A main cable in a large bridge is designed for a tensile force of 2,600,000 lb. The cable consists of 1470 parallel wires, each 0.16 in. in diameter. The wires are cold-drawn steel with an average ultimate strength of 230,000 psi. What factor of safety was used in the design of the cable

Respuesta :

Answer:

the factor of safety was used in the design of the cable is 2.6146

Explanation:

Given the data in the question;

Load on the main capable [tex]P_{initial[/tex] = 2600000 lb

number of parallel wires n = 1470

Diameter d = 0.16 in

average ultimate strength [tex]S_{ultimate[/tex] = 230000 psi

First we calculate the Load acting on each cable;

[tex]P_{initial[/tex] = P × n

P = [tex]P_{initial[/tex] / n

we substitute

P = 2600000 lb / 1470

P = 1768.70748 lb

Next we determine the working stress acting in a member;

[tex]S_{working[/tex] = P/A

{ Area A = [tex]\frac{\pi }{4}[/tex]d² }

[tex]S_{working[/tex] = P / [tex]\frac{\pi }{4}[/tex]d²

we substitute

[tex]S_{working[/tex] = 1768.70748 / [tex]\frac{\pi }{4}[/tex](0.16)²

[tex]S_{working[/tex] = 1768.70748 / 0.02010619298

[tex]S_{working[/tex] = 87968.29 psi

Now we calculate the factor of safety F.S

F.S = [tex]S_{ultimate[/tex] / [tex]S_{working[/tex]

we substitute

F.S = 230000 psi / 87968.29 psi

F.S = 2.6145785 ≈ 2.6146

Therefore, the factor of safety was used in the design of the cable is 2.6146