Summary. Structural Design “ce Board Exam Nov. 1992″.pdf

Problem 1. Structural Design “CE Board Exam Nov. 1992″ A steel cylinder 12 inches outside and a wall thickness of 1 in. is filled with concrete and used as a pier to support an axial load in compression If the allowable stress are 40,000 psi for steel and 3,500 psi for concrete and the youns modulus for steel is 30 x 106 psi and for concrete is 2.8 x 106 psi, what is the allowable load on the pier?

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Solution:

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Problem 2. Structural Design “CE Board Exam Nov. 1992″ A beam has the cross section shown in the figure below. It is subjected to a normal tensile force P whose line of action passes through the maximum allowable value of P if the maximum direct stress is limited to ± 150 N/mm2

Solution:

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Problem 3. Structural Design “CE Board Exam Nov. 1992″ Two 15 N weights A and B are connected by a massless string hanging over a smooth, frictionless peg. If a third weight of 15 N is added to A and the system is released, by how much is the force on the peg increased?

Solution:

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Member

L

A

S

U

SUL/A

AB

L

1200

P

1

[P(1)(L)]/a

BC

L

1200

P

1

[P(1)(L)]/a

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Problem 4 . Structural Design “CE Board Exam Nov. 1992″ A thin walled cylindrical shell has an internal diameter of 2m. and is fabricated from plates 20mm thick. Calculate the safe pressure in the shell if the tensile strength of the plate is 400 kN/mm2 and the factor of safety is 6.

Solution:

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Problem 5. Structural Design “CE Board Exam Nov. 1992″ A steel cylinder 12 inches outside and a wall thickness of 1 in. is filled with concrete and used as a pier to support an axial load in compression If the allowable stress are 40,000 psi for steel and 3,500 psi for concrete and the youns modulus for steel is 30 x 106 psi and for concrete is 2.8 x 106 psi, what is the allowable load on the pier?

Solution:

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Problem 6. Structural Design “CE Board Exam Nov. 1992″ Determine the horizontal deflection of joint C of the frame shown below. Disregard the contribution of axial and shear deformation to deflection. You may use the integration equation: Integral from 0 to L of (mM) dx = 1/3 m1 M1 L and integral from 0 to L of (mM) dx = 5/12 m2 M2 L.

Solution:

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Problem 7. Structural Design “CE Board Exam Nov. 1992″ Using USD or ultimate strength design method, design a simple supported reinforced concrete beam 0.20m. wide and 4.50m. long carrying only a wall load of 8.27 kN/m including its own weight. Keep the steel ratio within 1% and use 16mm dia. Reinforcing bars. Use fy = 413.7 MPa and fc’ = 27.6 MPa and a min. concrete cover of 63.5mm.Indicate the depth and number of reinforcing bars on the figure below. Solution:

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Problem 8. Structural Design “CE Board Exam Nov. 1992″ A pre-stress rectangular beam 0.50m x 0.75m has a simple span of 3m and is loaded by a uniform load of 45 kN/m including its own weight. The pre-stressing tendon is 0.225m. from the bottom and produces and effective pre-stress of 1,600 kN. Compute the total stresses of the pre-stressed beam shown.

Solution:

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Problem 9. Structural Design “CE Board Exam Nov. 1992″ Design a welded connection to sustain the design tensile strength of a double angle diagonal truss member consisting of two (2) angles 5” x 3 1/2° x 7/16 subjected to a total forced of 190 kips (847.88 kN). A 558 steel is used (fy = 50 ksi, 344.82 MPa), using 1/4° fillet weld and E 70 electrodes. Area of one angle is 3.53 sq.in. and the centroid is 1.63” from the smaller leg.

Solution:

T = As x 0.30 fu

For one angle only: T = 190/2 = 95 kips 95 = 0.707 ( ¼ ) L (0.3) (70) L = 25.59 in. T2 = 0.707 ( ¼ ) (5)(0.3)(70) T2 =18.56 kips T = T1 + T2 + T3 T3(5) T2(2.5) + T1(0) = T(3.37) 5 T3 + 18.56(2.5) + 0 = 95(3.37) T3 = 54.75 kips T1 + T – T2 + T3 T1 = 95 – 18.56 – 54.75 = 21.69 kips T1 = 0.707 ( ¼ ) L1 (0.3) (70) 21.69 = 0.707 ( ¼ ) L1 (0.3) (70) L1 = 5.84 in. T3 = 0.707 ( ¼ ) L3 (0.3) (70)

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54.75 = 0.707 ( ¼ ) L3 (0.3) (70) L3 = 14.75

Check: L = L1 + L2 + L3 25.59 = 5.84 + 5 + 14.75 25.59 = 25.59

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Problem 10. Structural Design “CE Board Exam Nov. 1992″ A precast concrete beam of length L is to be lifted from the casting bed and transported so that the maximum bending moment is as small as possible. If the beam is to be lifted by two slings, at what distance d from the ends should the slings be attached?

Solution:

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Problem 11. Structural Design “CE Board Exam Nov. 1992″ An object is place 3 ft. from the center of a horizontally rotating platform. The coefficient of friction is 0.30. The object will begin to slide off when the platform speed is nearest to.

Solution:

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Problem 12. Structural Design “CE Board Exam Nov. 1992″ A pendulum with a concentrated mass “m” is suspended vertically inside a stationary railroad freight car by means of a rigid weightless connecting rod. If the connecting rod is pivoted where it is attached to the box car, compute the angle that the rod makes with the vertical as a result of a constant horizontal acceleration of 2 feet/sec2 of the box car.

Solution:

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Problem 13. Structural Design “CE Board Exam Nov. 1992″ A body moves so that during the first part of its motion, its distance S in meters from the starting point is given by the expression: S = 6.8 t3 – 10.8 t. The acceleration in 3 seconds is:

Solution:

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Problem 14. Structural Design “CE Board Exam Nov. 1992″ An airtight closed box of weight P is suspended from a spring balance. A bird of weight W is placed on the floor of the box, and the balance reads W + P. If the bird flies around in the box at a constant elevation without accelerating, what is the balance reading?

Solution:

F = P + W/2 + W/2 F=P+W

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Problem 15. Structural Design “CE Board Exam Nov. 1992″ The figure below shows a beam ABCD supporting three concentrated loads two of which are inclined to the longitudinal axis of the beam. What is the value of the largest normal (axial) force?

Solution:

F = 6 Cos 60° – 4 Cos 60° F=3–2 F = 1 kN

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Problem 16. Structural Design “CE Board Exam Nov. 1992″ The coefficient of friction between the 60 kN block and the plane shown is 0.30. If the block is to remain in equilibrium, what is the maximum allowable magnitude for the force P?

Solution:

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Problem 17. Structural Design “CE Board Exam Nov. 1992″ Two circular shafts, one hollow and one solid, are made of the same material and have the diameters shown below. If Th is the twisting moment that the hollow shaft can resist and Ts is the twisting moment that the solid shaft can resist, the ratio of Th to Ts is:

Solution:

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Problem 18. Structural Design “CE Board Exam Nov. 1992″ The magnitude of the force acting in the member BC of the truss shown below is:

Solution:

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