Use LRFD and choose a pipe to be used as a tension member to resist a service dead load of 10 kips and service live load of 25 kips. The end

Question

Use LRFD and choose a pipe to be used as a tension member to resist a service dead load of 10 kips and service live load of 25 kips. The ends will be connected by welding completely around the circumference of the pipe. The length is 8 feet.

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Thông Đạt 5 years 2021-08-13T21:22:14+00:00 1 Answers 35 views 0

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  1. diemthu
    0
    2021-08-13T21:23:39+00:00
    Reply

    Answer:

    see explanation

    Explanation:

    By load resistance and factor design:

    calculate factored load using following load combination

    P_u = 1.2D + 1.6L

    P_u is factored load

    D is dead load

    L is live load

    Substitute 10kips for D and 25kips for L

    P_u = 1.2D + 1.6L\\\\P_u = 1.2(10) + 1.6(25)\\\\P_u = 52.0kips

    Calculate the required gross area 0f the member

    A_g = \frac{P_u}{0.9F_y} \\\\

    A_g is gross area of section

    F_y is yield strength

    substitute 52kips for P_u and 35kips for F_y

    A_g = \frac{P_u}{0.9F_y} \\\\\\A_g = \frac{52.0}{0.9(35)} \\\\\\A_g = 1.65in^2

    Calculate required effective area of the member

    A_e = \frac{P_u}{0.75F_u} \\\\

    A_e is the effective area

    F_u is the ultimate strength

    substitute 52kips for P_u and 60ksi for F_u

    A_e = \frac{P_u}{0.75F_u} \\\\A_e = \frac{52.0}{0.75 (60)} \\\\= 1.16in^2

    Calculate minimum value for radius of gyration (r_{min})

    (r_{min}) = \frac{L}{300} \\\\(r_{min}) = \frac{8 \times 12 }{300} \\\\= 0.32in

    Corresponding to the above calculated value, try pipe 3 standard

    For pipe 3 standard

    Check the above section requirement

    A_g = 2.07in^2\\2.07in^2 > 1.65in^2(OK)\\\\r_{min} = 1.17in\\1.17in > 0.32in (OK)

    Calculate effective net area of the section

    A_e = A_g\\\\= 2.07in^2\\2.07in^2 > 1.65in^2

    therefore the section is OK

    Hence , use pipe 3 standard

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