Aisc design guide 13 stiffening of wide flange column at moment connections

Page 64

Solution:

␾ Rv ⳱ 0.75 ⫻ 0.6F y d c tw 1 Ⳮ

Calculate the flange forces and panel-zone shear force: From Equation 2.1-2, the force at each flange need not be taken greater than Puf ⳱ ⳱

3b f t 2f d b d c tw

⳱ 0.75 ⫻ 0.6(50 ksi)(18.67 in.)(1.875 in.)

1.1 R y F y Z Ⳮ V u a d ⫺ tf

⫻ 1Ⳮ

in.3 ) Ⳮ (150

1.1(1.1)(50 ksi)(356 kips)(22.5 in.) (35.85 in. ⫺ 0.940 in.)

3(16.695 in.)(3.035 in.)2 (35.85 in.)(18.67 in.)(1.875 in.)

⳱ 1,080 kips ⬎ V u ⳱ 714 kips

o.k.

To prevent seismic shear buckling in the panel-zone, from Equation 2.2-7,

⳱ 714 kips

Neglecting the effects of story shear, the panel-zone web shear force is determined from Equation 2.1-5 as

tw min ⳱

V u ⳱ Puf ⳱ 714 kips

Determine the design panel-zone web shear strength: In a high-seismic application, either Equation 2.2-5 or Equation 2.2-6 is used.

d m Ⳮ d c ⫺ 2t f 90 (35.85 in. ⫺ 0.940 in.) Ⳮ 18.67 in. ⫺ 2(3.035 in.) 90

⳱ 0.528 in. ⬍ tw ⳱ 1.875 in.

P y ⳱ F y A ⳱ (50 ksi)(125 in. ) ⳱ 6,250 kips 2

o.k.

Therefore, the web of the W14⫻426 is adequate to resist the panel-zone web shear without reinforcement.

1,000 kips Pu ⳱ ⳱ 0.160 6,250 kips Py

Determine the transverse stiffener requirements: As indicated in Section 2.3, transverse stiffeners are required to match the configuration used in the qualifying

Since this ratio is less than 0.75, Equation 2.2-5 is applicable.

W14x426, Fy = 50 ksi W36x150, Fy = 50 ksi

Centerline of radiuscut RBS (location of plastic hinge)

22.5” Check if column stiffening is required Figure 6-13 Framing arrangement for Example 6-13 (problem statement). 60

© 2003 by American Institute of Steel Construction, Inc. All rights reserved. This publication or any part thereof must not be reproduced in any form without permission of the publisher.


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