing of rivet and bearing failure)
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(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 lb per 3.25 in.
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Internal pressure
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(1) Preliminary calculation: load that can transmitted by one rivet (shear or bearing)
(2) Possible method of failure
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d = 20.5 mm
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P-19.8 kN Row 1 (has 1-rivet) single shear 19.8 kN 19.8 kN main plate
cover plate 19.8 kN
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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
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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
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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 kN 4 x 26.7 kN Hence strength of row 2 is kN 2 x 26.7 kN 73.2 kN
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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 kN
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Total rivet capacity 74.6 kN 74.6 kN 19.8 kN
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Tearing at row 1 of main plate
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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
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Tearing capacity of cover plate
Row 1 Row 3 Row 2 19.8 kN
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79.2 kN outer cover plate inner cover plate Row 2 Row 1 Row 3 19.8 kN
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Rivets failure: kN Tearing of main plate: kN Tearing of cover plate: kN
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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
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the average shearing stress is
Row1 Row2 Row3 4 kips 4 kips the maximum average bearing stress is
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main plate (Row 1) main plate (Row 2) main plate (Row 3) 8 kips 2 kips
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Upper cover plate 4 kips 2 kips Lower cover plate 4 kips 2 kips
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Lower cover plate 4 kips 2 kips
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Lab joints (ต่อทาบ) Butt joints (ต่อชน)
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shearing capacity of 1-rivet
bearing capacity of 1-rivet Row1 upper plate Total rivets capacity
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Hence the joint capacity is
Efficiency = upper plate 26.94 kN Row2 Row3 26.94 kN
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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
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ให้นิสิตพยายามทำโจทย์ข้อ 1220 ถึงข้อ 1240 ให้ได้นะครับ
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สำหรับรอยต่อแบบ friction type ให้คิดแบบเดียวกับรอยต่อแบบ bearing type ยกเว้นไม่ต้องคำนวณค่าหน่วยแรงแบกทาน (Bearing stress) ที่เกิดขึ้นระหว่าง bolt และ plate
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Butt Weld (เชื่อมแบบต่อชน)
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Fillet Weld (เชื่อมแบบพอก)
base on AISC, for E70 electrodes, A36 steel
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Ans
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Ans
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Torsional couple: Centroid: Polar moment of inertia:
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